Merge pull request #20382 from javanna/enhancement/cleanup_parse_elements

Cleanup sub fetch phase extension point

buildSrc/src/main/resources/checkstyle_suppressions.xml

@@ -238,7 +238,6 @@
   <suppress files="core[/\\]src[/\\]main[/\\]java[/\\]org[/\\]elasticsearch[/\\]cluster[/\\]IncompatibleClusterStateVersionException.java" checks="LineLength" />
   <suppress files="core[/\\]src[/\\]main[/\\]java[/\\]org[/\\]elasticsearch[/\\]cluster[/\\]InternalClusterInfoService.java" checks="LineLength" />
   <suppress files="core[/\\]src[/\\]main[/\\]java[/\\]org[/\\]elasticsearch[/\\]cluster[/\\]LocalNodeMasterListener.java" checks="LineLength" />
-  <suppress files="core[/\\]src[/\\]main[/\\]java[/\\]org[/\\]elasticsearch[/\\]cluster[/\\]action[/\\]index[/\\]NodeIndexDeletedAction.java" checks="LineLength" />
   <suppress files="core[/\\]src[/\\]main[/\\]java[/\\]org[/\\]elasticsearch[/\\]cluster[/\\]action[/\\]index[/\\]NodeMappingRefreshAction.java" checks="LineLength" />
   <suppress files="core[/\\]src[/\\]main[/\\]java[/\\]org[/\\]elasticsearch[/\\]cluster[/\\]action[/\\]shard[/\\]ShardStateAction.java" checks="LineLength" />
   <suppress files="core[/\\]src[/\\]main[/\\]java[/\\]org[/\\]elasticsearch[/\\]cluster[/\\]block[/\\]ClusterBlock.java" checks="LineLength" />
@@ -415,7 +414,6 @@
   <suppress files="core[/\\]src[/\\]main[/\\]java[/\\]org[/\\]elasticsearch[/\\]index[/\\]mapper[/\\]RootObjectMapper.java" checks="LineLength" />
   <suppress files="core[/\\]src[/\\]main[/\\]java[/\\]org[/\\]elasticsearch[/\\]index[/\\]merge[/\\]MergeStats.java" checks="LineLength" />
   <suppress files="core[/\\]src[/\\]main[/\\]java[/\\]org[/\\]elasticsearch[/\\]index[/\\]query[/\\]AbstractQueryBuilder.java" checks="LineLength" />
-  <suppress files="core[/\\]src[/\\]main[/\\]java[/\\]org[/\\]elasticsearch[/\\]index[/\\]query[/\\]MatchQueryParser.java" checks="LineLength" />
   <suppress files="core[/\\]src[/\\]main[/\\]java[/\\]org[/\\]elasticsearch[/\\]index[/\\]query[/\\]QueryBuilders.java" checks="LineLength" />
   <suppress files="core[/\\]src[/\\]main[/\\]java[/\\]org[/\\]elasticsearch[/\\]index[/\\]query[/\\]QueryValidationException.java" checks="LineLength" />
   <suppress files="core[/\\]src[/\\]main[/\\]java[/\\]org[/\\]elasticsearch[/\\]index[/\\]query[/\\]support[/\\]InnerHitsQueryParserHelper.java" checks="LineLength" />
@@ -488,15 +486,12 @@
   <suppress files="core[/\\]src[/\\]main[/\\]java[/\\]org[/\\]elasticsearch[/\\]rest[/\\]action[/\\]cat[/\\]RestPendingClusterTasksAction.java" checks="LineLength" />
   <suppress files="core[/\\]src[/\\]main[/\\]java[/\\]org[/\\]elasticsearch[/\\]rest[/\\]action[/\\]cat[/\\]RestShardsAction.java" checks="LineLength" />
   <suppress files="core[/\\]src[/\\]main[/\\]java[/\\]org[/\\]elasticsearch[/\\]rest[/\\]action[/\\]cat[/\\]RestThreadPoolAction.java" checks="LineLength" />
-  <suppress files="core[/\\]src[/\\]main[/\\]java[/\\]org[/\\]elasticsearch[/\\]script[/\\]AbstractScriptParser.java" checks="LineLength" />
   <suppress files="core[/\\]src[/\\]main[/\\]java[/\\]org[/\\]elasticsearch[/\\]script[/\\]ScriptContextRegistry.java" checks="LineLength" />
   <suppress files="core[/\\]src[/\\]main[/\\]java[/\\]org[/\\]elasticsearch[/\\]script[/\\]ScriptModes.java" checks="LineLength" />
-  <suppress files="core[/\\]src[/\\]main[/\\]java[/\\]org[/\\]elasticsearch[/\\]script[/\\]ScriptParameterParser.java" checks="LineLength" />
   <suppress files="core[/\\]src[/\\]main[/\\]java[/\\]org[/\\]elasticsearch[/\\]script[/\\]ScriptService.java" checks="LineLength" />
   <suppress files="core[/\\]src[/\\]main[/\\]java[/\\]org[/\\]elasticsearch[/\\]script[/\\]ScriptSettings.java" checks="LineLength" />
   <suppress files="core[/\\]src[/\\]main[/\\]java[/\\]org[/\\]elasticsearch[/\\]script[/\\]Template.java" checks="LineLength" />
   <suppress files="core[/\\]src[/\\]main[/\\]java[/\\]org[/\\]elasticsearch[/\\]search[/\\]MultiValueMode.java" checks="LineLength" />
-  <suppress files="core[/\\]src[/\\]main[/\\]java[/\\]org[/\\]elasticsearch[/\\]search[/\\]SearchService.java" checks="LineLength" />
   <suppress files="core[/\\]src[/\\]main[/\\]java[/\\]org[/\\]elasticsearch[/\\]search[/\\]aggregations[/\\]AggregatorFactories.java" checks="LineLength" />
   <suppress files="core[/\\]src[/\\]main[/\\]java[/\\]org[/\\]elasticsearch[/\\]search[/\\]aggregations[/\\]InternalMultiBucketAggregation.java" checks="LineLength" />
   <suppress files="core[/\\]src[/\\]main[/\\]java[/\\]org[/\\]elasticsearch[/\\]search[/\\]aggregations[/\\]ValuesSourceAggregationBuilder.java" checks="LineLength" />
@@ -555,29 +550,19 @@
   <suppress files="core[/\\]src[/\\]main[/\\]java[/\\]org[/\\]elasticsearch[/\\]search[/\\]aggregations[/\\]support[/\\]ValuesSourceParser.java" checks="LineLength" />
   <suppress files="core[/\\]src[/\\]main[/\\]java[/\\]org[/\\]elasticsearch[/\\]search[/\\]aggregations[/\\]support[/\\]format[/\\]ValueFormat.java" checks="LineLength" />
   <suppress files="core[/\\]src[/\\]main[/\\]java[/\\]org[/\\]elasticsearch[/\\]search[/\\]aggregations[/\\]support[/\\]format[/\\]ValueParser.java" checks="LineLength" />
-  <suppress files="core[/\\]src[/\\]main[/\\]java[/\\]org[/\\]elasticsearch[/\\]search[/\\]builder[/\\]SearchSourceBuilder.java" checks="LineLength" />
   <suppress files="core[/\\]src[/\\]main[/\\]java[/\\]org[/\\]elasticsearch[/\\]search[/\\]controller[/\\]SearchPhaseController.java" checks="LineLength" />
   <suppress files="core[/\\]src[/\\]main[/\\]java[/\\]org[/\\]elasticsearch[/\\]search[/\\]dfs[/\\]AggregatedDfs.java" checks="LineLength" />
   <suppress files="core[/\\]src[/\\]main[/\\]java[/\\]org[/\\]elasticsearch[/\\]search[/\\]dfs[/\\]DfsSearchResult.java" checks="LineLength" />
   <suppress files="core[/\\]src[/\\]main[/\\]java[/\\]org[/\\]elasticsearch[/\\]search[/\\]fetch[/\\]FetchPhase.java" checks="LineLength" />
   <suppress files="core[/\\]src[/\\]main[/\\]java[/\\]org[/\\]elasticsearch[/\\]search[/\\]fetch[/\\]FetchSearchResult.java" checks="LineLength" />
   <suppress files="core[/\\]src[/\\]main[/\\]java[/\\]org[/\\]elasticsearch[/\\]search[/\\]fetch[/\\]FetchSubPhase.java" checks="LineLength" />
-  <suppress files="core[/\\]src[/\\]main[/\\]java[/\\]org[/\\]elasticsearch[/\\]search[/\\]fetch[/\\]FetchSubPhaseParseElement.java" checks="LineLength" />
-  <suppress files="core[/\\]src[/\\]main[/\\]java[/\\]org[/\\]elasticsearch[/\\]search[/\\]internal[/\\]DefaultSearchContext.java" checks="LineLength" />
-  <suppress files="core[/\\]src[/\\]main[/\\]java[/\\]org[/\\]elasticsearch[/\\]search[/\\]internal[/\\]FilteredSearchContext.java" checks="LineLength" />
   <suppress files="core[/\\]src[/\\]main[/\\]java[/\\]org[/\\]elasticsearch[/\\]search[/\\]internal[/\\]InternalSearchHit.java" checks="LineLength" />
-  <suppress files="core[/\\]src[/\\]main[/\\]java[/\\]org[/\\]elasticsearch[/\\]search[/\\]internal[/\\]SearchContext.java" checks="LineLength" />
