Merge remote-tracking branch 'origin/master' into feature/client_aggs_parsing

.dir-locals.el

@@ -83,6 +83,6 @@
       ))
    (c-basic-offset . 4)
    (c-comment-only-line-offset . (0 . 0))
-   (fill-column . 100)
-   (fci-rule-column . 100)
+   (fill-column . 140)
+   (fci-rule-column . 140)
    (compile-command . "gradle compileTestJava"))))

TESTING.asciidoc

@@ -362,7 +362,7 @@ quality boxes available in vagrant atlas:
 
 * sles-11
 
-We're missing the follow because our tests are very linux/bash centric:
+We're missing the following because our tests are very linux/bash centric:
 
 * Windows Server 2012
 
@@ -418,8 +418,8 @@ sudo -E bats $BATS_TESTS/*rpm*.bats
 If you wanted to retest all the release artifacts on a single VM you could:
 
 -------------------------------------------------
-gradle vagrantSetUp
-vagrant up ubuntu-1404 --provider virtualbox && vagrant ssh ubuntu-1404
+gradle setupBats
+cd qa/vagrant; vagrant up ubuntu-1404 --provider virtualbox && vagrant ssh ubuntu-1404
 cd $BATS_ARCHIVES
 sudo -E bats $BATS_TESTS/*.bats
 -------------------------------------------------
@@ -505,4 +505,3 @@ included as part of the build by checking the projects of the build.
 ---------------------------------------------------------------------------
 gradle projects
 ---------------------------------------------------------------------------
-

buildSrc/src/main/groovy/org/elasticsearch/gradle/test/ClusterConfiguration.groovy

@@ -88,7 +88,7 @@ class ClusterConfiguration {
         if (seedNode == node) {
             return null
         }
-        ant.waitfor(maxwait: '20', maxwaitunit: 'second', checkevery: '500', checkeveryunit: 'millisecond') {
+        ant.waitfor(maxwait: '40', maxwaitunit: 'second', checkevery: '500', checkeveryunit: 'millisecond') {
             resourceexists {
                 file(file: seedNode.transportPortsFile.toString())
             }
@@ -136,6 +136,8 @@ class ClusterConfiguration {
 
     LinkedHashMap<String, Object[]> setupCommands = new LinkedHashMap<>()
 
+    List<Object> dependencies = new ArrayList<>()
+
     @Input
     void systemProperty(String property, String value) {
         systemProperties.put(property, value)
@@ -179,4 +181,10 @@ class ClusterConfiguration {
         }
         extraConfigFiles.put(path, sourceFile)
     }
+
+    /** Add dependencies that must be run before the first task setting up the cluster. */
+    @Input
+    void dependsOn(Object... deps) {
+        dependencies.addAll(deps)
+    }
 }

buildSrc/src/main/groovy/org/elasticsearch/gradle/test/ClusterFormationTasks.groovy

@@ -57,7 +57,7 @@ class ClusterFormationTasks {
         // first we remove everything in the shared cluster directory to ensure there are no leftovers in repos or anything
         // in theory this should not be necessary but repositories are only deleted in the cluster-state and not on-disk
         // such that snapshots survive failures / test runs and there is no simple way today to fix that.
-        Task cleanup = project.tasks.create(name: "${prefix}#prepareCluster.cleanShared", type: Delete, dependsOn: runner.dependsOn.collect()) {
+        Task cleanup = project.tasks.create(name: "${prefix}#prepareCluster.cleanShared", type: Delete, dependsOn: config.dependencies) {
             delete sharedDir
             doLast {
                 sharedDir.mkdirs()
@@ -104,7 +104,7 @@ class ClusterFormationTasks {
             NodeInfo node = new NodeInfo(config, i, project, prefix, elasticsearchVersion, sharedDir)
             nodes.add(node)
             Task dependsOn = startTasks.empty ? cleanup : startTasks.get(0)
-            startTasks.add(configureNode(project, prefix, runner, dependsOn, node, distro, nodes.get(0)))
+            startTasks.add(configureNode(project, prefix, runner, dependsOn, node, config, distro, nodes.get(0)))
         }
 
         Task wait = configureWaitTask("${prefix}#wait", project, nodes, startTasks)
@@ -148,7 +148,8 @@ class ClusterFormationTasks {
      *
      * @return a task which starts the node.
      */
-    static Task configureNode(Project project, String prefix, Task runner, Object dependsOn, NodeInfo node, Configuration configuration, NodeInfo seedNode) {
+    static Task configureNode(Project project, String prefix, Task runner, Object dependsOn, NodeInfo node, ClusterConfiguration config,
+                              Configuration distribution, NodeInfo seedNode) {
 
         // tasks are chained so their execution order is maintained
         Task setup = project.tasks.create(name: taskName(prefix, node, 'clean'), type: Delete, dependsOn: dependsOn) {
@@ -161,7 +162,7 @@ class ClusterFormationTasks {
 
         setup = configureCheckPreviousTask(taskName(prefix, node, 'checkPrevious'), project, setup, node)
         setup = configureStopTask(taskName(prefix, node, 'stopPrevious'), project, setup, node)
-        setup = configureExtractTask(taskName(prefix, node, 'extract'), project, setup, node, configuration)
+        setup = configureExtractTask(taskName(prefix, node, 'extract'), project, setup, node, distribution)
         setup = configureWriteConfigTask(taskName(prefix, node, 'configure'), project, setup, node, seedNode)
         setup = configureCreateKeystoreTask(taskName(prefix, node, 'createKeystore'), project, setup, node)
         setup = configureAddKeystoreSettingTasks(prefix, project, setup, node)
@@ -205,6 +206,13 @@ class ClusterFormationTasks {
             // if we are running in the background, make sure to stop the server when the task completes
             runner.finalizedBy(stop)
             start.finalizedBy(stop)
+            for (Object dependency : config.dependencies) {
+                if (dependency instanceof Fixture) {
+                    Task depStop = ((Fixture)dependency).stopTask
+                    runner.finalizedBy(depStop)
+                    start.finalizedBy(depStop)
+                }
+            }
         }
         return start
     }
@@ -541,7 +549,7 @@ class ClusterFormationTasks {
     static Task configureWaitTask(String name, Project project, List<NodeInfo> nodes, List<Task> startTasks) {
         Task wait = project.tasks.create(name: name, dependsOn: startTasks)
         wait.doLast {
-            ant.waitfor(maxwait: '30', maxwaitunit: 'second', checkevery: '500', checkeveryunit: 'millisecond', timeoutproperty: "failed${name}") {
+            ant.waitfor(maxwait: '60', maxwaitunit: 'second', checkevery: '500', checkeveryunit: 'millisecond', timeoutproperty: "failed${name}") {
                 or {
                     for (NodeInfo node : nodes) {
                         resourceexists {

buildSrc/src/main/groovy/org/elasticsearch/gradle/vagrant/VagrantTestPlugin.groovy

@@ -477,10 +477,10 @@ class VagrantTestPlugin implements Plugin<Project> {
                     }
                 }
             }
-            packaging.doFirst {
+            platform.doFirst {
                 project.gradle.addListener(platformReproListener)
             }
-            packaging.doLast {
+            platform.doLast {
                 project.gradle.removeListener(platformReproListener)
             }
             if (project.extensions.esvagrant.boxes.contains(box)) {

client/rest-high-level/src/test/java/org/elasticsearch/client/CrudIT.java

@@ -308,7 +308,7 @@ public class CrudIT extends ESRestHighLevelClientTestCase {
 
             assertEquals(RestStatus.BAD_REQUEST, exception.status());
             assertEquals("Elasticsearch exception [type=illegal_argument_exception, " +
-                         "reason=Can't specify parent if no parent field has been configured]", exception.getMessage());
+                         "reason=can't specify parent if no parent field has been configured]", exception.getMessage());
         }
         {
             ElasticsearchStatusException exception = expectThrows(ElasticsearchStatusException.class, () -> {

core/src/main/java/org/elasticsearch/action/bulk/BulkProcessor.java

@@ -184,12 +184,7 @@ public class BulkProcessor implements Closeable {
         this.bulkActions = bulkActions;
         this.bulkSize = bulkSize.getBytes();
         this.bulkRequest = new BulkRequest();
-
-        if (concurrentRequests == 0) {
-            this.bulkRequestHandler = BulkRequestHandler.syncHandler(consumer, backoffPolicy, listener, threadPool);
-        } else {
-            this.bulkRequestHandler = BulkRequestHandler.asyncHandler(consumer, backoffPolicy, listener, threadPool, concurrentRequests);
-        }
+        this.bulkRequestHandler = new BulkRequestHandler(consumer, backoffPolicy, listener, threadPool, concurrentRequests);
 
         // Start period flushing task after everything is setup
         this.cancellableFlushTask = startFlushTask(flushInterval, threadPool);

core/src/main/java/org/elasticsearch/action/bulk/BulkRequestHandler.java

@@ -27,121 +27,50 @@ import org.elasticsearch.common.settings.Settings;
 import org.elasticsearch.common.util.concurrent.EsRejectedExecutionException;
 import org.elasticsearch.threadpool.ThreadPool;
 
+import java.util.concurrent.CountDownLatch;
 import java.util.concurrent.Semaphore;
 import java.util.concurrent.TimeUnit;
 import java.util.function.BiConsumer;
 
 /**
- * Abstracts the low-level details of bulk request handling
+ * Implements the low-level details of bulk request handling
  */
-abstract class BulkRequestHandler {
-    protected final Logger logger;
-    protected final BiConsumer<BulkRequest, ActionListener<BulkResponse>> consumer;
-    protected final ThreadPool threadPool;
-
-    protected BulkRequestHandler(BiConsumer<BulkRequest, ActionListener<BulkResponse>> consumer, ThreadPool threadPool) {
-        this.logger = Loggers.getLogger(getClass());
-        this.consumer = consumer;
-        this.threadPool = threadPool;
-    }
-
-
-    public abstract void execute(BulkRequest bulkRequest, long executionId);
-
-    public abstract boolean awaitClose(long timeout, TimeUnit unit) throws InterruptedException;
-
-
-    public static BulkRequestHandler syncHandler(BiConsumer<BulkRequest, ActionListener<BulkResponse>> consumer,
-                                                 BackoffPolicy backoffPolicy, BulkProcessor.Listener listener,
-                                                 ThreadPool threadPool) {
-        return new SyncBulkRequestHandler(consumer, backoffPolicy, listener, threadPool);
-    }
-
-    public static BulkRequestHandler asyncHandler(BiConsumer<BulkRequest, ActionListener<BulkResponse>> consumer,
-                                                  BackoffPolicy backoffPolicy, BulkProcessor.Listener listener,
-                                                  ThreadPool threadPool, int concurrentRequests) {
-        return new AsyncBulkRequestHandler(consumer, backoffPolicy, listener, threadPool, concurrentRequests);
-    }
-
-    private static class SyncBulkRequestHandler extends BulkRequestHandler {
-        private final BulkProcessor.Listener listener;
-        private final BackoffPolicy backoffPolicy;
-
-        SyncBulkRequestHandler(BiConsumer<BulkRequest, ActionListener<BulkResponse>> consumer, BackoffPolicy backoffPolicy,
-                               BulkProcessor.Listener listener, ThreadPool threadPool) {
-            super(consumer, threadPool);
-            this.backoffPolicy = backoffPolicy;
-            this.listener = listener;
-        }
-
-        @Override
-        public void execute(BulkRequest bulkRequest, long executionId) {
-            boolean afterCalled = false;
-            try {
-                listener.beforeBulk(executionId, bulkRequest);
-                BulkResponse bulkResponse = Retry
-                    .on(EsRejectedExecutionException.class)
-                    .policy(backoffPolicy)
-                    .using(threadPool)
-                    .withSyncBackoff(consumer, bulkRequest, Settings.EMPTY);
-                afterCalled = true;
-                listener.afterBulk(executionId, bulkRequest, bulkResponse);
-            } catch (InterruptedException e) {
-                Thread.currentThread().interrupt();
-                logger.info((Supplier<?>) () -> new ParameterizedMessage("Bulk request {} has been cancelled.", executionId), e);
-                if (!afterCalled) {
-                    listener.afterBulk(executionId, bulkRequest, e);
-                }
-            } catch (Exception e) {
-                logger.warn((Supplier<?>) () -> new ParameterizedMessage("Failed to execute bulk request {}.", executionId), e);
-                if (!afterCalled) {
-                    listener.afterBulk(executionId, bulkRequest, e);
-                }
-            }
-        }
-
-        @Override
-        public boolean awaitClose(long timeout, TimeUnit unit) throws InterruptedException {
-            // we are "closed" immediately as there is no request in flight
-            return true;
-        }
-    }
-
-    private static class AsyncBulkRequestHandler extends BulkRequestHandler {
-        private final BackoffPolicy backoffPolicy;
+public final class BulkRequestHandler {
+    private final Logger logger;
+    private final BiConsumer<BulkRequest, ActionListener<BulkResponse>> consumer;
     private final BulkProcessor.Listener listener;
     private final Semaphore semaphore;
+    private final Retry retry;
     private final int concurrentRequests;
 
-        private AsyncBulkRequestHandler(BiConsumer<BulkRequest, ActionListener<BulkResponse>> consumer, BackoffPolicy backoffPolicy,
+    BulkRequestHandler(BiConsumer<BulkRequest, ActionListener<BulkResponse>> consumer, BackoffPolicy backoffPolicy,
                        BulkProcessor.Listener listener, ThreadPool threadPool,
                        int concurrentRequests) {
-            super(consumer, threadPool);
-            this.backoffPolicy = backoffPolicy;
-            assert concurrentRequests > 0;
+        assert concurrentRequests >= 0;
+        this.logger = Loggers.getLogger(getClass());
+        this.consumer = consumer;
         this.listener = listener;
         this.concurrentRequests = concurrentRequests;
-            this.semaphore = new Semaphore(concurrentRequests);
+        this.retry = new Retry(EsRejectedExecutionException.class, backoffPolicy, threadPool);
+        this.semaphore = new Semaphore(concurrentRequests > 0 ? concurrentRequests : 1);
     }
 
-        @Override
     public void execute(BulkRequest bulkRequest, long executionId) {
+        Runnable toRelease = () -> {};
         boolean bulkRequestSetupSuccessful = false;
-            boolean acquired = false;
         try {
             listener.beforeBulk(executionId, bulkRequest);
             semaphore.acquire();
-                acquired = true;
-                Retry.on(EsRejectedExecutionException.class)
-                    .policy(backoffPolicy)
-                    .using(threadPool)
-                    .withAsyncBackoff(consumer, bulkRequest, new ActionListener<BulkResponse>() {
+            toRelease = semaphore::release;
+            CountDownLatch latch = new CountDownLatch(1);
+            retry.withBackoff(consumer, bulkRequest, new ActionListener<BulkResponse>() {
                 @Override
                 public void onResponse(BulkResponse response) {
                     try {
                         listener.afterBulk(executionId, bulkRequest, response);
                     } finally {
                         semaphore.release();
+                        latch.countDown();
                     }
                 }
 
@@ -151,10 +80,14 @@ abstract class BulkRequestHandler {
                         listener.afterBulk(executionId, bulkRequest, e);
                     } finally {
                         semaphore.release();
+                        latch.countDown();
                     }
                 }
             }, Settings.EMPTY);
             bulkRequestSetupSuccessful = true;
+            if (concurrentRequests == 0) {
+                latch.await();
+            }
         } catch (InterruptedException e) {
             Thread.currentThread().interrupt();
             logger.info((Supplier<?>) () -> new ParameterizedMessage("Bulk request {} has been cancelled.", executionId), e);
@@ -163,19 +96,17 @@ abstract class BulkRequestHandler {
             logger.warn((Supplier<?>) () -> new ParameterizedMessage("Failed to execute bulk request {}.", executionId), e);
             listener.afterBulk(executionId, bulkRequest, e);
         } finally {
-                if (!bulkRequestSetupSuccessful && acquired) {  // if we fail on client.bulk() release the semaphore
-                    semaphore.release();
+            if (bulkRequestSetupSuccessful == false) {  // if we fail on client.bulk() release the semaphore
+                toRelease.run();
             }
         }
     }
 
-        @Override
-        public boolean awaitClose(long timeout, TimeUnit unit) throws InterruptedException {
+    boolean awaitClose(long timeout, TimeUnit unit) throws InterruptedException {
         if (semaphore.tryAcquire(this.concurrentRequests, timeout, unit)) {
             semaphore.release(this.concurrentRequests);
             return true;
         }
         return false;
     }
-    }
 }

core/src/main/java/org/elasticsearch/action/bulk/Retry.java

@@ -25,20 +25,14 @@ import org.elasticsearch.action.support.PlainActionFuture;
 import org.elasticsearch.common.logging.Loggers;
 import org.elasticsearch.common.settings.Settings;
 import org.elasticsearch.common.unit.TimeValue;
-import org.elasticsearch.common.util.concurrent.EsExecutors;
 import org.elasticsearch.common.util.concurrent.FutureUtils;
 import org.elasticsearch.threadpool.ThreadPool;
 
 import java.util.ArrayList;
 import java.util.Iterator;
 import java.util.List;
-import java.util.concurrent.Executors;
-import java.util.concurrent.ScheduledExecutorService;
 import java.util.concurrent.ScheduledFuture;
-import java.util.concurrent.ScheduledThreadPoolExecutor;
-import java.util.concurrent.TimeUnit;
 import java.util.function.BiConsumer;
-import java.util.function.BiFunction;
 import java.util.function.Predicate;
 
 /**
@@ -46,62 +40,42 @@ import java.util.function.Predicate;
  */
 public class Retry {
     private final Class<? extends Throwable> retryOnThrowable;
+    private final BackoffPolicy backoffPolicy;
+    private final ThreadPool threadPool;
 
-    private BackoffPolicy backoffPolicy;
-    private ThreadPool threadPool;
 
-    public static Retry on(Class<? extends Throwable> retryOnThrowable) {
-        return new Retry(retryOnThrowable);
-    }
-
-    Retry(Class<? extends Throwable> retryOnThrowable) {
+    public Retry(Class<? extends Throwable> retryOnThrowable, BackoffPolicy backoffPolicy, ThreadPool threadPool) {
         this.retryOnThrowable = retryOnThrowable;
-    }
-
-    /**
-     * @param backoffPolicy The backoff policy that defines how long and how often to wait for retries.
-     */
-    public Retry policy(BackoffPolicy backoffPolicy) {
         this.backoffPolicy = backoffPolicy;
-        return this;
-    }
-
-    /**
-     * @param threadPool The threadPool that will be used to schedule retries.
-     */
-    public Retry using(ThreadPool threadPool) {
         this.threadPool = threadPool;
-        return this;
     }
 
     /**
-     * Invokes #apply(BulkRequest, ActionListener). Backs off on the provided exception and delegates results to the
-     * provided listener. Retries will be attempted using the provided schedule function
+     * Invokes #accept(BulkRequest, ActionListener). Backs off on the provided exception and delegates results to the
+     * provided listener. Retries will be scheduled using the class's thread pool.
      * @param consumer The consumer to which apply the request and listener
      * @param bulkRequest The bulk request that should be executed.
      * @param listener A listener that is invoked when the bulk request finishes or completes with an exception. The listener is not
      * @param settings settings
      */
-    public void withAsyncBackoff(BiConsumer<BulkRequest, ActionListener<BulkResponse>> consumer, BulkRequest bulkRequest, ActionListener<BulkResponse> listener, Settings settings) {
+    public void withBackoff(BiConsumer<BulkRequest, ActionListener<BulkResponse>> consumer, BulkRequest bulkRequest, ActionListener<BulkResponse> listener, Settings settings) {
         RetryHandler r = new RetryHandler(retryOnThrowable, backoffPolicy, consumer, listener, settings, threadPool);
         r.execute(bulkRequest);
     }
 
     /**
-     * Invokes #apply(BulkRequest, ActionListener). Backs off on the provided exception. Retries will be attempted using
-     * the provided schedule function.
+     * Invokes #accept(BulkRequest, ActionListener). Backs off on the provided exception. Retries will be scheduled using
+     * the class's thread pool.
      *
      * @param consumer The consumer to which apply the request and listener
      * @param bulkRequest The bulk request that should be executed.
      * @param settings settings
-     * @return the bulk response as returned by the client.
-     * @throws Exception Any exception thrown by the callable.
+     * @return a future representing the bulk response returned by the client.
      */
-    public BulkResponse withSyncBackoff(BiConsumer<BulkRequest, ActionListener<BulkResponse>> consumer, BulkRequest bulkRequest, Settings settings) throws Exception {
-        PlainActionFuture<BulkResponse> actionFuture = PlainActionFuture.newFuture();
-        RetryHandler r = new RetryHandler(retryOnThrowable, backoffPolicy, consumer, actionFuture, settings, threadPool);
-        r.execute(bulkRequest);
-        return actionFuture.actionGet();
+    public PlainActionFuture<BulkResponse> withBackoff(BiConsumer<BulkRequest, ActionListener<BulkResponse>> consumer, BulkRequest bulkRequest, Settings settings) {
+        PlainActionFuture<BulkResponse> future = PlainActionFuture.newFuture();
+        withBackoff(consumer, bulkRequest, future, settings);
+        return future;
     }
 
     static class RetryHandler implements ActionListener<BulkResponse> {

core/src/main/java/org/elasticsearch/action/bulk/TransportBulkAction.java

@@ -279,7 +279,7 @@ public class TransportBulkAction extends HandledTransportAction<BulkRequest, Bul
                             break;
                         default: throw new AssertionError("request type not supported: [" + docWriteRequest.opType() + "]");
                     }
-                } catch (ElasticsearchParseException | RoutingMissingException e) {
+                } catch (ElasticsearchParseException | IllegalArgumentException | RoutingMissingException e) {
                     BulkItemResponse.Failure failure = new BulkItemResponse.Failure(concreteIndex.getName(), docWriteRequest.type(), docWriteRequest.id(), e);
                     BulkItemResponse bulkItemResponse = new BulkItemResponse(i, docWriteRequest.opType(), failure);
                     responses.set(i, bulkItemResponse);

core/src/main/java/org/elasticsearch/action/bulk/byscroll/AbstractAsyncBulkByScrollAction.java

@@ -134,7 +134,7 @@ public abstract class AbstractAsyncBulkByScrollAction<Request extends AbstractBu
         this.mainRequest = mainRequest;
         this.listener = listener;
         BackoffPolicy backoffPolicy = buildBackoffPolicy();
-        bulkRetry = Retry.on(EsRejectedExecutionException.class).policy(BackoffPolicy.wrap(backoffPolicy, task::countBulkRetry)).using(threadPool);
+        bulkRetry = new Retry(EsRejectedExecutionException.class, BackoffPolicy.wrap(backoffPolicy, task::countBulkRetry), threadPool);
         scrollSource = buildScrollableResultSource(backoffPolicy);
         scriptApplier = Objects.requireNonNull(buildScriptApplier(), "script applier must not be null");
         /*
@@ -337,7 +337,7 @@ public abstract class AbstractAsyncBulkByScrollAction<Request extends AbstractBu
             finishHim(null);
             return;
         }
-        bulkRetry.withAsyncBackoff(client::bulk, request, new ActionListener<BulkResponse>() {
+        bulkRetry.withBackoff(client::bulk, request, new ActionListener<BulkResponse>() {
             @Override
             public void onResponse(BulkResponse response) {
                 onBulkResponse(thisBatchStartTime, response);

core/src/main/java/org/elasticsearch/action/index/IndexRequest.java

@@ -491,14 +491,18 @@ public class IndexRequest extends ReplicatedWriteRequest<IndexRequest> implement
             }
 
             if (parent != null && !mappingMd.hasParentField()) {
-                throw new IllegalArgumentException("Can't specify parent if no parent field has been configured");
+                throw new IllegalArgumentException("can't specify parent if no parent field has been configured");
             }
         } else {
             if (parent != null) {
-                throw new IllegalArgumentException("Can't specify parent if no parent field has been configured");
+                throw new IllegalArgumentException("can't specify parent if no parent field has been configured");
             }
         }
 
+        if ("".equals(id)) {
+            throw new IllegalArgumentException("if _id is specified it must not be empty");
+        }
+
         // generate id if not already provided
         if (id == null) {
             assert autoGeneratedTimestamp == -1 : "timestamp has already been generated!";

core/src/main/java/org/elasticsearch/bootstrap/Security.java

@@ -20,7 +20,6 @@
 package org.elasticsearch.bootstrap;
 
 import org.elasticsearch.SecureSM;
-import org.elasticsearch.common.Strings;
 import org.elasticsearch.common.SuppressForbidden;
 import org.elasticsearch.common.io.PathUtils;
 import org.elasticsearch.common.network.NetworkModule;
@@ -45,11 +44,9 @@ import java.security.NoSuchAlgorithmException;
 import java.security.Permissions;
 import java.security.Policy;
 import java.security.URIParameter;
-import java.util.ArrayList;
 import java.util.Collections;
 import java.util.HashMap;
 import java.util.LinkedHashSet;
-import java.util.List;
 import java.util.Map;
 import java.util.Set;
 
@@ -269,6 +266,26 @@ final class Security {
         for (Path path : environment.dataFiles()) {
             addPath(policy, Environment.PATH_DATA_SETTING.getKey(), path, "read,readlink,write,delete");
         }
+        /*
+         * If path.data and default.path.data are set, we need read access to the paths in default.path.data to check for the existence of
+         * index directories there that could have arisen from a bug in the handling of simultaneous configuration of path.data and
+         * default.path.data that was introduced in Elasticsearch 5.3.0.
+         *
+         * If path.data is not set then default.path.data would take precedence in setting the data paths for the environment and
+         * permissions would have been granted above.
+         *
+         * If path.data is not set and default.path.data is not set, then we would fallback to the default data directory under
+         * Elasticsearch home and again permissions would have been granted above.
+         *
+         * If path.data is set and default.path.data is not set, there is nothing to do here.
+         */
+        if (Environment.PATH_DATA_SETTING.exists(environment.settings())
+                && Environment.DEFAULT_PATH_DATA_SETTING.exists(environment.settings())) {
+            for (final String path : Environment.DEFAULT_PATH_DATA_SETTING.get(environment.settings())) {
+                // write permissions are not needed here, we are not going to be writing to any paths here
+                addPath(policy, Environment.DEFAULT_PATH_DATA_SETTING.getKey(), getPath(path), "read,readlink");
+            }
+        }
         for (Path path : environment.repoFiles()) {
             addPath(policy, Environment.PATH_REPO_SETTING.getKey(), path, "read,readlink,write,delete");
         }
@@ -278,6 +295,11 @@ final class Security {
         }
     }
 
+    @SuppressForbidden(reason = "read path that is not configured in environment")
+    private static Path getPath(final String path) {
+        return PathUtils.get(path);
+    }
+
     /**
      * Add dynamic {@link SocketPermission}s based on HTTP and transport settings.
      *

core/src/main/java/org/elasticsearch/common/bytes/ReleasablePagedBytesReference.java

@@ -30,13 +30,17 @@ import org.elasticsearch.common.util.ByteArray;
  */
 public final class ReleasablePagedBytesReference extends PagedBytesReference implements Releasable {
 
-    public ReleasablePagedBytesReference(BigArrays bigarrays, ByteArray byteArray, int length) {
+    private final Releasable releasable;
+
+    public ReleasablePagedBytesReference(BigArrays bigarrays, ByteArray byteArray, int length,
+                                         Releasable releasable) {
         super(bigarrays, byteArray, length);
+        this.releasable = releasable;
     }
 
     @Override
     public void close() {
-        Releasables.close(byteArray);
+        Releasables.close(releasable);
     }
 
 }

core/src/main/java/org/elasticsearch/common/compress/Compressor.java

@@ -20,6 +20,7 @@
 package org.elasticsearch.common.compress;
 
 import org.elasticsearch.common.bytes.BytesReference;
+import org.elasticsearch.common.io.stream.ReleasableBytesStreamOutput;
 import org.elasticsearch.common.io.stream.StreamInput;
 import org.elasticsearch.common.io.stream.StreamOutput;
 
@@ -31,5 +32,9 @@ public interface Compressor {
 
     StreamInput streamInput(StreamInput in) throws IOException;
 
