From c165afb4d5a0d90ac214307beb16fc10513c8995 Mon Sep 17 00:00:00 2001
From: Igor Motov <igor@motovs.org>
Date: Thu, 30 Apr 2015 13:47:19 -0400
Subject: [PATCH] Logging: Add logging of slow cluster state tasks

Closes #10874
---
 .../service/InternalClusterService.java       |  42 +++-
 .../ClusterDynamicSettingsModule.java         |   2 +
 .../cluster/ClusterServiceTests.java          | 216 +++++++++++++++++-
 .../elasticsearch/test/MockLogAppender.java   | 139 +++++++++++
 4 files changed, 392 insertions(+), 7 deletions(-)
 create mode 100644 src/test/java/org/elasticsearch/test/MockLogAppender.java

diff --git a/src/main/java/org/elasticsearch/cluster/service/InternalClusterService.java b/src/main/java/org/elasticsearch/cluster/service/InternalClusterService.java
index b1823e5d74e..a5b7470bfa1 100644
--- a/src/main/java/org/elasticsearch/cluster/service/InternalClusterService.java
+++ b/src/main/java/org/elasticsearch/cluster/service/InternalClusterService.java
@@ -20,7 +20,6 @@
 package org.elasticsearch.cluster.service;
 
 import com.google.common.collect.Iterables;
-import org.elasticsearch.ElasticsearchException;
 import org.elasticsearch.Version;
 import org.elasticsearch.cluster.*;
 import org.elasticsearch.cluster.ClusterState.Builder;
@@ -59,6 +58,9 @@ import static org.elasticsearch.common.util.concurrent.EsExecutors.daemonThreadF
  */
 public class InternalClusterService extends AbstractLifecycleComponent<ClusterService> implements ClusterService {
 
+    public static final String SETTING_CLUSTER_SERVICE_SLOW_TASK_LOGGING_THRESHOLD = "cluster.service.slow_task_logging_threshold";
+    public static final String SETTING_CLUSTER_SERVICE_RECONNECT_INTERVAL = "cluster.service.reconnect_interval";
+
     public static final String UPDATE_THREAD_NAME = "clusterService#updateTask";
     private final ThreadPool threadPool;
 
@@ -74,6 +76,8 @@ public class InternalClusterService extends AbstractLifecycleComponent<ClusterSe
 
     private final TimeValue reconnectInterval;
 
+    private TimeValue slowTaskLoggingThreshold;
+
     private volatile PrioritizedEsThreadPoolExecutor updateTasksExecutor;
 
     /**
@@ -115,8 +119,11 @@ public class InternalClusterService extends AbstractLifecycleComponent<ClusterSe
         this.clusterState = ClusterState.builder(clusterName).build();
 
         this.nodeSettingsService.setClusterService(this);
+        this.nodeSettingsService.addListener(new ApplySettings());
 
-        this.reconnectInterval = this.settings.getAsTime("cluster.service.reconnect_interval", TimeValue.timeValueSeconds(10));
+        this.reconnectInterval = this.settings.getAsTime(SETTING_CLUSTER_SERVICE_RECONNECT_INTERVAL, TimeValue.timeValueSeconds(10));
+
+        this.slowTaskLoggingThreshold = this.settings.getAsTime(SETTING_CLUSTER_SERVICE_SLOW_TASK_LOGGING_THRESHOLD, TimeValue.timeValueSeconds(30));
 
         localNodeMasterListeners = new LocalNodeMasterListeners(threadPool);
 
@@ -371,22 +378,24 @@ public class InternalClusterService extends AbstractLifecycleComponent<ClusterSe
                 return;
             }
             ClusterState newClusterState;
+            long startTime = System.currentTimeMillis();
             try {
                 newClusterState = updateTask.execute(previousClusterState);
             } catch (Throwable e) {
+                TimeValue executionTime = TimeValue.timeValueMillis(Math.max(0, System.currentTimeMillis() - startTime));
                 if (logger.isTraceEnabled()) {
-                    StringBuilder sb = new StringBuilder("failed to execute cluster state update, state:\nversion [").append(previousClusterState.version()).append("], source [").append(source).append("]\n");
+                    StringBuilder sb = new StringBuilder("failed to execute cluster state update in ").append(executionTime).append(", state:\nversion [").append(previousClusterState.version()).append("], source [").append(source).append("]\n");
                     sb.append(previousClusterState.nodes().prettyPrint());
                     sb.append(previousClusterState.routingTable().prettyPrint());
                     sb.append(previousClusterState.readOnlyRoutingNodes().prettyPrint());
                     logger.trace(sb.toString(), e);
                 }
+                warnAboutSlowTaskIfNeeded(executionTime, source);
                 updateTask.onFailure(source, e);
                 return;
             }
 
