Avoid I/O operations when rewriting shard search request (#54044) (#54139)

This commit ensures that we rewrite the shard request with a short-lived can_match searcher.
This is required for frozen indices since the high level rewrite is now performed on a network thread where we don't want to perform I/O.

Closes #53985

server/src/main/java/org/elasticsearch/index/shard/IndexShard.java

@@ -1228,12 +1228,12 @@ public class IndexShard extends AbstractIndexShardComponent implements IndicesCl
     }
 
     /**
-     * Acquire the searcher without applying the additional reader wrapper.
+     * Acquire a lightweight searcher which can be used to rewrite shard search requests.
      */
-    public Engine.Searcher acquireSearcherNoWrap(String source) {
+    public Engine.Searcher acquireCanMatchSearcher() {
         readAllowed();
         markSearcherAccessed();
-        return getEngine().acquireSearcher(source, Engine.SearcherScope.EXTERNAL);
+        return getEngine().acquireSearcher("can_match", Engine.SearcherScope.EXTERNAL);
     }
 
     public Engine.Searcher acquireSearcher(String source) {
@@ -1252,10 +1252,7 @@ public class IndexShard extends AbstractIndexShardComponent implements IndicesCl
         return wrapSearcher(searcher);
     }
 
-    /**
-     * Wraps the provided searcher acquired with {@link #acquireSearcherNoWrap(String)}.
-     */
-    public Engine.Searcher wrapSearcher(Engine.Searcher searcher) {
+    private Engine.Searcher wrapSearcher(Engine.Searcher searcher) {
         assert ElasticsearchDirectoryReader.unwrap(searcher.getDirectoryReader())
             != null : "DirectoryReader must be an instance or ElasticsearchDirectoryReader";
         boolean success = false;

server/src/main/java/org/elasticsearch/search/SearchService.java

@@ -33,6 +33,7 @@ import org.elasticsearch.action.search.SearchShardTask;
 import org.elasticsearch.action.search.SearchType;
 import org.elasticsearch.cluster.ClusterState;
 import org.elasticsearch.cluster.service.ClusterService;
+import org.elasticsearch.common.CheckedSupplier;
 import org.elasticsearch.common.UUIDs;
 import org.elasticsearch.common.breaker.CircuitBreaker;
 import org.elasticsearch.common.component.AbstractLifecycleComponent;
@@ -315,31 +316,24 @@ public class SearchService extends AbstractLifecycleComponent implements IndexEv
     }
 
     public void executeDfsPhase(ShardSearchRequest request, SearchShardTask task, ActionListener<SearchPhaseResult> listener) {
-        rewriteShardRequest(request, ActionListener.wrap(
-            // fork the execution in the search thread pool and wraps the searcher
-            // to execute the query
-            context -> {
-                try {
-                    context.wrapSearcher().execute(() -> {
-                        final SearchPhaseResult result;
-                        try {
-                            result = executeDfsPhase(context, task);
-                        } catch (Exception exc) {
-                            listener.onFailure(exc);
-                            return;
-                        }
-                        listener.onResponse(result);
-                    });
-                } catch (Exception exc) {
-                    // if the execution is rejected we need to close the searcher
-                    IOUtils.closeWhileHandlingException(context.searcher);
-                    listener.onFailure(exc);
-                }
-            }, listener::onFailure));
+        IndexService indexService = indicesService.indexServiceSafe(request.shardId().getIndex());
+        IndexShard shard = indexService.getShard(request.shardId().id());
+        rewriteAndFetchShardRequest(shard,  request, new ActionListener<ShardSearchRequest>() {
+            @Override
+            public void onResponse(ShardSearchRequest rewritten) {
+                // fork the execution in the search thread pool
+                runAsync(shard, () -> executeDfsPhase(request, task), listener);
+            }
+
+            @Override
+            public void onFailure(Exception exc) {
+                listener.onFailure(exc);
+            }
+        });
     }
 