+    /**
+     * Creates a new stream output that compresses the contents and writes to the provided stream
+     * output. Closing the returned {@link StreamOutput} will close the provided stream output.
+     */
     StreamOutput streamOutput(StreamOutput out) throws IOException;
 }

core/src/main/java/org/elasticsearch/common/compress/DeflateCompressor.java

@@ -20,7 +20,6 @@
 package org.elasticsearch.common.compress;
 
 import org.elasticsearch.common.bytes.BytesReference;
-import org.elasticsearch.common.compress.Compressor;
 import org.elasticsearch.common.io.stream.InputStreamStreamInput;
 import org.elasticsearch.common.io.stream.OutputStreamStreamOutput;
 import org.elasticsearch.common.io.stream.StreamInput;
@@ -47,7 +46,7 @@ public class DeflateCompressor implements Compressor {
     // It needs to be different from other compressors and to not be specific
     // enough so that no stream starting with these bytes could be detected as
     // a XContent
-    private static final byte[] HEADER = new byte[] { 'D', 'F', 'L', '\0' };
+    private static final byte[] HEADER = new byte[]{'D', 'F', 'L', '\0'};
     // 3 is a good trade-off between speed and compression ratio
     private static final int LEVEL = 3;
     // We use buffering on the input and output of in/def-laters in order to
@@ -88,6 +87,7 @@ public class DeflateCompressor implements Compressor {
         decompressedIn = new BufferedInputStream(decompressedIn, BUFFER_SIZE);
         return new InputStreamStreamInput(decompressedIn) {
             final AtomicBoolean closed = new AtomicBoolean(false);
+
             public void close() throws IOException {
                 try {
                     super.close();
@@ -107,10 +107,11 @@ public class DeflateCompressor implements Compressor {
         final boolean nowrap = true;
         final Deflater deflater = new Deflater(LEVEL, nowrap);
         final boolean syncFlush = true;
-        OutputStream compressedOut = new DeflaterOutputStream(out, deflater, BUFFER_SIZE, syncFlush);
-        compressedOut = new BufferedOutputStream(compressedOut, BUFFER_SIZE);
+        DeflaterOutputStream deflaterOutputStream = new DeflaterOutputStream(out, deflater, BUFFER_SIZE, syncFlush);
+        OutputStream compressedOut = new BufferedOutputStream(deflaterOutputStream, BUFFER_SIZE);
         return new OutputStreamStreamOutput(compressedOut) {
             final AtomicBoolean closed = new AtomicBoolean(false);
+
             public void close() throws IOException {
                 try {
                     super.close();

core/src/main/java/org/elasticsearch/common/io/ReleasableBytesStream.java

@@ -1,32 +0,0 @@
-/*
- * Licensed to Elasticsearch under one or more contributor
- * license agreements. See the NOTICE file distributed with
- * this work for additional information regarding copyright
- * ownership. Elasticsearch licenses this file to you under
- * the Apache License, Version 2.0 (the "License"); you may
- * not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *    http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing,
- * software distributed under the License is distributed on an
- * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
- * KIND, either express or implied.  See the License for the
- * specific language governing permissions and limitations
- * under the License.
- */
-
-package org.elasticsearch.common.io;
-
-import org.elasticsearch.common.bytes.ReleasablePagedBytesReference;
-
-/**
- * A bytes stream that requires its bytes to be released once no longer used.
- */
-public interface ReleasableBytesStream extends BytesStream {
-
-    @Override
-    ReleasablePagedBytesReference bytes();
-
-}

core/src/main/java/org/elasticsearch/common/io/Streams.java

@@ -20,6 +20,9 @@
 package org.elasticsearch.common.io;
 
 import org.apache.lucene.util.IOUtils;
+import org.elasticsearch.common.bytes.BytesReference;
+import org.elasticsearch.common.io.stream.BytesStream;
+import org.elasticsearch.common.io.stream.StreamOutput;
 import org.elasticsearch.common.util.Callback;
 
 import java.io.BufferedReader;
@@ -236,4 +239,56 @@ public abstract class Streams {
             }
         }
     }
+
+    /**
+     * Wraps the given {@link BytesStream} in a {@link StreamOutput} that simply flushes when
+     * close is called.
+     */
+    public static BytesStream flushOnCloseStream(BytesStream os) {
+        return new FlushOnCloseOutputStream(os);
+    }
+
+    /**
+     * A wrapper around a {@link BytesStream} that makes the close operation a flush. This is
+     * needed as sometimes a stream will be closed but the bytes that the stream holds still need
+     * to be used and the stream cannot be closed until the bytes have been consumed.
+     */
+    private static class FlushOnCloseOutputStream extends BytesStream {
+
+        private final BytesStream delegate;
+
+        private FlushOnCloseOutputStream(BytesStream bytesStreamOutput) {
+            this.delegate = bytesStreamOutput;
+        }
+
+        @Override
+        public void writeByte(byte b) throws IOException {
+            delegate.writeByte(b);
+        }
+
+        @Override
+        public void writeBytes(byte[] b, int offset, int length) throws IOException {
+            delegate.writeBytes(b, offset, length);
+        }
+
+        @Override
+        public void flush() throws IOException {
+            delegate.flush();
+        }
+
+        @Override
+        public void close() throws IOException {
+            flush();
+        }
+
+        @Override
+        public void reset() throws IOException {
+            delegate.reset();
+        }
+
+        @Override
+        public BytesReference bytes() {
+            return delegate.bytes();
+        }
+    }
 }

core/src/main/java/org/elasticsearch/common/io/stream/BytesStream.java

@@ -17,11 +17,11 @@
  * under the License.
  */
 
-package org.elasticsearch.common.io;
+package org.elasticsearch.common.io.stream;
 
 import org.elasticsearch.common.bytes.BytesReference;
 
-public interface BytesStream {
+public abstract class BytesStream extends StreamOutput {
 
-    BytesReference bytes();
+    public abstract BytesReference bytes();
 }

core/src/main/java/org/elasticsearch/common/io/stream/BytesStreamOutput.java

@@ -21,7 +21,6 @@ package org.elasticsearch.common.io.stream;
 
 import org.elasticsearch.common.bytes.BytesReference;
 import org.elasticsearch.common.bytes.PagedBytesReference;
-import org.elasticsearch.common.io.BytesStream;
 import org.elasticsearch.common.util.BigArrays;
 import org.elasticsearch.common.util.ByteArray;
 
@@ -31,7 +30,7 @@ import java.io.IOException;
  * A @link {@link StreamOutput} that uses {@link BigArrays} to acquire pages of
  * bytes, which avoids frequent reallocation & copying of the internal data.
  */
-public class BytesStreamOutput extends StreamOutput implements BytesStream {
+public class BytesStreamOutput extends BytesStream {
 
     protected final BigArrays bigArrays;
 
@@ -151,7 +150,7 @@ public class BytesStreamOutput extends StreamOutput implements BytesStream {
         return bytes.ramBytesUsed();
     }
 
-    private void ensureCapacity(long offset) {
+    void ensureCapacity(long offset) {
         if (offset > Integer.MAX_VALUE) {
             throw new IllegalArgumentException(getClass().getSimpleName() + " cannot hold more than 2GB of data");
         }

core/src/main/java/org/elasticsearch/common/io/stream/ReleasableBytesStreamOutput.java

@@ -20,29 +20,66 @@
 package org.elasticsearch.common.io.stream;
 
 import org.elasticsearch.common.bytes.ReleasablePagedBytesReference;
-import org.elasticsearch.common.io.ReleasableBytesStream;
+import org.elasticsearch.common.lease.Releasable;
+import org.elasticsearch.common.lease.Releasables;
 import org.elasticsearch.common.util.BigArrays;
+import org.elasticsearch.common.util.ByteArray;
 
 /**
  * An bytes stream output that allows providing a {@link BigArrays} instance
  * expecting it to require releasing its content ({@link #bytes()}) once done.
  * <p>
- * Please note, its is the responsibility of the caller to make sure the bytes
- * reference do not "escape" and are released only once.
+ * Please note, closing this stream will release the bytes that are in use by any
+ * {@link ReleasablePagedBytesReference} returned from {@link #bytes()}, so this
+ * stream should only be closed after the bytes have been output or copied
+ * elsewhere.
  */
-public class ReleasableBytesStreamOutput extends BytesStreamOutput implements ReleasableBytesStream {
+public class ReleasableBytesStreamOutput extends BytesStreamOutput
+    implements Releasable {
+
+    private Releasable releasable;
 
     public ReleasableBytesStreamOutput(BigArrays bigarrays) {
-        super(BigArrays.PAGE_SIZE_IN_BYTES, bigarrays);
+        this(BigArrays.PAGE_SIZE_IN_BYTES, bigarrays);
     }
 
     public ReleasableBytesStreamOutput(int expectedSize, BigArrays bigArrays) {
         super(expectedSize, bigArrays);
+        this.releasable = Releasables.releaseOnce(this.bytes);
+    }
+
+    /**
+     * Returns a {@link Releasable} implementation of a
+     * {@link org.elasticsearch.common.bytes.BytesReference} that represents the current state of
+     * the bytes in the stream.
+     */
+    @Override
+    public ReleasablePagedBytesReference bytes() {
+        return new ReleasablePagedBytesReference(bigArrays, bytes, count, releasable);
     }
 
     @Override
-    public ReleasablePagedBytesReference bytes() {
-        return new ReleasablePagedBytesReference(bigArrays, bytes, count);
+    public void close() {
+        Releasables.close(releasable);
     }
 
+    @Override
+    void ensureCapacity(long offset) {
+        final ByteArray prevBytes = this.bytes;
+        super.ensureCapacity(offset);
+        if (prevBytes != this.bytes) {
+            // re-create the releasable with the new reference
+            releasable = Releasables.releaseOnce(this.bytes);
+        }
+    }
+
+    @Override
+    public void reset() {
+        final ByteArray prevBytes = this.bytes;
+        super.reset();
+        if (prevBytes != this.bytes) {
+            // re-create the releasable with the new reference
+            releasable = Releasables.releaseOnce(this.bytes);
+        }
+    }
 }

core/src/main/java/org/elasticsearch/common/logging/DeprecationLogger.java

@@ -226,10 +226,41 @@ public class DeprecationLogger {
      * @return the extracted warning value
      */
     public static String extractWarningValueFromWarningHeader(final String s) {
+        /*
+         * We know the exact format of the warning header, so to extract the warning value we can skip forward from the front to the first
+         * quote, and skip backwards from the end to the penultimate quote:
+         *
+         *   299 Elasticsearch-6.0.0 "warning value" "Sat, 25, Feb 2017 10:27:43 GMT"
+         *                           ^               ^                              ^
+         *                           firstQuote      penultimateQuote               lastQuote
+         *
+         * We do it this way rather than seeking forward after the first quote because there could be escaped quotes in the warning value
+         * but since there are none in the warning date, we can skip backwards to find the quote that closes the quoted warning value.
+         *
+         * We parse this manually rather than using the capturing regular expression because the regular expression involves a lot of
+         * backtracking and carries a performance penalty. However, when assertions are enabled, we still use the regular expression to
+         * verify that we are maintaining the warning header format.
+         */
+        final int firstQuote = s.indexOf('\"');
+        final int lastQuote = s.lastIndexOf('\"');
+        final int penultimateQuote = s.lastIndexOf('\"', lastQuote - 1);
+        final String warningValue = s.substring(firstQuote + 1, penultimateQuote - 2);
+        assert assertWarningValue(s, warningValue);
+        return warningValue;
+    }
+
+    /**
+     * Assert that the specified string has the warning value equal to the provided warning value.
+     *
+     * @param s            the string representing a full warning header
+     * @param warningValue the expected warning header
+     * @return {@code true} if the specified string has the expected warning value
+     */
+    private static boolean assertWarningValue(final String s, final String warningValue) {
         final Matcher matcher = WARNING_HEADER_PATTERN.matcher(s);
         final boolean matches = matcher.matches();
         assert matches;
-        return matcher.group(1);
+        return matcher.group(1).equals(warningValue);
     }
 
     /**

core/src/main/java/org/elasticsearch/common/lucene/uid/PerThreadIDVersionAndSeqNoLookup.java

@@ -29,9 +29,12 @@ import org.apache.lucene.index.TermsEnum;
 import org.apache.lucene.search.DocIdSetIterator;
 import org.apache.lucene.util.Bits;
 import org.apache.lucene.util.BytesRef;
-import org.elasticsearch.common.lucene.uid.VersionsResolver.DocIdAndVersion;
+import org.elasticsearch.common.lucene.uid.VersionsAndSeqNoResolver.DocIdAndSeqNo;
+import org.elasticsearch.common.lucene.uid.VersionsAndSeqNoResolver.DocIdAndVersion;
+import org.elasticsearch.index.mapper.SeqNoFieldMapper;
 import org.elasticsearch.index.mapper.UidFieldMapper;
 import org.elasticsearch.index.mapper.VersionFieldMapper;
+import org.elasticsearch.index.seqno.SequenceNumbersService;
 
 import java.io.IOException;
 
@@ -43,7 +46,7 @@ import java.io.IOException;
  *  in more than one document!  It will only return the first one it
  *  finds. */
 
-final class PerThreadIDAndVersionLookup {
+final class PerThreadIDVersionAndSeqNoLookup {
     // TODO: do we really need to store all this stuff? some if it might not speed up anything.
     // we keep it around for now, to reduce the amount of e.g. hash lookups by field and stuff
 
@@ -51,7 +54,10 @@ final class PerThreadIDAndVersionLookup {
     private final TermsEnum termsEnum;
     /** _version data */
     private final NumericDocValues versions;
-
+    /** _seq_no data */
+    private final NumericDocValues seqNos;
+    /** _primary_term data */
+    private final NumericDocValues primaryTerms;
     /** Reused for iteration (when the term exists) */
     private PostingsEnum docsEnum;
 
@@ -61,7 +67,7 @@ final class PerThreadIDAndVersionLookup {
     /**
      * Initialize lookup for the provided segment
      */
-    PerThreadIDAndVersionLookup(LeafReader reader) throws IOException {
+    PerThreadIDVersionAndSeqNoLookup(LeafReader reader) throws IOException {
         Fields fields = reader.fields();
         Terms terms = fields.terms(UidFieldMapper.NAME);
         termsEnum = terms.iterator();
@@ -74,6 +80,8 @@ final class PerThreadIDAndVersionLookup {
             throw new IllegalArgumentException("reader misses the [" + VersionFieldMapper.NAME +
                 "] field");
         }
+        seqNos = reader.getNumericDocValues(SeqNoFieldMapper.NAME);
+        primaryTerms = reader.getNumericDocValues(SeqNoFieldMapper.PRIMARY_TERM_NAME);
         Object readerKey = null;
         assert (readerKey = reader.getCoreCacheKey()) != null;
         this.readerKey = readerKey;
@@ -113,4 +121,25 @@ final class PerThreadIDAndVersionLookup {
             return DocIdSetIterator.NO_MORE_DOCS;
         }
     }
+
+    /** Return null if id is not found. */
+    DocIdAndSeqNo lookupSeqNo(BytesRef id, Bits liveDocs, LeafReaderContext context) throws IOException {
+        assert context.reader().getCoreCacheKey().equals(readerKey) :
+            "context's reader is not the same as the reader class was initialized on.";
+        int docID = getDocID(id, liveDocs);
+        if (docID != DocIdSetIterator.NO_MORE_DOCS) {
+            return new DocIdAndSeqNo(docID, seqNos == null ? SequenceNumbersService.UNASSIGNED_SEQ_NO : seqNos.get(docID), context);
+        } else {
+            return null;
+        }
+    }
+
+    /**
+     * returns 0 if the primary term is not found.
+     *
+     * Note that 0 is an illegal primary term. See {@link org.elasticsearch.cluster.metadata.IndexMetaData#primaryTerm(int)}
+     **/
+    long lookUpPrimaryTerm(int docID) throws IOException {
+            return primaryTerms == null ? 0  : primaryTerms.get(docID);
+    }
 }

core/src/main/java/org/elasticsearch/common/lucene/uid/VersionsAndSeqNoResolver.java

@@ -0,0 +1,180 @@
+/*
+ * Licensed to Elasticsearch under one or more contributor
+ * license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright
+ * ownership. Elasticsearch licenses this file to you under
+ * the Apache License, Version 2.0 (the "License"); you may
+ * not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+package org.elasticsearch.common.lucene.uid;
+
+import org.apache.lucene.index.IndexReader;
+import org.apache.lucene.index.LeafReader;
+import org.apache.lucene.index.LeafReader.CoreClosedListener;
+import org.apache.lucene.index.LeafReaderContext;
+import org.apache.lucene.index.Term;
+import org.apache.lucene.util.CloseableThreadLocal;
+import org.elasticsearch.common.util.concurrent.ConcurrentCollections;
+import org.elasticsearch.index.mapper.UidFieldMapper;
+
+import java.io.IOException;
+import java.util.List;
+import java.util.concurrent.ConcurrentMap;
+
+import static org.elasticsearch.common.lucene.uid.Versions.NOT_FOUND;
+
+/** Utility class to resolve the Lucene doc ID, version, seqNo and primaryTerms for a given uid. */
+public final class VersionsAndSeqNoResolver {
+
+    static final ConcurrentMap<Object, CloseableThreadLocal<PerThreadIDVersionAndSeqNoLookup>> lookupStates =
+        ConcurrentCollections.newConcurrentMapWithAggressiveConcurrency();
+
+    // Evict this reader from lookupStates once it's closed:
+    private static final CoreClosedListener removeLookupState = key -> {
+        CloseableThreadLocal<PerThreadIDVersionAndSeqNoLookup> ctl = lookupStates.remove(key);
+        if (ctl != null) {
+            ctl.close();
+        }
+    };
+
+    private static PerThreadIDVersionAndSeqNoLookup getLookupState(LeafReader reader) throws IOException {
+        Object key = reader.getCoreCacheKey();
+        CloseableThreadLocal<PerThreadIDVersionAndSeqNoLookup> ctl = lookupStates.get(key);
+        if (ctl == null) {
+            // First time we are seeing this reader's core; make a new CTL:
+            ctl = new CloseableThreadLocal<>();
+            CloseableThreadLocal<PerThreadIDVersionAndSeqNoLookup> other = lookupStates.putIfAbsent(key, ctl);
+            if (other == null) {
+                // Our CTL won, we must remove it when the core is closed:
+                reader.addCoreClosedListener(removeLookupState);
+            } else {
+                // Another thread beat us to it: just use their CTL:
+                ctl = other;
+            }
+        }
+
+        PerThreadIDVersionAndSeqNoLookup lookupState = ctl.get();
+        if (lookupState == null) {
+            lookupState = new PerThreadIDVersionAndSeqNoLookup(reader);
+            ctl.set(lookupState);
+        }
+
+        return lookupState;
+    }
+
+    private VersionsAndSeqNoResolver() {
+    }
+
+    /** Wraps an {@link LeafReaderContext}, a doc ID <b>relative to the context doc base</b> and a version. */
+    public static class DocIdAndVersion {
+        public final int docId;
+        public final long version;
+        public final LeafReaderContext context;
+
+        DocIdAndVersion(int docId, long version, LeafReaderContext context) {
+            this.docId = docId;
+            this.version = version;
+            this.context = context;
+        }
+    }
+
+    /** Wraps an {@link LeafReaderContext}, a doc ID <b>relative to the context doc base</b> and a seqNo. */
+    public static class DocIdAndSeqNo {
+        public final int docId;
+        public final long seqNo;
+        public final LeafReaderContext context;
+
+        DocIdAndSeqNo(int docId, long seqNo, LeafReaderContext context) {
+            this.docId = docId;
+            this.seqNo = seqNo;
+            this.context = context;
+        }
+    }
+
+
+    /**
+     * Load the internal doc ID and version for the uid from the reader, returning<ul>
+     * <li>null if the uid wasn't found,
+     * <li>a doc ID and a version otherwise
+     * </ul>
+     */
+    public static DocIdAndVersion loadDocIdAndVersion(IndexReader reader, Term term) throws IOException {
+        assert term.field().equals(UidFieldMapper.NAME) : "unexpected term field " + term.field();
+        List<LeafReaderContext> leaves = reader.leaves();
+        if (leaves.isEmpty()) {
+            return null;
+        }
+        // iterate backwards to optimize for the frequently updated documents
+        // which are likely to be in the last segments
+        for (int i = leaves.size() - 1; i >= 0; i--) {
+            LeafReaderContext context = leaves.get(i);
+            LeafReader leaf = context.reader();
+            PerThreadIDVersionAndSeqNoLookup lookup = getLookupState(leaf);
+            DocIdAndVersion result = lookup.lookupVersion(term.bytes(), leaf.getLiveDocs(), context);
+            if (result != null) {
+                return result;
+            }
+        }
+        return null;
+    }
+
+    /**
+     * Load the internal doc ID and sequence number for the uid from the reader, returning<ul>
+     * <li>null if the uid wasn't found,
+     * <li>a doc ID and the associated seqNo otherwise
+     * </ul>
+     */
+    public static DocIdAndSeqNo loadDocIdAndSeqNo(IndexReader reader, Term term) throws IOException {
+        assert term.field().equals(UidFieldMapper.NAME) : "unexpected term field " + term.field();
+        List<LeafReaderContext> leaves = reader.leaves();
+        if (leaves.isEmpty()) {
+            return null;
+        }
+        // iterate backwards to optimize for the frequently updated documents
+        // which are likely to be in the last segments
+        for (int i = leaves.size() - 1; i >= 0; i--) {
+            LeafReaderContext context = leaves.get(i);
+            LeafReader leaf = context.reader();
+            PerThreadIDVersionAndSeqNoLookup lookup = getLookupState(leaf);
+            DocIdAndSeqNo result = lookup.lookupSeqNo(term.bytes(), leaf.getLiveDocs(), context);
+            if (result != null) {
+                return result;
+            }
+        }
+        return null;
+    }
+
+    /**
+     * Load the primaryTerm associated with the given {@link DocIdAndSeqNo}
+     */
+    public static long loadPrimaryTerm(DocIdAndSeqNo docIdAndSeqNo) throws IOException {
+        LeafReader leaf = docIdAndSeqNo.context.reader();
+        PerThreadIDVersionAndSeqNoLookup lookup = getLookupState(leaf);
+        long result = lookup.lookUpPrimaryTerm(docIdAndSeqNo.docId);
+        assert result > 0 : "should always resolve a primary term for a resolved sequence number. primary_term [" + result + "]"
+            + " docId [" + docIdAndSeqNo.docId + "] seqNo [" + docIdAndSeqNo.seqNo + "]";
+        return result;
+    }
+
+    /**
+     * Load the version for the uid from the reader, returning<ul>
+     * <li>{@link Versions#NOT_FOUND} if no matching doc exists,
+     * <li>the version associated with the provided uid otherwise
+     * </ul>
+     */
+    public static long loadVersion(IndexReader reader, Term term) throws IOException {
+        final DocIdAndVersion docIdAndVersion = loadDocIdAndVersion(reader, term);
+        return docIdAndVersion == null ? NOT_FOUND : docIdAndVersion.version;
+    }
+}

core/src/main/java/org/elasticsearch/common/lucene/uid/VersionsResolver.java

@@ -1,263 +0,0 @@
-/*
- * Licensed to Elasticsearch under one or more contributor
- * license agreements. See the NOTICE file distributed with
- * this work for additional information regarding copyright
- * ownership. Elasticsearch licenses this file to you under
- * the Apache License, Version 2.0 (the "License"); you may
- * not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *    http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing,
- * software distributed under the License is distributed on an
- * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
- * KIND, either express or implied.  See the License for the
- * specific language governing permissions and limitations
- * under the License.
- */
-
-package org.elasticsearch.common.lucene.uid;
-
-import org.apache.lucene.index.Fields;
-import org.apache.lucene.index.IndexReader;
-import org.apache.lucene.index.LeafReader;
-import org.apache.lucene.index.LeafReader.CoreClosedListener;
-import org.apache.lucene.index.LeafReaderContext;
-import org.apache.lucene.index.NumericDocValues;
-import org.apache.lucene.index.PostingsEnum;
-import org.apache.lucene.index.SortedNumericDocValues;
-import org.apache.lucene.index.Term;
-import org.apache.lucene.index.Terms;
-import org.apache.lucene.index.TermsEnum;
-import org.apache.lucene.search.DocIdSetIterator;
-import org.apache.lucene.util.Bits;
-import org.apache.lucene.util.BytesRef;
-import org.apache.lucene.util.CloseableThreadLocal;
-import org.elasticsearch.common.util.concurrent.ConcurrentCollections;
-import org.elasticsearch.index.mapper.SeqNoFieldMapper;
-import org.elasticsearch.index.mapper.UidFieldMapper;
-import org.elasticsearch.index.seqno.SequenceNumbersService;
-
-import java.io.IOException;
-import java.util.List;
-import java.util.concurrent.ConcurrentMap;
-
-import static org.elasticsearch.common.lucene.uid.Versions.NOT_FOUND;
-
-/** Utility class to resolve the Lucene doc ID and version for a given uid. */
-public class VersionsResolver {
-
-    static final ConcurrentMap<Object, CloseableThreadLocal<PerThreadIDAndVersionLookup>>
-        lookupStates = ConcurrentCollections.newConcurrentMapWithAggressiveConcurrency();
-
-    // Evict this reader from lookupStates once it's closed:
-    private static final CoreClosedListener removeLookupState = key -> {
-        CloseableThreadLocal<PerThreadIDAndVersionLookup> ctl = lookupStates.remove(key);
-        if (ctl != null) {
-            ctl.close();
-        }
-    };
-
-    private static PerThreadIDAndVersionLookup getLookupState(LeafReader reader)
-        throws IOException {
-        Object key = reader.getCoreCacheKey();
-        CloseableThreadLocal<PerThreadIDAndVersionLookup> ctl = lookupStates.get(key);
-        if (ctl == null) {
-            // First time we are seeing this reader's core; make a
-            // new CTL:
-            ctl = new CloseableThreadLocal<>();
-            CloseableThreadLocal<PerThreadIDAndVersionLookup> other =
-                lookupStates.putIfAbsent(key, ctl);
-            if (other == null) {
-                // Our CTL won, we must remove it when the
-                // core is closed:
-                reader.addCoreClosedListener(removeLookupState);
-            } else {
-                // Another thread beat us to it: just use
-                // their CTL:
-                ctl = other;
-            }
-        }
-
-        PerThreadIDAndVersionLookup lookupState = ctl.get();
-        if (lookupState == null) {
-            lookupState = new PerThreadIDAndVersionLookup(reader);
-            ctl.set(lookupState);
-        }
-
-        return lookupState;
-    }
-
-    private VersionsResolver() {
-    }
-
-    /**
-     * Wraps an {@link LeafReaderContext}, a doc ID <b>relative to the context doc base</b> and
-     * a version.
-     **/
-    public static class DocIdAndVersion {
-        public final int docId;
-        public final long version;
-        public final LeafReaderContext context;
-
-        public DocIdAndVersion(int docId, long version, LeafReaderContext context) {
-            this.docId = docId;
-            this.version = version;
-            this.context = context;
-        }
-    }
-
-    /**
-     * Load the internal doc ID and version for the uid from the reader, returning<ul>
-     * <li>null if the uid wasn't found,
-     * <li>a doc ID and a version otherwise
-     * </ul>
-     */
-    public static DocIdAndVersion loadDocIdAndVersion(IndexReader reader, Term term)
-        throws IOException {
-        assert term.field().equals(UidFieldMapper.NAME);
-        List<LeafReaderContext> leaves = reader.leaves();
-        if (leaves.isEmpty()) {
-            return null;
-        }
-        // iterate backwards to optimize for the frequently updated documents
-        // which are likely to be in the last segments
-        for (int i = leaves.size() - 1; i >= 0; i--) {
-            LeafReaderContext context = leaves.get(i);
-            LeafReader leaf = context.reader();
-            PerThreadIDAndVersionLookup lookup = getLookupState(leaf);
-            DocIdAndVersion result =
-                lookup.lookupVersion(term.bytes(), leaf.getLiveDocs(), context);
-            if (result != null) {
-                return result;
-            }
-        }
-        return null;
-    }
-
-    /**
-     * Load the version for the uid from the reader, returning<ul>
-     * <li>{@link Versions#NOT_FOUND} if no matching doc exists,
-     * <li>the version associated with the provided uid otherwise
-     * </ul>
-     */
-    public static long loadVersion(IndexReader reader, Term term) throws IOException {
-        final DocIdAndVersion docIdAndVersion = loadDocIdAndVersion(reader, term);
-        return docIdAndVersion == null ? NOT_FOUND : docIdAndVersion.version;
-    }
-
-    /**
-     * Returns the sequence number for the given uid term, returning
-     * {@code SequenceNumbersService.UNASSIGNED_SEQ_NO} if none is found.
-     */
-    public static long loadSeqNo(IndexReader reader, Term term) throws IOException {
-        assert term.field().equals(UidFieldMapper.NAME) : "can only load _seq_no by uid";
-        List<LeafReaderContext> leaves = reader.leaves();
-        if (leaves.isEmpty()) {
-            return SequenceNumbersService.UNASSIGNED_SEQ_NO;
-        }
-
-        // iterate backwards to optimize for the frequently updated documents
-        // which are likely to be in the last segments
-        for (int i = leaves.size() - 1; i >= 0; i--) {
-            LeafReader leaf = leaves.get(i).reader();
-            Bits liveDocs = leaf.getLiveDocs();
-
-            TermsEnum termsEnum = null;
-            SortedNumericDocValues dvField = null;
-            PostingsEnum docsEnum = null;
-
-            final Fields fields = leaf.fields();
-            if (fields != null) {
-                Terms terms = fields.terms(UidFieldMapper.NAME);
-                if (terms != null) {
-                    termsEnum = terms.iterator();
-                    assert termsEnum != null;
-                    dvField = leaf.getSortedNumericDocValues(SeqNoFieldMapper.NAME);
-                    assert dvField != null;
-
-                    final BytesRef id = term.bytes();
-                    if (termsEnum.seekExact(id)) {
-                        // there may be more than one matching docID, in the
-                        // case of nested docs, so we want the last one:
-                        docsEnum = termsEnum.postings(docsEnum, 0);
-                        int docID = DocIdSetIterator.NO_MORE_DOCS;
-                        for (int d = docsEnum.nextDoc();
-                             d != DocIdSetIterator.NO_MORE_DOCS; d = docsEnum.nextDoc()) {
-                            if (liveDocs != null && liveDocs.get(d) == false) {
-                                continue;
-                            }
-                            docID = d;
-                        }
-
-                        if (docID != DocIdSetIterator.NO_MORE_DOCS) {
-                            dvField.setDocument(docID);
-                            assert dvField.count() == 1 :
-                                "expected only a single value for _seq_no but got " +
-                                    dvField.count();
-                            return dvField.valueAt(0);
-                        }
-                    }
-                }
-            }
-
-        }
-        return SequenceNumbersService.UNASSIGNED_SEQ_NO;
-    }
-
-    /**
-     * Returns the primary term for the given uid term, returning {@code 0} if none is found.
-     */
-    public static long loadPrimaryTerm(IndexReader reader, Term term) throws IOException {
-        assert term.field().equals(UidFieldMapper.NAME) : "can only load _primary_term by uid";
-        List<LeafReaderContext> leaves = reader.leaves();
-        if (leaves.isEmpty()) {
-            return 0;
-        }
-
-        // iterate backwards to optimize for the frequently updated documents
-        // which are likely to be in the last segments
-        for (int i = leaves.size() - 1; i >= 0; i--) {
-            LeafReader leaf = leaves.get(i).reader();
-            Bits liveDocs = leaf.getLiveDocs();
-
-            TermsEnum termsEnum = null;
-            NumericDocValues dvField = null;
-            PostingsEnum docsEnum = null;
-
-            final Fields fields = leaf.fields();
-            if (fields != null) {
-                Terms terms = fields.terms(UidFieldMapper.NAME);
-                if (terms != null) {
-                    termsEnum = terms.iterator();
-                    assert termsEnum != null;
-                    dvField = leaf.getNumericDocValues(SeqNoFieldMapper.PRIMARY_TERM_NAME);
-                    assert dvField != null;
-
-                    final BytesRef id = term.bytes();
-                    if (termsEnum.seekExact(id)) {
-                        // there may be more than one matching docID, in the
-                        // case of nested docs, so we want the last one:
-                        docsEnum = termsEnum.postings(docsEnum, 0);
-                        int docID = DocIdSetIterator.NO_MORE_DOCS;
-                        for (int d = docsEnum.nextDoc();
-                             d != DocIdSetIterator.NO_MORE_DOCS;
-                             d = docsEnum.nextDoc()) {
-                            if (liveDocs != null && liveDocs.get(d) == false) {
-                                continue;
-                            }
-                            docID = d;
-                        }
-
-                        if (docID != DocIdSetIterator.NO_MORE_DOCS) {
-                            return dvField.get(docID);
-                        }
-                    }
-                }
-            }
-
-        }
-        return 0;
-    }
-}

core/src/main/java/org/elasticsearch/common/settings/ClusterSettings.java

@@ -311,9 +311,12 @@ public final class ClusterSettings extends AbstractScopedSettings {
                     HunspellService.HUNSPELL_IGNORE_CASE,
                     HunspellService.HUNSPELL_DICTIONARY_OPTIONS,
                     IndicesStore.INDICES_STORE_DELETE_SHARD_TIMEOUT,
+                    Environment.DEFAULT_PATH_CONF_SETTING,
                     Environment.PATH_CONF_SETTING,
+                    Environment.DEFAULT_PATH_DATA_SETTING,
                     Environment.PATH_DATA_SETTING,
                     Environment.PATH_HOME_SETTING,
+                    Environment.DEFAULT_PATH_LOGS_SETTING,
                     Environment.PATH_LOGS_SETTING,
                     Environment.PATH_REPO_SETTING,
                     Environment.PATH_SCRIPTS_SETTING,

core/src/main/java/org/elasticsearch/common/settings/Settings.java

@@ -57,6 +57,7 @@ import java.util.HashSet;
 import java.util.Iterator;
 import java.util.LinkedHashMap;
 import java.util.List;
+import java.util.Locale;
 import java.util.Map;
 import java.util.NoSuchElementException;
 import java.util.Objects;
@@ -442,6 +443,20 @@ public final class Settings implements ToXContent {
     public String[] getAsArray(String settingPrefix, String[] defaultArray, Boolean commaDelimited) throws SettingsException {
         List<String> result = new ArrayList<>();
 