   <suppress files="core[/\\]src[/\\]main[/\\]java[/\\]org[/\\]elasticsearch[/\\]search[/\\]internal[/\\]ShardSearchTransportRequest.java" checks="LineLength" />
   <suppress files="core[/\\]src[/\\]main[/\\]java[/\\]org[/\\]elasticsearch[/\\]search[/\\]lookup[/\\]FieldLookup.java" checks="LineLength" />
   <suppress files="core[/\\]src[/\\]main[/\\]java[/\\]org[/\\]elasticsearch[/\\]search[/\\]lookup[/\\]LeafDocLookup.java" checks="LineLength" />
   <suppress files="core[/\\]src[/\\]main[/\\]java[/\\]org[/\\]elasticsearch[/\\]search[/\\]lookup[/\\]LeafFieldsLookup.java" checks="LineLength" />
   <suppress files="core[/\\]src[/\\]main[/\\]java[/\\]org[/\\]elasticsearch[/\\]search[/\\]query[/\\]QueryPhase.java" checks="LineLength" />
   <suppress files="core[/\\]src[/\\]main[/\\]java[/\\]org[/\\]elasticsearch[/\\]search[/\\]rescore[/\\]QueryRescorer.java" checks="LineLength" />
-  <suppress files="core[/\\]src[/\\]main[/\\]java[/\\]org[/\\]elasticsearch[/\\]search[/\\]rescore[/\\]RescoreParseElement.java" checks="LineLength" />
-  <suppress files="core[/\\]src[/\\]main[/\\]java[/\\]org[/\\]elasticsearch[/\\]search[/\\]sort[/\\]GeoDistanceSortParser.java" checks="LineLength" />
-  <suppress files="core[/\\]src[/\\]main[/\\]java[/\\]org[/\\]elasticsearch[/\\]search[/\\]sort[/\\]ScriptSortParser.java" checks="LineLength" />
-  <suppress files="core[/\\]src[/\\]main[/\\]java[/\\]org[/\\]elasticsearch[/\\]search[/\\]sort[/\\]SortParseElement.java" checks="LineLength" />
-  <suppress files="core[/\\]src[/\\]main[/\\]java[/\\]org[/\\]elasticsearch[/\\]search[/\\]suggest[/\\]SuggestContextParser.java" checks="LineLength" />
   <suppress files="core[/\\]src[/\\]main[/\\]java[/\\]org[/\\]elasticsearch[/\\]search[/\\]suggest[/\\]SuggestUtils.java" checks="LineLength" />
   <suppress files="core[/\\]src[/\\]main[/\\]java[/\\]org[/\\]elasticsearch[/\\]search[/\\]suggest[/\\]completion[/\\]CompletionSuggestParser.java" checks="LineLength" />
   <suppress files="core[/\\]src[/\\]main[/\\]java[/\\]org[/\\]elasticsearch[/\\]search[/\\]suggest[/\\]completion[/\\]context[/\\]CategoryContextMapping.java" checks="LineLength" />
@@ -586,9 +571,7 @@
   <suppress files="core[/\\]src[/\\]main[/\\]java[/\\]org[/\\]elasticsearch[/\\]search[/\\]suggest[/\\]completion[/\\]context[/\\]GeoQueryContext.java" checks="LineLength" />
   <suppress files="core[/\\]src[/\\]main[/\\]java[/\\]org[/\\]elasticsearch[/\\]search[/\\]suggest[/\\]phrase[/\\]CandidateScorer.java" checks="LineLength" />
   <suppress files="core[/\\]src[/\\]main[/\\]java[/\\]org[/\\]elasticsearch[/\\]search[/\\]suggest[/\\]phrase[/\\]NoisyChannelSpellChecker.java" checks="LineLength" />
-  <suppress files="core[/\\]src[/\\]main[/\\]java[/\\]org[/\\]elasticsearch[/\\]search[/\\]suggest[/\\]phrase[/\\]PhraseSuggestParser.java" checks="LineLength" />
   <suppress files="core[/\\]src[/\\]main[/\\]java[/\\]org[/\\]elasticsearch[/\\]search[/\\]suggest[/\\]phrase[/\\]WordScorer.java" checks="LineLength" />
-  <suppress files="core[/\\]src[/\\]main[/\\]java[/\\]org[/\\]elasticsearch[/\\]search[/\\]suggest[/\\]term[/\\]TermSuggestParser.java" checks="LineLength" />
   <suppress files="core[/\\]src[/\\]main[/\\]java[/\\]org[/\\]elasticsearch[/\\]snapshots[/\\]RestoreService.java" checks="LineLength" />
   <suppress files="core[/\\]src[/\\]main[/\\]java[/\\]org[/\\]elasticsearch[/\\]snapshots[/\\]SnapshotShardFailure.java" checks="LineLength" />
   <suppress files="core[/\\]src[/\\]main[/\\]java[/\\]org[/\\]elasticsearch[/\\]snapshots[/\\]SnapshotShardsService.java" checks="LineLength" />
@@ -952,7 +935,6 @@
   <suppress files="core[/\\]src[/\\]test[/\\]java[/\\]org[/\\]elasticsearch[/\\]search[/\\]basic[/\\]TransportTwoNodesSearchIT.java" checks="LineLength" />
   <suppress files="core[/\\]src[/\\]test[/\\]java[/\\]org[/\\]elasticsearch[/\\]search[/\\]child[/\\]ChildQuerySearchIT.java" checks="LineLength" />
   <suppress files="core[/\\]src[/\\]test[/\\]java[/\\]org[/\\]elasticsearch[/\\]search[/\\]child[/\\]ParentFieldLoadingIT.java" checks="LineLength" />
-  <suppress files="core[/\\]src[/\\]test[/\\]java[/\\]org[/\\]elasticsearch[/\\]search[/\\]fetch[/\\]FetchSubPhasePluginIT.java" checks="LineLength" />
   <suppress files="core[/\\]src[/\\]test[/\\]java[/\\]org[/\\]elasticsearch[/\\]search[/\\]geo[/\\]GeoBoundingBoxIT.java" checks="LineLength" />
   <suppress files="core[/\\]src[/\\]test[/\\]java[/\\]org[/\\]elasticsearch[/\\]search[/\\]geo[/\\]GeoFilterIT.java" checks="LineLength" />
   <suppress files="core[/\\]src[/\\]test[/\\]java[/\\]org[/\\]elasticsearch[/\\]search[/\\]geo[/\\]GeoShapeQueryTests.java" checks="LineLength" />
@@ -1007,7 +989,6 @@
   <suppress files="modules[/\\]percolator[/\\]src[/\\]main[/\\]java[/\\]org[/\\]elasticsearch[/\\]percolator[/\\]MultiPercolateRequestBuilder.java" checks="LineLength" />
   <suppress files="modules[/\\]percolator[/\\]src[/\\]main[/\\]java[/\\]org[/\\]elasticsearch[/\\]percolator[/\\]PercolateShardResponse.java" checks="LineLength" />
   <suppress files="modules[/\\]percolator[/\\]src[/\\]main[/\\]java[/\\]org[/\\]elasticsearch[/\\]percolator[/\\]TransportMultiPercolateAction.java" checks="LineLength" />
-  <suppress files="modules[/\\]percolator[/\\]src[/\\]main[/\\]java[/\\]org[/\\]elasticsearch[/\\]percolator[/\\]TransportPercolateAction.java" checks="LineLength" />
   <suppress files="modules[/\\]percolator[/\\]src[/\\]main[/\\]java[/\\]org[/\\]elasticsearch[/\\]percolator[/\\]TransportShardMultiPercolateAction.java" checks="LineLength" />
   <suppress files="modules[/\\]percolator[/\\]src[/\\]test[/\\]java[/\\]org[/\\]elasticsearch[/\\]percolator[/\\]MultiPercolatorIT.java" checks="LineLength" />
   <suppress files="modules[/\\]percolator[/\\]src[/\\]test[/\\]java[/\\]org[/\\]elasticsearch[/\\]percolator[/\\]PercolatorIT.java" checks="LineLength" />
@@ -1084,7 +1065,6 @@
   <suppress files="test[/\\]framework[/\\]src[/\\]main[/\\]java[/\\]org[/\\]elasticsearch[/\\]test[/\\]IndexSettingsModule.java" checks="LineLength" />
   <suppress files="test[/\\]framework[/\\]src[/\\]main[/\\]java[/\\]org[/\\]elasticsearch[/\\]test[/\\]InternalTestCluster.java" checks="LineLength" />
   <suppress files="test[/\\]framework[/\\]src[/\\]main[/\\]java[/\\]org[/\\]elasticsearch[/\\]test[/\\]MockIndexEventListener.java" checks="LineLength" />
-  <suppress files="test[/\\]framework[/\\]src[/\\]main[/\\]java[/\\]org[/\\]elasticsearch[/\\]test[/\\]TestSearchContext.java" checks="LineLength" />
   <suppress files="test[/\\]framework[/\\]src[/\\]main[/\\]java[/\\]org[/\\]elasticsearch[/\\]test[/\\]cluster[/\\]NoopClusterService.java" checks="LineLength" />
   <suppress files="test[/\\]framework[/\\]src[/\\]main[/\\]java[/\\]org[/\\]elasticsearch[/\\]test[/\\]cluster[/\\]TestClusterService.java" checks="LineLength" />
   <suppress files="test[/\\]framework[/\\]src[/\\]main[/\\]java[/\\]org[/\\]elasticsearch[/\\]test[/\\]discovery[/\\]ClusterDiscoveryConfiguration.java" checks="LineLength" />