-    private DfsSearchResult executeDfsPhase(SearchRewriteContext rewriteContext, SearchShardTask task) throws IOException {
-        final SearchContext context = createAndPutContext(rewriteContext, task);
+    private DfsSearchResult executeDfsPhase(ShardSearchRequest request, SearchShardTask task) throws IOException {
+        final SearchContext context = createAndPutContext(request, task);
         context.incRef();
         try {
             contextProcessing(context);
@@ -371,58 +365,66 @@ public class SearchService extends AbstractLifecycleComponent implements IndexEv
     public void executeQueryPhase(ShardSearchRequest request, SearchShardTask task, ActionListener<SearchPhaseResult> listener) {
         assert request.canReturnNullResponseIfMatchNoDocs() == false || request.numberOfShards() > 1
             : "empty responses require more than one shard";
-        rewriteShardRequest(request, ActionListener.wrap(
-            context -> {
-                try {
-                    ShardSearchRequest rewritten = context.request;
-                    if (rewritten.canReturnNullResponseIfMatchNoDocs()
-                            && canRewriteToMatchNone(rewritten.source())
-                            && rewritten.source().query() instanceof MatchNoneQueryBuilder) {
-                        assert request.scroll() == null : "must always create search context for scroll requests";
-                        onMatchNoDocs(context, listener);
-                    } else {
-                        // fork the execution in the search thread pool and wraps the searcher
-                        // to execute the query
-                        context.wrapSearcher().execute(() -> {
-                            final SearchPhaseResult result;
-                            try {
-                                result = executeQueryPhase(context, task);
-                            } catch (Exception exc) {
-                                listener.onFailure(exc);
-                                return;
-                            }
-                            listener.onResponse(result);
-                        });
+        IndexService indexService = indicesService.indexServiceSafe(request.shardId().getIndex());
+        IndexShard shard = indexService.getShard(request.shardId().id());
+        rewriteAndFetchShardRequest(shard, request, new ActionListener<ShardSearchRequest>() {
+            @Override
+            public void onResponse(ShardSearchRequest orig) {
+                if (orig.canReturnNullResponseIfMatchNoDocs()) {
+                    // we clone the shard request and perform a quick rewrite using a lightweight
+                    // searcher since we are outside of the search thread pool.
+                    // If the request rewrites to "match none" we can shortcut the query phase
+                    // entirely. Otherwise we fork the execution in the search thread pool.
+                    ShardSearchRequest canMatchRequest = new ShardSearchRequest(orig);
+                    try (Engine.Searcher searcher = shard.acquireCanMatchSearcher()) {
+                        QueryShardContext context = indexService.newQueryShardContext(request.shardId().id(), searcher,
+                            request::nowInMillis, request.getClusterAlias());
+                        Rewriteable.rewrite(request.getRewriteable(), context, true);
+                    } catch (Exception exc) {
+                        listener.onFailure(exc);
+                    }
+                    if (canRewriteToMatchNone(canMatchRequest.source())
+                            && canMatchRequest.source().query() instanceof MatchNoneQueryBuilder) {
+                        assert canMatchRequest.scroll() == null : "must always create search context for scroll requests";
+                        listener.onResponse(QuerySearchResult.nullInstance());
+                        return;
                     }
-                } catch (Exception exc) {
-                    // if the execution is rejected we need to close the searcher
-                    IOUtils.closeWhileHandlingException(context.searcher);
-                    listener.onFailure(exc);
                 }
-            }, listener::onFailure));
+                // fork the execution in the search thread pool
+                runAsync(shard, () -> executeQueryPhase(orig, task), listener);
+            }
+
+            @Override
+            public void onFailure(Exception exc) {
+                listener.onFailure(exc);
+            }
+        });
     }
 
-    private void onMatchNoDocs(SearchRewriteContext rewriteContext, ActionListener<SearchPhaseResult> listener) throws IOException {
-        // creates a lightweight search context that we use to inform context listeners
-        // before closing
-        SearchContext searchContext = createSearchContext(rewriteContext, defaultSearchTimeout);
-        try (SearchContext dummy = searchContext) {
-            onNewContext(searchContext);
-            onFreeContext(searchContext);
+    private <T> void runAsync(IndexShard shard, CheckedSupplier<T, Exception> command, ActionListener<T> listener) {
+        Executor executor = getExecutor(shard);
+        try {
+            executor.execute(() -> {
+                T result;
+                try {
+                    result = command.get();
+                } catch (Exception exc) {
+                    listener.onFailure(exc);
+                    return;
+                }
+                listener.onResponse(result);
+            });
         } catch (Exception exc) {
             listener.onFailure(exc);
-            return;
         }
-        listener.onResponse(QuerySearchResult.nullInstance());
     }
 
     private <T> void runAsync(SearchContextId contextId, Supplier<T> executable, ActionListener<T> listener) {
         getExecutor(contextId).execute(ActionRunnable.supply(listener, executable::get));
     }
 
-    private SearchPhaseResult executeQueryPhase(SearchRewriteContext rewriteContext, SearchShardTask task) throws Exception {
-        final SearchContext context = createAndPutContext(rewriteContext, task);
-        final ShardSearchRequest request = rewriteContext.request;
+    private SearchPhaseResult executeQueryPhase(ShardSearchRequest request, SearchShardTask task) throws Exception {
+        final SearchContext context = createAndPutContext(request, task);
         context.incRef();
         try {
             final long afterQueryTime;
@@ -624,8 +626,8 @@ public class SearchService extends AbstractLifecycleComponent implements IndexEv
         }
     }
 
-    final SearchContext createAndPutContext(SearchRewriteContext rewriteContext, SearchShardTask task) throws IOException {
-        SearchContext context = createContext(rewriteContext, task);
+    final SearchContext createAndPutContext(ShardSearchRequest request, SearchShardTask task) throws IOException {
+        SearchContext context = createContext(request, task);
         onNewContext(context);
         boolean success = false;
         try {
@@ -658,10 +660,9 @@ public class SearchService extends AbstractLifecycleComponent implements IndexEv
         }
     }
 