+        final String valueFromPrefix = get(settingPrefix);
+        final String valueFromPreifx0 = get(settingPrefix + ".0");
+
+        if (valueFromPrefix != null && valueFromPreifx0 != null) {
+            final String message = String.format(
+                    Locale.ROOT,
+                    "settings object contains values for [%s=%s] and [%s=%s]",
+                    settingPrefix,
+                    valueFromPrefix,
+                    settingPrefix + ".0",
+                    valueFromPreifx0);
+            throw new IllegalStateException(message);
+        }
+
         if (get(settingPrefix) != null) {
             if (commaDelimited) {
                 String[] strings = Strings.splitStringByCommaToArray(get(settingPrefix));
@@ -1048,13 +1063,11 @@ public final class Settings implements ToXContent {
             return this;
         }
 
-        public Builder putProperties(Map<String, String> esSettings, Predicate<String> keyPredicate, Function<String, String> keyFunction) {
+        public Builder putProperties(final Map<String, String> esSettings, final Function<String, String> keyFunction) {
             for (final Map.Entry<String, String> esSetting : esSettings.entrySet()) {
                 final String key = esSetting.getKey();
-                if (keyPredicate.test(key)) {
                 map.put(keyFunction.apply(key), esSetting.getValue());
             }
-            }
             return this;
         }
 

core/src/main/java/org/elasticsearch/common/xcontent/XContentBuilder.java

@@ -22,7 +22,7 @@ package org.elasticsearch.common.xcontent;
 import org.apache.lucene.util.BytesRef;
 import org.elasticsearch.common.bytes.BytesReference;
 import org.elasticsearch.common.geo.GeoPoint;
-import org.elasticsearch.common.io.BytesStream;
+import org.elasticsearch.common.io.stream.BytesStream;
 import org.elasticsearch.common.io.stream.BytesStreamOutput;
 import org.elasticsearch.common.lease.Releasable;
 import org.elasticsearch.common.text.Text;
@@ -53,7 +53,7 @@ import java.util.concurrent.TimeUnit;
 /**
  * A utility to build XContent (ie json).
  */
-public final class XContentBuilder implements BytesStream, Releasable, Flushable {
+public final class XContentBuilder implements Releasable, Flushable {
 
     /**
      * Create a new {@link XContentBuilder} using the given {@link XContent} content.
@@ -1041,7 +1041,6 @@ public final class XContentBuilder implements BytesStream, Releasable, Flushable
         return this.generator;
     }
 
-    @Override
     public BytesReference bytes() {
         close();
         return ((BytesStream) bos).bytes();

core/src/main/java/org/elasticsearch/discovery/zen/ElectMasterService.java

@@ -111,14 +111,14 @@ public class ElectMasterService extends AbstractComponent {
         return minimumMasterNodes;
     }
 
-    public boolean hasEnoughMasterNodes(Iterable<DiscoveryNode> nodes) {
+    public int countMasterNodes(Iterable<DiscoveryNode> nodes) {
         int count = 0;
         for (DiscoveryNode node : nodes) {
             if (node.isMasterNode()) {
                 count++;
             }
         }
-        return count > 0 && (minimumMasterNodes < 0 || count >= minimumMasterNodes);
+        return count;
     }
 
     public boolean hasEnoughCandidates(Collection<MasterCandidate> candidates) {
@@ -149,13 +149,12 @@ public class ElectMasterService extends AbstractComponent {
         return activeMasters.stream().min(ElectMasterService::compareNodes).get();
     }
 
+    public boolean hasEnoughMasterNodes(Iterable<DiscoveryNode> nodes) {
+        return minimumMasterNodes < 1 || countMasterNodes(nodes) >= minimumMasterNodes;
+    }
+
     public boolean hasTooManyMasterNodes(Iterable<DiscoveryNode> nodes) {
-        int count = 0;
-        for (DiscoveryNode node : nodes) {
-            if (node.isMasterNode()) {
-                count++;
-            }
-        }
+        final int count = countMasterNodes(nodes);
         return count > 1 && minimumMasterNodes <= count / 2;
     }
 

core/src/main/java/org/elasticsearch/discovery/zen/ZenDiscovery.java

@@ -47,6 +47,7 @@ import org.elasticsearch.common.io.stream.NamedWriteableRegistry;
 import org.elasticsearch.common.io.stream.StreamInput;
 import org.elasticsearch.common.io.stream.StreamOutput;
 import org.elasticsearch.common.lease.Releasables;
+import org.elasticsearch.common.logging.LoggerMessageFormat;
 import org.elasticsearch.common.settings.Setting;
 import org.elasticsearch.common.settings.Setting.Property;
 import org.elasticsearch.common.settings.Settings;
@@ -580,8 +581,10 @@ public class ZenDiscovery extends AbstractLifecycleComponent implements Discover
             final ClusterState remainingNodesClusterState = remainingNodesClusterState(currentState, remainingNodesBuilder);
 
             final ClusterTasksResult.Builder<Task> resultBuilder = ClusterTasksResult.<Task>builder().successes(tasks);
-            if (!electMasterService.hasEnoughMasterNodes(remainingNodesClusterState.nodes())) {
-                rejoin.accept("not enough master nodes");
+            if (electMasterService.hasEnoughMasterNodes(remainingNodesClusterState.nodes()) == false) {
+                final int masterNodes = electMasterService.countMasterNodes(remainingNodesClusterState.nodes());
+                rejoin.accept(LoggerMessageFormat.format("not enough master nodes (has [{}], but needed [{}])",
+                                                         masterNodes, electMasterService.minimumMasterNodes()));
                 return resultBuilder.build(currentState);
             } else {
                 return resultBuilder.build(allocationService.deassociateDeadNodes(remainingNodesClusterState, true, describeTasks(tasks)));
@@ -920,7 +923,8 @@ public class ZenDiscovery extends AbstractLifecycleComponent implements Discover
                 return winner.getNode();
             } else {
                 // if we don't have enough master nodes, we bail, because there are not enough master to elect from
-                logger.trace("not enough master nodes [{}]", masterCandidates);
+                logger.warn("not enough master nodes discovered during pinging (found [{}], but needed [{}]), pinging again",
+                            masterCandidates, electMaster.minimumMasterNodes());
                 return null;
             }
         } else {

core/src/main/java/org/elasticsearch/env/Environment.java

@@ -49,11 +49,17 @@ import static org.elasticsearch.common.Strings.cleanPath;
 // public+forbidden api!
 public class Environment {
     public static final Setting<String> PATH_HOME_SETTING = Setting.simpleString("path.home", Property.NodeScope);
-    public static final Setting<String> PATH_CONF_SETTING = Setting.simpleString("path.conf", Property.NodeScope);
+    public static final Setting<String> DEFAULT_PATH_CONF_SETTING = Setting.simpleString("default.path.conf", Property.NodeScope);
+    public static final Setting<String> PATH_CONF_SETTING =
+            new Setting<>("path.conf", DEFAULT_PATH_CONF_SETTING, Function.identity(), Property.NodeScope);
     public static final Setting<String> PATH_SCRIPTS_SETTING = Setting.simpleString("path.scripts", Property.NodeScope);
+    public static final Setting<List<String>> DEFAULT_PATH_DATA_SETTING =
+            Setting.listSetting("default.path.data", Collections.emptyList(), Function.identity(), Property.NodeScope);
     public static final Setting<List<String>> PATH_DATA_SETTING =
-        Setting.listSetting("path.data", Collections.emptyList(), Function.identity(), Property.NodeScope);
-    public static final Setting<String> PATH_LOGS_SETTING = Setting.simpleString("path.logs", Property.NodeScope);
+            Setting.listSetting("path.data", DEFAULT_PATH_DATA_SETTING, Function.identity(), Property.NodeScope);
+    public static final Setting<String> DEFAULT_PATH_LOGS_SETTING = Setting.simpleString("default.path.logs", Property.NodeScope);
+    public static final Setting<String> PATH_LOGS_SETTING =
+            new Setting<>("path.logs", DEFAULT_PATH_LOGS_SETTING, Function.identity(), Property.NodeScope);
     public static final Setting<List<String>> PATH_REPO_SETTING =
         Setting.listSetting("path.repo", Collections.emptyList(), Function.identity(), Property.NodeScope);
     public static final Setting<String> PATH_SHARED_DATA_SETTING = Setting.simpleString("path.shared_data", Property.NodeScope);
@@ -115,7 +121,8 @@ public class Environment {
             throw new IllegalStateException(PATH_HOME_SETTING.getKey() + " is not configured");
         }
 
-        if (PATH_CONF_SETTING.exists(settings)) {
+        // this is trappy, Setting#get(Settings) will get a fallback setting yet return false for Settings#exists(Settings)
+        if (PATH_CONF_SETTING.exists(settings) || DEFAULT_PATH_CONF_SETTING.exists(settings)) {
             configFile = PathUtils.get(cleanPath(PATH_CONF_SETTING.get(settings)));
         } else {
             configFile = homeFile.resolve("config");
@@ -156,7 +163,9 @@ public class Environment {
         } else {
             repoFiles = new Path[0];
         }
-        if (PATH_LOGS_SETTING.exists(settings)) {
+
+        // this is trappy, Setting#get(Settings) will get a fallback setting yet return false for Settings#exists(Settings)
+        if (PATH_LOGS_SETTING.exists(settings) || DEFAULT_PATH_LOGS_SETTING.exists(settings)) {
             logsFile = PathUtils.get(cleanPath(PATH_LOGS_SETTING.get(settings)));
         } else {
             logsFile = homeFile.resolve("logs");
@@ -174,7 +183,9 @@ public class Environment {
 
         Settings.Builder finalSettings = Settings.builder().put(settings);
         finalSettings.put(PATH_HOME_SETTING.getKey(), homeFile);
+        if (PATH_DATA_SETTING.exists(settings)) {
             finalSettings.putArray(PATH_DATA_SETTING.getKey(), dataPaths);
+        }
         finalSettings.put(PATH_LOGS_SETTING.getKey(), logsFile);
         this.settings = finalSettings.build();
 

core/src/main/java/org/elasticsearch/env/NodeEnvironment.java

@@ -202,7 +202,7 @@ public final class NodeEnvironment  implements Closeable {
                 for (int dirIndex = 0; dirIndex < environment.dataFiles().length; dirIndex++) {
                     Path dataDirWithClusterName = environment.dataWithClusterFiles()[dirIndex];
                     Path dataDir = environment.dataFiles()[dirIndex];
-                    Path dir = dataDir.resolve(NODES_FOLDER).resolve(Integer.toString(possibleLockId));
+                    Path dir = resolveNodePath(dataDir, possibleLockId);
                     Files.createDirectories(dir);
 
                     try (Directory luceneDir = FSDirectory.open(dir, NativeFSLockFactory.INSTANCE)) {
@@ -268,6 +268,17 @@ public final class NodeEnvironment  implements Closeable {
         }
     }
 
+    /**
+     * Resolve a specific nodes/{node.id} path for the specified path and node lock id.
+     *
+     * @param path       the path
+     * @param nodeLockId the node lock id
+     * @return the resolved path
+     */
+    public static Path resolveNodePath(final Path path, final int nodeLockId) {
+        return path.resolve(NODES_FOLDER).resolve(Integer.toString(nodeLockId));
+    }
+
     /** Returns true if the directory is empty */
     private static boolean dirEmpty(final Path path) throws IOException {
         try (DirectoryStream<Path> stream = Files.newDirectoryStream(path)) {
@@ -724,6 +735,14 @@ public final class NodeEnvironment  implements Closeable {
         return nodePaths;
     }
 
+    public int getNodeLockId() {
+        assertEnvIsLocked();
+        if (nodePaths == null || locks == null) {
+            throw new IllegalStateException("node is not configured to store local location");
+        }
+        return nodeLockId;
+    }
+
     /**
      * Returns all index paths.
      */
@@ -736,6 +755,8 @@ public final class NodeEnvironment  implements Closeable {
         return indexPaths;
     }
 
+
+
     /**
      * Returns all shard paths excluding custom shard path. Note: Shards are only allocated on one of the
      * returned paths. The returned array may contain paths to non-existing directories.
@@ -764,6 +785,25 @@ public final class NodeEnvironment  implements Closeable {
         assertEnvIsLocked();
         Set<String> indexFolders = new HashSet<>();
         for (NodePath nodePath : nodePaths) {
+            indexFolders.addAll(availableIndexFoldersForPath(nodePath));
+        }
+        return indexFolders;
+
+    }
+
+    /**
+     * Return all directory names in the nodes/{node.id}/indices directory for the given node path.
+     *
+     * @param nodePath the path
+     * @return all directories that could be indices for the given node path.
+     * @throws IOException if an I/O exception occurs traversing the filesystem
+     */
+    public Set<String> availableIndexFoldersForPath(final NodePath nodePath) throws IOException {
+        if (nodePaths == null || locks == null) {
+            throw new IllegalStateException("node is not configured to store local location");
+        }
+        assertEnvIsLocked();
+        final Set<String> indexFolders = new HashSet<>();
         Path indicesLocation = nodePath.indicesPath;
         if (Files.isDirectory(indicesLocation)) {
             try (DirectoryStream<Path> stream = Files.newDirectoryStream(indicesLocation)) {
@@ -774,9 +814,7 @@ public final class NodeEnvironment  implements Closeable {
                 }
             }
         }
-        }
         return indexFolders;
-
     }
 
     /**

core/src/main/java/org/elasticsearch/index/engine/DeleteVersionValue.java

@@ -27,18 +27,13 @@ class DeleteVersionValue extends VersionValue {
 
     private static final long BASE_RAM_BYTES_USED = RamUsageEstimator.shallowSizeOfInstance(DeleteVersionValue.class);
 
-    private final long time;
+    final long time;
 
-    DeleteVersionValue(long version, long time) {
-        super(version);
+    DeleteVersionValue(long version,long seqNo, long term, long time) {
+        super(version, seqNo, term);
         this.time = time;
     }
 
-    @Override
-    public long getTime() {
-        return this.time;
-    }
-
     @Override
     public boolean isDelete() {
         return true;
@@ -52,7 +47,9 @@ class DeleteVersionValue extends VersionValue {
     @Override
     public String toString() {
         return "DeleteVersionValue{" +
-            "version=" + getVersion() +
+            "version=" + version +
+            ", seqNo=" + seqNo +
+            ", term=" + term +
             ",time=" + time +
             '}';
     }

core/src/main/java/org/elasticsearch/index/engine/Engine.java

@@ -55,8 +55,8 @@ import org.elasticsearch.common.lease.Releasables;
 import org.elasticsearch.common.logging.Loggers;
 import org.elasticsearch.common.lucene.Lucene;
 import org.elasticsearch.common.lucene.uid.Versions;
-import org.elasticsearch.common.lucene.uid.VersionsResolver;
-import org.elasticsearch.common.lucene.uid.VersionsResolver.DocIdAndVersion;
+import org.elasticsearch.common.lucene.uid.VersionsAndSeqNoResolver;
+import org.elasticsearch.common.lucene.uid.VersionsAndSeqNoResolver.DocIdAndVersion;
 import org.elasticsearch.common.metrics.CounterMetric;
 import org.elasticsearch.common.unit.TimeValue;
 import org.elasticsearch.common.util.concurrent.ReleasableLock;
@@ -464,7 +464,7 @@ public abstract class Engine implements Closeable {
         final Searcher searcher = searcherFactory.apply("get");
         final DocIdAndVersion docIdAndVersion;
         try {
-            docIdAndVersion = VersionsResolver.loadDocIdAndVersion(searcher.reader(), get.uid());
+            docIdAndVersion = VersionsAndSeqNoResolver.loadDocIdAndVersion(searcher.reader(), get.uid());
         } catch (Exception e) {
             Releasables.closeWhileHandlingException(searcher);
             //TODO: A better exception goes here

core/src/main/java/org/elasticsearch/index/engine/InternalEngine.java

@@ -51,7 +51,8 @@ import org.elasticsearch.common.lucene.LoggerInfoStream;
 import org.elasticsearch.common.lucene.Lucene;
 import org.elasticsearch.common.lucene.index.ElasticsearchDirectoryReader;
 import org.elasticsearch.common.lucene.uid.Versions;
-import org.elasticsearch.common.lucene.uid.VersionsResolver;
+import org.elasticsearch.common.lucene.uid.VersionsAndSeqNoResolver;
+import org.elasticsearch.common.lucene.uid.VersionsAndSeqNoResolver.DocIdAndSeqNo;
 import org.elasticsearch.common.metrics.CounterMetric;
 import org.elasticsearch.common.unit.ByteSizeValue;
 import org.elasticsearch.common.util.concurrent.AbstractRunnable;
@@ -298,7 +299,7 @@ public class InternalEngine extends Engine {
                 throw new IllegalStateException("no translog generation present in commit data but translog is expected to exist");
             }
             if (generation.translogUUID == null) {
-                throw new IndexFormatTooOldException("trasnlog", "translog has no generation nor a UUID - this might be an index from a previous version consider upgrading to N-1 first");
+                throw new IndexFormatTooOldException("translog", "translog has no generation nor a UUID - this might be an index from a previous version consider upgrading to N-1 first");
             }
         }
         final Translog translog = new Translog(translogConfig, generation, globalCheckpointSupplier);
@@ -389,10 +390,10 @@ public class InternalEngine extends Engine {
                     if (versionValue.isDelete()) {
                         return GetResult.NOT_EXISTS;
                     }
-                    if (get.versionType().isVersionConflictForReads(versionValue.getVersion(), get.version())) {
+                    if (get.versionType().isVersionConflictForReads(versionValue.version, get.version())) {
                         Uid uid = Uid.createUid(get.uid().text());
                         throw new VersionConflictEngineException(shardId, uid.type(), uid.id(),
-                            get.versionType().explainConflictForReads(versionValue.getVersion(), get.version()));
+                            get.versionType().explainConflictForReads(versionValue.version, get.version()));
                     }
                     refresh("realtime_get");
                 }
@@ -416,6 +417,43 @@ public class InternalEngine extends Engine {
         LUCENE_DOC_NOT_FOUND
     }
 
+    private OpVsLuceneDocStatus compareOpToLuceneDocBasedOnSeqNo(final Operation op) throws IOException {
+        assert op.seqNo() != SequenceNumbersService.UNASSIGNED_SEQ_NO : "resolving ops based on seq# but no seqNo is found";
+        final OpVsLuceneDocStatus status;
+        final VersionValue versionValue = versionMap.getUnderLock(op.uid());
+        assert incrementVersionLookup();
+        if (versionValue != null) {
+            if  (op.seqNo() > versionValue.seqNo ||
+                (op.seqNo() == versionValue.seqNo && op.primaryTerm() > versionValue.term))
+                status = OpVsLuceneDocStatus.OP_NEWER;
+            else {
+                status = OpVsLuceneDocStatus.OP_STALE_OR_EQUAL;
+            }
+        } else {
+            // load from index
+            assert incrementIndexVersionLookup();
+            try (Searcher searcher = acquireSearcher("load_seq_no")) {
+                DocIdAndSeqNo docAndSeqNo = VersionsAndSeqNoResolver.loadDocIdAndSeqNo(searcher.reader(), op.uid());
+                if (docAndSeqNo == null) {
+                    status = OpVsLuceneDocStatus.LUCENE_DOC_NOT_FOUND;
+                } else if (op.seqNo() > docAndSeqNo.seqNo) {
+                    status = OpVsLuceneDocStatus.OP_NEWER;
+                } else if (op.seqNo() == docAndSeqNo.seqNo) {
+                    // load term to tie break
+                    final long existingTerm = VersionsAndSeqNoResolver.loadPrimaryTerm(docAndSeqNo);
+                    if (op.primaryTerm() > existingTerm) {
+                        status = OpVsLuceneDocStatus.OP_NEWER;
+                    } else {
+                        status = OpVsLuceneDocStatus.OP_STALE_OR_EQUAL;
+                    }
+                } else {
+                    status = OpVsLuceneDocStatus.OP_STALE_OR_EQUAL;
+                }
+            }
+        }
+        return status;
+    }
+
     /** resolves the current version of the document, returning null if not found */
     private VersionValue resolveDocVersion(final Operation op) throws IOException {
         assert incrementVersionLookup(); // used for asserting in tests
@@ -424,11 +462,10 @@ public class InternalEngine extends Engine {
             assert incrementIndexVersionLookup(); // used for asserting in tests
             final long currentVersion = loadCurrentVersionFromIndex(op.uid());
             if (currentVersion != Versions.NOT_FOUND) {
-                versionValue = new VersionValue(currentVersion);
+                versionValue = new VersionValue(currentVersion, SequenceNumbersService.UNASSIGNED_SEQ_NO, 0L);
             }
         } else if (engineConfig.isEnableGcDeletes() && versionValue.isDelete() &&
-            (engineConfig.getThreadPool().relativeTimeInMillis() - versionValue.getTime()) >
-                getGcDeletesInMillis()) {
+            (engineConfig.getThreadPool().relativeTimeInMillis() - ((DeleteVersionValue)versionValue).time) > getGcDeletesInMillis()) {
             versionValue = null;
         }
         return versionValue;
@@ -436,12 +473,13 @@ public class InternalEngine extends Engine {
 
     private OpVsLuceneDocStatus compareOpToLuceneDocBasedOnVersions(final Operation op)
         throws IOException {
+        assert op.seqNo() == SequenceNumbersService.UNASSIGNED_SEQ_NO : "op is resolved based on versions but have a seq#";
         assert op.version() >= 0 : "versions should be non-negative. got " + op.version();
         final VersionValue versionValue = resolveDocVersion(op);
         if (versionValue == null) {
             return OpVsLuceneDocStatus.LUCENE_DOC_NOT_FOUND;
         } else {
-            return op.versionType().isVersionConflictForWrites(versionValue.getVersion(), op.version(), versionValue.isDelete()) ?
+            return op.versionType().isVersionConflictForWrites(versionValue.version, op.version(), versionValue.isDelete()) ?
                 OpVsLuceneDocStatus.OP_STALE_OR_EQUAL : OpVsLuceneDocStatus.OP_NEWER;
         }
     }
@@ -601,7 +639,16 @@ public class InternalEngine extends Engine {
             // unlike the primary, replicas don't really care to about creation status of documents
             // this allows to ignore the case where a document was found in the live version maps in
             // a delete state and return false for the created flag in favor of code simplicity
-            final OpVsLuceneDocStatus opVsLucene = compareOpToLuceneDocBasedOnVersions(index);
+            final OpVsLuceneDocStatus opVsLucene;
+            if (index.seqNo() != SequenceNumbersService.UNASSIGNED_SEQ_NO) {
+                opVsLucene = compareOpToLuceneDocBasedOnSeqNo(index);
+            } else {
+                // This can happen if the primary is still on an old node and send traffic without seq# or we recover from translog
+                // created by an old version.
+                assert config().getIndexSettings().getIndexVersionCreated().before(Version.V_6_0_0_alpha1_UNRELEASED) :
+                    "index is newly created but op has no sequence numbers. op: " + index;
+                opVsLucene = compareOpToLuceneDocBasedOnVersions(index);
+            }
             if (opVsLucene == OpVsLuceneDocStatus.OP_STALE_OR_EQUAL) {
                 plan = IndexingStrategy.processButSkipLucene(false, index.seqNo(), index.version());
             } else {
@@ -633,7 +680,7 @@ public class InternalEngine extends Engine {
                 currentVersion = Versions.NOT_FOUND;
                 currentNotFoundOrDeleted = true;
             } else {
-                currentVersion = versionValue.getVersion();
+                currentVersion = versionValue.version;
                 currentNotFoundOrDeleted = versionValue.isDelete();
             }
             if (index.versionType().isVersionConflictForWrites(
@@ -671,9 +718,9 @@ public class InternalEngine extends Engine {
                 assert assertDocDoesNotExist(index, canOptimizeAddDocument(index) == false);
                 index(index.docs(), indexWriter);
             }
-            versionMap.putUnderLock(index.uid().bytes(), new VersionValue(plan.versionForIndexing));
-            return new IndexResult(plan.versionForIndexing, plan.seqNoForIndexing,
-                plan.currentNotFoundOrDeleted);
+            versionMap.putUnderLock(index.uid().bytes(),
+                new VersionValue(plan.versionForIndexing, plan.seqNoForIndexing, index.primaryTerm()));
+            return new IndexResult(plan.versionForIndexing, plan.seqNoForIndexing, plan.currentNotFoundOrDeleted);
         } catch (Exception ex) {
             if (indexWriter.getTragicException() == null) {
                 /* There is no tragic event recorded so this must be a document failure.
@@ -873,7 +920,14 @@ public class InternalEngine extends Engine {
         // unlike the primary, replicas don't really care to about found status of documents
         // this allows to ignore the case where a document was found in the live version maps in
         // a delete state and return true for the found flag in favor of code simplicity
-        final OpVsLuceneDocStatus opVsLucene = compareOpToLuceneDocBasedOnVersions(delete);
+        final OpVsLuceneDocStatus opVsLucene;
+        if (delete.seqNo() != SequenceNumbersService.UNASSIGNED_SEQ_NO) {
+            opVsLucene = compareOpToLuceneDocBasedOnSeqNo(delete);
+        } else {
+            assert config().getIndexSettings().getIndexVersionCreated().before(Version.V_6_0_0_alpha1_UNRELEASED) :
+                "index is newly created but op has no sequence numbers. op: " + delete;
+            opVsLucene = compareOpToLuceneDocBasedOnVersions(delete);
+        }
 
         final DeletionStrategy plan;
         if (opVsLucene == OpVsLuceneDocStatus.OP_STALE_OR_EQUAL) {
@@ -898,7 +952,7 @@ public class InternalEngine extends Engine {
             currentVersion = Versions.NOT_FOUND;
             currentlyDeleted = true;
         } else {
-            currentVersion = versionValue.getVersion();
+            currentVersion = versionValue.version;
             currentlyDeleted = versionValue.isDelete();
         }
         final DeletionStrategy plan;
@@ -923,7 +977,7 @@ public class InternalEngine extends Engine {
                 indexWriter.deleteDocuments(delete.uid());
             }
             versionMap.putUnderLock(delete.uid().bytes(),
-                new DeleteVersionValue(plan.versionOfDeletion,
+                new DeleteVersionValue(plan.versionOfDeletion, plan.seqNoOfDeletion, delete.primaryTerm(),
                     engineConfig.getThreadPool().relativeTimeInMillis()));
             return new DeleteResult(
                 plan.versionOfDeletion, plan.seqNoOfDeletion, plan.currentlyDeleted == false);
@@ -1179,12 +1233,12 @@ public class InternalEngine extends Engine {
                     try {
                         translog.prepareCommit();
                         logger.trace("starting commit for flush; commitTranslog=true");
-                        commitIndexWriter(indexWriter, translog, null);
+                        final long committedGeneration = commitIndexWriter(indexWriter, translog, null);
                         logger.trace("finished commit for flush");
                         // we need to refresh in order to clear older version values
                         refresh("version_table_flush");
                         // after refresh documents can be retrieved from the index so we can now commit the translog
-                        translog.commit();
+                        translog.commit(committedGeneration);
                     } catch (Exception e) {
                         throw new FlushFailedEngineException(shardId, e);
                     }
@@ -1235,14 +1289,14 @@ public class InternalEngine extends Engine {
         // TODO: not good that we reach into LiveVersionMap here; can we move this inside VersionMap instead?  problem is the dirtyLock...
 
         // we only need to prune the deletes map; the current/old version maps are cleared on refresh:
-        for (Map.Entry<BytesRef, VersionValue> entry : versionMap.getAllTombstones()) {
+        for (Map.Entry<BytesRef, DeleteVersionValue> entry : versionMap.getAllTombstones()) {
             BytesRef uid = entry.getKey();
             try (Releasable ignored = acquireLock(uid)) { // can we do it without this lock on each value? maybe batch to a set and get the lock once per set?
 