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

@@ -25,10 +25,6 @@ import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
 import java.util.Objects;
-import java.util.stream.Collectors;
-import java.util.stream.Stream;
-
-import org.elasticsearch.plugins.Plugin;
 
 /**
  * A registry for {@link org.elasticsearch.common.io.stream.Writeable.Reader} readers of {@link NamedWriteable}.
@@ -47,7 +43,7 @@ public class NamedWriteableRegistry {
         /** A name for the writeable which is unique to the {@link #categoryClass}. */
         public final String name;
 
-        /** A reader captability of reading*/
+        /** A reader capability of reading*/
         public final Writeable.Reader<?> reader;
 
         /** Creates a new entry which can be stored by the registry. */

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

@@ -871,6 +871,16 @@ public abstract class StreamOutput extends OutputStream {
         }
     }
 
+    /**
+     * Writes a list of strings
+     */
+    public void writeStringList(List<String> list) throws IOException {
+        writeVInt(list.size());
+        for (String string: list) {
+            this.writeString(string);
+        }
+    }
+
     /**
      * Writes a list of {@link NamedWriteable} objects.
      */

core/src/main/java/org/elasticsearch/index/query/InnerHitBuilder.java

@@ -36,7 +36,6 @@ import org.elasticsearch.search.builder.SearchSourceBuilder;
 import org.elasticsearch.search.builder.SearchSourceBuilder.ScriptField;
 import org.elasticsearch.search.fetch.StoredFieldsContext;
 import org.elasticsearch.search.fetch.subphase.DocValueFieldsContext;
-import org.elasticsearch.search.fetch.subphase.DocValueFieldsFetchSubPhase;
 import org.elasticsearch.search.fetch.subphase.FetchSourceContext;
 import org.elasticsearch.search.fetch.subphase.InnerHitsContext;
 import org.elasticsearch.search.fetch.subphase.highlight.HighlightBuilder;
@@ -572,12 +571,7 @@ public final class InnerHitBuilder extends ToXContentToBytes implements Writeabl
             innerHitsContext.storedFieldsContext(storedFieldsContext);
         }
         if (docValueFields != null) {
-            DocValueFieldsContext docValueFieldsContext = innerHitsContext
-                    .getFetchSubPhaseContext(DocValueFieldsFetchSubPhase.CONTEXT_FACTORY);
-            for (String field : docValueFields) {
-                docValueFieldsContext.add(new DocValueFieldsContext.DocValueField(field));
-            }
-            docValueFieldsContext.setHitExecutionNeeded(true);
+            innerHitsContext.docValueFieldsContext(new DocValueFieldsContext(docValueFields));
         }
         if (scriptFields != null) {
             for (ScriptField field : scriptFields) {

core/src/main/java/org/elasticsearch/plugins/SearchPlugin.java

@@ -30,6 +30,8 @@ import org.elasticsearch.index.query.QueryBuilder;
 import org.elasticsearch.index.query.QueryParser;
 import org.elasticsearch.index.query.functionscore.ScoreFunctionBuilder;
 import org.elasticsearch.index.query.functionscore.ScoreFunctionParser;
+import org.elasticsearch.search.SearchExtBuilder;
+import org.elasticsearch.search.SearchExtParser;
 import org.elasticsearch.search.aggregations.Aggregation;
 import org.elasticsearch.search.aggregations.AggregationBuilder;
 import org.elasticsearch.search.aggregations.Aggregator;
@@ -82,6 +84,12 @@ public interface SearchPlugin {
     default List<FetchSubPhase> getFetchSubPhases(FetchPhaseConstructionContext context) {
         return emptyList();
     }
+    /**
+     * The new {@link SearchExtParser}s defined by this plugin.
+     */
+    default List<SearchExtSpec<?>> getSearchExts() {
+        return emptyList();
+    }
     /**
      * Get the {@link Highlighter}s defined by this plugin.
      */
@@ -160,7 +168,7 @@ public interface SearchPlugin {
     /**
      * Specification for an {@link Aggregation}.
      */
-    public static class AggregationSpec extends SearchExtensionSpec<AggregationBuilder, Aggregator.Parser> {
+    class AggregationSpec extends SearchExtensionSpec<AggregationBuilder, Aggregator.Parser> {
         private final Map<String, Writeable.Reader<? extends InternalAggregation>> resultReaders = new TreeMap<>();
 
         /**
@@ -217,7 +225,7 @@ public interface SearchPlugin {
     /**
      * Specification for a {@link PipelineAggregator}.
      */
-    public static class PipelineAggregationSpec extends SearchExtensionSpec<PipelineAggregationBuilder, PipelineAggregator.Parser> {
+    class PipelineAggregationSpec extends SearchExtensionSpec<PipelineAggregationBuilder, PipelineAggregator.Parser> {
         private final Map<String, Writeable.Reader<? extends InternalAggregation>> resultReaders = new TreeMap<>();
         private final Writeable.Reader<? extends PipelineAggregator> aggregatorReader;
 
@@ -290,6 +298,19 @@ public interface SearchPlugin {
         }
     }
 
+    /**
+     * Specification for a {@link SearchExtBuilder} which represents an additional section that can be
+     * parsed in a search request (within the ext element).
+     */
+    class SearchExtSpec<T extends SearchExtBuilder> extends SearchExtensionSpec<T, SearchExtParser<T>> {
+        public SearchExtSpec(ParseField name, Writeable.Reader<? extends T> reader, SearchExtParser<T> parser) {
+            super(name, reader, parser);
+        }
+
+        public SearchExtSpec(String name, Writeable.Reader<? extends T> reader, SearchExtParser<T> parser) {
+            super(name, reader, parser);
+        }
+    }
 
     /**
      * Specification of search time behavior extension like a custom {@link MovAvgModel} or {@link ScoreFunction}.

core/src/main/java/org/elasticsearch/rest/action/search/RestMultiSearchAction.java

@@ -19,10 +19,6 @@
 
 package org.elasticsearch.rest.action.search;
 
-import java.io.IOException;
-import java.util.Map;
-import java.util.function.BiConsumer;
-
 import org.elasticsearch.ElasticsearchParseException;
 import org.elasticsearch.action.search.MultiSearchRequest;
 import org.elasticsearch.action.search.SearchRequest;
@@ -40,12 +36,16 @@ import org.elasticsearch.index.query.QueryParseContext;
 import org.elasticsearch.rest.BaseRestHandler;
 import org.elasticsearch.rest.RestChannel;
 import org.elasticsearch.rest.RestController;
-import      org.elasticsearch.rest.RestRequest;
+import org.elasticsearch.rest.RestRequest;
 import org.elasticsearch.rest.action.RestActions;
 import org.elasticsearch.rest.action.RestToXContentListener;
 import org.elasticsearch.search.SearchRequestParsers;
 import org.elasticsearch.search.builder.SearchSourceBuilder;
 
+import java.io.IOException;
+import java.util.Map;
+import java.util.function.BiConsumer;
+
 import static org.elasticsearch.common.xcontent.support.XContentMapValues.lenientNodeBooleanValue;
 import static org.elasticsearch.common.xcontent.support.XContentMapValues.nodeStringArrayValue;
 import static org.elasticsearch.common.xcontent.support.XContentMapValues.nodeStringValue;
@@ -97,7 +97,7 @@ public class RestMultiSearchAction extends BaseRestHandler {
                 final QueryParseContext queryParseContext = new QueryParseContext(searchRequestParsers.queryParsers,
                     requestParser, parseFieldMatcher);
                 searchRequest.source(SearchSourceBuilder.fromXContent(queryParseContext,
-                    searchRequestParsers.aggParsers, searchRequestParsers.suggesters));
+                    searchRequestParsers.aggParsers, searchRequestParsers.suggesters, searchRequestParsers.searchExtParsers));
                 multiRequest.add(searchRequest);
             } catch (IOException e) {
                 throw new ElasticsearchParseException("Exception when parsing search request", e);

core/src/main/java/org/elasticsearch/rest/action/search/RestSearchAction.java

@@ -102,7 +102,8 @@ public class RestSearchAction extends BaseRestHandler {
         if (restContent != null) {
             try (XContentParser parser = XContentFactory.xContent(restContent).createParser(restContent)) {
                 QueryParseContext context = new QueryParseContext(searchRequestParsers.queryParsers, parser, parseFieldMatcher);
-                searchRequest.source().parseXContent(context, searchRequestParsers.aggParsers, searchRequestParsers.suggesters);
+                searchRequest.source().parseXContent(context, searchRequestParsers.aggParsers, searchRequestParsers.suggesters,
+                        searchRequestParsers.searchExtParsers);
             }
         }
 

core/src/main/java/org/elasticsearch/search/SearchExtBuilder.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.search;
+
+import org.elasticsearch.common.io.stream.NamedWriteable;
+import org.elasticsearch.common.io.stream.StreamInput;
+import org.elasticsearch.common.io.stream.StreamOutput;
+import org.elasticsearch.common.io.stream.Writeable;
+import org.elasticsearch.common.xcontent.ToXContent;
+import org.elasticsearch.plugins.SearchPlugin;
+import org.elasticsearch.plugins.SearchPlugin.SearchExtSpec;
+
+/**
+ * Intermediate serializable representation of a search ext section. To be subclassed by plugins that support
+ * a custom section as part of a search request, which will be provided within the ext element.
+ * Any state needs to be serialized as part of the {@link Writeable#writeTo(StreamOutput)} method and
+ * read from the incoming stream, usually done adding a constructor that takes {@link StreamInput} as
+ * an argument.
+ *
+ * Registration happens through {@link SearchPlugin#getSearchExts()}, which also needs a {@link SearchExtParser} that's able to parse
+ * the incoming request from the REST layer into the proper {@link SearchExtBuilder} subclass.
+ *
+ * {@link #getWriteableName()} must return the same name as the one used for the registration
+ * of the {@link SearchExtSpec}.
+ *
+ * @see SearchExtParser
+ * @see SearchExtSpec
+ */
+public abstract class SearchExtBuilder implements NamedWriteable, ToXContent {
+
+    public abstract int hashCode();
+
+    public abstract boolean equals(Object obj);
+}

core/src/main/java/org/elasticsearch/search/SearchExtParser.java

@@ -0,0 +1,43 @@
+/*
+ * 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;
+
+import org.elasticsearch.common.xcontent.XContentParser;
+
+import java.io.IOException;
+
+/**
+ * Defines a parser that is able to parse {@link org.elasticsearch.search.SearchExtBuilder}s
+ * from {@link org.elasticsearch.common.xcontent.XContent}.
+ *
+ * Registration happens through {@link org.elasticsearch.plugins.SearchPlugin#getSearchExts()}, which also needs a {@link SearchExtBuilder}
+ * implementation which is the object that this parser returns when reading an incoming request form the REST layer.
+ *
+ * @see SearchExtBuilder
+ * @see org.elasticsearch.plugins.SearchPlugin.SearchExtSpec
+ */
+@FunctionalInterface
+public interface SearchExtParser<T extends SearchExtBuilder> {
+
+    /**
+     * Parses the supported element placed within the ext section of a search request
+     */
+    T fromXContent(XContentParser parser) throws IOException;
+}

core/src/main/java/org/elasticsearch/search/SearchParseElement.java → core/src/main/java/org/elasticsearch/search/SearchExtRegistry.java