-    final SearchContext createContext(SearchRewriteContext rewriteContext, SearchShardTask searchTask) throws IOException {
-        final DefaultSearchContext context = createSearchContext(rewriteContext, defaultSearchTimeout);
+    final SearchContext createContext(ShardSearchRequest request, SearchShardTask searchTask) throws IOException {
+        final DefaultSearchContext context = createSearchContext(request, defaultSearchTimeout);
         try {
-            final ShardSearchRequest request = rewriteContext.request;
             if (request.scroll() != null) {
                 context.addReleasable(openScrollContexts::decrementAndGet, Lifetime.CONTEXT);
                 if (openScrollContexts.incrementAndGet() > maxOpenScrollContext) {
@@ -704,21 +705,19 @@ public class SearchService extends AbstractLifecycleComponent implements IndexEv
     }
 
     public DefaultSearchContext createSearchContext(ShardSearchRequest request, TimeValue timeout) throws IOException {
-        IndexShard shard = indicesService.indexServiceSafe(request.shardId().getIndex()).getShard(request.shardId().id());
-        SearchRewriteContext rewriteContext = acquireSearcherAndRewrite(request, shard);
-        // make sure that we wrap the searcher when executing the query
-        return createSearchContext(rewriteContext.wrapSearcher(), timeout);
+        return createSearchContext(request, timeout, "search");
     }
 
-    private DefaultSearchContext createSearchContext(SearchRewriteContext rewriteContext, TimeValue timeout) throws IOException {
+    private DefaultSearchContext createSearchContext(ShardSearchRequest request, TimeValue timeout, String source) throws IOException {
+        IndexService indexService = indicesService.indexServiceSafe(request.shardId().getIndex());
+        IndexShard indexShard = indexService.getShard(request.shardId().getId());
+        SearchShardTarget shardTarget = new SearchShardTarget(clusterService.localNode().getId(),
+            indexShard.shardId(), request.getClusterAlias(), OriginalIndices.NONE);
+        Engine.Searcher searcher = indexShard.acquireSearcher(source);
+
         boolean success = false;
+        DefaultSearchContext searchContext = null;
         try {
-            final ShardSearchRequest request = rewriteContext.request;
-            final Engine.Searcher searcher = rewriteContext.searcher;
-            IndexService indexService = indicesService.indexServiceSafe(request.shardId().getIndex());
-            IndexShard indexShard = indexService.getShard(request.shardId().getId());
-            SearchShardTarget shardTarget = new SearchShardTarget(clusterService.localNode().getId(),
-                indexShard.shardId(), request.getClusterAlias(), OriginalIndices.NONE);
             // TODO: If no changes are made since the last commit, and the searcher is opened from that commit, then we can use the
             //  commit_id as the context_id. And if the local checkpoint and max_seq_no of that commit equal the global checkpoint,
             //  then we can use a combination of history_uuid and one of these values as a **weaker** context_id.
@@ -727,19 +726,24 @@ public class SearchService extends AbstractLifecycleComponent implements IndexEv
             //  the Lucene doc ids can be different.
             final String readerId = UUIDs.base64UUID();
             final SearchContextId searchContextId = new SearchContextId(readerId, idGenerator.incrementAndGet());
-            DefaultSearchContext searchContext = new DefaultSearchContext(searchContextId, request, shardTarget,
+            searchContext = new DefaultSearchContext(searchContextId, request, shardTarget,
                 searcher, clusterService, indexService, indexShard, bigArrays, threadPool::relativeTimeInMillis, timeout,
                 fetchPhase, lowLevelCancellation, clusterService.state().nodes().getMinNodeVersion());
+            // we clone the query shard context here just for rewriting otherwise we
+            // might end up with incorrect state since we are using now() or script services
+            // during rewrite and normalized / evaluate templates etc.
+            QueryShardContext context = new QueryShardContext(searchContext.getQueryShardContext());
+            Rewriteable.rewrite(request.getRewriteable(), context, true);
+            assert searchContext.getQueryShardContext().isCacheable();
             success = true;
-            return searchContext;
         } finally {
             if (success == false) {
-                // we handle the case where `IndicesService#indexServiceSafe`or `IndexService#getShard`, or the DefaultSearchContext
-                // constructor throws an exception since we would otherwise leak a searcher and this can have severe implications
-                // (unable to obtain shard lock exceptions).
-                IOUtils.closeWhileHandlingException(rewriteContext.searcher);
+                // we handle the case where the DefaultSearchContext constructor throws an exception since we would otherwise
+                // leak a searcher and this can have severe implications (unable to obtain shard lock exceptions).
+                IOUtils.closeWhileHandlingException(searcher);
             }
         }
+        return searchContext;
     }
 