                 // Must re-get it here, vs using entry.getValue(), in case the uid was indexed/deleted since we pulled the iterator:
-                VersionValue versionValue = versionMap.getTombstoneUnderLock(uid);
+                DeleteVersionValue versionValue = versionMap.getTombstoneUnderLock(uid);
                 if (versionValue != null) {
-                    if (timeMSec - versionValue.getTime() > getGcDeletesInMillis()) {
+                    if (timeMSec - versionValue.time > getGcDeletesInMillis()) {
                         versionMap.removeTombstoneUnderLock(uid);
                     }
                 }
@@ -1490,7 +1544,7 @@ public class InternalEngine extends Engine {
     private long loadCurrentVersionFromIndex(Term uid) throws IOException {
         assert incrementIndexVersionLookup();
         try (Searcher searcher = acquireSearcher("load_version")) {
-            return VersionsResolver.loadVersion(searcher.reader(), uid);
+            return VersionsAndSeqNoResolver.loadVersion(searcher.reader(), uid);
         }
     }
 
@@ -1680,55 +1734,65 @@ public class InternalEngine extends Engine {
         }
     }
 
-    private void commitIndexWriter(IndexWriter writer, Translog translog, String syncId) throws IOException {
+    /**
+     * Commits the specified index writer.
+     *
+     * @param writer   the index writer to commit
+     * @param translog the translog
+     * @param syncId   the sync flush ID ({@code null} if not committing a synced flush)
+     * @return the minimum translog generation for the local checkpoint committed with the specified index writer
+     * @throws IOException if an I/O exception occurs committing the specfied writer
+     */
+    private long commitIndexWriter(final IndexWriter writer, final Translog translog, @Nullable final String syncId) throws IOException {
         ensureCanFlush();
         try {
-            Translog.TranslogGeneration translogGeneration = translog.getGeneration();
-
-            final String translogFileGen = Long.toString(translogGeneration.translogFileGeneration);
+            final long localCheckpoint = seqNoService().getLocalCheckpoint();
+            final Translog.TranslogGeneration translogGeneration = translog.getMinGenerationForSeqNo(localCheckpoint + 1);
+            final String translogFileGeneration = Long.toString(translogGeneration.translogFileGeneration);
             final String translogUUID = translogGeneration.translogUUID;
-            final String localCheckpoint = Long.toString(seqNoService().getLocalCheckpoint());
+            final String localCheckpointValue = Long.toString(localCheckpoint);
 
             writer.setLiveCommitData(() -> {
                 /*
                  * The user data captured above (e.g. local checkpoint) contains data that must be evaluated *before* Lucene flushes
-                 * segments, including the local checkpoint amongst other values. The maximum sequence number is different - we never want
+                 * segments, including the local checkpoint amongst other values. The maximum sequence number is different, we never want
                  * the maximum sequence number to be less than the last sequence number to go into a Lucene commit, otherwise we run the
                  * risk of re-using a sequence number for two different documents when restoring from this commit point and subsequently
                  * writing new documents to the index. Since we only know which Lucene documents made it into the final commit after the
-                 * {@link IndexWriter#commit()} call flushes all documents, we defer computation of the max_seq_no to the time of invocation
-                 * of the commit data iterator (which occurs after all documents have been flushed to Lucene).
+                 * {@link IndexWriter#commit()} call flushes all documents, we defer computation of the maximum sequence number to the time
+                 * of invocation of the commit data iterator (which occurs after all documents have been flushed to Lucene).
                  */
-                final Map<String, String> commitData = new HashMap<>(6);
-                commitData.put(Translog.TRANSLOG_GENERATION_KEY, translogFileGen);
+                final Map<String, String> commitData = new HashMap<>(5);
+                commitData.put(Translog.TRANSLOG_GENERATION_KEY, translogFileGeneration);
                 commitData.put(Translog.TRANSLOG_UUID_KEY, translogUUID);
-                commitData.put(SequenceNumbers.LOCAL_CHECKPOINT_KEY, localCheckpoint);
+                commitData.put(SequenceNumbers.LOCAL_CHECKPOINT_KEY, localCheckpointValue);
                 if (syncId != null) {
                     commitData.put(Engine.SYNC_COMMIT_ID, syncId);
                 }
                 commitData.put(SequenceNumbers.MAX_SEQ_NO, Long.toString(seqNoService().getMaxSeqNo()));
-                if (logger.isTraceEnabled()) {
                 logger.trace("committing writer with commit data [{}]", commitData);
-                }
                 return commitData.entrySet().iterator();
             });
 
             writer.commit();
-        } catch (Exception ex) {
+            return translogGeneration.translogFileGeneration;
+        } catch (final Exception ex) {
             try {
                 failEngine("lucene commit failed", ex);
-            } catch (Exception inner) {
+            } catch (final Exception inner) {
                 ex.addSuppressed(inner);
             }
             throw ex;
-        } catch (AssertionError e) {
-            // IndexWriter throws AssertionError on commit, if asserts are enabled, if any files don't exist, but tests that
-            // randomly throw FNFE/NSFE can also hit this:
+        } catch (final AssertionError e) {
+            /*
+             * If assertions are enabled, IndexWriter throws AssertionError on commit if any files don't exist, but tests that randomly
+             * throw FileNotFoundException or NoSuchFileException can also hit this.
+             */
             if (ExceptionsHelper.stackTrace(e).contains("org.apache.lucene.index.IndexWriter.filesExist")) {
-                EngineException engineException = new EngineException(shardId, "failed to commit engine", e);
+                final EngineException engineException = new EngineException(shardId, "failed to commit engine", e);
                 try {
                     failEngine("lucene commit failed", engineException);
-                } catch (Exception inner) {
+                } catch (final Exception inner) {
                     engineException.addSuppressed(inner);
                 }
                 throw engineException;
@@ -1812,7 +1876,7 @@ public class InternalEngine extends Engine {
      * Gets the commit data from {@link IndexWriter} as a map.
      */
     private static Map<String, String> commitDataAsMap(final IndexWriter indexWriter) {
-        Map<String, String> commitData = new HashMap<>(6);
+        Map<String, String> commitData = new HashMap<>(5);
         for (Map.Entry<String, String> entry : indexWriter.getLiveCommitData()) {
             commitData.put(entry.getKey(), entry.getValue());
         }

core/src/main/java/org/elasticsearch/index/engine/LiveVersionMap.java

@@ -55,7 +55,7 @@ class LiveVersionMap implements ReferenceManager.RefreshListener, Accountable {
     }
 
     // All deletes also go here, and delete "tombstones" are retained after refresh:
-    private final Map<BytesRef,VersionValue> tombstones = ConcurrentCollections.newConcurrentMapWithAggressiveConcurrency();
+    private final Map<BytesRef,DeleteVersionValue> tombstones = ConcurrentCollections.newConcurrentMapWithAggressiveConcurrency();
 
     private volatile Maps maps = new Maps();
 
@@ -180,7 +180,7 @@ class LiveVersionMap implements ReferenceManager.RefreshListener, Accountable {
         final VersionValue prevTombstone;
         if (version.isDelete()) {
             // Also enroll the delete into tombstones, and account for its RAM too:
-            prevTombstone = tombstones.put(uid, version);
+            prevTombstone = tombstones.put(uid, (DeleteVersionValue)version);
 
             // We initially account for BytesRef/VersionValue RAM for a delete against the tombstones, because this RAM will not be freed up
             // on refresh. Later, in removeTombstoneUnderLock, if we clear the tombstone entry but the delete remains in current, we shift
@@ -225,12 +225,12 @@ class LiveVersionMap implements ReferenceManager.RefreshListener, Accountable {
     }
 
     /** Caller has a lock, so that this uid will not be concurrently added/deleted by another thread. */
-    VersionValue getTombstoneUnderLock(BytesRef uid) {
+    DeleteVersionValue getTombstoneUnderLock(BytesRef uid) {
         return tombstones.get(uid);
     }
 
     /** Iterates over all deleted versions, including new ones (not yet exposed via reader) and old ones (exposed via reader but not yet GC'd). */
-    Iterable<Map.Entry<BytesRef,VersionValue>> getAllTombstones() {
+    Iterable<Map.Entry<BytesRef, DeleteVersionValue>> getAllTombstones() {
         return tombstones.entrySet();
     }
 

core/src/main/java/org/elasticsearch/index/engine/VersionValue.java

@@ -30,18 +30,17 @@ class VersionValue implements Accountable {
     private static final long BASE_RAM_BYTES_USED = RamUsageEstimator.shallowSizeOfInstance(VersionValue.class);
 
     /** the version of the document. used for versioned indexed operations and as a BWC layer, where no seq# are set yet */
-    private final long version;
+    final long version;
 
-    VersionValue(long version) {
+    /** the seq number of the operation that last changed the associated uuid */
+    final long seqNo;
+    /** the the term of the operation that last changed the associated uuid */
+    final long term;
+
+    VersionValue(long version, long seqNo, long term) {
         this.version = version;
-    }
-
-    public long getTime() {
-        throw new UnsupportedOperationException();
-    }
-
-    public long getVersion() {
-        return version;
+        this.seqNo = seqNo;
+        this.term = term;
     }
 
     public boolean isDelete() {
@@ -61,6 +60,9 @@ class VersionValue implements Accountable {
     @Override
     public String toString() {
         return "VersionValue{" +
-            "version=" + version + "}";
+            "version=" + version +
+            ", seqNo=" + seqNo +
+            ", term=" + term +
+            '}';
     }
 }

core/src/main/java/org/elasticsearch/index/get/ShardGetService.java

@@ -24,7 +24,7 @@ import org.elasticsearch.ElasticsearchException;
 import org.elasticsearch.common.Nullable;
 import org.elasticsearch.common.bytes.BytesReference;
 import org.elasticsearch.common.collect.Tuple;
-import org.elasticsearch.common.lucene.uid.VersionsResolver.DocIdAndVersion;
+import org.elasticsearch.common.lucene.uid.VersionsAndSeqNoResolver.DocIdAndVersion;
 import org.elasticsearch.common.metrics.CounterMetric;
 import org.elasticsearch.common.metrics.MeanMetric;
 import org.elasticsearch.common.util.set.Sets;

core/src/main/java/org/elasticsearch/index/mapper/ParseContext.java

@@ -254,12 +254,12 @@ public abstract class ParseContext {
         }
 
         @Override
-        public SeqNoFieldMapper.SequenceID seqID() {
+        public SeqNoFieldMapper.SequenceIDFields seqID() {
             return in.seqID();
         }
 
         @Override
-        public void seqID(SeqNoFieldMapper.SequenceID seqID) {
+        public void seqID(SeqNoFieldMapper.SequenceIDFields seqID) {
             in.seqID(seqID);
         }
 
@@ -310,7 +310,7 @@ public abstract class ParseContext {
 
         private Field version;
 
-        private SeqNoFieldMapper.SequenceID seqID;
+        private SeqNoFieldMapper.SequenceIDFields seqID;
 
         private final AllEntries allEntries;
 
@@ -404,12 +404,12 @@ public abstract class ParseContext {
         }
 
         @Override
-        public SeqNoFieldMapper.SequenceID seqID() {
+        public SeqNoFieldMapper.SequenceIDFields seqID() {
             return this.seqID;
         }
 
         @Override
-        public void seqID(SeqNoFieldMapper.SequenceID seqID) {
+        public void seqID(SeqNoFieldMapper.SequenceIDFields seqID) {
             this.seqID = seqID;
         }
 
@@ -539,9 +539,9 @@ public abstract class ParseContext {
 
     public abstract void version(Field version);
 
-    public abstract SeqNoFieldMapper.SequenceID seqID();
+    public abstract SeqNoFieldMapper.SequenceIDFields seqID();
 
-    public abstract void seqID(SeqNoFieldMapper.SequenceID seqID);
+    public abstract void seqID(SeqNoFieldMapper.SequenceIDFields seqID);
 
     public final boolean includeInAll(Boolean includeInAll, FieldMapper mapper) {
         return includeInAll(includeInAll, mapper.fieldType().indexOptions() != IndexOptions.NONE);

core/src/main/java/org/elasticsearch/index/mapper/ParsedDocument.java

@@ -36,7 +36,7 @@ public class ParsedDocument {
 
     private final String id, type;
     private final BytesRef uid;
-    private final SeqNoFieldMapper.SequenceID seqID;
+    private final SeqNoFieldMapper.SequenceIDFields seqID;
 
     private final String routing;
 
@@ -50,7 +50,7 @@ public class ParsedDocument {
     private String parent;
 
     public ParsedDocument(Field version,
-                          SeqNoFieldMapper.SequenceID seqID,
+                          SeqNoFieldMapper.SequenceIDFields seqID,
                           String id,
                           String type,
                           String routing,

core/src/main/java/org/elasticsearch/index/mapper/SeqNoFieldMapper.java

@@ -22,7 +22,6 @@ package org.elasticsearch.index.mapper;
 import org.apache.lucene.document.Field;
 import org.apache.lucene.document.LongPoint;
 import org.apache.lucene.document.NumericDocValuesField;
-import org.apache.lucene.document.SortedNumericDocValuesField;
 import org.apache.lucene.index.DocValuesType;
 import org.apache.lucene.index.IndexReader;
 import org.apache.lucene.index.IndexableField;
@@ -66,13 +65,13 @@ public class SeqNoFieldMapper extends MetadataFieldMapper {
      * A sequence ID, which is made up of a sequence number (both the searchable
      * and doc_value version of the field) and the primary term.
      */
-    public static class SequenceID {
+    public static class SequenceIDFields {
 
         public final Field seqNo;
         public final Field seqNoDocValue;
         public final Field primaryTerm;
 
-        public SequenceID(Field seqNo, Field seqNoDocValue, Field primaryTerm) {
+        public SequenceIDFields(Field seqNo, Field seqNoDocValue, Field primaryTerm) {
             Objects.requireNonNull(seqNo, "sequence number field cannot be null");
             Objects.requireNonNull(seqNoDocValue, "sequence number dv field cannot be null");
             Objects.requireNonNull(primaryTerm, "primary term field cannot be null");
@@ -81,9 +80,9 @@ public class SeqNoFieldMapper extends MetadataFieldMapper {
             this.primaryTerm = primaryTerm;
         }
 
-        public static SequenceID emptySeqID() {
-            return new SequenceID(new LongPoint(NAME, SequenceNumbersService.UNASSIGNED_SEQ_NO),
-                    new SortedNumericDocValuesField(NAME, SequenceNumbersService.UNASSIGNED_SEQ_NO),
+        public static SequenceIDFields emptySeqID() {
+            return new SequenceIDFields(new LongPoint(NAME, SequenceNumbersService.UNASSIGNED_SEQ_NO),
+                    new NumericDocValuesField(NAME, SequenceNumbersService.UNASSIGNED_SEQ_NO),
                     new NumericDocValuesField(PRIMARY_TERM_NAME, 0));
         }
     }
@@ -242,7 +241,7 @@ public class SeqNoFieldMapper extends MetadataFieldMapper {
     protected void parseCreateField(ParseContext context, List<IndexableField> fields) throws IOException {
         // see InternalEngine.innerIndex to see where the real version value is set
         // also see ParsedDocument.updateSeqID (called by innerIndex)
-        SequenceID seqID = SequenceID.emptySeqID();
+        SequenceIDFields seqID = SequenceIDFields.emptySeqID();
         context.seqID(seqID);
         fields.add(seqID.seqNo);
         fields.add(seqID.seqNoDocValue);
@@ -264,7 +263,7 @@ public class SeqNoFieldMapper extends MetadataFieldMapper {
         for (int i = 1; i < context.docs().size(); i++) {
             final Document doc = context.docs().get(i);
             doc.add(new LongPoint(NAME, 1));
-            doc.add(new SortedNumericDocValuesField(NAME, 1L));
+            doc.add(new NumericDocValuesField(NAME, 1L));
             doc.add(new NumericDocValuesField(PRIMARY_TERM_NAME, 0L));
         }
     }

core/src/main/java/org/elasticsearch/index/termvectors/TermVectorsService.java

@@ -34,7 +34,7 @@ import org.elasticsearch.action.termvectors.TermVectorsResponse;
 import org.elasticsearch.common.Nullable;
 import org.elasticsearch.common.Strings;
 import org.elasticsearch.common.bytes.BytesReference;
-import org.elasticsearch.common.lucene.uid.VersionsResolver.DocIdAndVersion;
+import org.elasticsearch.common.lucene.uid.VersionsAndSeqNoResolver.DocIdAndVersion;
 import org.elasticsearch.common.xcontent.XContentHelper;
 import org.elasticsearch.common.xcontent.XContentType;
 import org.elasticsearch.common.xcontent.support.XContentMapValues;

core/src/main/java/org/elasticsearch/index/translog/Translog.java

@@ -85,14 +85,14 @@ import java.util.stream.Stream;
  * When a translog is opened the checkpoint is use to retrieve the latest translog file generation and subsequently to open the last written file to recovery operations.
  * The {@link org.elasticsearch.index.translog.Translog.TranslogGeneration}, given when the translog is opened / constructed is compared against
  * the latest generation and all consecutive translog files singe the given generation and the last generation in the checkpoint will be recovered and preserved until the next
- * generation is committed using {@link Translog#commit()}. In the common case the translog file generation in the checkpoint and the generation passed to the translog on creation are
- * the same. The only situation when they can be different is when an actual translog commit fails in between {@link Translog#prepareCommit()} and {@link Translog#commit()}. In such a case
+ * generation is committed using {@link Translog#commit(long)}. In the common case the translog file generation in the checkpoint and the generation passed to the translog on creation are
+ * the same. The only situation when they can be different is when an actual translog commit fails in between {@link Translog#prepareCommit()} and {@link Translog#commit(long)}. In such a case
  * the currently being committed translog file will not be deleted since it's commit was not successful. Yet, a new/current translog file is already opened at that point such that there is more than
  * one translog file present. Such an uncommitted translog file always has a <tt>translog-${gen}.ckp</tt> associated with it which is an fsynced copy of the it's last <tt>translog.ckp</tt> such that in
  * disaster recovery last fsynced offsets, number of operation etc. are still preserved.
  * </p>
  */
-public class Translog extends AbstractIndexShardComponent implements IndexShardComponent, Closeable, TwoPhaseCommit {
+public class Translog extends AbstractIndexShardComponent implements IndexShardComponent, Closeable {
 
     /*
      * TODO
@@ -439,7 +439,7 @@ public class Translog extends AbstractIndexShardComponent implements IndexShardC
             }
             throw new TranslogException(shardId, "Failed to write operation [" + operation + "]", e);
         } finally {
-            Releasables.close(out.bytes());
+            Releasables.close(out);
         }
     }
 
@@ -804,6 +804,8 @@ public class Translog extends AbstractIndexShardComponent implements IndexShardC
 
         long seqNo();
 
+        long primaryTerm();
+
         /**
          * Reads the type and the operation from the given stream. The operation must be written with
          * {@link Operation#writeType(Operation, StreamOutput)}
@@ -953,6 +955,7 @@ public class Translog extends AbstractIndexShardComponent implements IndexShardC
             return seqNo;
         }
 
+        @Override
         public long primaryTerm() {
             return primaryTerm;
         }
@@ -1104,6 +1107,7 @@ public class Translog extends AbstractIndexShardComponent implements IndexShardC
             return seqNo;
         }
 
+        @Override
         public long primaryTerm() {
             return primaryTerm;
         }
@@ -1180,6 +1184,7 @@ public class Translog extends AbstractIndexShardComponent implements IndexShardC
             return seqNo;
         }
 
+        @Override
         public long primaryTerm() {
             return primaryTerm;
         }
@@ -1332,7 +1337,7 @@ public class Translog extends AbstractIndexShardComponent implements IndexShardC
                 bytes.writeTo(outStream);
             }
         } finally {
-            Releasables.close(out.bytes());
+            Releasables.close(out);
         }
 
     }
@@ -1347,6 +1352,31 @@ public class Translog extends AbstractIndexShardComponent implements IndexShardC
         out.writeInt((int) checksum);
     }
 
+    /**
+     * Gets the minimum generation that could contain any sequence number after the specified sequence number, or the current generation if
+     * there is no generation that could any such sequence number.
+     *
+     * @param seqNo the sequence number
+     * @return the minimum generation for the sequence number
+     */
+    public TranslogGeneration getMinGenerationForSeqNo(final long seqNo) {
+        try (ReleasableLock ignored = writeLock.acquire()) {
+            /*
+             * When flushing, the engine will ask the translog for the minimum generation that could contain any sequence number after the
+             * local checkpoint. Immediately after flushing, there will be no such generation, so this minimum generation in this case will
+             * be the current translog generation as we do not need any prior generations to have a complete history up to the current local
+             * checkpoint.
+             */
+            long minTranslogFileGeneration = this.currentFileGeneration();
+            for (final TranslogReader reader : readers) {
+                if (seqNo <= reader.getCheckpoint().maxSeqNo) {
+                    minTranslogFileGeneration = Math.min(minTranslogFileGeneration, reader.getGeneration());
+                }
+            }
+            return new TranslogGeneration(translogUUID, minTranslogFileGeneration);
+        }
+    }
+
     /**
      * Roll the current translog generation into a new generation. This does not commit the
      * translog.
@@ -1375,27 +1405,38 @@ public class Translog extends AbstractIndexShardComponent implements IndexShardC
         }
     }
 
-    @Override
-    public long prepareCommit() throws IOException {
+    /**
+     * Prepares a translog commit by setting the current committing generation and rolling the translog generation.
+     *
+     * @throws IOException if an I/O exception occurred while rolling the translog generation
+     */
+    public void prepareCommit() throws IOException {
         try (ReleasableLock ignored = writeLock.acquire()) {
             ensureOpen();
             if (currentCommittingGeneration != NOT_SET_GENERATION) {
-                final String message = String.format(
-                        Locale.ROOT,
-                        "already committing a translog with generation [%d]",
-                        currentCommittingGeneration);
+                final String message =
+                        String.format(Locale.ROOT, "already committing a translog with generation [%d]", currentCommittingGeneration);
                 throw new IllegalStateException(message);
             }
             currentCommittingGeneration = current.getGeneration();
             rollGeneration();
         }
-        return 0;
     }
 
-    @Override
-    public long commit() throws IOException {
+    /**
+     * Commits the translog and sets the last committed translog generation to the specified generation. The specified committed generation
+     * will be used when trimming unreferenced translog generations such that generations from the committed generation will be preserved.
+     *
+     * If {@link Translog#prepareCommit()} was not called before calling commit, this method will be invoked too causing the translog
+     * generation to be rolled.
+     *
+     * @param committedGeneration the minimum translog generation to preserve after trimming unreferenced generations
+     * @throws IOException if an I/O exception occurred preparing the translog commit
+     */
+    public void commit(final long committedGeneration) throws IOException {
         try (ReleasableLock ignored = writeLock.acquire()) {
             ensureOpen();
+            assert assertCommittedGenerationIsInValidRange(committedGeneration);
             if (currentCommittingGeneration == NOT_SET_GENERATION) {
                 prepareCommit();
             }
@@ -1403,26 +1444,39 @@ public class Translog extends AbstractIndexShardComponent implements IndexShardC
             assert readers.stream().anyMatch(r -> r.getGeneration() == currentCommittingGeneration)
                     : "readers missing committing generation [" + currentCommittingGeneration + "]";
             // set the last committed generation otherwise old files will not be cleaned up
-            lastCommittedTranslogFileGeneration = currentCommittingGeneration + 1;
+            lastCommittedTranslogFileGeneration = committedGeneration;
             currentCommittingGeneration = NOT_SET_GENERATION;
             trimUnreferencedReaders();
         }
-        return 0;
     }
 
+    private boolean assertCommittedGenerationIsInValidRange(final long committedGeneration) {
+        assert committedGeneration <= current.generation
+                : "tried to commit generation [" + committedGeneration + "] after current generation [" + current.generation + "]";
+        final long min = readers.stream().map(TranslogReader::getGeneration).min(Long::compareTo).orElse(Long.MIN_VALUE);
+        assert committedGeneration >= min
+                : "tried to commit generation [" + committedGeneration + "] before minimum generation [" + min + "]";
+        return true;
+    }
+
+    /**
+     * Trims unreferenced translog generations. The guarantee here is that translog generations will be preserved for all outstanding views
+     * and from the last committed translog generation defined by {@link Translog#lastCommittedTranslogFileGeneration}.
+     */
     void trimUnreferencedReaders() {
         try (ReleasableLock ignored = writeLock.acquire()) {
             if (closed.get()) {
-                // we're shutdown potentially on some tragic event - don't delete anything
+                // we're shutdown potentially on some tragic event, don't delete anything
                 return;
             }
-            long minReferencedGen = outstandingViews.stream().mapToLong(View::minTranslogGeneration).min().orElse(Long.MAX_VALUE);
-            minReferencedGen = Math.min(lastCommittedTranslogFileGeneration, minReferencedGen);
-            final long finalMinReferencedGen = minReferencedGen;
-            List<TranslogReader> unreferenced = readers.stream().filter(r -> r.getGeneration() < finalMinReferencedGen).collect(Collectors.toList());
+            long minReferencedGen = Math.min(
+                    lastCommittedTranslogFileGeneration,
+                    outstandingViews.stream().mapToLong(View::minTranslogGeneration).min().orElse(Long.MAX_VALUE));
+            final List<TranslogReader> unreferenced =
+                    readers.stream().filter(r -> r.getGeneration() < minReferencedGen).collect(Collectors.toList());
             for (final TranslogReader unreferencedReader : unreferenced) {
-                Path translogPath = unreferencedReader.path();
-                logger.trace("delete translog file - not referenced and not current anymore {}", translogPath);
+                final Path translogPath = unreferencedReader.path();
+                logger.trace("delete translog file [{}], not referenced and not current anymore", translogPath);
                 IOUtils.closeWhileHandlingException(unreferencedReader);
                 IOUtils.deleteFilesIgnoringExceptions(translogPath,
                         translogPath.resolveSibling(getCommitCheckpointFileName(unreferencedReader.getGeneration())));
@@ -1442,13 +1496,6 @@ public class Translog extends AbstractIndexShardComponent implements IndexShardC
         }
     }
 
-
-    @Override
-    public void rollback() throws IOException {
-        ensureOpen();
-        close();
-    }
-
     /**
      * References a transaction log generation
      */

core/src/main/java/org/elasticsearch/node/InternalSettingsPreparer.java

@@ -37,17 +37,12 @@ import java.util.List;
 import java.util.Map;
 import java.util.Set;
 import java.util.function.Function;
-import java.util.function.Predicate;
-import java.util.function.UnaryOperator;
 
 import static org.elasticsearch.common.Strings.cleanPath;
 
 public class InternalSettingsPreparer {
 
     private static final String[] ALLOWED_SUFFIXES = {".yml", ".yaml", ".json"};
-    private static final String PROPERTY_DEFAULTS_PREFIX = "default.";
-    private static final Predicate<String> PROPERTY_DEFAULTS_PREDICATE = key -> key.startsWith(PROPERTY_DEFAULTS_PREFIX);
-    private static final UnaryOperator<String> STRIP_PROPERTY_DEFAULTS_PREFIX = key -> key.substring(PROPERTY_DEFAULTS_PREFIX.length());
 
     public static final String SECRET_PROMPT_VALUE = "${prompt.secret}";
     public static final String TEXT_PROMPT_VALUE = "${prompt.text}";
@@ -125,15 +120,16 @@ public class InternalSettingsPreparer {
     }
 
     /**
-     * Initializes the builder with the given input settings, and loads system properties settings if allowed.
-     * If loadDefaults is true, system property default settings are loaded.
+     * Initializes the builder with the given input settings, and applies settings from the specified map (these settings typically come
+     * from the command line).
+     *
+     * @param output the settings builder to apply the input and default settings to
+     * @param input the input settings
+     * @param esSettings a map from which to apply settings
      */
-    private static void initializeSettings(Settings.Builder output, Settings input, Map<String, String> esSettings) {
+    static void initializeSettings(final Settings.Builder output, final Settings input, final Map<String, String> esSettings) {
         output.put(input);
-        output.putProperties(esSettings,
-            PROPERTY_DEFAULTS_PREDICATE.and(key -> output.get(STRIP_PROPERTY_DEFAULTS_PREFIX.apply(key)) == null),
-            STRIP_PROPERTY_DEFAULTS_PREFIX);
-        output.putProperties(esSettings, PROPERTY_DEFAULTS_PREDICATE.negate(), Function.identity());
+        output.putProperties(esSettings, Function.identity());
         output.replacePropertyPlaceholders();
     }
 

core/src/main/java/org/elasticsearch/node/Node.java

@@ -50,6 +50,7 @@ import org.elasticsearch.cluster.routing.RoutingService;
 import org.elasticsearch.cluster.routing.allocation.AllocationService;
 import org.elasticsearch.cluster.service.ClusterService;
 import org.elasticsearch.common.StopWatch;
+import org.elasticsearch.common.SuppressForbidden;
 import org.elasticsearch.common.component.Lifecycle;
 import org.elasticsearch.common.component.LifecycleComponent;
 import org.elasticsearch.common.inject.Binder;
@@ -58,6 +59,7 @@ import org.elasticsearch.common.inject.Key;
 import org.elasticsearch.common.inject.Module;
 import org.elasticsearch.common.inject.ModulesBuilder;
 import org.elasticsearch.common.inject.util.Providers;
+import org.elasticsearch.common.io.PathUtils;
 import org.elasticsearch.common.io.stream.NamedWriteableRegistry;
 import org.elasticsearch.common.lease.Releasables;
 import org.elasticsearch.common.logging.DeprecationLogger;
@@ -146,7 +148,9 @@ import java.util.Arrays;
 import java.util.Collection;
 import java.util.Collections;
 import java.util.List;
+import java.util.Locale;
 import java.util.Map;
+import java.util.Set;
 import java.util.concurrent.CountDownLatch;
 import java.util.concurrent.TimeUnit;
 import java.util.function.Consumer;
@@ -262,6 +266,9 @@ public class Node implements Closeable {
             Logger logger = Loggers.getLogger(Node.class, tmpSettings);
             final String nodeId = nodeEnvironment.nodeId();
             tmpSettings = addNodeNameIfNeeded(tmpSettings, nodeId);
+            if (DiscoveryNode.nodeRequiresLocalStorage(tmpSettings)) {
+                checkForIndexDataInDefaultPathData(tmpSettings, nodeEnvironment, logger);
+            }
             // this must be captured after the node name is possibly added to the settings
             final String nodeName = NODE_NAME_SETTING.get(tmpSettings);
             if (hadPredefinedNodeName == false) {
@@ -500,6 +507,58 @@ public class Node implements Closeable {
         }
     }
 
+    /**
+     * Checks for path.data and default.path.data being configured, and there being index data in any of the paths in default.path.data.
+     *
+     * @param settings the settings to check for path.data and default.path.data
+     * @param nodeEnv  the current node environment
+     * @param logger   a logger where messages regarding the detection will be logged
+     * @throws IOException if an I/O exception occurs reading the directory structure
+     */
+    static void checkForIndexDataInDefaultPathData(
+            final Settings settings, final NodeEnvironment nodeEnv, final Logger logger) throws IOException {
+        if (!Environment.PATH_DATA_SETTING.exists(settings) || !Environment.DEFAULT_PATH_DATA_SETTING.exists(settings)) {
+            return;
+        }
+
+        boolean clean = true;
+        for (final String defaultPathData : Environment.DEFAULT_PATH_DATA_SETTING.get(settings)) {
+            final Path nodeDirectory = NodeEnvironment.resolveNodePath(getPath(defaultPathData), nodeEnv.getNodeLockId());
+            if (Files.exists(nodeDirectory) == false) {
+                continue;
+            }
+            final NodeEnvironment.NodePath nodePath = new NodeEnvironment.NodePath(nodeDirectory);
+            final Set<String> availableIndexFolders = nodeEnv.availableIndexFoldersForPath(nodePath);
+            if (availableIndexFolders.isEmpty()) {
+                continue;
+            }
+            clean = false;
+            logger.error("detected index data in default.path.data [{}] where there should not be any", nodePath.indicesPath);
+            for (final String availableIndexFolder : availableIndexFolders) {
+                logger.info(
+                        "index folder [{}] in default.path.data [{}] must be moved to any of {}",
+                        availableIndexFolder,
+                        nodePath.indicesPath,
+                        Arrays.stream(nodeEnv.nodePaths()).map(np -> np.indicesPath).collect(Collectors.toList()));
+            }
+        }
+
+        if (clean) {
+            return;
+        }
+
+        final String message = String.format(
+                Locale.ROOT,
+                "detected index data in default.path.data %s where there should not be any; check the logs for details",
+                Environment.DEFAULT_PATH_DATA_SETTING.get(settings));
+        throw new IllegalStateException(message);
+    }
+
+    @SuppressForbidden(reason = "read path that is not configured in environment")
+    private static Path getPath(final String path) {
+        return PathUtils.get(path);
+    }
+
     // visible for testing
     static void warnIfPreRelease(final Version version, final boolean isSnapshot, final Logger logger) {
         if (!version.isRelease() || isSnapshot) {

core/src/main/java/org/elasticsearch/rest/AbstractRestChannel.java

@@ -20,12 +20,14 @@ package org.elasticsearch.rest;
 
 import org.elasticsearch.common.Nullable;
 import org.elasticsearch.common.Strings;
+import org.elasticsearch.common.io.Streams;
 import org.elasticsearch.common.io.stream.BytesStreamOutput;
 import org.elasticsearch.common.xcontent.XContentBuilder;
 import org.elasticsearch.common.xcontent.XContentFactory;
 import org.elasticsearch.common.xcontent.XContentType;
 
 import java.io.IOException;
+import java.io.OutputStream;
 import java.util.Collections;
 import java.util.Set;
 import java.util.function.Predicate;
@@ -97,7 +99,9 @@ public abstract class AbstractRestChannel implements RestChannel {
             excludes = filters.stream().filter(EXCLUDE_FILTER).map(f -> f.substring(1)).collect(toSet());
         }
 