@@ -19,13 +19,14 @@
 
 package org.elasticsearch.search;
 
-import org.elasticsearch.common.xcontent.XContentParser;
-import org.elasticsearch.search.internal.SearchContext;
+import org.elasticsearch.common.xcontent.ParseFieldRegistry;
 
 /**
- *
+ * Extensions to ParseFieldRegistry to make Guice happy.
  */
-public interface SearchParseElement {
+public class SearchExtRegistry extends ParseFieldRegistry<SearchExtParser> {
 
-    void parse(XContentParser parser, SearchContext context) throws Exception;
+    public SearchExtRegistry() {
+        super("ext");
+    }
 }

core/src/main/java/org/elasticsearch/search/SearchModule.java

@@ -93,6 +93,7 @@ import org.elasticsearch.plugins.SearchPlugin.FetchPhaseConstructionContext;
 import org.elasticsearch.plugins.SearchPlugin.PipelineAggregationSpec;
 import org.elasticsearch.plugins.SearchPlugin.QuerySpec;
 import org.elasticsearch.plugins.SearchPlugin.ScoreFunctionSpec;
+import org.elasticsearch.plugins.SearchPlugin.SearchExtSpec;
 import org.elasticsearch.plugins.SearchPlugin.SearchExtensionSpec;
 import org.elasticsearch.search.action.SearchTransportService;
 import org.elasticsearch.search.aggregations.AggregationBuilder;
@@ -306,6 +307,7 @@ public class SearchModule extends AbstractModule {
             "moving_avg_model");
 
     private final List<FetchSubPhase> fetchSubPhases = new ArrayList<>();
+    private final SearchExtRegistry searchExtParserRegistry = new SearchExtRegistry();
 
     private final Settings settings;
     private final List<Entry> namedWriteables = new ArrayList<>();
@@ -326,8 +328,9 @@ public class SearchModule extends AbstractModule {
         registerAggregations(plugins);
         registerPipelineAggregations(plugins);
         registerFetchSubPhases(plugins);
+        registerSearchExts(plugins);
         registerShapes();
-        searchRequestParsers = new SearchRequestParsers(queryParserRegistry, aggregatorParsers, getSuggesters());
+        searchRequestParsers = new SearchRequestParsers(queryParserRegistry, aggregatorParsers, getSuggesters(), searchExtParserRegistry);
     }
 
     public List<Entry> getNamedWriteables() {
@@ -380,6 +383,7 @@ public class SearchModule extends AbstractModule {
         if (false == transportClient) {
             bind(IndicesQueriesRegistry.class).toInstance(queryParserRegistry);
             bind(SearchRequestParsers.class).toInstance(searchRequestParsers);
+            bind(SearchExtRegistry.class).toInstance(searchExtParserRegistry);
             configureSearch();
         }
     }
@@ -725,6 +729,15 @@ public class SearchModule extends AbstractModule {
         registerFromPlugin(plugins, p -> p.getFetchSubPhases(context), this::registerFetchSubPhase);
     }
 
+    private void registerSearchExts(List<SearchPlugin> plugins) {
+        registerFromPlugin(plugins, SearchPlugin::getSearchExts, this::registerSearchExt);
+    }
+
+    private void registerSearchExt(SearchExtSpec<?> spec) {
+        searchExtParserRegistry.register(spec.getParser(), spec.getName());
+        namedWriteables.add(new Entry(SearchExtBuilder.class, spec.getName().getPreferredName(), spec.getReader()));
+    }
+
     private void registerFetchSubPhase(FetchSubPhase subPhase) {
         Class<?> subPhaseClass = subPhase.getClass();
         if (fetchSubPhases.stream().anyMatch(p -> p.getClass().equals(subPhaseClass))) {

core/src/main/java/org/elasticsearch/search/SearchPhase.java

@@ -21,22 +21,18 @@ package org.elasticsearch.search;
 
 import org.elasticsearch.search.internal.SearchContext;
 
-import java.util.Collections;
-import java.util.Map;
-
 /**
- *
+ * Represents a phase of a search request e.g. query, fetch etc.
  */
 public interface SearchPhase {
 
-    default Map<String, ? extends SearchParseElement> parseElements() {
-        return Collections.emptyMap();
-    }
-
     /**
      * Performs pre processing of the search context before the execute.
      */
     void preProcess(SearchContext context);
 
+    /**
+     * Executes the search phase
+     */
     void execute(SearchContext context);
 }

core/src/main/java/org/elasticsearch/search/SearchRequestParsers.java

@@ -37,7 +37,8 @@ public class SearchRequestParsers {
     /**
      * Query parsers that may be used in search requests.
      * @see org.elasticsearch.index.query.QueryParseContext
-     * @see org.elasticsearch.search.builder.SearchSourceBuilder#fromXContent(QueryParseContext, AggregatorParsers, Suggesters)
+     * @see org.elasticsearch.search.builder.SearchSourceBuilder#fromXContent(QueryParseContext, AggregatorParsers,
+     *      Suggesters, SearchExtRegistry)
      */
     public final IndicesQueriesRegistry queryParsers;
 
@@ -45,20 +46,29 @@ public class SearchRequestParsers {
     // and pipeline agg parsers should be here
     /**
      * Agg and pipeline agg parsers that may be used in search requests.
-     * @see org.elasticsearch.search.builder.SearchSourceBuilder#fromXContent(QueryParseContext, AggregatorParsers, Suggesters)
+     * @see org.elasticsearch.search.builder.SearchSourceBuilder#fromXContent(QueryParseContext, AggregatorParsers,
+     *      Suggesters, SearchExtRegistry)
      */
     public final AggregatorParsers aggParsers;
 
     // TODO: Suggesters should be removed and the underlying map moved here
     /**
      * Suggesters that may be used in search requests.
-     * @see org.elasticsearch.search.builder.SearchSourceBuilder#fromXContent(QueryParseContext, AggregatorParsers, Suggesters)
+     * @see org.elasticsearch.search.builder.SearchSourceBuilder#fromXContent(QueryParseContext, AggregatorParsers,
+     *      Suggesters, SearchExtRegistry)
      */
     public final Suggesters suggesters;
 
-    public SearchRequestParsers(IndicesQueriesRegistry queryParsers, AggregatorParsers aggParsers, Suggesters suggesters) {
+    /**
+     * Pluggable section that can be parsed out of a search section, within the ext element
+     */
+    public final SearchExtRegistry searchExtParsers;
+
+    public SearchRequestParsers(IndicesQueriesRegistry queryParsers, AggregatorParsers aggParsers, Suggesters suggesters,
+                                SearchExtRegistry searchExtParsers) {
         this.queryParsers = queryParsers;
         this.aggParsers = aggParsers;
         this.suggesters = suggesters;
+        this.searchExtParsers = searchExtParsers;
     }
 }

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

@@ -39,9 +39,6 @@ import org.elasticsearch.common.unit.TimeValue;
 import org.elasticsearch.common.util.BigArrays;
 import org.elasticsearch.common.util.concurrent.ConcurrentCollections;
 import org.elasticsearch.common.util.concurrent.ConcurrentMapLong;
-import org.elasticsearch.common.xcontent.XContentFactory;
-import org.elasticsearch.common.xcontent.XContentLocation;
-import org.elasticsearch.common.xcontent.XContentParser;
 import org.elasticsearch.index.Index;
 import org.elasticsearch.index.IndexService;
 import org.elasticsearch.index.engine.Engine;
@@ -67,8 +64,6 @@ import org.elasticsearch.search.fetch.QueryFetchSearchResult;
 import org.elasticsearch.search.fetch.ScrollQueryFetchSearchResult;
 import org.elasticsearch.search.fetch.ShardFetchRequest;
 import org.elasticsearch.search.fetch.subphase.DocValueFieldsContext;
-import org.elasticsearch.search.fetch.subphase.DocValueFieldsContext.DocValueField;
-import org.elasticsearch.search.fetch.subphase.DocValueFieldsFetchSubPhase;
 import org.elasticsearch.search.fetch.subphase.ScriptFieldsContext.ScriptField;
 import org.elasticsearch.search.fetch.subphase.highlight.HighlightBuilder;
 import org.elasticsearch.search.internal.DefaultSearchContext;
@@ -102,7 +97,6 @@ import java.util.Optional;
 import java.util.concurrent.ExecutionException;
 import java.util.concurrent.atomic.AtomicLong;
 