 
@@ -1110,7 +1114,7 @@ public class SearchService extends AbstractLifecycleComponent implements IndexEv
         IndexShard indexShard = indexService.getShard(request.shardId().getId());
         // we don't want to use the reader wrapper since it could run costly operations
         // and we can afford false positives.
-        try (Engine.Searcher searcher = indexShard.acquireSearcherNoWrap("can_match")) {
+        try (Engine.Searcher searcher = indexShard.acquireCanMatchSearcher()) {
             QueryShardContext context = indexService.newQueryShardContext(request.shardId().id(), searcher,
                 request::nowInMillis, request.getClusterAlias());
             Rewriteable.rewrite(request.getRewriteable(), context, false);
@@ -1146,50 +1150,17 @@ public class SearchService extends AbstractLifecycleComponent implements IndexEv
         return aggregations == null || aggregations.mustVisitAllDocs() == false;
     }
 
-    /*
-     * Rewrites the search request with a light weight rewrite context in order to fetch resources asynchronously
-     * and then rewrites with a searcher when the shard is active.
-     * The provided action listener is executed on the same thread or in a listener threadpool.
-     */
-    private void rewriteShardRequest(ShardSearchRequest request, ActionListener<SearchRewriteContext> listener) {
-        IndexShard shard = indicesService.indexServiceSafe(request.shardId().getIndex()).getShard(request.shardId().id());
+    private void rewriteAndFetchShardRequest(IndexShard shard, ShardSearchRequest request, ActionListener<ShardSearchRequest> listener) {
         ActionListener<Rewriteable> actionListener = ActionListener.wrap(r ->
-                // now we need to check if there is a pending refresh and register
-                shard.awaitShardSearchActive(b -> {
-                    try {
-                        // we can now acquire a searcher and rewrite the request with it
-                        SearchRewriteContext rewriteContext = acquireSearcherAndRewrite(request, shard);
-                        listener.onResponse(rewriteContext);
-                    } catch (Exception e) {
-                        listener.onFailure(e);
-                    }
-                }), listener::onFailure);
+            // now we need to check if there is a pending refresh and register
+            shard.awaitShardSearchActive(b -> listener.onResponse(request)),
+            listener::onFailure);
         // we also do rewrite on the coordinating node (TransportSearchService) but we also need to do it here for BWC as well as
         // AliasFilters that might need to be rewritten. These are edge-cases but we are every efficient doing the rewrite here so it's not
         // adding a lot of overhead
         Rewriteable.rewriteAndFetch(request.getRewriteable(), indicesService.getRewriteContext(request::nowInMillis), actionListener);
     }
 
-    SearchRewriteContext acquireSearcherAndRewrite(ShardSearchRequest request, IndexShard shard) throws IOException {
-        // acquire the searcher for rewrite with no wrapping in order to avoid costly
-        // operations. We'll wrap the searcher at a later stage (when executing the query).
-        Engine.Searcher searcher = shard.acquireSearcherNoWrap("search");
-        boolean success = false;
-        try {
-            IndexService indexService = indicesService.indexServiceSafe(request.shardId().getIndex());
-            QueryShardContext context = indexService.newQueryShardContext(request.shardId().id(), searcher,
-                request::nowInMillis, request.getClusterAlias());
-            Rewriteable.rewrite(request.getRewriteable(), context, true);
-            SearchRewriteContext rewrite = new SearchRewriteContext(request, shard, searcher, getExecutor(shard));
-            success = true;
-            return rewrite;
-        } finally {
-            if (success == false) {
-                IOUtils.closeWhileHandlingException(searcher);
-            }
-        }
-    }
-
     /**
      * Returns a new {@link QueryRewriteContext} with the given {@code now} provider
      */
@@ -1228,37 +1199,6 @@ public class SearchService extends AbstractLifecycleComponent implements IndexEv
         return request.source().aggregations().buildPipelineTree();
     }
 
-    static class SearchRewriteContext {
-        private final ShardSearchRequest request;
-        private final IndexShard shard;
-        private Engine.Searcher searcher;
-        private final Executor executor;
-
-        private boolean isWrapped;
-
-        private SearchRewriteContext(ShardSearchRequest request,
-                                     IndexShard shard,
-                                     Engine.Searcher searcher,
-                                     Executor executor) {
-            this.request = request;
-            this.shard = shard;
-            this.searcher = searcher;
-            this.executor = executor;
-        }
-
-        SearchRewriteContext wrapSearcher() {
-            assert isWrapped == false : "searcher already wrapped";
-            isWrapped = true;
-            searcher = shard.wrapSearcher(searcher);
-            return this;
-        }
-
-        void execute(Runnable runnable) {
-            assert isWrapped : "searcher is not wrapped";
-            executor.execute(runnable);
-        }
-    }
-
     public static final class CanMatchResponse extends SearchPhaseResult {
         private final boolean canMatch;
         private final MinAndMax<?> minAndMax;

server/src/main/java/org/elasticsearch/search/internal/ShardSearchRequest.java

@@ -195,6 +195,26 @@ public class ShardSearchRequest extends TransportRequest implements IndicesReque
         originalIndices = OriginalIndices.readOriginalIndices(in);
     }
 