-        XContentBuilder builder = new XContentBuilder(XContentFactory.xContent(responseContentType), bytesOutput(), includes, excludes);
+        OutputStream unclosableOutputStream = Streams.flushOnCloseStream(bytesOutput());
+        XContentBuilder builder =
+            new XContentBuilder(XContentFactory.xContent(responseContentType), unclosableOutputStream, includes, excludes);
         if (pretty) {
             builder.prettyPrint().lfAtEnd();
         }
@@ -107,8 +111,9 @@ public abstract class AbstractRestChannel implements RestChannel {
     }
 
     /**
-     * A channel level bytes output that can be reused. It gets reset on each call to this
-     * method.
+     * A channel level bytes output that can be reused. The bytes output is lazily instantiated
+     * by a call to {@link #newBytesOutput()}. Once the stream is created, it gets reset on each
+     * call to this method.
      */
     @Override
     public final BytesStreamOutput bytesOutput() {
@@ -120,6 +125,14 @@ public abstract class AbstractRestChannel implements RestChannel {
         return bytesOut;
     }
 
+    /**
+     * An accessor to the raw value of the channel bytes output. This method will not instantiate
+     * a new stream if one does not exist and this method will not reset the stream.
+     */
+    protected final BytesStreamOutput bytesOutputOrNull() {
+        return bytesOut;
+    }
+
     protected BytesStreamOutput newBytesOutput() {
         return new BytesStreamOutput();
     }

core/src/main/java/org/elasticsearch/rest/BytesRestResponse.java

@@ -30,7 +30,6 @@ import org.elasticsearch.common.bytes.BytesReference;
 import org.elasticsearch.common.logging.ESLoggerFactory;
 import org.elasticsearch.common.xcontent.ToXContent;
 import org.elasticsearch.common.xcontent.XContentBuilder;
-import org.elasticsearch.common.xcontent.json.JsonXContent;
 import org.elasticsearch.common.xcontent.XContentParser;
 
 import java.io.IOException;
@@ -147,8 +146,8 @@ public class BytesRestResponse extends RestResponse {
         return builder;
     }
 
-    static BytesRestResponse createSimpleErrorResponse(RestStatus status, String errorMessage) throws IOException {
-        return new BytesRestResponse(status, JsonXContent.contentBuilder().startObject()
+    static BytesRestResponse createSimpleErrorResponse(RestChannel channel, RestStatus status, String errorMessage) throws IOException {
+        return new BytesRestResponse(status, channel.newErrorBuilder().startObject()
             .field("error", errorMessage)
             .field("status", status.getStatus())
             .endObject());

core/src/main/java/org/elasticsearch/rest/RestController.java

@@ -178,8 +178,9 @@ public class RestController extends AbstractComponent implements HttpServerTrans
                 sendContentTypeErrorMessage(request, responseChannel);
             } else if (contentLength > 0 && handler != null && handler.supportsContentStream() &&
                 request.getXContentType() != XContentType.JSON && request.getXContentType() != XContentType.SMILE) {
-                responseChannel.sendResponse(BytesRestResponse.createSimpleErrorResponse(RestStatus.NOT_ACCEPTABLE, "Content-Type [" +
-                    request.getXContentType() + "] does not support stream parsing. Use JSON or SMILE instead"));
+                responseChannel.sendResponse(BytesRestResponse.createSimpleErrorResponse(responseChannel,
+                    RestStatus.NOT_ACCEPTABLE, "Content-Type [" + request.getXContentType() +
+                        "] does not support stream parsing. Use JSON or SMILE instead"));
             } else {
                 if (canTripCircuitBreaker(request)) {
                     inFlightRequestsBreaker(circuitBreakerService).addEstimateBytesAndMaybeBreak(contentLength, "<http_request>");
@@ -229,7 +230,8 @@ public class RestController extends AbstractComponent implements HttpServerTrans
     void dispatchRequest(final RestRequest request, final RestChannel channel, final NodeClient client, ThreadContext threadContext,
                          final RestHandler handler) throws Exception {
         if (checkRequestParameters(request, channel) == false) {
-            channel.sendResponse(BytesRestResponse.createSimpleErrorResponse(BAD_REQUEST, "error traces in responses are disabled."));
+            channel
+                .sendResponse(BytesRestResponse.createSimpleErrorResponse(channel,BAD_REQUEST, "error traces in responses are disabled."));
         } else {
             for (String key : headersToCopy) {
                 String httpHeader = request.header(key);
@@ -283,7 +285,7 @@ public class RestController extends AbstractComponent implements HttpServerTrans
                 Strings.collectionToCommaDelimitedString(restRequest.getAllHeaderValues("Content-Type")) + "] is not supported";
         }
 
-        channel.sendResponse(BytesRestResponse.createSimpleErrorResponse(NOT_ACCEPTABLE, errorMessage));
+        channel.sendResponse(BytesRestResponse.createSimpleErrorResponse(channel, NOT_ACCEPTABLE, errorMessage));
     }
 
     /**

core/src/main/java/org/elasticsearch/rest/action/cat/AbstractCatAction.java

@@ -20,8 +20,9 @@ package org.elasticsearch.rest.action.cat;
 
 import org.elasticsearch.client.node.NodeClient;
 import org.elasticsearch.common.Table;
+import org.elasticsearch.common.io.Streams;
 import org.elasticsearch.common.io.UTF8StreamWriter;
-import org.elasticsearch.common.io.stream.BytesStreamOutput;
+import org.elasticsearch.common.io.stream.BytesStream;
 import org.elasticsearch.common.settings.Settings;
 import org.elasticsearch.rest.BaseRestHandler;
 import org.elasticsearch.rest.BytesRestResponse;
@@ -56,7 +57,7 @@ public abstract class AbstractCatAction extends BaseRestHandler {
             return channel -> {
                 Table table = getTableWithHeader(request);
                 int[] width = buildHelpWidths(table, request);
-                BytesStreamOutput bytesOutput = channel.bytesOutput();
+                BytesStream bytesOutput = Streams.flushOnCloseStream(channel.bytesOutput());
                 UTF8StreamWriter out = new UTF8StreamWriter().setOutput(bytesOutput);
                 for (Table.Cell cell : table.getHeaders()) {
                     // need to do left-align always, so create new cells

core/src/main/java/org/elasticsearch/rest/action/cat/RestTable.java

@@ -22,8 +22,9 @@ package org.elasticsearch.rest.action.cat;
 import org.elasticsearch.common.Booleans;
 import org.elasticsearch.common.Strings;
 import org.elasticsearch.common.Table;
+import org.elasticsearch.common.io.Streams;
 import org.elasticsearch.common.io.UTF8StreamWriter;
-import org.elasticsearch.common.io.stream.BytesStreamOutput;
+import org.elasticsearch.common.io.stream.BytesStream;
 import org.elasticsearch.common.regex.Regex;
 import org.elasticsearch.common.unit.ByteSizeValue;
 import org.elasticsearch.common.unit.SizeValue;
@@ -82,7 +83,7 @@ public class RestTable {
         List<DisplayHeader> headers = buildDisplayHeaders(table, request);
         int[] width = buildWidths(table, request, verbose, headers);
 
-        BytesStreamOutput bytesOut = channel.bytesOutput();
+        BytesStream bytesOut = Streams.flushOnCloseStream(channel.bytesOutput());
         UTF8StreamWriter out = new UTF8StreamWriter().setOutput(bytesOut);
         int lastHeader = headers.size() - 1;
         if (verbose) {

core/src/main/java/org/elasticsearch/search/aggregations/metrics/geocentroid/GeoCentroidAggregator.java

@@ -42,12 +42,12 @@ import java.util.Map;
 /**
  * A geo metric aggregator that computes a geo-centroid from a {@code geo_point} type field
  */
-public final class GeoCentroidAggregator extends MetricsAggregator {
+final class GeoCentroidAggregator extends MetricsAggregator {
     private final ValuesSource.GeoPoint valuesSource;
-    LongArray centroids;
-    LongArray counts;
+    private LongArray centroids;
+    private LongArray counts;
 
-    protected GeoCentroidAggregator(String name, SearchContext context, Aggregator parent,
+    GeoCentroidAggregator(String name, SearchContext context, Aggregator parent,
                                     ValuesSource.GeoPoint valuesSource, List<PipelineAggregator> pipelineAggregators,
                                     Map<String, Object> metaData) throws IOException {
         super(name, context, parent, pipelineAggregators, metaData);

core/src/main/java/org/elasticsearch/search/aggregations/metrics/geocentroid/GeoCentroidAggregatorFactory.java

@@ -32,9 +32,9 @@ import java.io.IOException;
 import java.util.List;
 import java.util.Map;
 
-public class GeoCentroidAggregatorFactory extends ValuesSourceAggregatorFactory<ValuesSource.GeoPoint, GeoCentroidAggregatorFactory> {
+class GeoCentroidAggregatorFactory extends ValuesSourceAggregatorFactory<ValuesSource.GeoPoint, GeoCentroidAggregatorFactory> {
 
-    public GeoCentroidAggregatorFactory(String name, ValuesSourceConfig<ValuesSource.GeoPoint> config,
+    GeoCentroidAggregatorFactory(String name, ValuesSourceConfig<ValuesSource.GeoPoint> config,
             SearchContext context, AggregatorFactory<?> parent, AggregatorFactories.Builder subFactoriesBuilder,
             Map<String, Object> metaData) throws IOException {
         super(name, config, context, parent, subFactoriesBuilder, metaData);

core/src/main/java/org/elasticsearch/search/aggregations/metrics/geocentroid/InternalGeoCentroid.java

@@ -38,7 +38,7 @@ public class InternalGeoCentroid extends InternalAggregation implements GeoCentr
     protected final GeoPoint centroid;
     protected final long count;
 
-    public InternalGeoCentroid(String name, GeoPoint centroid, long count, List<PipelineAggregator>
+    InternalGeoCentroid(String name, GeoPoint centroid, long count, List<PipelineAggregator>
             pipelineAggregators, Map<String, Object> metaData) {
         super(name, pipelineAggregators, metaData);
         assert (centroid == null) == (count == 0);
@@ -132,7 +132,7 @@ public class InternalGeoCentroid extends InternalAggregation implements GeoCentr
     }
 
     static class Fields {
-        public static final String CENTROID = "location";
+        static final String CENTROID = "location";
     }
 
     @Override

core/src/main/java/org/elasticsearch/search/aggregations/metrics/percentiles/InternalPercentile.java

@@ -1,41 +0,0 @@
-/*
- * Licensed to Elasticsearch under one or more contributor
- * license agreements. See the NOTICE file distributed with
- * this work for additional information regarding copyright
- * ownership. Elasticsearch licenses this file to you under
- * the Apache License, Version 2.0 (the "License"); you may
- * not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *    http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing,
- * software distributed under the License is distributed on an
- * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
- * KIND, either express or implied.  See the License for the
- * specific language governing permissions and limitations
- * under the License.
- */
-
-package org.elasticsearch.search.aggregations.metrics.percentiles;
-
-public class InternalPercentile implements Percentile {
-
-    private final double percent;
-    private final double value;
-
-    public InternalPercentile(double percent, double value) {
-        this.percent = percent;
-        this.value = value;
-    }
-
-    @Override
-    public double getPercent() {
-        return percent;
-    }
-
-    @Override
-    public double getValue() {
-        return value;
-    }
-}

core/src/main/java/org/elasticsearch/search/aggregations/metrics/percentiles/Percentile.java

@@ -19,10 +19,41 @@
 
 package org.elasticsearch.search.aggregations.metrics.percentiles;
 
-public interface Percentile {
+import java.util.Objects;
 
-    double getPercent();
+public class Percentile {
 
-    double getValue();
+    private final double percent;
+    private final double value;
 
+    public Percentile(double percent, double value) {
+        this.percent = percent;
+        this.value = value;
+    }
+
+    public double getPercent() {
+        return percent;
+    }
+
+    public double getValue() {
+        return value;
+    }
+
+    @Override
+    public boolean equals(Object o) {
+        if (this == o) {
+            return true;
+        }
+        if (o == null || getClass() != o.getClass()) {
+            return false;
+        }
+        Percentile that = (Percentile) o;
+        return Double.compare(that.percent, percent) == 0
+                && Double.compare(that.value, value) == 0;
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(percent, value);
+    }
 }

core/src/main/java/org/elasticsearch/search/aggregations/metrics/percentiles/hdr/InternalHDRPercentileRanks.java

@@ -21,7 +21,6 @@ package org.elasticsearch.search.aggregations.metrics.percentiles.hdr;
 import org.HdrHistogram.DoubleHistogram;
 import org.elasticsearch.common.io.stream.StreamInput;
 import org.elasticsearch.search.DocValueFormat;
-import org.elasticsearch.search.aggregations.metrics.percentiles.InternalPercentile;
 import org.elasticsearch.search.aggregations.metrics.percentiles.Percentile;
 import org.elasticsearch.search.aggregations.metrics.percentiles.PercentileRanks;
 import org.elasticsearch.search.aggregations.pipeline.PipelineAggregator;
@@ -109,7 +108,7 @@ public class InternalHDRPercentileRanks extends AbstractInternalHDRPercentiles i
 
         @Override
         public Percentile next() {
-            final Percentile next = new InternalPercentile(percentileRank(state, values[i]), values[i]);
+            final Percentile next = new Percentile(percentileRank(state, values[i]), values[i]);
             ++i;
             return next;
         }

core/src/main/java/org/elasticsearch/search/aggregations/metrics/percentiles/hdr/InternalHDRPercentiles.java

@@ -21,7 +21,6 @@ package org.elasticsearch.search.aggregations.metrics.percentiles.hdr;
 import org.HdrHistogram.DoubleHistogram;
 import org.elasticsearch.common.io.stream.StreamInput;
 import org.elasticsearch.search.DocValueFormat;
-import org.elasticsearch.search.aggregations.metrics.percentiles.InternalPercentile;
 import org.elasticsearch.search.aggregations.metrics.percentiles.Percentile;
 import org.elasticsearch.search.aggregations.metrics.percentiles.Percentiles;
 import org.elasticsearch.search.aggregations.pipeline.PipelineAggregator;
@@ -99,7 +98,7 @@ public class InternalHDRPercentiles extends AbstractInternalHDRPercentiles imple
 
         @Override
         public Percentile next() {
-            final Percentile next = new InternalPercentile(percents[i], state.getValueAtPercentile(percents[i]));
+            final Percentile next = new Percentile(percents[i], state.getValueAtPercentile(percents[i]));
             ++i;
             return next;
         }

core/src/main/java/org/elasticsearch/search/aggregations/metrics/percentiles/tdigest/InternalTDigestPercentileRanks.java

@@ -20,7 +20,6 @@ package org.elasticsearch.search.aggregations.metrics.percentiles.tdigest;
 
 import org.elasticsearch.common.io.stream.StreamInput;
 import org.elasticsearch.search.DocValueFormat;
-import org.elasticsearch.search.aggregations.metrics.percentiles.InternalPercentile;
 import org.elasticsearch.search.aggregations.metrics.percentiles.Percentile;
 import org.elasticsearch.search.aggregations.metrics.percentiles.PercentileRanks;
 import org.elasticsearch.search.aggregations.pipeline.PipelineAggregator;
@@ -106,7 +105,7 @@ public class InternalTDigestPercentileRanks extends AbstractInternalTDigestPerce
 
         @Override
         public Percentile next() {
-            final Percentile next = new InternalPercentile(percentileRank(state, values[i]), values[i]);
+            final Percentile next = new Percentile(percentileRank(state, values[i]), values[i]);
             ++i;
             return next;
         }

core/src/main/java/org/elasticsearch/search/aggregations/metrics/percentiles/tdigest/InternalTDigestPercentiles.java

@@ -20,7 +20,6 @@ package org.elasticsearch.search.aggregations.metrics.percentiles.tdigest;
 
 import org.elasticsearch.common.io.stream.StreamInput;
 import org.elasticsearch.search.DocValueFormat;
-import org.elasticsearch.search.aggregations.metrics.percentiles.InternalPercentile;
 import org.elasticsearch.search.aggregations.metrics.percentiles.Percentile;
 import org.elasticsearch.search.aggregations.metrics.percentiles.Percentiles;
 import org.elasticsearch.search.aggregations.pipeline.PipelineAggregator;
@@ -95,7 +94,7 @@ public class InternalTDigestPercentiles extends AbstractInternalTDigestPercentil
 
         @Override
         public Percentile next() {
-            final Percentile next = new InternalPercentile(percents[i], state.quantile(percents[i] / 100));
+            final Percentile next = new Percentile(percents[i], state.quantile(percents[i] / 100));
             ++i;
             return next;
         }

core/src/main/java/org/elasticsearch/search/aggregations/pipeline/bucketmetrics/percentile/InternalPercentilesBucket.java

@@ -26,7 +26,6 @@ import org.elasticsearch.search.DocValueFormat;
 import org.elasticsearch.search.aggregations.InternalAggregation;
 import org.elasticsearch.search.aggregations.metrics.InternalNumericMetricsAggregation;
 import org.elasticsearch.search.aggregations.metrics.max.InternalMax;
-import org.elasticsearch.search.aggregations.metrics.percentiles.InternalPercentile;
 import org.elasticsearch.search.aggregations.metrics.percentiles.Percentile;
 import org.elasticsearch.search.aggregations.pipeline.PipelineAggregator;
 
@@ -136,7 +135,7 @@ public class InternalPercentilesBucket extends InternalNumericMetricsAggregation
 
         @Override
         public Percentile next() {
-            final Percentile next = new InternalPercentile(percents[i], percentiles[i]);
+            final Percentile next = new Percentile(percents[i], percentiles[i]);
             ++i;
             return next;
         }

core/src/main/java/org/elasticsearch/tasks/TaskInfo.java

@@ -183,7 +183,7 @@ public final class TaskInfo implements Writeable, ToXContent {
     }
 
     public static final ConstructingObjectParser<TaskInfo, Void> PARSER = new ConstructingObjectParser<>(
-            "task_info", a -> {
+            "task_info", true, a -> {
                 int i = 0;
                 TaskId id = new TaskId((String) a[i++], (Long) a[i++]);
                 String type = (String) a[i++];
@@ -196,11 +196,11 @@ public final class TaskInfo implements Writeable, ToXContent {
                 String parentTaskIdString = (String) a[i++];
 
                 RawTaskStatus status = statusBytes == null ? null : new RawTaskStatus(statusBytes);
-                TaskId parentTaskId = parentTaskIdString == null ? TaskId.EMPTY_TASK_ID : new TaskId((String) parentTaskIdString);
+                TaskId parentTaskId = parentTaskIdString == null ? TaskId.EMPTY_TASK_ID : new TaskId(parentTaskIdString);
                 return new TaskInfo(id, type, action, description, status, startTime, runningTimeNanos, cancellable, parentTaskId);
             });
     static {
-        // Note for the future: this has to be backwards compatible with all changes to the task storage format
+        // Note for the future: this has to be backwards and forwards compatible with all changes to the task storage format
         PARSER.declareString(constructorArg(), new ParseField("node"));
         PARSER.declareLong(constructorArg(), new ParseField("id"));
         PARSER.declareString(constructorArg(), new ParseField("type"));

core/src/main/java/org/elasticsearch/transport/TcpTransport.java

@@ -41,7 +41,7 @@ import org.elasticsearch.common.component.Lifecycle;
 import org.elasticsearch.common.compress.Compressor;
 import org.elasticsearch.common.compress.CompressorFactory;
 import org.elasticsearch.common.compress.NotCompressedException;
-import org.elasticsearch.common.io.ReleasableBytesStream;
+import org.elasticsearch.common.io.Streams;
 import org.elasticsearch.common.io.stream.BytesStreamOutput;
 import org.elasticsearch.common.io.stream.NamedWriteableAwareStreamInput;
 import org.elasticsearch.common.io.stream.NamedWriteableRegistry;
@@ -1025,10 +1025,8 @@ public abstract class TcpTransport<Channel> extends AbstractLifecycleComponent i
         }
         status = TransportStatus.setRequest(status);
         ReleasableBytesStreamOutput bStream = new ReleasableBytesStreamOutput(bigArrays);
-        // we wrap this in a release once since if the onRequestSent callback throws an exception
-        // we might release things twice and this should be prevented
-        final Releasable toRelease = Releasables.releaseOnce(() -> Releasables.close(bStream.bytes()));
-        StreamOutput stream = bStream;
+        boolean addedReleaseListener = false;
+        StreamOutput stream = Streams.flushOnCloseStream(bStream);
         try {
             // only compress if asked, and, the request is not bytes, since then only
             // the header part is compressed, and the "body" can't be extracted as compressed
@@ -1047,12 +1045,17 @@ public abstract class TcpTransport<Channel> extends AbstractLifecycleComponent i
             stream.writeString(action);
             BytesReference message = buildMessage(requestId, status, node.getVersion(), request, stream, bStream);
             final TransportRequestOptions finalOptions = options;
+            final StreamOutput finalStream = stream;
             // this might be called in a different thread
-            SendListener onRequestSent = new SendListener(toRelease,
+            SendListener onRequestSent = new SendListener(
+                () -> IOUtils.closeWhileHandlingException(finalStream, bStream),
                 () -> transportServiceAdapter.onRequestSent(node, requestId, action, request, finalOptions));
             internalSendMessage(targetChannel, message, onRequestSent);
+            addedReleaseListener = true;
         } finally {
-            IOUtils.close(stream);
+            if (!addedReleaseListener) {
+                IOUtils.close(stream, bStream);
+            }
         }
     }
 
@@ -1114,10 +1117,8 @@ public abstract class TcpTransport<Channel> extends AbstractLifecycleComponent i
         }
         status = TransportStatus.setResponse(status); // TODO share some code with sendRequest
         ReleasableBytesStreamOutput bStream = new ReleasableBytesStreamOutput(bigArrays);
-        // we wrap this in a release once since if the onRequestSent callback throws an exception
-        // we might release things twice and this should be prevented
-        final Releasable toRelease = Releasables.releaseOnce(() -> Releasables.close(bStream.bytes()));
-        StreamOutput stream = bStream;
+        boolean addedReleaseListener = false;
+        StreamOutput stream = Streams.flushOnCloseStream(bStream);
         try {
             if (options.compress()) {
                 status = TransportStatus.setCompress(status);
@@ -1128,12 +1129,16 @@ public abstract class TcpTransport<Channel> extends AbstractLifecycleComponent i
             BytesReference reference = buildMessage(requestId, status, nodeVersion, response, stream, bStream);
 
             final TransportResponseOptions finalOptions = options;
+            final StreamOutput finalStream = stream;
             // this might be called in a different thread
-            SendListener listener = new SendListener(toRelease,
+            SendListener listener = new SendListener(() -> IOUtils.closeWhileHandlingException(finalStream, bStream),
                 () -> transportServiceAdapter.onResponseSent(requestId, action, response, finalOptions));
             internalSendMessage(channel, reference, listener);
+            addedReleaseListener = true;
         } finally {
-            IOUtils.close(stream);
+            if (!addedReleaseListener) {
+                IOUtils.close(stream, bStream);
+            }
         }
     }
 
@@ -1161,7 +1166,7 @@ public abstract class TcpTransport<Channel> extends AbstractLifecycleComponent i
      * Serializes the given message into a bytes representation
      */
     private BytesReference buildMessage(long requestId, byte status, Version nodeVersion, TransportMessage message, StreamOutput stream,
-                                        ReleasableBytesStream writtenBytes) throws IOException {
+                                        ReleasableBytesStreamOutput writtenBytes) throws IOException {
         final BytesReference zeroCopyBuffer;
         if (message instanceof BytesTransportRequest) { // what a shitty optimization - we should use a direct send method instead
             BytesTransportRequest bRequest = (BytesTransportRequest) message;

core/src/test/java/org/elasticsearch/action/bulk/RetryTests.java

@@ -80,43 +80,37 @@ public class RetryTests extends ESTestCase {
         return request;
     }
 
-    public void testSyncRetryBacksOff() throws Exception {
+    public void testRetryBacksOff() throws Exception {
         BackoffPolicy backoff = BackoffPolicy.constantBackoff(DELAY, CALLS_TO_FAIL);
 
         BulkRequest bulkRequest = createBulkRequest();
-        BulkResponse response = Retry
-                .on(EsRejectedExecutionException.class)
-                .policy(backoff)
-                .using(bulkClient.threadPool())
-                .withSyncBackoff(bulkClient::bulk, bulkRequest, bulkClient.settings());
+        BulkResponse response = new Retry(EsRejectedExecutionException.class, backoff, bulkClient.threadPool())
+            .withBackoff(bulkClient::bulk, bulkRequest, bulkClient.settings())
+            .actionGet();
 
         assertFalse(response.hasFailures());
         assertThat(response.getItems().length, equalTo(bulkRequest.numberOfActions()));
     }
 
-    public void testSyncRetryFailsAfterBackoff() throws Exception {
+    public void testRetryFailsAfterBackoff() throws Exception {
         BackoffPolicy backoff = BackoffPolicy.constantBackoff(DELAY, CALLS_TO_FAIL - 1);
 
         BulkRequest bulkRequest = createBulkRequest();
-        BulkResponse response = Retry
-                .on(EsRejectedExecutionException.class)
-                .policy(backoff)
-                .using(bulkClient.threadPool())
-                .withSyncBackoff(bulkClient::bulk, bulkRequest, bulkClient.settings());
+        BulkResponse response = new Retry(EsRejectedExecutionException.class, backoff, bulkClient.threadPool())
+            .withBackoff(bulkClient::bulk, bulkRequest, bulkClient.settings())
+            .actionGet();
 
         assertTrue(response.hasFailures());
         assertThat(response.getItems().length, equalTo(bulkRequest.numberOfActions()));
     }
 
-    public void testAsyncRetryBacksOff() throws Exception {
+    public void testRetryWithListenerBacksOff() throws Exception {
         BackoffPolicy backoff = BackoffPolicy.constantBackoff(DELAY, CALLS_TO_FAIL);
         AssertingListener listener = new AssertingListener();
 
         BulkRequest bulkRequest = createBulkRequest();
-        Retry.on(EsRejectedExecutionException.class)
-                .policy(backoff)
-                .using(bulkClient.threadPool())
-                .withAsyncBackoff(bulkClient::bulk, bulkRequest, listener, bulkClient.settings());
+        Retry retry = new Retry(EsRejectedExecutionException.class, backoff, bulkClient.threadPool());
+        retry.withBackoff(bulkClient::bulk, bulkRequest, listener, bulkClient.settings());
 
         listener.awaitCallbacksCalled();
         listener.assertOnResponseCalled();
@@ -125,15 +119,13 @@ public class RetryTests extends ESTestCase {
         listener.assertOnFailureNeverCalled();
     }
 
-    public void testAsyncRetryFailsAfterBacksOff() throws Exception {
+    public void testRetryWithListenerFailsAfterBacksOff() throws Exception {
         BackoffPolicy backoff = BackoffPolicy.constantBackoff(DELAY, CALLS_TO_FAIL - 1);
         AssertingListener listener = new AssertingListener();
 
         BulkRequest bulkRequest = createBulkRequest();
-        Retry.on(EsRejectedExecutionException.class)
-                .policy(backoff)
-                .using(bulkClient.threadPool())
-                .withAsyncBackoff(bulkClient::bulk, bulkRequest, listener, bulkClient.settings());
+        Retry retry = new Retry(EsRejectedExecutionException.class, backoff, bulkClient.threadPool());
+        retry.withBackoff(bulkClient::bulk, bulkRequest, listener, bulkClient.settings());
 
         listener.awaitCallbacksCalled();
 

core/src/test/java/org/elasticsearch/bwcompat/OldIndexBackwardsCompatibilityIT.java

@@ -166,6 +166,7 @@ public class OldIndexBackwardsCompatibilityIT extends ESIntegTestCase {
         Files.createDirectories(multiDataPath[0]);
         Files.createDirectories(multiDataPath[1]);
         logger.info("--> Multi data paths: {}, {}", multiDataPath[0], multiDataPath[1]);
+        ensureGreen();
     }
 
     void upgradeIndexFolder() throws Exception {

core/src/test/java/org/elasticsearch/common/io/stream/ReleasableBytesStreamOutputTests.java