-import static java.util.Collections.unmodifiableMap;
 import static org.elasticsearch.common.unit.TimeValue.timeValueMillis;
 import static org.elasticsearch.common.unit.TimeValue.timeValueMinutes;
 
@@ -145,8 +139,6 @@ public class SearchService extends AbstractLifecycleComponent implements IndexEv
 
     private final ConcurrentMapLong<SearchContext> activeContexts = ConcurrentCollections.newConcurrentMapLongWithAggressiveConcurrency();
 
-    private final Map<String, SearchParseElement> elementParsers;
-
     private final ParseFieldMatcher parseFieldMatcher;
 
     @Inject
@@ -165,12 +157,6 @@ public class SearchService extends AbstractLifecycleComponent implements IndexEv
         TimeValue keepAliveInterval = KEEPALIVE_INTERVAL_SETTING.get(settings);
         this.defaultKeepAlive = DEFAULT_KEEPALIVE_SETTING.get(settings).millis();
 
-        Map<String, SearchParseElement> elementParsers = new HashMap<>();
-        elementParsers.putAll(dfsPhase.parseElements());
-        elementParsers.putAll(queryPhase.parseElements());
-        elementParsers.putAll(fetchPhase.parseElements());
-        this.elementParsers = unmodifiableMap(elementParsers);
-
         this.keepAliveReaper = threadPool.scheduleWithFixedDelay(new Reaper(), keepAliveInterval, Names.SAME);
 
         defaultSearchTimeout = DEFAULT_SEARCH_TIMEOUT_SETTING.get(settings);
@@ -465,7 +451,8 @@ public class SearchService extends AbstractLifecycleComponent implements IndexEv
                 throw ExceptionsHelper.convertToRuntime(e);
             }
             operationListener.onFetchPhase(context, System.nanoTime() - time2);
-            return new ScrollQueryFetchSearchResult(new QueryFetchSearchResult(context.queryResult(), context.fetchResult()), context.shardTarget());
+            return new ScrollQueryFetchSearchResult(new QueryFetchSearchResult(context.queryResult(), context.fetchResult()),
+                    context.shardTarget());
         } catch (Exception e) {
             logger.trace("Fetch phase failed", e);
             processFailure(context, e);
@@ -736,11 +723,7 @@ public class SearchService extends AbstractLifecycleComponent implements IndexEv
             context.fetchSourceContext(source.fetchSource());
         }
         if (source.docValueFields() != null) {
-            DocValueFieldsContext docValuesFieldsContext = context.getFetchSubPhaseContext(DocValueFieldsFetchSubPhase.CONTEXT_FACTORY);
-            for (String field : source.docValueFields()) {
-                docValuesFieldsContext.add(new DocValueField(field));
-            }
-            docValuesFieldsContext.setHitExecutionNeeded(true);
+            context.docValueFieldsContext(new DocValueFieldsContext(source.docValueFields()));
         }
         if (source.highlighter() != null) {
             HighlightBuilder highlightBuilder = source.highlighter();
@@ -758,47 +741,8 @@ public class SearchService extends AbstractLifecycleComponent implements IndexEv
             }
         }
         if (source.ext() != null) {
-            XContentParser extParser = null;
-            try {
-                extParser = XContentFactory.xContent(source.ext()).createParser(source.ext());
-                if (extParser.nextToken() != XContentParser.Token.START_OBJECT) {
-                    throw new SearchParseException(context, "expected start object, found [" + extParser.currentToken() + "] instead",
-                            extParser.getTokenLocation());
-                }
-                XContentParser.Token token;
-                String currentFieldName = null;
-                while ((token = extParser.nextToken()) != XContentParser.Token.END_OBJECT) {
-                    if (token == XContentParser.Token.FIELD_NAME) {
-                        currentFieldName = extParser.currentName();
-                    } else {
-                        SearchParseElement parseElement = this.elementParsers.get(currentFieldName);
-                        if (parseElement == null) {
-                            if (currentFieldName != null && currentFieldName.equals("suggest")) {
-                                throw new SearchParseException(context,
-                                    "suggest is not supported in [ext], please use SearchSourceBuilder#suggest(SuggestBuilder) instead",
-                                    extParser.getTokenLocation());
-                            }
-                            throw new SearchParseException(context, "Unknown element [" + currentFieldName + "] in [ext]",
-                                    extParser.getTokenLocation());
-                        } else {
-                            parseElement.parse(extParser, context);
-                        }
-                    }
-                }
-            } catch (Exception e) {
-                String sSource = "_na_";
-                try {
-                    sSource = source.toString();
-                } catch (Exception inner) {
-                    e.addSuppressed(inner);
-                    // ignore
-                }
-                XContentLocation location = extParser != null ? extParser.getTokenLocation() : null;
-                throw new SearchParseException(context, "failed to parse ext source [" + sSource + "]", location, e);
-            } finally {
-                if (extParser != null) {
-                    extParser.close();
-                }
+            for (SearchExtBuilder searchExtBuilder : source.ext()) {
+                context.addSearchExt(searchExtBuilder);
             }
         }
         if (source.version() != null) {
@@ -914,7 +858,8 @@ public class SearchService extends AbstractLifecycleComponent implements IndexEv
                     continue;
                 }
                 if ((time - lastAccessTime > context.keepAlive())) {
-                    logger.debug("freeing search context [{}], time [{}], lastAccessTime [{}], keepAlive [{}]", context.id(), time, lastAccessTime, context.keepAlive());
+                    logger.debug("freeing search context [{}], time [{}], lastAccessTime [{}], keepAlive [{}]", context.id(), time,
+                            lastAccessTime, context.keepAlive());
                     freeContext(context.id());
                 }
             }

core/src/main/java/org/elasticsearch/search/aggregations/AggregationPhase.java

@@ -40,7 +40,7 @@ import java.util.Collections;
 import java.util.List;
 
 /**
- *
+ * Aggregation phase of a search request, used to collect aggregations
  */
 public class AggregationPhase implements SearchPhase {
 

core/src/main/java/org/elasticsearch/search/aggregations/metrics/tophits/TopHitsAggregatorFactory.java

@@ -19,7 +19,6 @@
 
 package org.elasticsearch.search.aggregations.metrics.tophits;
 
-import org.elasticsearch.search.fetch.StoredFieldsContext;
 import org.elasticsearch.script.ScriptContext;
 import org.elasticsearch.script.SearchScript;
 import org.elasticsearch.search.aggregations.Aggregator;
@@ -29,9 +28,8 @@ import org.elasticsearch.search.aggregations.InternalAggregation.Type;
 import org.elasticsearch.search.aggregations.pipeline.PipelineAggregator;
 import org.elasticsearch.search.aggregations.support.AggregationContext;
 import org.elasticsearch.search.builder.SearchSourceBuilder.ScriptField;
+import org.elasticsearch.search.fetch.StoredFieldsContext;
 import org.elasticsearch.search.fetch.subphase.DocValueFieldsContext;
-import org.elasticsearch.search.fetch.subphase.DocValueFieldsContext.DocValueField;
-import org.elasticsearch.search.fetch.subphase.DocValueFieldsFetchSubPhase;
 import org.elasticsearch.search.fetch.subphase.FetchSourceContext;
 import org.elasticsearch.search.fetch.subphase.highlight.HighlightBuilder;
 import org.elasticsearch.search.internal.SubSearchContext;
@@ -98,12 +96,7 @@ public class TopHitsAggregatorFactory extends AggregatorFactory<TopHitsAggregato
             subSearchContext.storedFieldsContext(storedFieldsContext);
         }
         if (docValueFields != null) {
-            DocValueFieldsContext docValueFieldsContext = subSearchContext
-                    .getFetchSubPhaseContext(DocValueFieldsFetchSubPhase.CONTEXT_FACTORY);
-            for (String field : docValueFields) {
-                docValueFieldsContext.add(new DocValueField(field));
-            }
-            docValueFieldsContext.setHitExecutionNeeded(true);
+            subSearchContext.docValueFieldsContext(new DocValueFieldsContext(docValueFields));
         }
         if (scriptFields != null) {
             for (ScriptField field : scriptFields) {

core/src/main/java/org/elasticsearch/search/builder/SearchSourceBuilder.java

@@ -25,7 +25,6 @@ import org.elasticsearch.common.Nullable;
 import org.elasticsearch.common.ParseField;
 import org.elasticsearch.common.ParsingException;
 import org.elasticsearch.common.Strings;
-import org.elasticsearch.common.bytes.BytesReference;
 import org.elasticsearch.common.collect.Tuple;
 import org.elasticsearch.common.io.stream.StreamInput;
 import org.elasticsearch.common.io.stream.StreamOutput;
@@ -33,13 +32,14 @@ import org.elasticsearch.common.io.stream.Writeable;
 import org.elasticsearch.common.unit.TimeValue;
 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.index.query.QueryBuilder;
 import org.elasticsearch.index.query.QueryParseContext;
 import org.elasticsearch.index.query.QueryShardContext;
 import org.elasticsearch.script.Script;
+import org.elasticsearch.search.SearchExtBuilder;
+import org.elasticsearch.search.SearchExtParser;
+import org.elasticsearch.search.SearchExtRegistry;
 import org.elasticsearch.search.aggregations.AggregationBuilder;
 import org.elasticsearch.search.aggregations.AggregatorFactories;
 import org.elasticsearch.search.aggregations.AggregatorParsers;
@@ -108,9 +108,9 @@ public final class SearchSourceBuilder extends ToXContentToBytes implements Writ
     public static final ParseField SLICE = new ParseField("slice");
 
     public static SearchSourceBuilder fromXContent(QueryParseContext context, AggregatorParsers aggParsers,
-            Suggesters suggesters) throws IOException {
+            Suggesters suggesters, SearchExtRegistry searchExtRegistry) throws IOException {
         SearchSourceBuilder builder = new SearchSourceBuilder();
-        builder.parseXContent(context, aggParsers, suggesters);
+        builder.parseXContent(context, aggParsers, suggesters, searchExtRegistry);
         return builder;
     }
 