+    public ShardSearchRequest(ShardSearchRequest clone) {
+        this.shardId = clone.shardId;
+        this.searchType = clone.searchType;
+        this.numberOfShards = clone.numberOfShards;
+        this.scroll = clone.scroll;
+        this.source = clone.source;
+        this.types = clone.types;
+        this.aliasFilter = clone.aliasFilter;
+        this.indexBoost = clone.indexBoost;
+        this.nowInMillis = clone.nowInMillis;
+        this.requestCache = clone.requestCache;
+        this.clusterAlias = clone.clusterAlias;
+        this.allowPartialSearchResults = clone.allowPartialSearchResults;
+        this.indexRoutings = clone.indexRoutings;
+        this.preference = clone.preference;
+        this.canReturnNullResponseIfMatchNoDocs = clone.canReturnNullResponseIfMatchNoDocs;
+        this.bottomSortValues = clone.bottomSortValues;
+        this.originalIndices = clone.originalIndices;
+    }
+
     @Override
     public void writeTo(StreamOutput out) throws IOException {
         super.writeTo(out);

server/src/test/java/org/elasticsearch/search/SearchServiceTests.java

@@ -364,11 +364,15 @@ public class SearchServiceTests extends ESSingleNodeTestCase {
         final IndexService indexService = indicesService.indexServiceSafe(resolveIndex("index"));
         final IndexShard indexShard = indexService.getShard(0);
         SearchRequest searchRequest = new SearchRequest().allowPartialSearchResults(true);
-        SearchService.SearchRewriteContext rewriteContext = service.acquireSearcherAndRewrite(
-            new ShardSearchRequest(OriginalIndices.NONE, searchRequest, indexShard.shardId(), 1,
-                new AliasFilter(null, Strings.EMPTY_ARRAY), 1.0f, -1, null, null),
-            indexShard);
-        final SearchContext contextWithDefaultTimeout = service.createContext(rewriteContext, null);
+        final SearchContext contextWithDefaultTimeout = service.createContext(
+                new ShardSearchRequest(
+                        OriginalIndices.NONE,
+                        searchRequest,
+                        indexShard.shardId(),
+                        1,
+                        new AliasFilter(null, Strings.EMPTY_ARRAY),
+                        1.0f, -1, null, null
+                ), null);
         try {
             // the search context should inherit the default timeout
             assertThat(contextWithDefaultTimeout.timeout(), equalTo(TimeValue.timeValueSeconds(5)));
@@ -379,11 +383,15 @@ public class SearchServiceTests extends ESSingleNodeTestCase {
 