             if (previousClusterState == newClusterState) {
-                logger.debug("processing [{}]: no change in cluster_state", source);
                 if (updateTask instanceof AckedClusterStateUpdateTask) {
                     //no need to wait for ack if nothing changed, the update can be counted as acknowledged
                     ((AckedClusterStateUpdateTask) updateTask).onAllNodesAcked(null);
@@ -394,6 +403,9 @@ public class InternalClusterService extends AbstractLifecycleComponent<ClusterSe
                 if (updateTask instanceof ProcessedClusterStateUpdateTask) {
                     ((ProcessedClusterStateUpdateTask) updateTask).clusterStateProcessed(source, previousClusterState, newClusterState);
                 }
+                TimeValue executionTime = TimeValue.timeValueMillis(Math.max(0, System.currentTimeMillis() - startTime));
+                logger.debug("processing [{}]: took {} no change in cluster_state", source, executionTime);
+                warnAboutSlowTaskIfNeeded(executionTime, source);
                 return;
             }
 
@@ -511,9 +523,12 @@ public class InternalClusterService extends AbstractLifecycleComponent<ClusterSe
                     ((ProcessedClusterStateUpdateTask) updateTask).clusterStateProcessed(source, previousClusterState, newClusterState);
                 }
 
-                logger.debug("processing [{}]: done applying updated cluster_state (version: {}, uuid: {})", source, newClusterState.version(), newClusterState.uuid());
+                TimeValue executionTime = TimeValue.timeValueMillis(Math.max(0, System.currentTimeMillis() - startTime));
+                logger.debug("processing [{}]: took {} done applying updated cluster_state (version: {}, uuid: {})", source, executionTime, newClusterState.version(), newClusterState.uuid());
+                warnAboutSlowTaskIfNeeded(executionTime, source);
             } catch (Throwable t) {
-                StringBuilder sb = new StringBuilder("failed to apply updated cluster state:\nversion [").append(newClusterState.version()).append("], uuid [").append(newClusterState.uuid()).append("], source [").append(source).append("]\n");
+                TimeValue executionTime = TimeValue.timeValueMillis(Math.max(0, System.currentTimeMillis() - startTime));
+                StringBuilder sb = new StringBuilder("failed to apply updated cluster state in ").append(executionTime).append(":\nversion [").append(newClusterState.version()).append("], uuid [").append(newClusterState.uuid()).append("], source [").append(source).append("]\n");
                 sb.append(newClusterState.nodes().prettyPrint());
                 sb.append(newClusterState.routingTable().prettyPrint());
                 sb.append(newClusterState.readOnlyRoutingNodes().prettyPrint());
@@ -523,6 +538,12 @@ public class InternalClusterService extends AbstractLifecycleComponent<ClusterSe
         }
     }
 