@@ -164,13 +164,13 @@ public final class SearchSourceBuilder extends ToXContentToBytes implements Writ
 
     private SuggestBuilder suggestBuilder;
 
-    private List<RescoreBuilder<?>> rescoreBuilders;
+    private List<RescoreBuilder> rescoreBuilders;
 
     private ObjectFloatHashMap<String> indexBoost = null;
 
     private List<String> stats;
 
-    private BytesReference ext = null;
+    private List<SearchExtBuilder> extBuilders = Collections.emptyList();
 
     private boolean profile = false;
 
@@ -203,18 +203,10 @@ public final class SearchSourceBuilder extends ToXContentToBytes implements Writ
         postQueryBuilder = in.readOptionalNamedWriteable(QueryBuilder.class);
         queryBuilder = in.readOptionalNamedWriteable(QueryBuilder.class);
         if (in.readBoolean()) {
-            int size = in.readVInt();
-            rescoreBuilders = new ArrayList<>();
-            for (int i = 0; i < size; i++) {
-                rescoreBuilders.add(in.readNamedWriteable(RescoreBuilder.class));
-            }
+            rescoreBuilders = in.readNamedWriteableList(RescoreBuilder.class);
         }
         if (in.readBoolean()) {
-            int size = in.readVInt();
-            scriptFields = new ArrayList<>(size);
-            for (int i = 0; i < size; i++) {
-                scriptFields.add(new ScriptField(in));
-            }
+            scriptFields = in.readList(ScriptField::new);
         }
         size = in.readVInt();
         if (in.readBoolean()) {
@@ -225,18 +217,14 @@ public final class SearchSourceBuilder extends ToXContentToBytes implements Writ
             }
         }
         if (in.readBoolean()) {
-            int size = in.readVInt();
-            stats = new ArrayList<>();
-            for (int i = 0; i < size; i++) {
-                stats.add(in.readString());
-            }
+            stats = in.readList(StreamInput::readString);
         }
         suggestBuilder = in.readOptionalWriteable(SuggestBuilder::new);
         terminateAfter = in.readVInt();
         timeout = in.readOptionalWriteable(TimeValue::new);
         trackScores = in.readBoolean();
         version = in.readOptionalBoolean();
-        ext = in.readOptionalBytesReference();
+        extBuilders = in.readNamedWriteableList(SearchExtBuilder.class);
         profile = in.readBoolean();
         searchAfterBuilder = in.readOptionalWriteable(SearchAfterBuilder::new);
         sliceBuilder = in.readOptionalWriteable(SliceBuilder::new);
@@ -262,18 +250,12 @@ public final class SearchSourceBuilder extends ToXContentToBytes implements Writ
         boolean hasRescoreBuilders = rescoreBuilders != null;
         out.writeBoolean(hasRescoreBuilders);
         if (hasRescoreBuilders) {
-            out.writeVInt(rescoreBuilders.size());
-            for (RescoreBuilder<?> rescoreBuilder : rescoreBuilders) {
-                out.writeNamedWriteable(rescoreBuilder);
-            }
+            out.writeNamedWriteableList(rescoreBuilders);
         }
         boolean hasScriptFields = scriptFields != null;
         out.writeBoolean(hasScriptFields);
         if (hasScriptFields) {
-            out.writeVInt(scriptFields.size());
-            for (ScriptField scriptField : scriptFields) {
-                scriptField.writeTo(out);
-            }
+            out.writeList(scriptFields);
         }
         out.writeVInt(size);
         boolean hasSorts = sorts != null;
@@ -287,17 +269,14 @@ public final class SearchSourceBuilder extends ToXContentToBytes implements Writ
         boolean hasStats = stats != null;
         out.writeBoolean(hasStats);
         if (hasStats) {
-            out.writeVInt(stats.size());
-            for (String stat : stats) {
-                out.writeString(stat);
-            }
+            out.writeStringList(stats);
         }
         out.writeOptionalWriteable(suggestBuilder);
         out.writeVInt(terminateAfter);
         out.writeOptionalWriteable(timeout);
         out.writeBoolean(trackScores);
         out.writeOptionalBoolean(version);
-        out.writeOptionalBytesReference(ext);
+        out.writeNamedWriteableList(extBuilders);
         out.writeBoolean(profile);
         out.writeOptionalWriteable(searchAfterBuilder);
         out.writeOptionalWriteable(sliceBuilder);
@@ -649,7 +628,7 @@ public final class SearchSourceBuilder extends ToXContentToBytes implements Writ
     /**
      * Gets the bytes representing the rescore builders for this request.
      */
-    public List<RescoreBuilder<?>> rescores() {
+    public List<RescoreBuilder> rescores() {
         return rescoreBuilders;
     }
 
@@ -875,13 +854,13 @@ public final class SearchSourceBuilder extends ToXContentToBytes implements Writ
         return stats;
     }
 
-    public SearchSourceBuilder ext(XContentBuilder ext) {
-        this.ext = ext.bytes();
+    public SearchSourceBuilder ext(List<SearchExtBuilder> searchExtBuilders) {
+        this.extBuilders = Objects.requireNonNull(searchExtBuilders, "searchExtBuilders must not be null");
         return this;
     }
 
-    public BytesReference ext() {
-        return ext;
+    public List<SearchExtBuilder> ext() {
+        return extBuilders;
     }
 
     /**
@@ -919,7 +898,7 @@ public final class SearchSourceBuilder extends ToXContentToBytes implements Writ
             SearchSourceBuilder rewrittenBuilder = new SearchSourceBuilder();
             rewrittenBuilder.aggregations = aggregations;
             rewrittenBuilder.explain = explain;
-            rewrittenBuilder.ext = ext;
+            rewrittenBuilder.extBuilders = extBuilders;
             rewrittenBuilder.fetchSourceContext = fetchSourceContext;
             rewrittenBuilder.docValueFields = docValueFields;
             rewrittenBuilder.storedFieldsContext = storedFieldsContext;
@@ -948,17 +927,18 @@ public final class SearchSourceBuilder extends ToXContentToBytes implements Writ
     /**
      * Parse some xContent into this SearchSourceBuilder, overwriting any values specified in the xContent. Use this if you need to set up
      * different defaults than a regular SearchSourceBuilder would have and use
-     * {@link #fromXContent(QueryParseContext, AggregatorParsers, Suggesters)} if you have normal defaults.
+     * {@link #fromXContent(QueryParseContext, AggregatorParsers, Suggesters, SearchExtRegistry)} if you have normal defaults.
      */
-    public void parseXContent(QueryParseContext context, AggregatorParsers aggParsers, Suggesters suggesters)
+    public void parseXContent(QueryParseContext context, AggregatorParsers aggParsers,
+                              Suggesters suggesters, SearchExtRegistry searchExtRegistry)
         throws IOException {
 