         final long seconds = randomIntBetween(6, 10);
         searchRequest.source(new SearchSourceBuilder().timeout(TimeValue.timeValueSeconds(seconds)));
-        rewriteContext = service.acquireSearcherAndRewrite(
-            new ShardSearchRequest(OriginalIndices.NONE, searchRequest, indexShard.shardId(), 1,
-                new AliasFilter(null, Strings.EMPTY_ARRAY), 1.0f, -1, null, null),
-            indexShard);
-        final SearchContext context = service.createContext(rewriteContext, null);
+        final SearchContext context = service.createContext(
+                new ShardSearchRequest(
+                        OriginalIndices.NONE,
+                        searchRequest,
+                        indexShard.shardId(),
+                        1,
+                        new AliasFilter(null, Strings.EMPTY_ARRAY),
+                        1.0f, -1, null, null
+                ), null);
         try {
             // the search context should inherit the query timeout
             assertThat(context.timeout(), equalTo(TimeValue.timeValueSeconds(seconds)));
@@ -411,22 +419,16 @@ public class SearchServiceTests extends ESSingleNodeTestCase {
         for (int i = 0; i < indexService.getIndexSettings().getMaxDocvalueFields(); i++) {
             searchSourceBuilder.docValueField("field" + i);
         }
-
-        ShardSearchRequest shardRequest =  new ShardSearchRequest(OriginalIndices.NONE, searchRequest, indexShard.shardId(), 1,
-            new AliasFilter(null, Strings.EMPTY_ARRAY), 1.0f, -1, null, null);
-
-        {
-            SearchService.SearchRewriteContext rewriteContext = service.acquireSearcherAndRewrite(shardRequest, indexShard);
-            try (SearchContext context = service.createContext(rewriteContext, null)) {
-                assertNotNull(context);
-            }
-        }
-
-        {
-            SearchService.SearchRewriteContext rewriteContext = service.acquireSearcherAndRewrite(shardRequest, indexShard);
+        try (SearchContext context = service.createContext(
+            new ShardSearchRequest(OriginalIndices.NONE,
+                searchRequest, indexShard.shardId(), 1,
+                new AliasFilter(null, Strings.EMPTY_ARRAY), 1.0f, -1, null, null
+            ), null)) {
+            assertNotNull(context);
             searchSourceBuilder.docValueField("one_field_too_much");
             IllegalArgumentException ex = expectThrows(IllegalArgumentException.class,
-                () -> service.createContext(rewriteContext, null));
+                    () -> service.createContext(new ShardSearchRequest(OriginalIndices.NONE, searchRequest, indexShard.shardId(), 1,
+                        new AliasFilter(null, Strings.EMPTY_ARRAY), 1.0f, -1, null, null), null));
             assertEquals(
                 "Trying to retrieve too many docvalue_fields. Must be less than or equal to: [100] but was [101]. "
                     + "This limit can be set by changing the [index.max_docvalue_fields_search] index level setting.", ex.getMessage());
@@ -452,28 +454,20 @@ public class SearchServiceTests extends ESSingleNodeTestCase {
             searchSourceBuilder.scriptField("field" + i,
                     new Script(ScriptType.INLINE, MockScriptEngine.NAME, CustomScriptPlugin.DUMMY_SCRIPT, Collections.emptyMap()));
         }
-
-        ShardSearchRequest shardRequest = new ShardSearchRequest(OriginalIndices.NONE, searchRequest, indexShard.shardId(), 1,
-            new AliasFilter(null, Strings.EMPTY_ARRAY), 1.0f, -1, null, null);
-
-        {
-            SearchService.SearchRewriteContext rewriteContext = service.acquireSearcherAndRewrite(shardRequest, indexShard);
-            try (SearchContext context = service.createContext(rewriteContext, null)) {
-                assertNotNull(context);
-            }
-        }
-
-        {
+        try (SearchContext context = service.createContext(new ShardSearchRequest(OriginalIndices.NONE, searchRequest,
+                indexShard.shardId(), 1, new AliasFilter(null, Strings.EMPTY_ARRAY),
+                1.0f, -1, null, null), null)) {
+            assertNotNull(context);
             searchSourceBuilder.scriptField("anotherScriptField",
                 new Script(ScriptType.INLINE, MockScriptEngine.NAME, CustomScriptPlugin.DUMMY_SCRIPT, Collections.emptyMap()));
-            SearchService.SearchRewriteContext rewriteContext = service.acquireSearcherAndRewrite(shardRequest, indexShard);
             IllegalArgumentException ex = expectThrows(IllegalArgumentException.class,
-                    () -> service.createContext(rewriteContext, null));
+                    () -> service.createContext(new ShardSearchRequest(OriginalIndices.NONE, searchRequest, indexShard.shardId(), 1,
+                        new AliasFilter(null, Strings.EMPTY_ARRAY), 1.0f, -1, null, null),  null));
             assertEquals(
-                "Trying to retrieve too many script_fields. Must be less than or equal to: [" + maxScriptFields + "] but was ["
-                    + (maxScriptFields + 1)
-                    + "]. This limit can be set by changing the [index.max_script_fields] index level setting.",
-                ex.getMessage());
+                    "Trying to retrieve too many script_fields. Must be less than or equal to: [" + maxScriptFields + "] but was ["
+                            + (maxScriptFields + 1)
+                            + "]. This limit can be set by changing the [index.max_script_fields] index level setting.",
+                    ex.getMessage());
         }
     }
 
@@ -490,19 +484,17 @@ public class SearchServiceTests extends ESSingleNodeTestCase {
         searchSourceBuilder.scriptField("field" + 0,
                 new Script(ScriptType.INLINE, MockScriptEngine.NAME, CustomScriptPlugin.DUMMY_SCRIPT, Collections.emptyMap()));
         searchSourceBuilder.size(0);
-        SearchService.SearchRewriteContext rewriteContext = service.acquireSearcherAndRewrite(
-            new ShardSearchRequest(OriginalIndices.NONE, searchRequest, indexShard.shardId(), 1,
-                new AliasFilter(null, Strings.EMPTY_ARRAY), 1.0f, -1, null, null),
-            indexShard);
-        try (SearchContext context = service.createContext(rewriteContext, null)) {
-            assertEquals(0, context.scriptFields().fields().size());
+        try (SearchContext context = service.createContext(new ShardSearchRequest(OriginalIndices.NONE,
+            searchRequest, indexShard.shardId(), 1, new AliasFilter(null, Strings.EMPTY_ARRAY),
+                1.0f, -1, null, null),  null)) {
+                assertEquals(0, context.scriptFields().fields().size());
         }
     }
 
     /**
      * test that creating more than the allowed number of scroll contexts throws an exception
      */
-    public void testMaxOpenScrollContexts() throws RuntimeException, IOException {
+    public void testMaxOpenScrollContexts() throws RuntimeException {
         createIndex("index");
         client().prepareIndex("index", "type", "1").setSource("field", "value").setRefreshPolicy(IMMEDIATE).get();
 
@@ -528,10 +520,8 @@ public class SearchServiceTests extends ESSingleNodeTestCase {
             client().prepareSearch("index").setSize(1).setScroll("1m").get();
         }
 