+    private void warnAboutSlowTaskIfNeeded(TimeValue executionTime, String source) {
+        if (executionTime.getMillis() > slowTaskLoggingThreshold.getMillis()) {
+            logger.warn("cluster state update task [{}] took {} above the warn threshold of {}", source, executionTime, slowTaskLoggingThreshold);
+        }
+    }
+
     class NotifyTimeout implements Runnable {
         final TimeoutClusterStateListener listener;
         final TimeValue timeout;
@@ -755,4 +776,13 @@ public class InternalClusterService extends AbstractLifecycleComponent<ClusterSe
             }
         }
     }
+
+    class ApplySettings implements NodeSettingsService.Listener {
+        @Override
+        public void onRefreshSettings(Settings settings) {
+            final TimeValue slowTaskLoggingThreshold = settings.getAsTime(SETTING_CLUSTER_SERVICE_SLOW_TASK_LOGGING_THRESHOLD, InternalClusterService.this.slowTaskLoggingThreshold);
+            InternalClusterService.this.slowTaskLoggingThreshold = slowTaskLoggingThreshold;
+        }
+    }
+
 }
diff --git a/src/main/java/org/elasticsearch/cluster/settings/ClusterDynamicSettingsModule.java b/src/main/java/org/elasticsearch/cluster/settings/ClusterDynamicSettingsModule.java
index 4c9c8e23091..0bcada3c827 100644
--- a/src/main/java/org/elasticsearch/cluster/settings/ClusterDynamicSettingsModule.java
+++ b/src/main/java/org/elasticsearch/cluster/settings/ClusterDynamicSettingsModule.java
@@ -25,6 +25,7 @@ import org.elasticsearch.cluster.action.index.MappingUpdatedAction;
 import org.elasticsearch.cluster.metadata.MetaData;
 import org.elasticsearch.cluster.routing.allocation.allocator.BalancedShardsAllocator;
 import org.elasticsearch.cluster.routing.allocation.decider.*;
+import org.elasticsearch.cluster.service.InternalClusterService;
 import org.elasticsearch.common.inject.AbstractModule;
 import org.elasticsearch.discovery.DiscoverySettings;
 import org.elasticsearch.discovery.zen.ZenDiscovery;
@@ -101,6 +102,7 @@ public class ClusterDynamicSettingsModule extends AbstractModule {
         clusterDynamicSettings.addDynamicSetting(HierarchyCircuitBreakerService.FIELDDATA_CIRCUIT_BREAKER_OVERHEAD_SETTING, Validator.NON_NEGATIVE_DOUBLE);
         clusterDynamicSettings.addDynamicSetting(HierarchyCircuitBreakerService.REQUEST_CIRCUIT_BREAKER_LIMIT_SETTING, Validator.MEMORY_SIZE);
         clusterDynamicSettings.addDynamicSetting(HierarchyCircuitBreakerService.REQUEST_CIRCUIT_BREAKER_OVERHEAD_SETTING, Validator.NON_NEGATIVE_DOUBLE);
+        clusterDynamicSettings.addDynamicSetting(InternalClusterService.SETTING_CLUSTER_SERVICE_SLOW_TASK_LOGGING_THRESHOLD, Validator.TIME_NON_NEGATIVE);
     }
 
     public void addDynamicSettings(String... settings) {
diff --git a/src/test/java/org/elasticsearch/cluster/ClusterServiceTests.java b/src/test/java/org/elasticsearch/cluster/ClusterServiceTests.java
index 2abb769f748..8b183212893 100644
--- a/src/test/java/org/elasticsearch/cluster/ClusterServiceTests.java
+++ b/src/test/java/org/elasticsearch/cluster/ClusterServiceTests.java
@@ -21,10 +21,12 @@ package org.elasticsearch.cluster;
 import com.google.common.base.Predicate;
 import com.google.common.util.concurrent.ListenableFuture;
 
-import org.elasticsearch.ElasticsearchException;
+import org.apache.log4j.Level;
+import org.apache.log4j.Logger;
 import org.elasticsearch.action.admin.cluster.health.ClusterHealthResponse;
 import org.elasticsearch.action.admin.cluster.tasks.PendingClusterTasksResponse;
 import org.elasticsearch.cluster.node.DiscoveryNode;
+import org.elasticsearch.cluster.service.InternalClusterService;
 import org.elasticsearch.cluster.service.PendingClusterTask;
 import org.elasticsearch.common.Nullable;
 import org.elasticsearch.common.Priority;
@@ -38,6 +40,8 @@ import org.elasticsearch.common.unit.TimeValue;
 import org.elasticsearch.plugins.AbstractPlugin;
 import org.elasticsearch.test.ElasticsearchIntegrationTest;
 import org.elasticsearch.test.ElasticsearchIntegrationTest.ClusterScope;
+import org.elasticsearch.test.MockLogAppender;
+import org.elasticsearch.test.junit.annotations.TestLogging;
 import org.elasticsearch.threadpool.ThreadPool;
 import org.junit.Test;
 
@@ -48,6 +52,7 @@ import java.util.concurrent.atomic.AtomicBoolean;
 
 import static org.elasticsearch.common.settings.ImmutableSettings.settingsBuilder;
 import static org.elasticsearch.test.ElasticsearchIntegrationTest.Scope;
+import static org.elasticsearch.test.hamcrest.ElasticsearchAssertions.assertAcked;
 import static org.hamcrest.Matchers.*;
 