@@ -0,0 +1,51 @@
+/*
+ * Licensed to Elasticsearch under one or more contributor
+ * license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright
+ * ownership. Elasticsearch licenses this file to you under
+ * the Apache License, Version 2.0 (the "License"); you may
+ * not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+package org.elasticsearch.common.io.stream;
+
+import org.elasticsearch.common.settings.Settings;
+import org.elasticsearch.common.util.MockBigArrays;
+import org.elasticsearch.indices.breaker.NoneCircuitBreakerService;
+import org.elasticsearch.test.ESTestCase;
+
+import java.io.IOException;
+
+public class ReleasableBytesStreamOutputTests extends ESTestCase {
+
+    public void testRelease() throws Exception {
+        MockBigArrays mockBigArrays =
+            new MockBigArrays(Settings.EMPTY, new NoneCircuitBreakerService());
+        try (ReleasableBytesStreamOutput output =
+                 getRandomReleasableBytesStreamOutput(mockBigArrays)) {
+            output.writeBoolean(randomBoolean());
+        }
+        MockBigArrays.ensureAllArraysAreReleased();
+    }
+
+    private ReleasableBytesStreamOutput getRandomReleasableBytesStreamOutput(
+                                                MockBigArrays mockBigArrays) throws IOException {
+        ReleasableBytesStreamOutput output = new ReleasableBytesStreamOutput(mockBigArrays);
+        if (randomBoolean()) {
+            for (int i = 0; i < scaledRandomIntBetween(1, 32); i++) {
+                output.write(randomByte());
+            }
+        }
+        return output;
+    }
+}

core/src/test/java/org/elasticsearch/common/lucene/uid/VersionLookupTests.java

@@ -31,7 +31,7 @@ import org.apache.lucene.util.Bits;
 import org.apache.lucene.util.BytesRef;
 import org.apache.lucene.util.FixedBitSet;
 import org.elasticsearch.common.lucene.Lucene;
-import org.elasticsearch.common.lucene.uid.VersionsResolver.DocIdAndVersion;
+import org.elasticsearch.common.lucene.uid.VersionsAndSeqNoResolver.DocIdAndVersion;
 import org.elasticsearch.index.mapper.UidFieldMapper;
 import org.elasticsearch.index.mapper.VersionFieldMapper;
 import org.elasticsearch.test.ESTestCase;
@@ -53,7 +53,7 @@ public class VersionLookupTests extends ESTestCase {
         writer.addDocument(doc);
         DirectoryReader reader = DirectoryReader.open(writer);
         LeafReaderContext segment = reader.leaves().get(0);
-        PerThreadIDAndVersionLookup lookup = new PerThreadIDAndVersionLookup(segment.reader());
+        PerThreadIDVersionAndSeqNoLookup lookup = new PerThreadIDVersionAndSeqNoLookup(segment.reader());
         // found doc
         DocIdAndVersion result = lookup.lookupVersion(new BytesRef("6"), null, segment);
         assertNotNull(result);
@@ -81,7 +81,7 @@ public class VersionLookupTests extends ESTestCase {
         writer.addDocument(doc);
         DirectoryReader reader = DirectoryReader.open(writer);
         LeafReaderContext segment = reader.leaves().get(0);
-        PerThreadIDAndVersionLookup lookup = new PerThreadIDAndVersionLookup(segment.reader());
+        PerThreadIDVersionAndSeqNoLookup lookup = new PerThreadIDVersionAndSeqNoLookup(segment.reader());
         // return the last doc when there are duplicates
         DocIdAndVersion result = lookup.lookupVersion(new BytesRef("6"), null, segment);
         assertNotNull(result);

core/src/test/java/org/elasticsearch/common/lucene/uid/VersionsTests.java

@@ -38,8 +38,8 @@ import java.io.IOException;
 import java.util.ArrayList;
 import java.util.List;
 
-import static org.elasticsearch.common.lucene.uid.VersionsResolver.loadDocIdAndVersion;
-import static org.elasticsearch.common.lucene.uid.VersionsResolver.loadVersion;
+import static org.elasticsearch.common.lucene.uid.VersionsAndSeqNoResolver.loadDocIdAndVersion;
+import static org.elasticsearch.common.lucene.uid.VersionsAndSeqNoResolver.loadVersion;
 import static org.hamcrest.Matchers.equalTo;
 import static org.hamcrest.Matchers.nullValue;
 
@@ -145,7 +145,7 @@ public class VersionsTests extends ESTestCase {
 
     /** Test that version map cache works, is evicted on close, etc */
     public void testCache() throws Exception {
-        int size = VersionsResolver.lookupStates.size();
+        int size = VersionsAndSeqNoResolver.lookupStates.size();
 
         Directory dir = newDirectory();
         IndexWriter writer = new IndexWriter(dir, new IndexWriterConfig(Lucene.STANDARD_ANALYZER));
@@ -156,21 +156,21 @@ public class VersionsTests extends ESTestCase {
         DirectoryReader reader = DirectoryReader.open(writer);
         // should increase cache size by 1
         assertEquals(87, loadVersion(reader, new Term(UidFieldMapper.NAME, "6")));
-        assertEquals(size+1, VersionsResolver.lookupStates.size());
+        assertEquals(size+1, VersionsAndSeqNoResolver.lookupStates.size());
         // should be cache hit
         assertEquals(87, loadVersion(reader, new Term(UidFieldMapper.NAME, "6")));
-        assertEquals(size+1, VersionsResolver.lookupStates.size());
+        assertEquals(size+1, VersionsAndSeqNoResolver.lookupStates.size());
 
         reader.close();
         writer.close();
         // core should be evicted from the map
-        assertEquals(size, VersionsResolver.lookupStates.size());
+        assertEquals(size, VersionsAndSeqNoResolver.lookupStates.size());
         dir.close();
     }
 
     /** Test that version map cache behaves properly with a filtered reader */
     public void testCacheFilterReader() throws Exception {
-        int size = VersionsResolver.lookupStates.size();
+        int size = VersionsAndSeqNoResolver.lookupStates.size();
 
         Directory dir = newDirectory();
         IndexWriter writer = new IndexWriter(dir, new IndexWriterConfig(Lucene.STANDARD_ANALYZER));
@@ -180,17 +180,17 @@ public class VersionsTests extends ESTestCase {
         writer.addDocument(doc);
         DirectoryReader reader = DirectoryReader.open(writer);
         assertEquals(87, loadVersion(reader, new Term(UidFieldMapper.NAME, "6")));
-        assertEquals(size+1, VersionsResolver.lookupStates.size());
+        assertEquals(size+1, VersionsAndSeqNoResolver.lookupStates.size());
         // now wrap the reader
         DirectoryReader wrapped = ElasticsearchDirectoryReader.wrap(reader, new ShardId("bogus", "_na_", 5));
         assertEquals(87, loadVersion(wrapped, new Term(UidFieldMapper.NAME, "6")));
         // same size map: core cache key is shared
-        assertEquals(size+1, VersionsResolver.lookupStates.size());
+        assertEquals(size+1, VersionsAndSeqNoResolver.lookupStates.size());
 
         reader.close();
         writer.close();
         // core should be evicted from the map
-        assertEquals(size, VersionsResolver.lookupStates.size());
+        assertEquals(size, VersionsAndSeqNoResolver.lookupStates.size());
         dir.close();
     }
 }

core/src/test/java/org/elasticsearch/common/settings/SettingsTests.java

@@ -562,4 +562,16 @@ public class SettingsTests extends ESTestCase {
         IllegalArgumentException e = expectThrows(IllegalArgumentException.class, () -> setting.get(settings));
         assertTrue(e.getMessage().contains("must be stored inside the Elasticsearch keystore"));
     }
+
+    public void testGetAsArrayFailsOnDuplicates() {
+        final Settings settings =
+                Settings.builder()
+                        .put("foobar.0", "bar")
+                        .put("foobar.1", "baz")
+                        .put("foobar", "foo")
+                        .build();
+        final IllegalStateException e = expectThrows(IllegalStateException.class, () -> settings.getAsArray("foobar"));
+        assertThat(e, hasToString(containsString("settings object contains values for [foobar=foo] and [foobar.0=bar]")));
+    }
+
 }

core/src/test/java/org/elasticsearch/discovery/zen/ElectMasterServiceTests.java

@@ -139,4 +139,19 @@ public class ElectMasterServiceTests extends ESTestCase {
             }
         }
     }
+
+    public void testCountMasterNodes() {
+        List<DiscoveryNode> nodes = generateRandomNodes();
+        ElectMasterService service = electMasterService();
+
+        int masterNodes = 0;
+
+        for (DiscoveryNode node : nodes) {
+            if (node.isMasterNode()) {
+                masterNodes++;
+            }
+        }
+
+        assertEquals(masterNodes, service.countMasterNodes(nodes));
+    }
 }

core/src/test/java/org/elasticsearch/discovery/zen/NodeRemovalClusterStateTaskExecutorTests.java

@@ -108,6 +108,8 @@ public class NodeRemovalClusterStateTaskExecutorTests extends ESTestCase {
         final ClusterStateTaskExecutor.ClusterTasksResult<ZenDiscovery.NodeRemovalClusterStateTaskExecutor.Task> result =
                 executor.execute(clusterState, tasks);
         verify(electMasterService).hasEnoughMasterNodes(eq(remainingNodesClusterState.get().nodes()));
+        verify(electMasterService).countMasterNodes(eq(remainingNodesClusterState.get().nodes()));
+        verify(electMasterService).minimumMasterNodes();
         verifyNoMoreInteractions(electMasterService);
 
         // ensure that we did not reroute

core/src/test/java/org/elasticsearch/env/EnvironmentTests.java

@@ -23,10 +23,12 @@ import org.elasticsearch.test.ESTestCase;
 
 import java.io.IOException;
 import java.net.URL;
+import java.nio.file.Path;
 
 import static org.hamcrest.CoreMatchers.endsWith;
 import static org.hamcrest.CoreMatchers.notNullValue;
 import static org.hamcrest.CoreMatchers.nullValue;
+import static org.hamcrest.Matchers.equalTo;
 
 /**
  * Simple unit-tests for Environment.java
@@ -71,4 +73,104 @@ public class EnvironmentTests extends ESTestCase {
         assertThat(environment.resolveRepoURL(new URL("jar:http://localhost/test/../repo1?blah!/repo/")), nullValue());
     }
 
+    public void testDefaultPathData() {
+        final Path defaultPathData = createTempDir().toAbsolutePath();
+        final Settings settings = Settings.builder()
+                .put("path.home", createTempDir().toAbsolutePath())
+                .put("default.path.data", defaultPathData)
+                .build();
+        final Environment environment = new Environment(settings);
+        assertThat(environment.dataFiles(), equalTo(new Path[] { defaultPathData }));
+    }
+
+    public void testPathDataOverrideDefaultPathData() {
+        final Path pathData = createTempDir().toAbsolutePath();
+        final Path defaultPathData = createTempDir().toAbsolutePath();
+        final Settings settings = Settings.builder()
+                .put("path.home", createTempDir().toAbsolutePath())
+                .put("path.data", pathData)
+                .put("default.path.data", defaultPathData)
+                .build();
+        final Environment environment = new Environment(settings);
+        assertThat(environment.dataFiles(), equalTo(new Path[] { pathData }));
+    }
+
+    public void testPathDataWhenNotSet() {
+        final Path pathHome = createTempDir().toAbsolutePath();
+        final Settings settings = Settings.builder().put("path.home", pathHome).build();
+        final Environment environment = new Environment(settings);
+        assertThat(environment.dataFiles(), equalTo(new Path[]{pathHome.resolve("data")}));
+    }
+
+    public void testPathDataNotSetInEnvironmentIfNotSet() {
+        final Path defaultPathData = createTempDir().toAbsolutePath();
+        final Settings settings = Settings.builder()
+                .put("path.home", createTempDir().toAbsolutePath())
+                .put("default.path.data", defaultPathData)
+                .build();
+        assertFalse(Environment.PATH_DATA_SETTING.exists(settings));
+        assertTrue(Environment.DEFAULT_PATH_DATA_SETTING.exists(settings));
+        final Environment environment = new Environment(settings);
+        assertFalse(Environment.PATH_DATA_SETTING.exists(environment.settings()));
+        assertTrue(Environment.DEFAULT_PATH_DATA_SETTING.exists(environment.settings()));
+    }
+
+    public void testDefaultPathLogs() {
+        final Path defaultPathLogs = createTempDir().toAbsolutePath();
+        final Settings settings = Settings.builder()
+                .put("path.home", createTempDir().toAbsolutePath())
+                .put("default.path.logs", defaultPathLogs)
+                .build();
+        final Environment environment = new Environment(settings);
+        assertThat(environment.logsFile(), equalTo(defaultPathLogs));
+    }
+
+    public void testPathLogsOverrideDefaultPathLogs() {
+        final Path pathLogs = createTempDir().toAbsolutePath();
+        final Path defaultPathLogs = createTempDir().toAbsolutePath();
+        final Settings settings = Settings.builder()
+                .put("path.home", createTempDir().toAbsolutePath())
+                .put("path.logs", pathLogs)
+                .put("default.path.logs", defaultPathLogs)
+                .build();
+        final Environment environment = new Environment(settings);
+        assertThat(environment.logsFile(), equalTo(pathLogs));
+    }
+
+    public void testPathLogsWhenNotSet() {
+        final Path pathHome = createTempDir().toAbsolutePath();
+        final Settings settings = Settings.builder().put("path.home", pathHome).build();
+        final Environment environment = new Environment(settings);
+        assertThat(environment.logsFile(), equalTo(pathHome.resolve("logs")));
+    }
+
+    public void testDefaultPathConf() {
+        final Path defaultPathConf = createTempDir().toAbsolutePath();
+        final Settings settings = Settings.builder()
+                .put("path.home", createTempDir().toAbsolutePath())
+                .put("default.path.conf", defaultPathConf)
+                .build();
+        final Environment environment = new Environment(settings);
+        assertThat(environment.configFile(), equalTo(defaultPathConf));
+    }
+
+    public void testPathConfOverrideDefaultPathConf() {
+        final Path pathConf = createTempDir().toAbsolutePath();
+        final Path defaultPathConf = createTempDir().toAbsolutePath();
+        final Settings settings = Settings.builder()
+                .put("path.home", createTempDir().toAbsolutePath())
+                .put("path.conf", pathConf)
+                .put("default.path.conf", defaultPathConf)
+                .build();
+        final Environment environment = new Environment(settings);
+        assertThat(environment.configFile(), equalTo(pathConf));
+    }
+
+    public void testPathConfWhenNotSet() {
+        final Path pathHome = createTempDir().toAbsolutePath();
+        final Settings settings = Settings.builder().put("path.home", pathHome).build();
+        final Environment environment = new Environment(settings);
+        assertThat(environment.configFile(), equalTo(pathHome.resolve("config")));
+    }
+
 }

core/src/test/java/org/elasticsearch/index/IndexingSlowLogTests.java

@@ -41,7 +41,7 @@ import static org.hamcrest.Matchers.startsWith;
 public class IndexingSlowLogTests extends ESTestCase {
     public void testSlowLogParsedDocumentPrinterSourceToLog() throws IOException {
         BytesReference source = JsonXContent.contentBuilder().startObject().field("foo", "bar").endObject().bytes();
-        ParsedDocument pd = new ParsedDocument(new NumericDocValuesField("version", 1), SeqNoFieldMapper.SequenceID.emptySeqID(), "id",
+        ParsedDocument pd = new ParsedDocument(new NumericDocValuesField("version", 1), SeqNoFieldMapper.SequenceIDFields.emptySeqID(), "id",
                 "test", null, null, source, XContentType.JSON, null);
         Index index = new Index("foo", "123");
         // Turning off document logging doesn't log source[]

core/src/test/java/org/elasticsearch/index/engine/InternalEngineTests.java

@@ -83,7 +83,8 @@ import org.elasticsearch.common.io.FileSystemUtils;
 import org.elasticsearch.common.logging.Loggers;
 import org.elasticsearch.common.lucene.Lucene;
 import org.elasticsearch.common.lucene.uid.Versions;
-import org.elasticsearch.common.lucene.uid.VersionsResolver;
+import org.elasticsearch.common.lucene.uid.VersionsAndSeqNoResolver;
+import org.elasticsearch.common.lucene.uid.VersionsAndSeqNoResolver.DocIdAndSeqNo;
 import org.elasticsearch.common.settings.Settings;
 import org.elasticsearch.common.unit.TimeValue;
 import org.elasticsearch.common.util.BigArrays;
@@ -150,6 +151,7 @@ import java.util.Base64;
 import java.util.Collections;
 import java.util.Comparator;
 import java.util.HashSet;
+import java.util.LinkedHashMap;
 import java.util.List;
 import java.util.Locale;
 import java.util.Map;
@@ -165,6 +167,8 @@ import java.util.concurrent.atomic.AtomicReference;
 import java.util.function.BiFunction;
 import java.util.function.LongSupplier;
 import java.util.function.Supplier;
+import java.util.stream.Collectors;
+import java.util.stream.LongStream;
 
 import static java.util.Collections.emptyMap;
 import static java.util.Collections.shuffle;
@@ -292,7 +296,7 @@ public class InternalEngineTests extends ESTestCase {
     private static ParsedDocument testParsedDocument(String id, String type, String routing, Document document, BytesReference source, Mapping mappingUpdate) {
         Field uidField = new Field("_uid", Uid.createUid(type, id), UidFieldMapper.Defaults.FIELD_TYPE);
         Field versionField = new NumericDocValuesField("_version", 0);
-        SeqNoFieldMapper.SequenceID seqID = SeqNoFieldMapper.SequenceID.emptySeqID();
+        SeqNoFieldMapper.SequenceIDFields seqID = SeqNoFieldMapper.SequenceIDFields.emptySeqID();
         document.add(uidField);
         document.add(versionField);
         document.add(seqID.seqNo);
@@ -833,6 +837,58 @@ public class InternalEngineTests extends ESTestCase {
         }
     }
 
+    public void testTranslogRecoveryWithMultipleGenerations() throws IOException {
+        final int docs = randomIntBetween(1, 4096);
+        final List<Long> seqNos = LongStream.range(0, docs).boxed().collect(Collectors.toList());
+        Randomness.shuffle(seqNos);
+        engine.close();
+        Engine initialEngine = null;
+        try {
+            final AtomicInteger counter = new AtomicInteger();
+            initialEngine = new InternalEngine(copy(engine.config(), EngineConfig.OpenMode.CREATE_INDEX_AND_TRANSLOG)) {
+                @Override
+                public SequenceNumbersService seqNoService() {
+                    return new SequenceNumbersService(
+                            engine.shardId,
+                            engine.config().getIndexSettings(),
+                            SequenceNumbersService.NO_OPS_PERFORMED,
+                            SequenceNumbersService.NO_OPS_PERFORMED,
+                            SequenceNumbersService.UNASSIGNED_SEQ_NO) {
+                        @Override
+                        public long generateSeqNo() {
+                            return seqNos.get(counter.getAndIncrement());
+                        }
+                    };
+                }
+            };
+            for (int i = 0; i < docs; i++) {
+                final String id = Integer.toString(i);
+                final ParsedDocument doc = testParsedDocument(id, "test", null, testDocumentWithTextField(), SOURCE, null);
+                initialEngine.index(indexForDoc(doc));
+                if (rarely()) {
+                    initialEngine.getTranslog().rollGeneration();
+                } else if (rarely()) {
+                    initialEngine.flush();
+                }
+            }
+        } finally {
+            IOUtils.close(initialEngine);
+        }
+
+        Engine recoveringEngine = null;
+        try {
+            recoveringEngine = new InternalEngine(copy(initialEngine.config(), EngineConfig.OpenMode.OPEN_INDEX_AND_TRANSLOG));
+            recoveringEngine.recoverFromTranslog();
+            try (Engine.Searcher searcher = recoveringEngine.acquireSearcher("test")) {
+                TopDocs topDocs = searcher.searcher().search(new MatchAllDocsQuery(), docs);
+                assertEquals(docs, topDocs.totalHits);
+            }
+        } finally {
+            IOUtils.close(recoveringEngine);
+        }
+
+    }
+
     public void testConcurrentGetAndFlush() throws Exception {
         ParsedDocument doc = testParsedDocument("1", "test", null, testDocumentWithTextField(), B_1, null);
         engine.index(indexForDoc(doc));
@@ -1369,19 +1425,10 @@ public class InternalEngineTests extends ESTestCase {
 
     public void testOutOfOrderDocsOnReplica() throws IOException {
         final List<Engine.Operation> ops = generateSingleDocHistory(true,
-            randomFrom(VersionType.INTERNAL, VersionType.EXTERNAL), false, 2, 2, 20);
+            randomFrom(VersionType.INTERNAL, VersionType.EXTERNAL, VersionType.EXTERNAL_GTE, VersionType.FORCE), false, 2, 2, 20);
         assertOpsOnReplica(ops, replicaEngine, true);
     }
 
-    public void testNonStandardVersioningOnReplica() throws IOException {
-        // TODO: this can be folded into testOutOfOrderDocsOnReplica once out of order
-        // is detected using seq#
-        final List<Engine.Operation> ops = generateSingleDocHistory(true,
-            randomFrom(VersionType.EXTERNAL_GTE, VersionType.FORCE), false, 2, 2, 20);
-        assertOpsOnReplica(ops, replicaEngine, false);
-    }
-
-
     public void testOutOfOrderDocsOnReplicaOldPrimary() throws IOException {
         IndexSettings oldSettings = IndexSettingsModule.newIndexSettings("testOld", Settings.builder()
             .put(IndexSettings.INDEX_GC_DELETES_SETTING.getKey(), "1h") // make sure this doesn't kick in on us
@@ -3357,18 +3404,24 @@ public class InternalEngineTests extends ESTestCase {
         searchResult.close();
     }
 
-    public void testSequenceNumberAdvancesToMaxSeqOnEngineOpenOnPrimary() throws BrokenBarrierException, InterruptedException, IOException {
-        engine.close();
-        final int docs = randomIntBetween(1, 32);
-        InternalEngine initialEngine = null;
-        try {
-            final CountDownLatch latch = new CountDownLatch(1);
-            final CyclicBarrier barrier = new CyclicBarrier(2);
-            final AtomicBoolean skip = new AtomicBoolean();
-            final AtomicLong expectedLocalCheckpoint = new AtomicLong(SequenceNumbersService.NO_OPS_PERFORMED);
-            final List<Thread> threads = new ArrayList<>();
-            final SequenceNumbersService seqNoService =
-                new SequenceNumbersService(
+    /**
+     * A sequence number service that will generate a sequence number and if {@code stall} is set to {@code true} will wait on the barrier
+     * and the referenced latch before returning. If the local checkpoint should advance (because {@code stall} is {@code false}), then the
+     * value of {@code expectedLocalCheckpoint} is set accordingly.
+     *
+     * @param latchReference          to latch the thread for the purpose of stalling
+     * @param barrier                 to signal the thread has generated a new sequence number
+     * @param stall                   whether or not the thread should stall
+     * @param expectedLocalCheckpoint the expected local checkpoint after generating a new sequence
+     *                                number
+     * @return a sequence number service
+     */
+    private SequenceNumbersService getStallingSeqNoService(
+            final AtomicReference<CountDownLatch> latchReference,
+            final CyclicBarrier barrier,
+            final AtomicBoolean stall,
+            final AtomicLong expectedLocalCheckpoint) {
+        return new SequenceNumbersService(
                 shardId,
                 defaultSettings,
                 SequenceNumbersService.NO_OPS_PERFORMED,
@@ -3377,7 +3430,8 @@ public class InternalEngineTests extends ESTestCase {
             @Override
             public long generateSeqNo() {
                 final long seqNo = super.generateSeqNo();
-                        if (skip.get()) {
+                final CountDownLatch latch = latchReference.get();
+                if (stall.get()) {
                     try {
                         barrier.await();
                         latch.await();
@@ -3392,13 +3446,26 @@ public class InternalEngineTests extends ESTestCase {
                 return seqNo;
             }
         };
+    }
+
+    public void testSequenceNumberAdvancesToMaxSeqOnEngineOpenOnPrimary() throws BrokenBarrierException, InterruptedException, IOException {
+        engine.close();
+        final int docs = randomIntBetween(1, 32);
+        InternalEngine initialEngine = null;
+        try {
+            final AtomicReference<CountDownLatch> latchReference = new AtomicReference<>(new CountDownLatch(1));
+            final CyclicBarrier barrier = new CyclicBarrier(2);
+            final AtomicBoolean stall = new AtomicBoolean();
+            final AtomicLong expectedLocalCheckpoint = new AtomicLong(SequenceNumbersService.NO_OPS_PERFORMED);
+            final List<Thread> threads = new ArrayList<>();
+            final SequenceNumbersService seqNoService = getStallingSeqNoService(latchReference, barrier, stall, expectedLocalCheckpoint);
             initialEngine = createEngine(defaultSettings, store, primaryTranslogDir, newMergePolicy(), null, () -> seqNoService);
             final InternalEngine finalInitialEngine = initialEngine;
             for (int i = 0; i < docs; i++) {
                 final String id = Integer.toString(i);
                 final ParsedDocument doc = testParsedDocument(id, "test", null, testDocumentWithTextField(), SOURCE, null);
 
-                skip.set(randomBoolean());
+                stall.set(randomBoolean());
                 final Thread thread = new Thread(() -> {
                     try {
                         finalInitialEngine.index(indexForDoc(doc));
@@ -3407,7 +3474,7 @@ public class InternalEngineTests extends ESTestCase {
                     }
                 });
                 thread.start();
-                if (skip.get()) {
+                if (stall.get()) {
                     threads.add(thread);
                     barrier.await();
                 } else {
@@ -3419,7 +3486,7 @@ public class InternalEngineTests extends ESTestCase {
             assertThat(initialEngine.seqNoService().getMaxSeqNo(), equalTo((long) (docs - 1)));
             initialEngine.flush(true, true);
 
-            latch.countDown();
+            latchReference.get().countDown();
             for (final Thread thread : threads) {
                 thread.join();
             }
@@ -3594,6 +3661,78 @@ public class InternalEngineTests extends ESTestCase {
         }
     }
 
+    public void testMinGenerationForSeqNo() throws IOException, BrokenBarrierException, InterruptedException {
+        engine.close();
+        final int numberOfTriplets = randomIntBetween(1, 32);
+        InternalEngine actualEngine = null;
+        try {
+            final AtomicReference<CountDownLatch> latchReference = new AtomicReference<>();
+            final CyclicBarrier barrier = new CyclicBarrier(2);
+            final AtomicBoolean stall = new AtomicBoolean();
+            final AtomicLong expectedLocalCheckpoint = new AtomicLong(SequenceNumbersService.NO_OPS_PERFORMED);
+            final Map<Thread, CountDownLatch> threads = new LinkedHashMap<>();
+            final SequenceNumbersService seqNoService = getStallingSeqNoService(latchReference, barrier, stall, expectedLocalCheckpoint);
+            actualEngine = createEngine(defaultSettings, store, primaryTranslogDir, newMergePolicy(), null, () -> seqNoService);
+            final InternalEngine finalActualEngine = actualEngine;
+            final Translog translog = finalActualEngine.getTranslog();
+            final long generation = finalActualEngine.getTranslog().currentFileGeneration();
+            for (int i = 0; i < numberOfTriplets; i++) {
+                /*
+                 * Index three documents with the first and last landing in the same generation and the middle document being stalled until
+                 * a later generation.
+                 */
+                stall.set(false);
+                index(finalActualEngine, 3 * i);
+
+                final CountDownLatch latch = new CountDownLatch(1);
+                latchReference.set(latch);
+                final int skipId = 3 * i + 1;
+                stall.set(true);
+                final Thread thread = new Thread(() -> {
+                    try {
+                        index(finalActualEngine, skipId);
+                    } catch (IOException e) {
+                        throw new AssertionError(e);
+                    }
+                });
+                thread.start();
+                threads.put(thread, latch);
+                barrier.await();
+
+                stall.set(false);
+                index(finalActualEngine, 3 * i + 2);
+                finalActualEngine.flush();
+
+                /*
+                 * This sequence number landed in the last generation, but the lower and upper bounds for an earlier generation straddle
+                 * this sequence number.
+                 */
+                assertThat(translog.getMinGenerationForSeqNo(3 * i + 1).translogFileGeneration, equalTo(i + generation));
+            }
+
+            int i = 0;
+            for (final Map.Entry<Thread, CountDownLatch> entry : threads.entrySet()) {
+                final Map<String, String> userData = finalActualEngine.commitStats().getUserData();
+                assertThat(userData.get(SequenceNumbers.LOCAL_CHECKPOINT_KEY), equalTo(Long.toString(3 * i)));
+                assertThat(userData.get(Translog.TRANSLOG_GENERATION_KEY), equalTo(Long.toString(i + generation)));
+                entry.getValue().countDown();
+                entry.getKey().join();
+                finalActualEngine.flush();
+                i++;
+            }
+
+        } finally {
+            IOUtils.close(actualEngine);
+        }
+    }
+
+    private void index(final InternalEngine engine, final int id) throws IOException {
+        final String docId = Integer.toString(id);
+        final ParsedDocument doc =
+                testParsedDocument(docId, "test", null, testDocumentWithTextField(), SOURCE, null);
+        engine.index(indexForDoc(doc));
+    }
+
     /**
      * Return a tuple representing the sequence ID for the given {@code Get}
      * operation. The first value in the tuple is the sequence number, the
@@ -3601,9 +3740,17 @@ public class InternalEngineTests extends ESTestCase {
      */
     private Tuple<Long, Long> getSequenceID(Engine engine, Engine.Get get) throws EngineException {
         try (Searcher searcher = engine.acquireSearcher("get")) {
-            long seqNum = VersionsResolver.loadSeqNo(searcher.reader(), get.uid());
-            long primaryTerm = VersionsResolver.loadPrimaryTerm(searcher.reader(), get.uid());
-            return new Tuple<>(seqNum, primaryTerm);
+            final long primaryTerm;
+            final long seqNo;
+            DocIdAndSeqNo docIdAndSeqNo = VersionsAndSeqNoResolver.loadDocIdAndSeqNo(searcher.reader(), get.uid());
+            if (docIdAndSeqNo == null) {
+                primaryTerm = 0;
+                seqNo = SequenceNumbersService.UNASSIGNED_SEQ_NO;
+            } else {
+                seqNo = docIdAndSeqNo.seqNo;
+                primaryTerm = VersionsAndSeqNoResolver.loadPrimaryTerm(docIdAndSeqNo);
+            }
+            return new Tuple<>(seqNo, primaryTerm);
         } catch (Exception e) {
             throw new EngineException(shardId, "unable to retrieve sequence id", e);
         }

core/src/test/java/org/elasticsearch/index/engine/LiveVersionMapTests.java

@@ -33,7 +33,7 @@ public class LiveVersionMapTests extends ESTestCase {
         for (int i = 0; i < 100000; ++i) {
             BytesRefBuilder uid = new BytesRefBuilder();
             uid.copyChars(TestUtil.randomSimpleString(random(), 10, 20));
-            VersionValue version = new VersionValue(randomLong());
+            VersionValue version = new VersionValue(randomLong(), randomLong(), randomLong());
             map.putUnderLock(uid.toBytesRef(), version);
         }
         long actualRamBytesUsed = RamUsageTester.sizeOf(map);
@@ -48,7 +48,7 @@ public class LiveVersionMapTests extends ESTestCase {
         for (int i = 0; i < 100000; ++i) {
             BytesRefBuilder uid = new BytesRefBuilder();
             uid.copyChars(TestUtil.randomSimpleString(random(), 10, 20));
-            VersionValue version = new VersionValue(randomLong());
+            VersionValue version = new VersionValue(randomLong(), randomLong(), randomLong());
             map.putUnderLock(uid.toBytesRef(), version);
         }
         actualRamBytesUsed = RamUsageTester.sizeOf(map);

core/src/test/java/org/elasticsearch/index/engine/VersionValueTests.java

@@ -25,12 +25,12 @@ import org.elasticsearch.test.ESTestCase;
 public class VersionValueTests extends ESTestCase {
 
     public void testRamBytesUsed() {
-        VersionValue versionValue = new VersionValue(randomLong());
+        VersionValue versionValue = new VersionValue(randomLong(), randomLong(), randomLong());
         assertEquals(RamUsageTester.sizeOf(versionValue), versionValue.ramBytesUsed());
     }
 
     public void testDeleteRamBytesUsed() {
-        DeleteVersionValue versionValue = new DeleteVersionValue(randomLong(), randomLong());
+        DeleteVersionValue versionValue = new DeleteVersionValue(randomLong(), randomLong(), randomLong(), randomLong());
         assertEquals(RamUsageTester.sizeOf(versionValue), versionValue.ramBytesUsed());
     }
 

core/src/test/java/org/elasticsearch/index/replication/ESIndexLevelReplicationTestCase.java