-        SearchService.SearchRewriteContext rewriteContext =
-            service.acquireSearcherAndRewrite(new ShardScrollRequestTest(indexShard.shardId()), indexShard);
         ElasticsearchException ex = expectThrows(ElasticsearchException.class,
-            () -> service.createAndPutContext(rewriteContext, null));
+            () -> service.createAndPutContext(new ShardScrollRequestTest(indexShard.shardId()), null));
         assertEquals(
             "Trying to create too many scroll contexts. Must be less than or equal to: [" +
                 SearchService.MAX_OPEN_SCROLL_CONTEXT.get(Settings.EMPTY) + "]. " +
@@ -554,10 +544,8 @@ public class SearchServiceTests extends ESSingleNodeTestCase {
                 try {
                     latch.await();
                     for (; ; ) {
-                        SearchService.SearchRewriteContext rewriteContext =
-                            searchService.acquireSearcherAndRewrite(new ShardScrollRequestTest(indexShard.shardId()), indexShard);
                         try {
-                            searchService.createAndPutContext(rewriteContext, null);
+                            searchService.createAndPutContext(new ShardScrollRequestTest(indexShard.shardId()), null);
                         } catch (ElasticsearchException e) {
                             assertThat(e.getMessage(), equalTo(
                                 "Trying to create too many scroll contexts. Must be less than or equal to: " +
@@ -657,7 +645,6 @@ public class SearchServiceTests extends ESSingleNodeTestCase {
         final IndexService indexService = indicesService.indexServiceSafe(resolveIndex("index"));
         final IndexShard indexShard = indexService.getShard(0);
         SearchRequest searchRequest = new SearchRequest().allowPartialSearchResults(true);
-        int numWrapReader = numWrapInvocations.get();
         assertTrue(service.canMatch(new ShardSearchRequest(OriginalIndices.NONE, searchRequest, indexShard.shardId(), 1,
             new AliasFilter(null, Strings.EMPTY_ARRAY), 1f, -1, null, null)).canMatch());
 
@@ -681,7 +668,7 @@ public class SearchServiceTests extends ESSingleNodeTestCase {
         searchRequest.source(new SearchSourceBuilder().query(new MatchNoneQueryBuilder()));
         assertFalse(service.canMatch(new ShardSearchRequest(OriginalIndices.NONE, searchRequest, indexShard.shardId(), 1,
             new AliasFilter(null, Strings.EMPTY_ARRAY), 1f, -1, null, null)).canMatch());
-        assertEquals(numWrapReader, numWrapInvocations.get());
+        assertEquals(0, numWrapInvocations.get());
 
         ShardSearchRequest request = new ShardSearchRequest(OriginalIndices.NONE, searchRequest, indexShard.shardId(), 1,
             new AliasFilter(null, Strings.EMPTY_ARRAY), 1.0f, -1, null, null);
@@ -693,7 +680,7 @@ public class SearchServiceTests extends ESSingleNodeTestCase {
             public void onResponse(SearchPhaseResult searchPhaseResult) {
                 try {
                     // make sure that the wrapper is called when the query is actually executed
-                    assertEquals(numWrapReader+1, numWrapInvocations.get());
+                    assertEquals(1, numWrapInvocations.get());
                 } finally {
                     latch.countDown();
                 }
@@ -826,16 +813,15 @@ public class SearchServiceTests extends ESSingleNodeTestCase {
         final ShardId shardId = new ShardId(indexService.index(), 0);
         IndexShard indexShard = indexService.getShard(0);
 
-        SearchService.SearchRewriteContext rewriteContext = service.acquireSearcherAndRewrite(
-            new ShardSearchRequest(shardId, null, 0, AliasFilter.EMPTY) {
-                @Override
-                public SearchType searchType() {
-                    // induce an artificial NPE
-                    throw new NullPointerException("expected");
-                }
-            }, indexShard);
         NullPointerException e = expectThrows(NullPointerException.class,
-            () -> service.createContext(rewriteContext, null));
+            () -> service.createContext(
+                new ShardSearchRequest(shardId, null, 0, AliasFilter.EMPTY) {
+                    @Override
+                    public SearchType searchType() {
+                        // induce an artificial NPE
+                        throw new NullPointerException("expected");
+                    }
+                }, null));
         assertEquals("expected", e.getMessage());
         assertEquals("should have 2 store refs (IndexService + InternalEngine)", 2, indexService.getShard(0).store().refCount());
     }
@@ -987,8 +973,7 @@ public class SearchServiceTests extends ESSingleNodeTestCase {
         List<SearchContextId> contextIds = new ArrayList<>();
         int numContexts = randomIntBetween(1, 10);
         for (int i = 0; i < numContexts; i++) {
-            SearchService.SearchRewriteContext rewriteContext = searchService.acquireSearcherAndRewrite(shardSearchRequest, indexShard);
-            final SearchContext searchContext = searchService.createContext(rewriteContext, null);
+            final SearchContext searchContext = searchService.createContext(shardSearchRequest, null);
             assertThat(searchContext.id().getId(), equalTo((long) (i + 1)));
             searchService.putContext(searchContext);
             contextIds.add(searchContext.id());

server/src/test/java/org/elasticsearch/search/internal/ShardSearchRequestTests.java