 /**
@@ -721,6 +726,215 @@ public class ClusterServiceTests extends ElasticsearchIntegrationTest {
         }
     }
 
+    @Test
+    @TestLogging("cluster:TRACE") // To ensure that we log cluster state events on TRACE level
+    public void testClusterStateUpdateLogging() throws Exception {
+        Settings settings = settingsBuilder()
+                .put("discovery.type", "local")
+                .build();
+        internalCluster().startNode(settings);
+        ClusterService clusterService1 = internalCluster().getInstance(ClusterService.class);
+        MockLogAppender mockAppender = new MockLogAppender();
+        mockAppender.addExpectation(new MockLogAppender.SeenEventExpectation("test1", "cluster.service", Level.DEBUG, "*processing [test1]: took * no change in cluster_state"));
+        mockAppender.addExpectation(new MockLogAppender.SeenEventExpectation("test2", "cluster.service", Level.TRACE, "*failed to execute cluster state update in *"));
+        mockAppender.addExpectation(new MockLogAppender.SeenEventExpectation("test3", "cluster.service", Level.DEBUG, "*processing [test3]: took * done applying updated cluster_state (version: *, uuid: *)"));
+
+        Logger rootLogger = Logger.getRootLogger();
+        rootLogger.addAppender(mockAppender);
+        try {
+            final CountDownLatch latch = new CountDownLatch(4);
+            clusterService1.submitStateUpdateTask("test1", new ProcessedClusterStateUpdateTask() {
+                @Override
+                public ClusterState execute(ClusterState currentState) throws Exception {
+                    return currentState;
+                }
+
+                @Override
+                public void clusterStateProcessed(String source, ClusterState oldState, ClusterState newState) {
+                    latch.countDown();
+                }
+
+                @Override
+                public void onFailure(String source, Throwable t) {
+                    fail();
+                }
+            });
+            clusterService1.submitStateUpdateTask("test2", new ProcessedClusterStateUpdateTask() {
+                @Override
+                public ClusterState execute(ClusterState currentState) {
+                    throw new IllegalArgumentException("Testing handling of exceptions in the cluster state task");
+                }
+
+                @Override
+                public void clusterStateProcessed(String source, ClusterState oldState, ClusterState newState) {
+                    fail();
+                }
+
+                @Override
+                public void onFailure(String source, Throwable t) {
+                    latch.countDown();
+                }
+            });
+            clusterService1.submitStateUpdateTask("test3", new ProcessedClusterStateUpdateTask() {
+                @Override
+                public ClusterState execute(ClusterState currentState) {
+                    return ClusterState.builder(currentState).incrementVersion().build();
+                }
+
+                @Override
+                public void clusterStateProcessed(String source, ClusterState oldState, ClusterState newState) {
+                    latch.countDown();
+                }
+
+                @Override
+                public void onFailure(String source, Throwable t) {
+                    fail();
+                }
+            });
+            // Additional update task to make sure all previous logging made it to the logger
+            // We don't check logging for this on since there is no guarantee that it will occur before our check
+            clusterService1.submitStateUpdateTask("test4", new ProcessedClusterStateUpdateTask() {
+                @Override
+                public ClusterState execute(ClusterState currentState) {
+                    return currentState;
+                }
+
+                @Override
+                public void clusterStateProcessed(String source, ClusterState oldState, ClusterState newState) {
+                    latch.countDown();
+                }
+
+                @Override
+                public void onFailure(String source, Throwable t) {
+                    fail();
+                }
+            });
+            assertThat(latch.await(1, TimeUnit.SECONDS), equalTo(true));
+        } finally {
+            rootLogger.removeAppender(mockAppender);
+        }
+        mockAppender.assertAllExpectationsMatched();
+    }
+
+    @Test
+    @TestLogging("cluster:WARN") // To ensure that we log cluster state events on WARN level
+    public void testLongClusterStateUpdateLogging() throws Exception {
+        Settings settings = settingsBuilder()
+                .put("discovery.type", "local")
+                .put(InternalClusterService.SETTING_CLUSTER_SERVICE_SLOW_TASK_LOGGING_THRESHOLD, "10s")
+                .build();
+        internalCluster().startNode(settings);
+        ClusterService clusterService1 = internalCluster().getInstance(ClusterService.class);
+        MockLogAppender mockAppender = new MockLogAppender();
+        mockAppender.addExpectation(new MockLogAppender.UnseenEventExpectation("test1 shouldn't see because setting is too low", "cluster.service", Level.WARN, "*cluster state update task [test1] took * above the warn threshold of *"));