@@ -27,13 +27,9 @@ import org.elasticsearch.action.DocWriteResponse;
 import org.elasticsearch.action.admin.indices.flush.FlushRequest;
 import org.elasticsearch.action.bulk.BulkItemRequest;
 import org.elasticsearch.action.bulk.BulkItemResponse;
-import org.elasticsearch.action.bulk.BulkRequest;
-import org.elasticsearch.action.bulk.BulkResponse;
 import org.elasticsearch.action.bulk.BulkShardRequest;
 import org.elasticsearch.action.bulk.BulkShardResponse;
 import org.elasticsearch.action.bulk.TransportShardBulkActionTests;
-import org.elasticsearch.action.bulk.TransportSingleItemBulkWriteAction;
-import org.elasticsearch.action.delete.DeleteRequest;
 import org.elasticsearch.action.index.IndexRequest;
 import org.elasticsearch.action.index.IndexResponse;
 import org.elasticsearch.action.support.PlainActionFuture;
@@ -98,6 +94,10 @@ public abstract class ESIndexLevelReplicationTestCase extends IndexShardTestCase
     }
 
     protected IndexMetaData buildIndexMetaData(int replicas) throws IOException {
+        return buildIndexMetaData(replicas, indexMapping);
+    }
+
+    protected IndexMetaData buildIndexMetaData(int replicas, Map<String, String> mappings) throws IOException {
         Settings settings = Settings.builder().put(IndexMetaData.SETTING_VERSION_CREATED, Version.CURRENT)
             .put(IndexMetaData.SETTING_NUMBER_OF_REPLICAS, replicas)
             .put(IndexMetaData.SETTING_NUMBER_OF_SHARDS, 1)
@@ -105,7 +105,7 @@ public abstract class ESIndexLevelReplicationTestCase extends IndexShardTestCase
         IndexMetaData.Builder metaData = IndexMetaData.builder(index.getName())
             .settings(settings)
             .primaryTerm(0, 1);
-        for (Map.Entry<String, String> typeMapping : indexMapping.entrySet()) {
+        for (Map.Entry<String, String> typeMapping : mappings.entrySet()) {
             metaData.putMapping(typeMapping.getKey(), typeMapping.getValue());
         }
         return metaData.build();
@@ -224,15 +224,24 @@ public abstract class ESIndexLevelReplicationTestCase extends IndexShardTestCase
             updateAllocationIDsOnPrimary();
         }
 
-        public synchronized IndexShard addReplica() throws IOException {
+        public IndexShard addReplica() throws IOException {
             final ShardRouting replicaRouting = createShardRouting("s" + replicaId.incrementAndGet(), false);
             final IndexShard replica =
                 newShard(replicaRouting, indexMetaData, null, this::syncGlobalCheckpoint, getEngineFactory(replicaRouting));
-            replicas.add(replica);
-            updateAllocationIDsOnPrimary();
+            addReplica(replica);
             return replica;
         }
 
+        public synchronized void addReplica(IndexShard replica) {
+            assert shardRoutings().stream()
+                .filter(shardRouting -> shardRouting.isSameAllocation(replica.routingEntry())).findFirst().isPresent() == false :
+                "replica with aId [" + replica.routingEntry().allocationId() + "] already exists";
+            replica.updatePrimaryTerm(primary.getPrimaryTerm());
+            replicas.add(replica);
+            updateAllocationIDsOnPrimary();
+        }
+
+
         public synchronized IndexShard addReplicaWithExistingPath(final ShardPath shardPath, final String nodeId) throws IOException {
             final ShardRouting shardRouting = TestShardRouting.newShardRouting(
                 shardId,
@@ -264,6 +273,7 @@ public abstract class ESIndexLevelReplicationTestCase extends IndexShardTestCase
             }
             boolean found = replicas.remove(replica);
             assert found;
+            closeShards(primary);
             primary = replica;
             replica.updateRoutingEntry(replica.routingEntry().moveActiveReplicaToPrimary());
             updateAllocationIDsOnPrimary();

core/src/test/java/org/elasticsearch/index/replication/IndexLevelReplicationTests.java

@@ -18,6 +18,9 @@
  */
 package org.elasticsearch.index.replication;
 
+import org.apache.lucene.index.Term;
+import org.apache.lucene.search.TermQuery;
+import org.apache.lucene.search.TopDocs;
 import org.elasticsearch.action.DocWriteResponse;
 import org.elasticsearch.action.index.IndexRequest;
 import org.elasticsearch.action.index.IndexResponse;
@@ -37,6 +40,7 @@ import org.elasticsearch.indices.recovery.RecoveryTarget;
 
 import java.io.IOException;
 import java.util.Collections;
+import java.util.Map;
 import java.util.concurrent.CountDownLatch;
 import java.util.concurrent.Future;
 
@@ -152,4 +156,28 @@ public class IndexLevelReplicationTests extends ESIndexLevelReplicationTestCase
         }
     }
 
+    public void testConflictingOpsOnReplica() throws Exception {
+        Map<String, String> mappings =
+            Collections.singletonMap("type", "{ \"type\": { \"properties\": { \"f\": { \"type\": \"keyword\"} }}}");
+        try (ReplicationGroup shards = new ReplicationGroup(buildIndexMetaData(2, mappings))) {
+            shards.startAll();
+            IndexShard replica1 = shards.getReplicas().get(0);
+            logger.info("--> isolated replica " + replica1.routingEntry());
+            shards.removeReplica(replica1);
+            IndexRequest indexRequest = new IndexRequest(index.getName(), "type", "1").source("{ \"f\": \"1\"}", XContentType.JSON);
+            shards.index(indexRequest);
+            shards.addReplica(replica1);
+            logger.info("--> promoting replica to primary " + replica1.routingEntry());
+            shards.promoteReplicaToPrimary(replica1);
+            indexRequest = new IndexRequest(index.getName(), "type", "1").source("{ \"f\": \"2\"}", XContentType.JSON);
+            shards.index(indexRequest);
+            shards.refresh("test");
+            for (IndexShard shard : shards) {
+                try (Engine.Searcher searcher = shard.acquireSearcher("test")) {
+                    TopDocs search = searcher.searcher().search(new TermQuery(new Term("f", "2")), 10);
+                    assertEquals("shard " + shard.routingEntry() + " misses new version", 1, search.totalHits);
+                }
+            }
+        }
+    }
 }

core/src/test/java/org/elasticsearch/index/shard/IndexShardIT.java

@@ -107,7 +107,7 @@ public class IndexShardIT extends ESSingleNodeTestCase {
                                               Mapping mappingUpdate) {
         Field uidField = new Field("_uid", Uid.createUid(type, id), UidFieldMapper.Defaults.FIELD_TYPE);
         Field versionField = new NumericDocValuesField("_version", 0);
-        SeqNoFieldMapper.SequenceID seqID = SeqNoFieldMapper.SequenceID.emptySeqID();
+        SeqNoFieldMapper.SequenceIDFields seqID = SeqNoFieldMapper.SequenceIDFields.emptySeqID();
         document.add(uidField);
         document.add(versionField);
         document.add(seqID.seqNo);

core/src/test/java/org/elasticsearch/index/shard/IndexShardTests.java

@@ -551,7 +551,7 @@ public class IndexShardTests extends IndexShardTestCase {
                                               ParseContext.Document document, BytesReference source, Mapping mappingUpdate) {
         Field uidField = new Field("_uid", Uid.createUid(type, id), UidFieldMapper.Defaults.FIELD_TYPE);
         Field versionField = new NumericDocValuesField("_version", 0);
-        SeqNoFieldMapper.SequenceID seqID = SeqNoFieldMapper.SequenceID.emptySeqID();
+        SeqNoFieldMapper.SequenceIDFields seqID = SeqNoFieldMapper.SequenceIDFields.emptySeqID();
         document.add(uidField);
         document.add(versionField);
         document.add(seqID.seqNo);

core/src/test/java/org/elasticsearch/index/shard/RefreshListenersTests.java

@@ -332,7 +332,7 @@ public class RefreshListenersTests extends ESTestCase {
         document.add(new TextField("test", testFieldValue, Field.Store.YES));
         Field uidField = new Field("_uid", Uid.createUid(type, id), UidFieldMapper.Defaults.FIELD_TYPE);
         Field versionField = new NumericDocValuesField("_version", Versions.MATCH_ANY);
-        SeqNoFieldMapper.SequenceID seqID = SeqNoFieldMapper.SequenceID.emptySeqID();
+        SeqNoFieldMapper.SequenceIDFields seqID = SeqNoFieldMapper.SequenceIDFields.emptySeqID();
         document.add(uidField);
         document.add(versionField);
         document.add(seqID.seqNo);

core/src/test/java/org/elasticsearch/index/translog/TranslogTests.java

@@ -36,8 +36,10 @@ import org.apache.lucene.util.LineFileDocs;
 import org.apache.lucene.util.LuceneTestCase;
 import org.elasticsearch.Version;
 import org.elasticsearch.cluster.metadata.IndexMetaData;
+import org.elasticsearch.common.Randomness;
 import org.elasticsearch.common.bytes.BytesArray;
 import org.elasticsearch.common.bytes.BytesReference;
+import org.elasticsearch.common.collect.Tuple;
 import org.elasticsearch.common.io.FileSystemUtils;
 import org.elasticsearch.common.io.stream.BytesStreamOutput;
 import org.elasticsearch.common.io.stream.StreamInput;
@@ -84,6 +86,7 @@ import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Collection;
 import java.util.Collections;
+import java.util.HashMap;
 import java.util.HashSet;
 import java.util.Iterator;
 import java.util.List;
@@ -101,6 +104,7 @@ import java.util.concurrent.atomic.AtomicInteger;
 import java.util.concurrent.atomic.AtomicLong;
 import java.util.concurrent.atomic.AtomicReference;
 import java.util.stream.Collectors;
+import java.util.stream.LongStream;
 
 import static org.elasticsearch.common.util.BigArrays.NON_RECYCLING_INSTANCE;
 import static org.hamcrest.Matchers.containsString;
@@ -124,7 +128,7 @@ public class TranslogTests extends ESTestCase {
 
         if (translog.isOpen()) {
             if (translog.currentFileGeneration() > 1) {
-                translog.commit();
+                translog.commit(translog.currentFileGeneration());
                 assertFileDeleted(translog, translog.currentFileGeneration() - 1);
             }
             translog.close();
@@ -287,7 +291,7 @@ public class TranslogTests extends ESTestCase {
         assertThat(snapshot, SnapshotMatchers.equalsTo(ops));
         assertThat(snapshot.totalOperations(), equalTo(ops.size()));
 
-        translog.commit();
+        translog.commit(translog.currentFileGeneration());
         snapshot = translog.newSnapshot();
         assertThat(snapshot, SnapshotMatchers.size(0));
         assertThat(snapshot.totalOperations(), equalTo(0));
@@ -373,7 +377,7 @@ public class TranslogTests extends ESTestCase {
             }
         }
 
-        translog.commit();
+        translog.commit(translog.currentFileGeneration());
         {
             final TranslogStats stats = stats();
             assertThat(stats.estimatedNumberOfOperations(), equalTo(0L));
@@ -446,7 +450,7 @@ public class TranslogTests extends ESTestCase {
 
         try (Translog.View view = translog.newView()) {
             Translog.Snapshot snapshot2 = translog.newSnapshot();
-            translog.commit();
+            translog.commit(translog.currentFileGeneration());
             assertThat(snapshot2, SnapshotMatchers.equalsTo(ops));
             assertThat(snapshot2.totalOperations(), equalTo(ops.size()));
         }
@@ -821,7 +825,7 @@ public class TranslogTests extends ESTestCase {
                         break;
                     }
                 }
-                translog.commit();
+                translog.commit(translog.currentFileGeneration());
             }
         } finally {
             run.set(false);
@@ -858,7 +862,7 @@ public class TranslogTests extends ESTestCase {
                 assertTrue("we only synced a previous operation yet", translog.syncNeeded());
             }
             if (rarely()) {
-                translog.commit();
+                translog.commit(translog.currentFileGeneration());
                 assertFalse("location is from a previous translog - already synced", translog.ensureSynced(location)); // not syncing now
                 assertFalse("no sync needed since no operations in current translog", translog.syncNeeded());
             }
@@ -878,7 +882,7 @@ public class TranslogTests extends ESTestCase {
             ArrayList<Location> locations = new ArrayList<>();
             for (int op = 0; op < translogOperations; op++) {
                 if (rarely()) {
-                    translog.commit(); // do this first so that there is at least one pending tlog entry
+                    translog.commit(translog.currentFileGeneration()); // do this first so that there is at least one pending tlog entry
                 }
                 final Translog.Location location = translog.add(new Translog.Index("test", "" + op, Integer.toString(++count).getBytes(Charset.forName("UTF-8"))));
                 locations.add(location);
@@ -889,7 +893,7 @@ public class TranslogTests extends ESTestCase {
                 assertTrue("this operation has not been synced", translog.ensureSynced(locations.stream()));
                 assertFalse("the last call to ensureSycned synced all previous ops", translog.syncNeeded()); // we are the last location so everything should be synced
             } else if (rarely()) {
-                translog.commit();
+                translog.commit(translog.currentFileGeneration());
                 assertFalse("location is from a previous translog - already synced", translog.ensureSynced(locations.stream())); // not syncing now
                 assertFalse("no sync needed since no operations in current translog", translog.syncNeeded());
             } else {
@@ -909,7 +913,7 @@ public class TranslogTests extends ESTestCase {
         for (int op = 0; op < translogOperations; op++) {
             locations.add(translog.add(new Translog.Index("test", "" + op, Integer.toString(++count).getBytes(Charset.forName("UTF-8")))));
             if (rarely() && translogOperations > op + 1) {
-                translog.commit();
+                translog.commit(translog.currentFileGeneration());
             }
         }
         Collections.shuffle(locations, random());
@@ -1074,7 +1078,7 @@ public class TranslogTests extends ESTestCase {
             locations.add(translog.add(new Translog.Index("test", "" + op, Integer.toString(op).getBytes(Charset.forName("UTF-8")))));
             final boolean commit = commitOften ? frequently() : rarely();
             if (commit && op < translogOperations - 1) {
-                translog.commit();
+                translog.commit(translog.currentFileGeneration());
                 minUncommittedOp = op + 1;
                 translogGeneration = translog.getGeneration();
             }
@@ -1300,7 +1304,7 @@ public class TranslogTests extends ESTestCase {
         for (int op = 0; op < translogOperations; op++) {
             locations.add(translog.add(new Translog.Index("test", "" + op, Integer.toString(op).getBytes(Charset.forName("UTF-8")))));
             if (randomBoolean()) {
-                translog.commit();
+                translog.commit(translog.currentFileGeneration());
                 firstUncommitted = op + 1;
             }
         }
@@ -1483,7 +1487,7 @@ public class TranslogTests extends ESTestCase {
         }
 
         try {
-            translog.commit();
+            translog.commit(translog.currentFileGeneration());
             fail("already closed");
         } catch (AlreadyClosedException ex) {
             assertNotNull(ex.getCause());
@@ -1930,7 +1934,7 @@ public class TranslogTests extends ESTestCase {
                             if (randomBoolean()) {
                                 failableTLog.prepareCommit();
                             }
-                            failableTLog.commit();
+                            failableTLog.commit(translog.currentFileGeneration());
                             syncedDocs.clear();
                         }
                     }
@@ -2048,7 +2052,7 @@ public class TranslogTests extends ESTestCase {
 
     public void testTranslogOpSerialization() throws Exception {
         BytesReference B_1 = new BytesArray(new byte[]{1});
-        SeqNoFieldMapper.SequenceID seqID = SeqNoFieldMapper.SequenceID.emptySeqID();
+        SeqNoFieldMapper.SequenceIDFields seqID = SeqNoFieldMapper.SequenceIDFields.emptySeqID();
         assert Version.CURRENT.major <= 6 : "Using UNASSIGNED_SEQ_NO can be removed in 7.0, because 6.0+ nodes have actual sequence numbers";
         long randomSeqNum = randomBoolean() ? SequenceNumbersService.UNASSIGNED_SEQ_NO : randomNonNegativeLong();
         long randomPrimaryTerm = randomBoolean() ? 0 : randomNonNegativeLong();
@@ -2110,12 +2114,13 @@ public class TranslogTests extends ESTestCase {
         for (int i = 0; i <= rolls; i++) {
             assertFileIsPresent(translog, generation + i);
         }
-        translog.commit();
+        translog.commit(generation + rolls);
         assertThat(translog.currentFileGeneration(), equalTo(generation + rolls + 1));
         assertThat(translog.totalOperations(), equalTo(0));
-        for (int i = 0; i <= rolls; i++) {
+        for (int i = 0; i < rolls; i++) {
             assertFileDeleted(translog, generation + i);
         }
+        assertFileIsPresent(translog, generation + rolls);
         assertFileIsPresent(translog, generation + rolls + 1);
     }
 
@@ -2167,7 +2172,7 @@ public class TranslogTests extends ESTestCase {
             }
         }
 
-        translog.commit();
+        translog.commit(generation + rollsBefore + 1);
 
         for (int i = 0; i <= rollsBefore; i++) {
             assertFileDeleted(translog, generation + i);
@@ -2178,4 +2183,130 @@ public class TranslogTests extends ESTestCase {
 
     }
 
+    public void testMinGenerationForSeqNo() throws IOException {
+        final long initialGeneration = translog.getGeneration().translogFileGeneration;
+        final int operations = randomIntBetween(1, 4096);
+        final List<Long> shuffledSeqNos = LongStream.range(0, operations).boxed().collect(Collectors.toList());
+        Randomness.shuffle(shuffledSeqNos);
+        final List<Tuple<Long, Long>> seqNos = new ArrayList<>();
+        final Map<Long, Long> terms = new HashMap<>();
+        for (final Long seqNo : shuffledSeqNos) {
+            seqNos.add(Tuple.tuple(seqNo, terms.computeIfAbsent(seqNo, k -> 0L)));
+            Long repeatingTermSeqNo = randomFrom(seqNos.stream().map(Tuple::v1).collect(Collectors.toList()));
+            seqNos.add(Tuple.tuple(repeatingTermSeqNo, terms.computeIfPresent(repeatingTermSeqNo, (s, t) -> t + 1)));
+        }
+
+        for (final Tuple<Long, Long> tuple : seqNos) {
+            translog.add(new Translog.NoOp(tuple.v1(), tuple.v2(), "test"));
+            if (rarely()) {
+                translog.rollGeneration();
+            }
+        }
+
+        Map<Long, Set<Tuple<Long, Long>>> generations = new HashMap<>();
+
+        translog.commit(initialGeneration);
+        for (long seqNo = 0; seqNo < operations; seqNo++) {
+            final Set<Tuple<Long, Long>> seenSeqNos = new HashSet<>();
+            final long generation = translog.getMinGenerationForSeqNo(seqNo).translogFileGeneration;
+            for (long g = generation; g < translog.currentFileGeneration(); g++) {
+                if (!generations.containsKey(g)) {
+                    final Set<Tuple<Long, Long>> generationSeenSeqNos = new HashSet<>();
+                    final Checkpoint checkpoint = Checkpoint.read(translog.location().resolve(Translog.getCommitCheckpointFileName(g)));
+                    try (TranslogReader reader = translog.openReader(translog.location().resolve(Translog.getFilename(g)), checkpoint)) {
+                        Translog.Snapshot snapshot = reader.newSnapshot();
+                        Translog.Operation operation;
+                        while ((operation = snapshot.next()) != null) {
+                            generationSeenSeqNos.add(Tuple.tuple(operation.seqNo(), operation.primaryTerm()));
+                        }
+                    }
+                    generations.put(g, generationSeenSeqNos);
+
+                }
+                seenSeqNos.addAll(generations.get(g));
+            }
+
+            final long seqNoLowerBound = seqNo;
+            final Set<Tuple<Long, Long>> expected = seqNos.stream().filter(t -> t.v1() >= seqNoLowerBound).collect(Collectors.toSet());
+            seenSeqNos.retainAll(expected);
+            assertThat(seenSeqNos, equalTo(expected));
+        }
+    }
+
+    public void testSimpleCommit() throws IOException {
+        final int operations = randomIntBetween(1, 4096);
+        long seqNo = 0;
+        for (int i = 0; i < operations; i++) {
+            translog.add(new Translog.NoOp(seqNo++, 0, "test'"));
+            if (rarely()) {
+                translog.rollGeneration();
+            }
+        }
+
+        final long generation =
+                randomIntBetween(1, Math.toIntExact(translog.currentFileGeneration()));
+        translog.commit(generation);
+        for (long i = 0; i < generation; i++) {
+            assertFileDeleted(translog, i);
+        }
+        for (long i = generation; i <= translog.currentFileGeneration(); i++) {
+            assertFileIsPresent(translog, i);
+        }
+    }
+
+    public void testPrepareCommitAndCommit() throws IOException {
+        final int operations = randomIntBetween(1, 4096);
+        long seqNo = 0;
+        long last = -1;
+        for (int i = 0; i < operations; i++) {
+            translog.add(new Translog.NoOp(seqNo++, 0, "test"));
+            if (rarely()) {
+                final long generation = translog.currentFileGeneration();
+                translog.prepareCommit();
+                if (rarely()) {
+                    // simulate generation filling up and rolling between preparing the commit and committing
+                    translog.rollGeneration();
+                }
+                final int committedGeneration = randomIntBetween(Math.max(1, Math.toIntExact(last)), Math.toIntExact(generation));
+                translog.commit(committedGeneration);
+                last = committedGeneration;
+                for (long g = 0; i < generation; g++) {
+                    assertFileDeleted(translog, g);
+                }
+                for (long g = generation; g < translog.currentFileGeneration(); g++) {
+                    assertFileIsPresent(translog, g);
+                }
+            }
+        }
+    }
+
+    public void testCommitWithOpenView() throws IOException {
+        final int operations = randomIntBetween(1, 4096);
+        long seqNo = 0;
+        long lastCommittedGeneration = -1;
+        for (int i = 0; i < operations; i++) {
+            translog.add(new Translog.NoOp(seqNo++, 0, "test"));
+            if (rarely()) {
+                try (Translog.View ignored = translog.newView()) {
+                    final long viewGeneration = lastCommittedGeneration;
+                    translog.prepareCommit();
+                    final long committedGeneration = randomIntBetween(
+                            Math.max(1, Math.toIntExact(lastCommittedGeneration)),
+                            Math.toIntExact(translog.currentFileGeneration()));
+                    translog.commit(committedGeneration);
+                    lastCommittedGeneration = committedGeneration;
+                    // with an open view, committing should preserve generations back to the last committed generation
+                    for (long g = 1; g < Math.min(lastCommittedGeneration, viewGeneration); g++) {
+                        assertFileDeleted(translog, g);
+                    }
+                    // the view generation could be -1 if no commit has been performed
+                    final long max = Math.max(1, Math.min(lastCommittedGeneration, viewGeneration));
+                    for (long g = max; g < translog.currentFileGeneration(); g++) {
+                        assertFileIsPresent(translog, g);
+                    }
+                }
+            }
+        }
+    }
+
 }

core/src/test/java/org/elasticsearch/indices/cluster/AbstractIndicesClusterStateServiceTestCase.java

@@ -91,7 +91,11 @@ public abstract class AbstractIndicesClusterStateServiceTestCase extends ESTestC
         RoutingNode localRoutingNode = state.getRoutingNodes().node(state.getNodes().getLocalNodeId());
         if (localRoutingNode != null) {
             if (enableRandomFailures == false) {
-                assertThat("failed shard cache should be empty", failedShardsCache.values(), empty());
+                // initializing a shard should succeed when enableRandomFailures is disabled
+                // active shards can be failed if state persistence was disabled in an earlier CS update
+                if (failedShardsCache.values().stream().anyMatch(ShardRouting::initializing)) {
+                    fail("failed shard cache should not contain initializing shard routing: " + failedShardsCache.values());
+                }
             }
             // check that all shards in local routing nodes have been allocated
             for (ShardRouting shardRouting : localRoutingNode) {
@@ -100,16 +104,23 @@ public abstract class AbstractIndicesClusterStateServiceTestCase extends ESTestC
 
                 MockIndexShard shard = indicesService.getShardOrNull(shardRouting.shardId());
                 ShardRouting failedShard = failedShardsCache.get(shardRouting.shardId());
-                if (enableRandomFailures) {
-                    if (shard == null && failedShard == null) {
-                        fail("Shard with id " + shardRouting + " expected but missing in indicesService and failedShardsCache");
+
+                if (state.blocks().disableStatePersistence()) {
+                    if (shard != null) {
+                        fail("Shard with id " + shardRouting + " should be removed from indicesService due to disabled state persistence");
                     }
+                } else {
                     if (failedShard != null && failedShard.isSameAllocation(shardRouting) == false) {
                         fail("Shard cache has not been properly cleaned for " + failedShard);
                     }
-                } else {
-                    if (shard == null) {
-                        fail("Shard with id " + shardRouting + " expected but missing in indicesService");
+                    if (shard == null && failedShard == null) {
+                        // shard must either be there or there must be a failure
+                        fail("Shard with id " + shardRouting + " expected but missing in indicesService and failedShardsCache");
+                    }
+                    if (enableRandomFailures == false) {
+                        if (shard == null && shardRouting.initializing() && failedShard == shardRouting) {
+                            // initializing a shard should succeed when enableRandomFailures is disabled
+                            fail("Shard with id " + shardRouting + " expected but missing in indicesService " + failedShard);
                         }
                     }
 
@@ -132,16 +143,22 @@ public abstract class AbstractIndicesClusterStateServiceTestCase extends ESTestC
                                 .map(r -> r.allocationId().getId()).collect(Collectors.toSet());
                             Set<String> initializingIds = shardRoutingTable.getAllInitializingShards().stream()
                                 .map(r -> r.allocationId().getId()).collect(Collectors.toSet());
-                        assertThat(shard.routingEntry() + " isn't updated with active aIDs", shard.activeAllocationIds, equalTo(activeIds));
+                            assertThat(shard.routingEntry() + " isn't updated with active aIDs", shard.activeAllocationIds,
+                                equalTo(activeIds));
                             assertThat(shard.routingEntry() + " isn't updated with init aIDs", shard.initializingAllocationIds,
                                 equalTo(initializingIds));
                         }
                     }
                 }
             }
+        }
 
         // all other shards / indices have been cleaned up
         for (AllocatedIndex<? extends Shard> indexService : indicesService) {
+            if (state.blocks().disableStatePersistence()) {
+                fail("Index service " + indexService.index() + " should be removed from indicesService due to disabled state persistence");
+            }
+
             assertTrue(state.metaData().getIndexSafe(indexService.index()) != null);
 
             boolean shardsFound = false;
@@ -158,13 +175,9 @@ public abstract class AbstractIndicesClusterStateServiceTestCase extends ESTestC
             }
 
             if (shardsFound == false) {
-                if (enableRandomFailures) {
                 // check if we have shards of that index in failedShardsCache
                 // if yes, we might not have cleaned the index as failedShardsCache can be populated by another thread
                 assertFalse(failedShardsCache.keySet().stream().noneMatch(shardId -> shardId.getIndex().equals(indexService.index())));
-                } else {
-                    fail("index service for index " + indexService.index() + " has no shards");
-                }
             }
 
         }

core/src/test/java/org/elasticsearch/indices/cluster/IndicesClusterStateServiceRandomUpdatesTests.java

@@ -32,6 +32,8 @@ import org.elasticsearch.action.support.replication.ClusterStateCreationUtils;
 import org.elasticsearch.cluster.ClusterChangedEvent;
 import org.elasticsearch.cluster.ClusterState;
 import org.elasticsearch.cluster.action.shard.ShardStateAction;
+import org.elasticsearch.cluster.block.ClusterBlock;
+import org.elasticsearch.cluster.block.ClusterBlocks;
 import org.elasticsearch.cluster.metadata.IndexMetaData;
 import org.elasticsearch.cluster.metadata.MetaData;
 import org.elasticsearch.cluster.node.DiscoveryNode;
@@ -44,6 +46,7 @@ import org.elasticsearch.cluster.service.ClusterService;
 import org.elasticsearch.common.UUIDs;
 import org.elasticsearch.common.settings.Settings;
 import org.elasticsearch.common.util.set.Sets;
+import org.elasticsearch.discovery.DiscoverySettings;
 import org.elasticsearch.index.Index;
 import org.elasticsearch.indices.recovery.PeerRecoveryTargetService;
 import org.elasticsearch.repositories.RepositoriesService;
@@ -231,6 +234,23 @@ public class IndicesClusterStateServiceRandomUpdatesTests extends AbstractIndice
     public ClusterState randomlyUpdateClusterState(ClusterState state,
                                                    Map<DiscoveryNode, IndicesClusterStateService> clusterStateServiceMap,
                                                    Supplier<MockIndicesService> indicesServiceSupplier) {
+        // randomly remove no_master blocks
+        if (randomBoolean() && state.blocks().hasGlobalBlock(DiscoverySettings.NO_MASTER_BLOCK_ID)) {
+            state = ClusterState.builder(state).blocks(
+                ClusterBlocks.builder().blocks(state.blocks()).removeGlobalBlock(DiscoverySettings.NO_MASTER_BLOCK_ID)).build();
+        }
+
+        // randomly add no_master blocks
+        if (rarely() && state.blocks().hasGlobalBlock(DiscoverySettings.NO_MASTER_BLOCK_ID) == false) {
+            ClusterBlock block = randomBoolean() ? DiscoverySettings.NO_MASTER_BLOCK_ALL : DiscoverySettings.NO_MASTER_BLOCK_WRITES;
+            state = ClusterState.builder(state).blocks(ClusterBlocks.builder().blocks(state.blocks()).addGlobalBlock(block)).build();
+        }
+
+        // if no_master block is in place, make no other cluster state changes
+        if (state.blocks().hasGlobalBlock(DiscoverySettings.NO_MASTER_BLOCK_ID)) {
+            return state;
+        }
+
         // randomly create new indices (until we have 200 max)
         for (int i = 0; i < randomInt(5); i++) {
             if (state.metaData().indices().size() > 200) {

core/src/test/java/org/elasticsearch/indices/recovery/RecoverySourceHandlerTests.java