         XContentParser parser = context.parser();
         XContentParser.Token token = parser.currentToken();
         String currentFieldName = null;
         if (token != XContentParser.Token.START_OBJECT && (token = parser.nextToken()) != XContentParser.Token.START_OBJECT) {
-            throw new ParsingException(parser.getTokenLocation(), "Expected [" + XContentParser.Token.START_OBJECT + "] but found [" + token + "]",
-                    parser.getTokenLocation());
+            throw new ParsingException(parser.getTokenLocation(), "Expected [" + XContentParser.Token.START_OBJECT +
+                    "] but found [" + token + "]", parser.getTokenLocation());
         }
         while ((token = parser.nextToken()) != XContentParser.Token.END_OBJECT) {
             if (token == XContentParser.Token.FIELD_NAME) {
@@ -1017,8 +997,8 @@ public final class SearchSourceBuilder extends ToXContentToBytes implements Writ
                         } else if (token.isValue()) {
                             indexBoost.put(currentFieldName, parser.floatValue());
                         } else {
-                            throw new ParsingException(parser.getTokenLocation(), "Unknown key for a " + token + " in [" + currentFieldName + "].",
-                                    parser.getTokenLocation());
+                            throw new ParsingException(parser.getTokenLocation(), "Unknown key for a " + token +
+                                    " in [" + currentFieldName + "].", parser.getTokenLocation());
                         }
                     }
                 } else if (context.getParseFieldMatcher().match(currentFieldName, AGGREGATIONS_FIELD)
@@ -1034,8 +1014,23 @@ public final class SearchSourceBuilder extends ToXContentToBytes implements Writ
                     rescoreBuilders = new ArrayList<>();
                     rescoreBuilders.add(RescoreBuilder.parseFromXContent(context));
                 } else if (context.getParseFieldMatcher().match(currentFieldName, EXT_FIELD)) {
-                    XContentBuilder xContentBuilder = XContentFactory.jsonBuilder().copyCurrentStructure(parser);
-                    ext = xContentBuilder.bytes();
+                    extBuilders = new ArrayList<>();
+                    String extSectionName = null;
+                    while ((token = parser.nextToken()) != XContentParser.Token.END_OBJECT) {
+                        if (token == XContentParser.Token.FIELD_NAME) {
+                            extSectionName = parser.currentName();
+                        } else {
+                            SearchExtParser searchExtParser = searchExtRegistry.lookup(extSectionName,
+                                    context.getParseFieldMatcher(), parser.getTokenLocation());
+                            SearchExtBuilder searchExtBuilder = searchExtParser.fromXContent(parser);
+                            if (searchExtBuilder.getWriteableName().equals(extSectionName) == false) {
+                                throw new IllegalStateException("The parsed [" + searchExtBuilder.getClass().getName() + "] object has a "
+                                        + "different writeable name compared to the name of the section that it was parsed from: found ["
+                                        + searchExtBuilder.getWriteableName() + "] expected [" + extSectionName + "]");
+                            }
+                            extBuilders.add(searchExtBuilder);
+                        }
+                    }
                 } else if (context.getParseFieldMatcher().match(currentFieldName, SLICE)) {
                     sliceBuilder = SliceBuilder.fromXContent(context);
                 } else {
@@ -1051,8 +1046,8 @@ public final class SearchSourceBuilder extends ToXContentToBytes implements Writ
                         if (token == XContentParser.Token.VALUE_STRING) {
                             docValueFields.add(parser.text());
                         } else {
-                            throw new ParsingException(parser.getTokenLocation(), "Expected [" + XContentParser.Token.VALUE_STRING + "] in ["
-                                    + currentFieldName + "] but found [" + token + "]", parser.getTokenLocation());
+                            throw new ParsingException(parser.getTokenLocation(), "Expected [" + XContentParser.Token.VALUE_STRING +
+                                    "] in [" + currentFieldName + "] but found [" + token + "]", parser.getTokenLocation());
                         }
                     }
                 } else if (context.getParseFieldMatcher().match(currentFieldName, SORT_FIELD)) {
@@ -1068,8 +1063,8 @@ public final class SearchSourceBuilder extends ToXContentToBytes implements Writ
                         if (token == XContentParser.Token.VALUE_STRING) {
                             stats.add(parser.text());
                         } else {
-                            throw new ParsingException(parser.getTokenLocation(), "Expected [" + XContentParser.Token.VALUE_STRING + "] in ["
-                                    + currentFieldName + "] but found [" + token + "]", parser.getTokenLocation());
+                            throw new ParsingException(parser.getTokenLocation(), "Expected [" + XContentParser.Token.VALUE_STRING +
+                                    "] in [" + currentFieldName + "] but found [" + token + "]", parser.getTokenLocation());
                         }
                     }
                 } else if (context.getParseFieldMatcher().match(currentFieldName, _SOURCE_FIELD)) {
@@ -1221,12 +1216,12 @@ public final class SearchSourceBuilder extends ToXContentToBytes implements Writ
             builder.field(STATS_FIELD.getPreferredName(), stats);
         }
 
-        if (ext != null) {
-            builder.field(EXT_FIELD.getPreferredName());
-            try (XContentParser parser = XContentFactory.xContent(XContentType.JSON).createParser(ext)) {
-                parser.nextToken();
-                builder.copyCurrentStructure(parser);
+        if (extBuilders != null) {
+            builder.startObject(EXT_FIELD.getPreferredName());
+            for (SearchExtBuilder extBuilder : extBuilders) {
+                extBuilder.toXContent(builder, params);
             }
+            builder.endObject();
         }
     }
 
@@ -1344,9 +1339,9 @@ public final class SearchSourceBuilder extends ToXContentToBytes implements Writ
 
     @Override
     public int hashCode() {
-        return Objects.hash(aggregations, explain, fetchSourceContext, docValueFields, storedFieldsContext, from,
-                highlightBuilder, indexBoost, minScore, postQueryBuilder, queryBuilder, rescoreBuilders, scriptFields,
-                size, sorts, searchAfterBuilder, sliceBuilder, stats, suggestBuilder, terminateAfter, timeout, trackScores, version, profile);
+        return Objects.hash(aggregations, explain, fetchSourceContext, docValueFields, storedFieldsContext, from, highlightBuilder,
+                indexBoost, minScore, postQueryBuilder, queryBuilder, rescoreBuilders, scriptFields, size, sorts, searchAfterBuilder,
+                sliceBuilder, stats, suggestBuilder, terminateAfter, timeout, trackScores, version, profile, extBuilders);
     }
 
     @Override
@@ -1381,7 +1376,7 @@ public final class SearchSourceBuilder extends ToXContentToBytes implements Writ
                 && Objects.equals(timeout, other.timeout)
                 && Objects.equals(trackScores, other.trackScores)
                 && Objects.equals(version, other.version)
-                && Objects.equals(profile, other.profile);
+                && Objects.equals(profile, other.profile)
+                && Objects.equals(extBuilders, other.extBuilders);
     }
-
 }

core/src/main/java/org/elasticsearch/search/dfs/DfsPhase.java

@@ -37,7 +37,8 @@ import java.util.Collection;
 import java.util.Iterator;
 
 /**
- *
+ * Dfs phase of a search request, used to make scoring 100% accurate by collecting additional info from each shard before the query phase.
+ * The additional information is used to better compare the scores coming from all the shards, which depend on local factors (e.g. idf)
  */
 public class DfsPhase implements SearchPhase {
 

core/src/main/java/org/elasticsearch/search/fetch/FetchPhase.java

@@ -43,7 +43,6 @@ import org.elasticsearch.index.mapper.ObjectMapper;
 import org.elasticsearch.index.mapper.SourceFieldMapper;
 import org.elasticsearch.search.SearchHit;
 import org.elasticsearch.search.SearchHitField;
-import org.elasticsearch.search.SearchParseElement;
 import org.elasticsearch.search.SearchPhase;
 import org.elasticsearch.search.fetch.subphase.FetchSourceContext;
 import org.elasticsearch.search.fetch.subphase.InnerHitsFetchSubPhase;
@@ -62,11 +61,11 @@ import java.util.List;
 import java.util.Map;
 import java.util.Set;
 
-import static java.util.Collections.unmodifiableMap;
 import static org.elasticsearch.common.xcontent.XContentFactory.contentBuilder;
 
 /**
- *
+ * Fetch phase of a search request, used to fetch the actual top matching documents to be returned to the client, identified
+ * after reducing all of the matches returned by the query phase
  */
 public class FetchPhase implements SearchPhase {
 
@@ -77,15 +76,6 @@ public class FetchPhase implements SearchPhase {
         this.fetchSubPhases[fetchSubPhases.size()] = new InnerHitsFetchSubPhase(this);
     }
 
-    @Override
-    public Map<String, ? extends SearchParseElement> parseElements() {
-        Map<String, SearchParseElement> parseElements = new HashMap<>();
-        for (FetchSubPhase fetchSubPhase : fetchSubPhases) {
-            parseElements.putAll(fetchSubPhase.parseElements());
-        }
-        return unmodifiableMap(parseElements);
-    }
-
     @Override
     public void preProcess(SearchContext context) {
     }

core/src/main/java/org/elasticsearch/search/fetch/FetchSubPhase.java

@@ -22,11 +22,9 @@ import org.apache.lucene.index.IndexReader;
 import org.apache.lucene.index.LeafReader;
 import org.apache.lucene.index.LeafReaderContext;
 import org.apache.lucene.search.IndexSearcher;
-import org.elasticsearch.search.SearchParseElement;
 import org.elasticsearch.search.internal.InternalSearchHit;
 import org.elasticsearch.search.internal.SearchContext;
 
-import java.util.Collections;
 import java.util.HashMap;
 import java.util.Map;
 
@@ -69,10 +67,6 @@ public interface FetchSubPhase {
             return searcher.getIndexReader();
         }
 
-        public IndexSearcher topLevelSearcher() {
-            return searcher;
-        }
-
         public Map<String, Object> cache() {
             if (cache == null) {
                 cache = new HashMap<>();
@@ -82,10 +76,6 @@ public interface FetchSubPhase {
 
     }
 
-    default Map<String, ? extends SearchParseElement> parseElements() {
-        return Collections.emptyMap();
-    }
-
     /**
      * Executes the hit level phase, with a reader and doc id (note, its a low level reader, and the matching doc).
      */
@@ -93,23 +83,4 @@ public interface FetchSubPhase {
 
 
     default void hitsExecute(SearchContext context, InternalSearchHit[] hits) {}
-
-    /**
-     * This interface is in the fetch phase plugin mechanism.
-     * Whenever a new search is executed we create a new {@link SearchContext} that holds individual contexts for each {@link org.elasticsearch.search.fetch.FetchSubPhase}.
-     * Fetch phases that use the plugin mechanism must provide a ContextFactory to the SearchContext that creates the fetch phase context and also associates them with a name.
-     * See {@link SearchContext#getFetchSubPhaseContext(FetchSubPhase.ContextFactory)}
-     */
-    interface ContextFactory<SubPhaseContext extends FetchSubPhaseContext> {
-
-        /**
-         * The name of the context.
-         */
-        String getName();
-
-        /**
-         * Creates a new instance of a FetchSubPhaseContext that holds all information a FetchSubPhase needs to execute on hits.
-         */
-        SubPhaseContext newContextInstance();
-    }
 }

core/src/main/java/org/elasticsearch/search/fetch/FetchSubPhaseContext.java

@@ -1,49 +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.fetch;
-
-import org.elasticsearch.search.fetch.subphase.DocValueFieldsContext;
-
-/**
- * All configuration and context needed by the FetchSubPhase to execute on hits.
- * The only required information in this base class is whether or not the sub phase needs to be run at all.
- * It can be extended by FetchSubPhases to hold information the phase needs to execute on hits.
- * See {@link org.elasticsearch.search.fetch.FetchSubPhase.ContextFactory} and also {@link DocValueFieldsContext} for an example.
- */
-public class FetchSubPhaseContext {
-
-    // This is to store if the FetchSubPhase should be executed at all.
-    private boolean hitExecutionNeeded = false;
-
-    /**
-     * Set if this phase should be executed at all.
-     */
-    public void setHitExecutionNeeded(boolean hitExecutionNeeded) {
-        this.hitExecutionNeeded = hitExecutionNeeded;
-    }
-
-    /**
-     * Returns if this phase be executed at all.
-     */
-    public boolean hitExecutionNeeded() {
-        return hitExecutionNeeded;
-    }
-
-}

core/src/main/java/org/elasticsearch/search/fetch/subphase/DocValueFieldsContext.java