+        mockAppender.addExpectation(new MockLogAppender.SeenEventExpectation("test2", "cluster.service", Level.WARN, "*cluster state update task [test2] took * above the warn threshold of 10ms"));
+        mockAppender.addExpectation(new MockLogAppender.SeenEventExpectation("test3", "cluster.service", Level.WARN, "*cluster state update task [test3] took * above the warn threshold of 10ms"));
+        mockAppender.addExpectation(new MockLogAppender.SeenEventExpectation("test4", "cluster.service", Level.WARN, "*cluster state update task [test4] took * above the warn threshold of 10ms"));
+
+        Logger rootLogger = Logger.getRootLogger();
+        rootLogger.addAppender(mockAppender);
+        try {
+            final CountDownLatch latch = new CountDownLatch(5);
+            final CountDownLatch processedFirstTask = new CountDownLatch(1);
+            clusterService1.submitStateUpdateTask("test1", new ProcessedClusterStateUpdateTask() {
+                @Override
+                public ClusterState execute(ClusterState currentState) throws Exception {
+                    Thread.sleep(100);
+                    return currentState;
+                }
+
+                @Override
+                public void clusterStateProcessed(String source, ClusterState oldState, ClusterState newState) {
+                    latch.countDown();
+                    processedFirstTask.countDown();
+                }
+
+                @Override
+                public void onFailure(String source, Throwable t) {
+                    fail();
+                }
+            });
+
+            processedFirstTask.await(1, TimeUnit.SECONDS);
+            assertAcked(client().admin().cluster().prepareUpdateSettings().setTransientSettings(settingsBuilder()
+                    .put(InternalClusterService.SETTING_CLUSTER_SERVICE_SLOW_TASK_LOGGING_THRESHOLD, "10ms")));
+
+            clusterService1.submitStateUpdateTask("test2", new ProcessedClusterStateUpdateTask() {
+                @Override
+                public ClusterState execute(ClusterState currentState) throws Exception {
+                    Thread.sleep(100);
+                    throw new IllegalArgumentException("Testing handling of exceptions in the cluster state task");
+                }
+
+                @Override
+                public void clusterStateProcessed(String source, ClusterState oldState, ClusterState newState) {
+                    fail();
+                }
+
+                @Override
+                public void onFailure(String source, Throwable t) {
+                    latch.countDown();
+                }
+            });
+            clusterService1.submitStateUpdateTask("test3", new ProcessedClusterStateUpdateTask() {
+                @Override
+                public ClusterState execute(ClusterState currentState) throws Exception {
+                    Thread.sleep(100);
+                    return ClusterState.builder(currentState).incrementVersion().build();
+                }
+
+                @Override
+                public void clusterStateProcessed(String source, ClusterState oldState, ClusterState newState) {
+                    latch.countDown();
+                }
+
+                @Override
+                public void onFailure(String source, Throwable t) {
+                    fail();
+                }
+            });
+            clusterService1.submitStateUpdateTask("test4", new ProcessedClusterStateUpdateTask() {
+                @Override
+                public ClusterState execute(ClusterState currentState) throws Exception {
+                    Thread.sleep(100);
+                    return currentState;
+                }
+
+                @Override
+                public void clusterStateProcessed(String source, ClusterState oldState, ClusterState newState) {
+                    latch.countDown();
+                }
+
+                @Override
+                public void onFailure(String source, Throwable t) {
+                    fail();
+                }
+            });
+            // Additional update task to make sure all previous logging made it to the logger
+            // We don't check logging for this on since there is no guarantee that it will occur before our check
+            clusterService1.submitStateUpdateTask("test5", new ProcessedClusterStateUpdateTask() {
+                @Override
+                public ClusterState execute(ClusterState currentState) {
+                    return currentState;
+                }
+
+                @Override
+                public void clusterStateProcessed(String source, ClusterState oldState, ClusterState newState) {
+                    latch.countDown();
+                }
+
+                @Override
+                public void onFailure(String source, Throwable t) {
+                    fail();
+                }
+            });
+            assertThat(latch.await(5, TimeUnit.SECONDS), equalTo(true));
+        } finally {
+            rootLogger.removeAppender(mockAppender);
+        }
+        mockAppender.assertAllExpectationsMatched();
+    }
+
     private static class BlockingTask extends ClusterStateUpdateTask {
         private final CountDownLatch latch = new CountDownLatch(1);
 