@@ -60,26 +60,15 @@ public class ShardSearchRequestTests extends AbstractSearchTestCase {
         ShardSearchRequest shardSearchTransportRequest = createShardSearchRequest();
         ShardSearchRequest deserializedRequest =
             copyWriteable(shardSearchTransportRequest, namedWriteableRegistry, ShardSearchRequest::new);
-        assertEquals(deserializedRequest.scroll(), shardSearchTransportRequest.scroll());
-        assertEquals(deserializedRequest.getAliasFilter(), shardSearchTransportRequest.getAliasFilter());
-        assertArrayEquals(deserializedRequest.indices(), shardSearchTransportRequest.indices());
-        assertArrayEquals(deserializedRequest.types(), shardSearchTransportRequest.types());
-        assertEquals(deserializedRequest.indicesOptions(), shardSearchTransportRequest.indicesOptions());
-        assertEquals(deserializedRequest.nowInMillis(), shardSearchTransportRequest.nowInMillis());
-        assertEquals(deserializedRequest.source(), shardSearchTransportRequest.source());
-        assertEquals(deserializedRequest.searchType(), shardSearchTransportRequest.searchType());
-        assertEquals(deserializedRequest.shardId(), shardSearchTransportRequest.shardId());
-        assertEquals(deserializedRequest.numberOfShards(), shardSearchTransportRequest.numberOfShards());
-        assertArrayEquals(deserializedRequest.indexRoutings(), shardSearchTransportRequest.indexRoutings());
-        assertEquals(deserializedRequest.preference(), shardSearchTransportRequest.preference());
-        assertEquals(deserializedRequest.cacheKey(), shardSearchTransportRequest.cacheKey());
-        assertNotSame(deserializedRequest, shardSearchTransportRequest);
-        assertEquals(deserializedRequest.getAliasFilter(), shardSearchTransportRequest.getAliasFilter());
-        assertEquals(deserializedRequest.indexBoost(), shardSearchTransportRequest.indexBoost(), 0.0f);
-        assertEquals(deserializedRequest.getClusterAlias(), shardSearchTransportRequest.getClusterAlias());
-        assertEquals(shardSearchTransportRequest.allowPartialSearchResults(), deserializedRequest.allowPartialSearchResults());
-        assertEquals(deserializedRequest.canReturnNullResponseIfMatchNoDocs(),
-            shardSearchTransportRequest.canReturnNullResponseIfMatchNoDocs());
+        assertEquals(shardSearchTransportRequest, deserializedRequest);
+    }
+
+    public void testClone() throws Exception {
+        for (int i = 0; i < 10; i++) {
+            ShardSearchRequest shardSearchTransportRequest = createShardSearchRequest();
+            ShardSearchRequest clone = new ShardSearchRequest(shardSearchTransportRequest);
+            assertEquals(shardSearchTransportRequest, clone);
+        }
     }
 
     public void testAllowPartialResultsSerializationPre7_0_0() throws IOException {
@@ -161,6 +150,28 @@ public class ShardSearchRequestTests extends AbstractSearchTestCase {
         expectThrows(InvalidAliasNameException.class, () -> aliasFilter(finalIndexMetadata, "unknown"));
     }
 
+    private static void assertEquals(ShardSearchRequest orig, ShardSearchRequest copy) throws IOException {
+        assertEquals(orig.scroll(), copy.scroll());
+        assertEquals(orig.getAliasFilter(), copy.getAliasFilter());
+        assertArrayEquals(orig.indices(), copy.indices());
+        assertEquals(orig.indicesOptions(), copy.indicesOptions());
+        assertEquals(orig.nowInMillis(), copy.nowInMillis());
+        assertEquals(orig.source(), copy.source());
+        assertEquals(orig.searchType(), copy.searchType());
+        assertEquals(orig.shardId(), copy.shardId());
+        assertEquals(orig.numberOfShards(), copy.numberOfShards());
+        assertArrayEquals(orig.indexRoutings(), copy.indexRoutings());
+        assertEquals(orig.preference(), copy.preference());
+        assertEquals(orig.cacheKey(), copy.cacheKey());
+        assertNotSame(orig, copy);
+        assertEquals(orig.getAliasFilter(), copy.getAliasFilter());
+        assertEquals(orig.indexBoost(), copy.indexBoost(), 0.0f);
+        assertEquals(orig.getClusterAlias(), copy.getClusterAlias());
+        assertEquals(orig.allowPartialSearchResults(), copy.allowPartialSearchResults());
+        assertEquals(orig.canReturnNullResponseIfMatchNoDocs(),
+            orig.canReturnNullResponseIfMatchNoDocs());
+    }
+
     public static CompressedXContent filter(QueryBuilder filterBuilder) throws IOException {
         XContentBuilder builder = XContentFactory.jsonBuilder();
         filterBuilder.toXContent(builder, ToXContent.EMPTY_PARAMS);