@@ -204,7 +204,7 @@ public class RecoverySourceHandlerTests extends ESTestCase {
         document.add(new TextField("test", "test", Field.Store.YES));
         final Field uidField = new Field("_uid", Uid.createUid(type, id), UidFieldMapper.Defaults.FIELD_TYPE);
         final Field versionField = new NumericDocValuesField("_version", Versions.MATCH_ANY);
-        final SeqNoFieldMapper.SequenceID seqID = SeqNoFieldMapper.SequenceID.emptySeqID();
+        final SeqNoFieldMapper.SequenceIDFields seqID = SeqNoFieldMapper.SequenceIDFields.emptySeqID();
         document.add(uidField);
         document.add(versionField);
         document.add(seqID.seqNo);

core/src/test/java/org/elasticsearch/node/InternalSettingsPreparerTests.java

@@ -17,7 +17,7 @@
  * under the License.
  */
 
-package org.elasticsearch.node.internal;
+package org.elasticsearch.node;
 
 import org.elasticsearch.cli.MockTerminal;
 import org.elasticsearch.cluster.ClusterName;
@@ -182,18 +182,11 @@ public class InternalSettingsPreparerTests extends ESTestCase {
         assertEquals("secret", fakeSetting.get(env.settings()).toString());
     }
 
-    public void testDefaultProperties() throws Exception {
+    public void testDefaultPropertiesDoNothing() throws Exception {
         Map<String, String> props = Collections.singletonMap("default.setting", "foo");
         Environment env = InternalSettingsPreparer.prepareEnvironment(baseEnvSettings, null, props);
-        assertEquals("foo", env.settings().get("setting"));
+        assertEquals("foo", env.settings().get("default.setting"));
+        assertNull(env.settings().get("setting"));
     }
 
-    public void testDefaultPropertiesOverride() throws Exception {
-        Path configDir = homeDir.resolve("config");
-        Files.createDirectories(configDir);
-        Files.write(configDir.resolve("elasticsearch.yml"), Collections.singletonList("setting: bar"), StandardCharsets.UTF_8);
-        Map<String, String> props = Collections.singletonMap("default.setting", "foo");
-        Environment env = InternalSettingsPreparer.prepareEnvironment(baseEnvSettings, null, props);
-        assertEquals("bar", env.settings().get("setting"));
-    }
 }

core/src/test/java/org/elasticsearch/search/aggregations/bucket/sampler/InternalSamplerTests.java

@@ -0,0 +1,45 @@
+/*
+ * Licensed to Elasticsearch under one or more contributor
+ * license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright
+ * ownership. Elasticsearch licenses this file to you under
+ * the Apache License, Version 2.0 (the "License"); you may
+ * not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+package org.elasticsearch.search.aggregations.bucket.sampler;
+
+import org.elasticsearch.common.io.stream.Writeable;
+import org.elasticsearch.search.aggregations.InternalAggregations;
+import org.elasticsearch.search.aggregations.bucket.InternalSingleBucketAggregationTestCase;
+import org.elasticsearch.search.aggregations.pipeline.PipelineAggregator;
+
+import java.util.List;
+import java.util.Map;
+
+public class InternalSamplerTests extends InternalSingleBucketAggregationTestCase<InternalSampler> {
+    @Override
+    protected InternalSampler createTestInstance(String name, long docCount, InternalAggregations aggregations,
+                                                 List<PipelineAggregator> pipelineAggregators, Map<String, Object> metaData) {
+        return new InternalSampler(name, docCount, aggregations, pipelineAggregators, metaData);
+    }
+
+    @Override
+    protected void extraAssertReduced(InternalSampler reduced, List<InternalSampler> inputs) {
+        // Nothing extra to assert
+    }
+
+    @Override
+    protected Writeable.Reader<InternalSampler> instanceReader() {
+        return InternalSampler::new;
+    }
+}

core/src/test/java/org/elasticsearch/search/aggregations/metrics/geocentroid/GeoCentroidAggregatorTests.java

@@ -0,0 +1,153 @@
+/*
+ * Licensed to Elasticsearch under one or more contributor
+ * license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright
+ * ownership. Elasticsearch licenses this file to you under
+ * the Apache License, Version 2.0 (the "License"); you may
+ * not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+package org.elasticsearch.search.aggregations.metrics.geocentroid;
+
+import org.apache.lucene.document.Document;
+import org.apache.lucene.document.LatLonDocValuesField;
+import org.apache.lucene.index.IndexReader;
+import org.apache.lucene.index.RandomIndexWriter;
+import org.apache.lucene.search.IndexSearcher;
+import org.apache.lucene.search.MatchAllDocsQuery;
+import org.apache.lucene.store.Directory;
+import org.elasticsearch.common.geo.GeoPoint;
+import org.elasticsearch.index.mapper.GeoPointFieldMapper;
+import org.elasticsearch.index.mapper.MappedFieldType;
+import org.elasticsearch.search.aggregations.AggregatorTestCase;
+import org.elasticsearch.test.geo.RandomGeoGenerator;
+
+import java.io.IOException;
+
+public class GeoCentroidAggregatorTests extends AggregatorTestCase {
+
+    private static final double GEOHASH_TOLERANCE = 1E-4D;
+
+    public void testEmpty() throws Exception {
+        try (Directory dir = newDirectory();
+             RandomIndexWriter w = new RandomIndexWriter(random(), dir)) {
+            GeoCentroidAggregationBuilder aggBuilder = new GeoCentroidAggregationBuilder("my_agg")
+                    .field("field");
+
+            MappedFieldType fieldType = new GeoPointFieldMapper.GeoPointFieldType();
+            fieldType.setHasDocValues(true);
+            fieldType.setName("field");
+            try (IndexReader reader = w.getReader()) {
+                IndexSearcher searcher = new IndexSearcher(reader);
+                InternalGeoCentroid result = search(searcher, new MatchAllDocsQuery(), aggBuilder, fieldType);
+                assertNull(result.centroid());
+            }
+        }
+    }
+
+    public void testUnmapped() throws Exception {
+        try (Directory dir = newDirectory();
+             RandomIndexWriter w = new RandomIndexWriter(random(), dir)) {
+            GeoCentroidAggregationBuilder aggBuilder = new GeoCentroidAggregationBuilder("my_agg")
+                    .field("another_field");
+
+            Document document = new Document();
+            document.add(new LatLonDocValuesField("field", 10, 10));
+            w.addDocument(document);
+            try (IndexReader reader = w.getReader()) {
+                IndexSearcher searcher = new IndexSearcher(reader);
+
+                MappedFieldType fieldType = new GeoPointFieldMapper.GeoPointFieldType();
+                fieldType.setHasDocValues(true);
+                fieldType.setName("another_field");
+                InternalGeoCentroid result = search(searcher, new MatchAllDocsQuery(), aggBuilder, fieldType);
+                assertNull(result.centroid());
+
+                fieldType = new GeoPointFieldMapper.GeoPointFieldType();
+                fieldType.setHasDocValues(true);
+                fieldType.setName("field");
+                result = search(searcher, new MatchAllDocsQuery(), aggBuilder, fieldType);
+                assertNull(result.centroid());
+            }
+        }
+    }
+
+    public void testSingleValuedField() throws Exception {
+        int numDocs = scaledRandomIntBetween(64, 256);
+        int numUniqueGeoPoints = randomIntBetween(1, numDocs);
+        try (Directory dir = newDirectory();
+            RandomIndexWriter w = new RandomIndexWriter(random(), dir)) {
+            GeoPoint expectedCentroid = new GeoPoint(0, 0);
+            GeoPoint[] singleValues = new GeoPoint[numUniqueGeoPoints];
+            for (int i = 0 ; i < singleValues.length; i++) {
+                singleValues[i] = RandomGeoGenerator.randomPoint(random());
+            }
+            GeoPoint singleVal;
+            for (int i = 0; i < numDocs; i++) {
+                singleVal = singleValues[i % numUniqueGeoPoints];
+                Document document = new Document();
+                document.add(new LatLonDocValuesField("field", singleVal.getLat(), singleVal.getLon()));
+                w.addDocument(document);
+                expectedCentroid = expectedCentroid.reset(expectedCentroid.lat() + (singleVal.lat() - expectedCentroid.lat()) / (i + 1),
+                        expectedCentroid.lon() + (singleVal.lon() - expectedCentroid.lon()) / (i + 1));
+            }
+            assertCentroid(w, expectedCentroid);
+        }
+    }
+
+    public void testMultiValuedField() throws Exception {
+        int numDocs = scaledRandomIntBetween(64, 256);
+        int numUniqueGeoPoints = randomIntBetween(1, numDocs);
+        try (Directory dir = newDirectory();
+            RandomIndexWriter w = new RandomIndexWriter(random(), dir)) {
+
+            GeoPoint expectedCentroid = new GeoPoint(0, 0);
+            GeoPoint[] multiValues = new GeoPoint[numUniqueGeoPoints];
+            for (int i = 0 ; i < multiValues.length; i++) {
+                multiValues[i] = RandomGeoGenerator.randomPoint(random());
+            }
+            final GeoPoint[] multiVal = new GeoPoint[2];
+            for (int i = 0; i < numDocs; i++) {
+                multiVal[0] = multiValues[i % numUniqueGeoPoints];
+                multiVal[1] = multiValues[(i+1) % numUniqueGeoPoints];
+                Document document = new Document();
+                document.add(new LatLonDocValuesField("field", multiVal[0].getLat(), multiVal[0].getLon()));
+                document.add(new LatLonDocValuesField("field", multiVal[1].getLat(), multiVal[1].getLon()));
+                w.addDocument(document);
+                double newMVLat = (multiVal[0].lat() + multiVal[1].lat())/2d;
+                double newMVLon = (multiVal[0].lon() + multiVal[1].lon())/2d;
+                expectedCentroid = expectedCentroid.reset(expectedCentroid.lat() + (newMVLat - expectedCentroid.lat()) / (i + 1),
+                        expectedCentroid.lon() + (newMVLon - expectedCentroid.lon()) / (i + 1));
+            }
+            assertCentroid(w, expectedCentroid);
+        }
+    }
+
+    private void assertCentroid(RandomIndexWriter w, GeoPoint expectedCentroid) throws IOException {
+        MappedFieldType fieldType = new GeoPointFieldMapper.GeoPointFieldType();
+        fieldType.setHasDocValues(true);
+        fieldType.setName("field");
+        GeoCentroidAggregationBuilder aggBuilder = new GeoCentroidAggregationBuilder("my_agg")
+                .field("field");
+        try (IndexReader reader = w.getReader()) {
+            IndexSearcher searcher = new IndexSearcher(reader);
+            InternalGeoCentroid result = search(searcher, new MatchAllDocsQuery(), aggBuilder, fieldType);
+
+            assertEquals("my_agg", result.getName());
+            GeoPoint centroid = result.centroid();
+            assertNotNull(centroid);
+            assertEquals(expectedCentroid.getLat(), centroid.getLat(), GEOHASH_TOLERANCE);
+            assertEquals(expectedCentroid.getLon(), centroid.getLon(), GEOHASH_TOLERANCE);
+        }
+    }
+
+}

core/src/test/java/org/elasticsearch/search/aggregations/metrics/percentiles/tdigest/InternalTDigestPercentilesTests.java

@@ -0,0 +1,81 @@
+/*
+ * Licensed to Elasticsearch under one or more contributor
+ * license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright
+ * ownership. Elasticsearch licenses this file to you under
+ * the Apache License, Version 2.0 (the "License"); you may
+ * not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+package org.elasticsearch.search.aggregations.metrics.percentiles.tdigest;
+
+import org.elasticsearch.common.io.stream.Writeable;
+import org.elasticsearch.search.DocValueFormat;
+import org.elasticsearch.search.aggregations.InternalAggregationTestCase;
+import org.elasticsearch.search.aggregations.pipeline.PipelineAggregator;
+
+import java.util.List;
+import java.util.Map;
+
+public class InternalTDigestPercentilesTests extends InternalAggregationTestCase<InternalTDigestPercentiles> {
+
+    private final double[] percents = randomPercents();
+
+    @Override
+    protected InternalTDigestPercentiles createTestInstance(String name,
+                                                            List<PipelineAggregator> pipelineAggregators,
+                                                            Map<String, Object> metaData) {
+        boolean keyed = randomBoolean();
+        DocValueFormat format = DocValueFormat.RAW;
+        TDigestState state = new TDigestState(100);
+
+        int numValues = randomInt(10);
+        for (int i = 0; i < numValues; ++i) {
+            state.add(randomDouble() * 100);
+        }
+        assertEquals(state.centroidCount(), numValues);
+        return new InternalTDigestPercentiles(name, percents, state, keyed, format, pipelineAggregators, metaData);
+    }
+
+    @Override
+    protected void assertReduced(InternalTDigestPercentiles reduced, List<InternalTDigestPercentiles> inputs) {
+        final TDigestState expectedState = new TDigestState(reduced.state.compression());
+
+        long totalCount = 0;
+        for (InternalTDigestPercentiles input : inputs) {
+            assertArrayEquals(reduced.keys, input.keys, 0d);
+            expectedState.add(input.state);
+            totalCount += input.state.size();
+        }
+
+        assertEquals(totalCount, reduced.state.size());
+        if (totalCount > 0) {
+            assertEquals(expectedState.quantile(0), reduced.state.quantile(0), 0d);
+            assertEquals(expectedState.quantile(1), reduced.state.quantile(1), 0d);
+        }
+    }
+
+    @Override
+    protected Writeable.Reader<InternalTDigestPercentiles> instanceReader() {
+        return InternalTDigestPercentiles::new;
+    }
+
+    private static double[] randomPercents() {
+        List<Double> randomCdfValues = randomSubsetOf(randomIntBetween(1, 7), 0.01d, 0.05d, 0.25d, 0.50d, 0.75d, 0.95d, 0.99d);
+        double[] percents = new double[randomCdfValues.size()];
+        for (int i = 0; i < randomCdfValues.size(); i++) {
+            percents[i] = randomCdfValues.get(i);
+        }
+        return percents;
+    }
+}

core/src/test/java/org/elasticsearch/search/aggregations/metrics/tophits/InternalTopHitsTests.java

@@ -155,7 +155,8 @@ public class InternalTopHitsTests extends InternalAggregationTestCase<InternalTo
         for (int i = 0; i < expectedHitsHits.length; i++) {
             expectedHitsHits[i] = allHits.get(i).v2();
         }
-        SearchHits expectedHits = new SearchHits(expectedHitsHits, totalHits, maxScore);
+        // Lucene's TopDocs initializes the maxScore to Float.NaN, if there is no maxScore
+        SearchHits expectedHits = new SearchHits(expectedHitsHits, totalHits, maxScore == Float.MIN_VALUE ? Float.NaN : maxScore);
         assertEqualsWithErrorMessageFromXContent(expectedHits, actualHits);
     }
 

core/src/test/java/org/elasticsearch/search/child/ChildQuerySearchIT.java

@@ -1182,13 +1182,13 @@ public class ChildQuerySearchIT extends ESIntegTestCase {
             client().prepareIndex("test", "child1", "c1").setParent("p1").setSource("c_field", "blue").get();
             fail();
         } catch (IllegalArgumentException e) {
-            assertThat(e.toString(), containsString("Can't specify parent if no parent field has been configured"));
+            assertThat(e.toString(), containsString("can't specify parent if no parent field has been configured"));
         }
         try {
             client().prepareIndex("test", "child2", "c2").setParent("p1").setSource("c_field", "blue").get();
             fail();
         } catch (IllegalArgumentException e) {
-            assertThat(e.toString(), containsString("Can't specify parent if no parent field has been configured"));
+            assertThat(e.toString(), containsString("can't specify parent if no parent field has been configured"));
         }
 
         refresh();

core/src/test/java/org/elasticsearch/tasks/TaskResultTests.java

@@ -26,6 +26,7 @@ import org.elasticsearch.common.io.stream.NamedWriteableRegistry;
 import org.elasticsearch.common.io.stream.StreamInput;
 import org.elasticsearch.common.xcontent.ToXContent;
 import org.elasticsearch.common.xcontent.XContentBuilder;
+import org.elasticsearch.common.xcontent.XContentFactory;
 import org.elasticsearch.common.xcontent.XContentParser;
 import org.elasticsearch.common.xcontent.XContentType;
 import org.elasticsearch.test.ESTestCase;
@@ -74,6 +75,42 @@ public class TaskResultTests extends ESTestCase {
         assertEquals(result, read);
     }
 
+    public void testTaskInfoIsForwardCompatible() throws IOException {
+        TaskInfo taskInfo = randomTaskInfo();
+        TaskInfo read;
+        try (XContentBuilder builder = XContentBuilder.builder(randomFrom(XContentType.values()).xContent())) {
+            builder.startObject();
+            taskInfo.toXContent(builder, ToXContent.EMPTY_PARAMS);
+            builder.endObject();
+            try (XContentBuilder withExtraFields = addRandomUnknownFields(builder)) {
+                try (XContentBuilder shuffled = shuffleXContent(withExtraFields)) {
+                    try (XContentParser parser = createParser(shuffled)) {
+                        read = TaskInfo.PARSER.apply(parser, null);
+                    }
+                }
+            }
+        } catch (IOException e) {
+            throw new IOException("Error processing [" + taskInfo + "]", e);
+        }
+        assertEquals(taskInfo, read);
+    }
+
+    private XContentBuilder addRandomUnknownFields(XContentBuilder builder) throws IOException {
+        try (XContentParser parser = createParser(builder)) {
+            Map<String, Object> map = parser.mapOrdered();
+            int numberOfNewFields = randomIntBetween(2, 10);
+            for (int i = 0; i < numberOfNewFields; i++) {
+                if (randomBoolean()) {
+                    map.put("unknown_field" + i, randomAlphaOfLength(20));
+                } else {
+                    map.put("unknown_field" + i, Collections.singletonMap("inner", randomAlphaOfLength(20)));
+                }
+            }
+            XContentBuilder xContentBuilder = XContentFactory.contentBuilder(parser.contentType());
+            return xContentBuilder.map(map);
+        }
+    }
+
     private static TaskResult randomTaskResult() throws IOException {
         switch (between(0, 2)) {
             case 0:

core/src/test/java/org/elasticsearch/versioning/SimpleVersioningIT.java

@@ -325,7 +325,7 @@ public class SimpleVersioningIT extends ESIntegTestCase {
                 ids = new IDSource() {
                     @Override
                     public String next() {
-                        return TestUtil.randomSimpleString(random);
+                        return TestUtil.randomSimpleString(random, 1, 10);
                     }
                 };
                 break;
@@ -335,7 +335,7 @@ public class SimpleVersioningIT extends ESIntegTestCase {
                 ids = new IDSource() {
                     @Override
                     public String next() {
-                        return TestUtil.randomRealisticUnicodeString(random);
+                        return TestUtil.randomRealisticUnicodeString(random, 1, 20);
                     }
                 };
                 break;

distribution/build.gradle

@@ -127,13 +127,13 @@ configure(distributions) {
   apply plugin: 'elasticsearch.standalone-rest-test'
   apply plugin: 'elasticsearch.rest-test'
   project.integTest {
-    dependsOn project.assemble
     includePackaged project.name == 'integ-test-zip'
     if (project.name != 'integ-test-zip') {
       mustRunAfter ':distribution:integ-test-zip:integTest'
     }
   }
   project.integTestCluster {
+    dependsOn project.assemble
     distribution = project.name
   }
 

distribution/bwc-zip/build.gradle

@@ -30,7 +30,7 @@ import org.elasticsearch.gradle.LoggedExec
 apply plugin: 'distribution'
 
 File checkoutDir = file("${buildDir}/bwc/checkout-5.x")
-task createClone(type: Exec) {
+task createClone(type: LoggedExec) {
   onlyIf { checkoutDir.exists() == false }
   commandLine = ['git', 'clone', rootDir, checkoutDir]
 }

distribution/deb/src/main/packaging/init.d/elasticsearch

@@ -32,10 +32,6 @@ fi
 
 # The following variables can be overwritten in $DEFAULT
 
-# Run Elasticsearch as this user ID and group ID
-ES_USER=elasticsearch
-ES_GROUP=elasticsearch
-
 # Directory where the Elasticsearch binary distribution resides
 ES_HOME=/usr/share/$NAME
 
@@ -76,6 +72,12 @@ if [ ! -z "$CONF_FILE" ]; then
     exit 1
 fi
 
+# ES_USER and ES_GROUP settings were removed
+if [ ! -z "$ES_USER" ] || [ ! -z "$ES_GROUP" ]; then
+    echo "ES_USER and ES_GROUP settings are no longer supported. To run as a custom user/group use the archive distribution of Elasticsearch."
+    exit 1
+fi
+
 # Define other required variables
 PID_FILE="$PID_DIR/$NAME.pid"
 DAEMON=$ES_HOME/bin/elasticsearch
@@ -119,10 +121,10 @@ case "$1" in
 
 	# Ensure that the PID_DIR exists (it is cleaned at OS startup time)
 	if [ -n "$PID_DIR" ] && [ ! -e "$PID_DIR" ]; then
-		mkdir -p "$PID_DIR" && chown "$ES_USER":"$ES_GROUP" "$PID_DIR"
+		mkdir -p "$PID_DIR" && chown elasticsearch:elasticsearch "$PID_DIR"
 	fi
 	if [ -n "$PID_FILE" ] && [ ! -e "$PID_FILE" ]; then
-		touch "$PID_FILE" && chown "$ES_USER":"$ES_GROUP" "$PID_FILE"
+		touch "$PID_FILE" && chown elasticsearch:elasticsearch "$PID_FILE"
 	fi
 
 	if [ -n "$MAX_OPEN_FILES" ]; then
@@ -138,7 +140,7 @@ case "$1" in
 	fi
 
 	# Start Daemon
-	start-stop-daemon -d $ES_HOME --start --user "$ES_USER" -c "$ES_USER" --pidfile "$PID_FILE" --exec $DAEMON -- $DAEMON_OPTS
+	start-stop-daemon -d $ES_HOME --start --user elasticsearch -c elasticsearch --pidfile "$PID_FILE" --exec $DAEMON -- $DAEMON_OPTS
 	return=$?
 	if [ $return -eq 0 ]; then
 		i=0
@@ -162,7 +164,7 @@ case "$1" in
 
 	if [ -f "$PID_FILE" ]; then
 		start-stop-daemon --stop --pidfile "$PID_FILE" \
-			--user "$ES_USER" \
+			--user elasticsearch \
 			--quiet \
 			--retry forever/TERM/20 > /dev/null
 		if [ $? -eq 1 ]; then

distribution/rpm/src/main/packaging/init.d/elasticsearch

@@ -32,8 +32,6 @@ if [ -f /etc/rc.d/init.d/functions ]; then
 fi
 
 # Sets the default values for elasticsearch variables used in this script
-ES_USER="elasticsearch"
-ES_GROUP="elasticsearch"
 ES_HOME="/usr/share/elasticsearch"
 MAX_OPEN_FILES=65536
 MAX_MAP_COUNT=262144
@@ -55,6 +53,12 @@ if [ ! -z "$CONF_FILE" ]; then
     exit 1
 fi
 
+# ES_USER and ES_GROUP settings were removed
+if [ ! -z "$ES_USER" ] || [ ! -z "$ES_GROUP" ]; then
+    echo "ES_USER and ES_GROUP settings are no longer supported. To run as a custom user/group use the archive distribution of Elasticsearch."
+    exit 1
+fi
+
 exec="$ES_HOME/bin/elasticsearch"
 prog="elasticsearch"
 pidfile="$PID_DIR/${prog}.pid"
@@ -67,11 +71,6 @@ export ES_STARTUP_SLEEP_TIME
 
 lockfile=/var/lock/subsys/$prog
 
-# backwards compatibility for old config sysconfig files, pre 0.90.1
-if [ -n $USER ] && [ -z $ES_USER ] ; then
-   ES_USER=$USER
-fi
-
 if [ ! -x "$exec" ]; then
     echo "The elasticsearch startup script does not exists or it is not executable, tried: $exec"
     exit 1
@@ -106,16 +105,16 @@ start() {
 
     # Ensure that the PID_DIR exists (it is cleaned at OS startup time)
     if [ -n "$PID_DIR" ] && [ ! -e "$PID_DIR" ]; then
-        mkdir -p "$PID_DIR" && chown "$ES_USER":"$ES_GROUP" "$PID_DIR"
+        mkdir -p "$PID_DIR" && chown elasticsearch:elasticsearch "$PID_DIR"
     fi
     if [ -n "$pidfile" ] && [ ! -e "$pidfile" ]; then
-        touch "$pidfile" && chown "$ES_USER":"$ES_GROUP" "$pidfile"
+        touch "$pidfile" && chown elasticsearch:elasticsearch "$pidfile"
     fi
 
     cd $ES_HOME
     echo -n $"Starting $prog: "
     # if not running, start it up here, usually something like "daemon $exec"
-    daemon --user $ES_USER --pidfile $pidfile $exec -p $pidfile -d -Edefault.path.logs=$LOG_DIR -Edefault.path.data=$DATA_DIR -Edefault.path.conf=$CONF_DIR
+    daemon --user elasticsearch --pidfile $pidfile $exec -p $pidfile -d -Edefault.path.logs=$LOG_DIR -Edefault.path.data=$DATA_DIR -Edefault.path.conf=$CONF_DIR
     retval=$?
     echo
     [ $retval -eq 0 ] && touch $lockfile

distribution/src/main/packaging/env/elasticsearch

@@ -32,14 +32,6 @@
 
 # SysV init.d
 #
-# When executing the init script, this user will be used to run the elasticsearch service.
-# The default value is 'elasticsearch' and is declared in the init.d file.
-# Note that this setting is only used by the init script. If changed, make sure that
-# the configured user can read and write into the data, work, plugins and log directories.
-# For systemd service, the user is usually configured in file /usr/lib/systemd/system/elasticsearch.service
-#ES_USER=elasticsearch
-#ES_GROUP=elasticsearch
-
 # The number of seconds to wait before checking if Elasticsearch started successfully as a daemon process
 ES_STARTUP_SLEEP_TIME=5
 

distribution/src/main/packaging/scripts/postinst

@@ -10,10 +10,6 @@
 
 
 
-# Sets the default values for elasticsearch variables used in this script
-ES_USER="elasticsearch"
-ES_GROUP="elasticsearch"
-
 # Source the default env file
 ES_ENV_FILE="${path.env}"
 if [ -f "$ES_ENV_FILE" ]; then
@@ -110,9 +106,9 @@ elif [ "$RESTART_ON_UPGRADE" = "true" ]; then
     echo " OK"
 fi
 
-chown -R $ES_USER:$ES_GROUP /var/lib/elasticsearch
-chown -R $ES_USER:$ES_GROUP /var/log/elasticsearch
-chown -R root:$ES_GROUP /etc/elasticsearch
+chown -R elasticsearch:elasticsearch /var/lib/elasticsearch
+chown -R elasticsearch:elasticsearch /var/log/elasticsearch
+chown -R root:elasticsearch /etc/elasticsearch
 chmod 0750 /etc/elasticsearch
 chmod 0750 /etc/elasticsearch/scripts
 

distribution/src/main/packaging/scripts/postrm

@@ -46,8 +46,6 @@ case "$1" in
 esac
 
 # Sets the default values for elasticsearch variables used in this script
-ES_USER="elasticsearch"
-ES_GROUP="elasticsearch"
 LOG_DIR="/var/log/elasticsearch"
 PLUGINS_DIR="/usr/share/elasticsearch/plugins"
 PID_DIR="/var/run/elasticsearch"
@@ -95,12 +93,12 @@ if [ "$REMOVE_DIRS" = "true" ]; then
 fi
 
 if [ "$REMOVE_USER_AND_GROUP" = "true" ]; then
-    if id "$ES_USER" > /dev/null 2>&1 ; then
-        userdel "$ES_USER"
+    if id elasticsearch > /dev/null 2>&1 ; then
+        userdel elasticsearch
     fi
 
-    if getent group "$ES_GROUP" > /dev/null 2>&1 ; then
-        groupdel "$ES_GROUP"
+    if getent group elasticsearch > /dev/null 2>&1 ; then
+        groupdel elasticsearch
     fi
 fi
 

distribution/src/main/packaging/scripts/preinst

@@ -11,10 +11,6 @@
 
 
 
-# Sets the default values for elasticsearch variables used in this script
-ES_USER="elasticsearch"
-ES_GROUP="elasticsearch"
-
 # Source the default env file
 ES_ENV_FILE="${path.env}"
 if [ -f "$ES_ENV_FILE" ]; then
@@ -27,22 +23,22 @@ case "$1" in
     install|upgrade)
 
         # Create elasticsearch group if not existing
-        if ! getent group "$ES_GROUP" > /dev/null 2>&1 ; then
-            echo -n "Creating $ES_GROUP group..."
-            addgroup --quiet --system "$ES_GROUP"
+        if ! getent group elasticsearch > /dev/null 2>&1 ; then
+            echo -n "Creating elasticsearch group..."
+            addgroup --quiet --system elasticsearch
             echo " OK"
         fi
 
         # Create elasticsearch user if not existing
-        if ! id $ES_USER > /dev/null 2>&1 ; then
-            echo -n "Creating $ES_USER user..."
+        if ! id elasticsearch > /dev/null 2>&1 ; then
+            echo -n "Creating elasticsearch user..."
             adduser --quiet \
                     --system \
                     --no-create-home \
-                    --ingroup "$ES_GROUP" \
+                    --ingroup elasticsearch \
                     --disabled-password \
                     --shell /bin/false \
-                    "$ES_USER"
+                    elasticsearch
             echo " OK"
         fi
     ;;
@@ -53,21 +49,21 @@ case "$1" in
     1|2)
 
         # Create elasticsearch group if not existing
-        if ! getent group "$ES_GROUP" > /dev/null 2>&1 ; then
-            echo -n "Creating $ES_GROUP group..."
-            groupadd -r "$ES_GROUP"
+        if ! getent group elasticsearch > /dev/null 2>&1 ; then
+            echo -n "Creating elasticsearch group..."
+            groupadd -r elasticsearch
             echo " OK"
         fi
 
         # Create elasticsearch user if not existing
-        if ! id $ES_USER > /dev/null 2>&1 ; then
-            echo -n "Creating $ES_USER user..."
+        if ! id elasticsearch > /dev/null 2>&1 ; then
+            echo -n "Creating elasticsearch user..."
             useradd -r \
                     -M \
-                    --gid "$ES_GROUP" \
+                    --gid elasticsearch \
                     --shell /sbin/nologin \
                     --comment "elasticsearch user" \
-                    "$ES_USER"
+                    elasticsearch
             echo " OK"
         fi
     ;;