diff --git a/src/test/java/org/elasticsearch/test/MockLogAppender.java b/src/test/java/org/elasticsearch/test/MockLogAppender.java
new file mode 100644
index 00000000000..2e0c293c1de
--- /dev/null
+++ b/src/test/java/org/elasticsearch/test/MockLogAppender.java
@@ -0,0 +1,139 @@
+/*
+ * 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.test;
+
+import org.apache.log4j.AppenderSkeleton;
+import org.apache.log4j.Level;
+import org.apache.log4j.spi.LoggingEvent;
+import org.elasticsearch.common.regex.Regex;
+
+import java.util.List;
+
+import static com.google.common.collect.Lists.newArrayList;
+import static org.hamcrest.CoreMatchers.equalTo;
+import static org.hamcrest.MatcherAssert.assertThat;
+
+/**
+ * Test appender that can be used to verify that certain events were logged correctly
+ */
+public class MockLogAppender extends AppenderSkeleton {
+
+    private final static String COMMON_PREFIX = System.getProperty("es.logger.prefix", "org.elasticsearch.");
+
+    private List<LoggingExpectation> expectations;
+
+    public MockLogAppender() {
+        expectations = newArrayList();
+    }
+
+    public void addExpectation(LoggingExpectation expectation) {
+        expectations.add(expectation);
+    }
+
+    @Override
+    protected void append(LoggingEvent loggingEvent) {
+        for (LoggingExpectation expectation : expectations) {
+            expectation.match(loggingEvent);
+        }
+    }
+
+    @Override
+    public void close() {
+
+    }
+
+    @Override
+    public boolean requiresLayout() {
+        return false;
+    }
+
+    public void assertAllExpectationsMatched() {
+        for (LoggingExpectation expectation : expectations) {
+            expectation.assertMatched();
+        }
+    }
+
+    public interface LoggingExpectation {
+        void match(LoggingEvent loggingEvent);
+
+        void assertMatched();
+    }
+
+    public static abstract class AbstractEventExpectation implements LoggingExpectation {
+        protected final String name;
+        protected final String logger;
+        protected final Level level;
+        protected final String message;
+        protected boolean saw;
+
+        public AbstractEventExpectation(String name, String logger, Level level, String message) {
+            this.name = name;
+            this.logger = getLoggerName(logger);
+            this.level = level;
+            this.message = message;
+            this.saw = false;
+        }
+
+        @Override
+        public void match(LoggingEvent event) {
+            if (event.getLevel() == level && event.getLoggerName().equals(logger)) {
+                if (Regex.isSimpleMatchPattern(message)) {
+                    if (Regex.simpleMatch(message, event.getMessage().toString())) {
+                        saw = true;
+                    }
+                } else {
+                    if (event.getMessage().toString().contains(message)) {
+                        saw = true;
+                    }
+                }
+            }
+        }
+    }
+
+    public static class UnseenEventExpectation extends AbstractEventExpectation {
+
+        public UnseenEventExpectation(String name, String logger, Level level, String message) {
+            super(name, logger, level, message);
+        }
+
+        @Override
+        public void assertMatched() {
+            assertThat(name, saw, equalTo(false));
+        }
+    }
+
+    public static class SeenEventExpectation extends AbstractEventExpectation {
+
+        public SeenEventExpectation(String name, String logger, Level level, String message) {
+            super(name, logger, level, message);
+        }
+
+        @Override
+        public void assertMatched() {
+            assertThat(name, saw, equalTo(true));
+        }
+    }
+
+    private static String getLoggerName(String name) {
+        if (name.startsWith("org.elasticsearch.")) {
+            name = name.substring("org.elasticsearch.".length());
+        }
+        return COMMON_PREFIX + name;
+    }
+}