@@ -18,38 +18,23 @@
  */
 package org.elasticsearch.search.fetch.subphase;
 
-import org.elasticsearch.search.fetch.FetchSubPhaseContext;
-
-import java.util.ArrayList;
 import java.util.List;
 
 /**
  * All the required context to pull a field from the doc values.
  */
-public class DocValueFieldsContext extends FetchSubPhaseContext {
-
-    public static class DocValueField {
-        private final String name;
+public class DocValueFieldsContext {
 
-        public DocValueField(String name) {
-            this.name = name;
-        }
-
-        public String name() {
-            return name;
-        }
-    }
-
-    private List<DocValueField> fields = new ArrayList<>();
-
-    public DocValueFieldsContext() {
-    }
+    private final List<String> fields;
 
-    public void add(DocValueField field) {
-        this.fields.add(field);
+    public DocValueFieldsContext(List<String> fields) {
+        this.fields = fields;
     }
 
-    public List<DocValueField> fields() {
+    /**
+     * Returns the required docvalue fields
+     */
+    public List<String> fields() {
         return this.fields;
     }
 }

core/src/main/java/org/elasticsearch/search/fetch/subphase/DocValueFieldsFetchSubPhase.java

@@ -36,35 +36,21 @@ import java.util.HashMap;
  */
 public final class DocValueFieldsFetchSubPhase implements FetchSubPhase {
 
-    public static final String NAME = "docvalue_fields";
-    public static final ContextFactory<DocValueFieldsContext> CONTEXT_FACTORY = new ContextFactory<DocValueFieldsContext>() {
-
-        @Override
-        public String getName() {
-            return NAME;
-        }
-
-        @Override
-        public DocValueFieldsContext newContextInstance() {
-            return new DocValueFieldsContext();
-        }
-    };
-
     @Override
     public void hitExecute(SearchContext context, HitContext hitContext) {
-        if (context.getFetchSubPhaseContext(CONTEXT_FACTORY).hitExecutionNeeded() == false) {
+        if (context.docValueFieldsContext() == null) {
             return;
         }
-        for (DocValueFieldsContext.DocValueField field : context.getFetchSubPhaseContext(CONTEXT_FACTORY).fields()) {
+        for (String field : context.docValueFieldsContext().fields()) {
             if (hitContext.hit().fieldsOrNull() == null) {
                 hitContext.hit().fields(new HashMap<>(2));
             }
-            SearchHitField hitField = hitContext.hit().fields().get(field.name());
+            SearchHitField hitField = hitContext.hit().fields().get(field);
             if (hitField == null) {
-                hitField = new InternalSearchHitField(field.name(), new ArrayList<>(2));
-                hitContext.hit().fields().put(field.name(), hitField);
+                hitField = new InternalSearchHitField(field, new ArrayList<>(2));
+                hitContext.hit().fields().put(field, hitField);
             }
-            MappedFieldType fieldType = context.mapperService().fullName(field.name());
+            MappedFieldType fieldType = context.mapperService().fullName(field);
             if (fieldType != null) {
                 AtomicFieldData data = context.fieldData().getForField(fieldType).load(hitContext.readerContext());
                 ScriptDocValues values = data.getScriptValues();

core/src/main/java/org/elasticsearch/search/internal/DefaultSearchContext.java

@@ -50,17 +50,17 @@ import org.elasticsearch.index.mapper.TypeFieldMapper;
 import org.elasticsearch.index.query.AbstractQueryBuilder;
 import org.elasticsearch.index.query.ParsedQuery;
 import org.elasticsearch.index.query.QueryShardContext;
-import org.elasticsearch.search.fetch.StoredFieldsContext;
 import org.elasticsearch.index.shard.IndexShard;
 import org.elasticsearch.index.similarity.SimilarityService;
 import org.elasticsearch.script.ScriptService;
+import org.elasticsearch.search.SearchExtBuilder;
 import org.elasticsearch.search.SearchShardTarget;
 import org.elasticsearch.search.aggregations.SearchContextAggregations;
 import org.elasticsearch.search.dfs.DfsSearchResult;
 import org.elasticsearch.search.fetch.FetchPhase;
 import org.elasticsearch.search.fetch.FetchSearchResult;
-import org.elasticsearch.search.fetch.FetchSubPhase;
-import org.elasticsearch.search.fetch.FetchSubPhaseContext;
+import org.elasticsearch.search.fetch.StoredFieldsContext;
+import org.elasticsearch.search.fetch.subphase.DocValueFieldsContext;
 import org.elasticsearch.search.fetch.subphase.FetchSourceContext;
 import org.elasticsearch.search.fetch.subphase.ScriptFieldsContext;
 import org.elasticsearch.search.fetch.subphase.highlight.SearchContextHighlight;
@@ -80,9 +80,6 @@ import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
 
-/**
- *
- */
 public class DefaultSearchContext extends SearchContext {
 
     private final long id;
@@ -110,6 +107,7 @@ public class DefaultSearchContext extends SearchContext {
     private StoredFieldsContext storedFields;
     private ScriptFieldsContext scriptFields;
     private FetchSourceContext fetchSourceContext;
+    private DocValueFieldsContext docValueFieldsContext;
     private int from = -1;
     private int size = -1;
     private SortAndFormats sort;
@@ -148,7 +146,7 @@ public class DefaultSearchContext extends SearchContext {
     private volatile long lastAccessTime = -1;
     private Profilers profilers;
 
-    private final Map<String, FetchSubPhaseContext> subPhaseContexts = new HashMap<>();
+    private final Map<String, SearchExtBuilder> searchExtBuilders = new HashMap<>();
     private final Map<Class<?>, Collector> queryCollectors = new HashMap<>();
     private final QueryShardContext queryShardContext;
     private FetchPhase fetchPhase;
@@ -388,14 +386,16 @@ public class DefaultSearchContext extends SearchContext {
     }
 
     @Override
-    public <SubPhaseContext extends FetchSubPhaseContext> SubPhaseContext getFetchSubPhaseContext(FetchSubPhase.ContextFactory<SubPhaseContext> contextFactory) {
-        String subPhaseName = contextFactory.getName();
-        if (subPhaseContexts.get(subPhaseName) == null) {
-            subPhaseContexts.put(subPhaseName, contextFactory.newContextInstance());
-        }
-        return (SubPhaseContext) subPhaseContexts.get(subPhaseName);
+    public void addSearchExt(SearchExtBuilder searchExtBuilder) {
+        //it's ok to use the writeable name here given that we enforce it to be the same as the name of the element that gets
+        //parsed by the corresponding parser. There is one single name and one single way to retrieve the parsed object from the context.
+        searchExtBuilders.put(searchExtBuilder.getWriteableName(), searchExtBuilder);
     }
 
+    @Override
+    public SearchExtBuilder getSearchExt(String name) {
+        return searchExtBuilders.get(name);
+    }
 
     @Override
     public SearchContextHighlight highlight() {
@@ -470,6 +470,17 @@ public class DefaultSearchContext extends SearchContext {
         return this;
     }
 
+    @Override
+    public DocValueFieldsContext docValueFieldsContext() {
+        return docValueFieldsContext;
+    }
+
+    @Override
+    public SearchContext docValueFieldsContext(DocValueFieldsContext docValueFieldsContext) {
+        this.docValueFieldsContext = docValueFieldsContext;
+        return this;
+    }
+
     @Override
     public ContextIndexSearcher searcher() {
         return this.searcher;

core/src/main/java/org/elasticsearch/search/internal/FilteredSearchContext.java

@@ -35,17 +35,16 @@ import org.elasticsearch.index.mapper.MapperService;
 import org.elasticsearch.index.mapper.ObjectMapper;
 import org.elasticsearch.index.query.ParsedQuery;
 import org.elasticsearch.index.query.QueryShardContext;
-import org.elasticsearch.search.fetch.StoredFieldsContext;
 import org.elasticsearch.index.shard.IndexShard;
 import org.elasticsearch.index.similarity.SimilarityService;
 import org.elasticsearch.script.ScriptService;
+import org.elasticsearch.search.SearchExtBuilder;
 import org.elasticsearch.search.SearchShardTarget;
 import org.elasticsearch.search.aggregations.SearchContextAggregations;
 import org.elasticsearch.search.dfs.DfsSearchResult;
 import org.elasticsearch.search.fetch.FetchPhase;
 import org.elasticsearch.search.fetch.FetchSearchResult;
-import org.elasticsearch.search.fetch.FetchSubPhase;
-import org.elasticsearch.search.fetch.FetchSubPhaseContext;
+import org.elasticsearch.search.fetch.StoredFieldsContext;
 import org.elasticsearch.search.fetch.subphase.FetchSourceContext;
 import org.elasticsearch.search.fetch.subphase.InnerHitsContext;
 import org.elasticsearch.search.fetch.subphase.ScriptFieldsContext;
@@ -512,8 +511,13 @@ public abstract class FilteredSearchContext extends SearchContext {
     }
 
     @Override
-    public <SubPhaseContext extends FetchSubPhaseContext> SubPhaseContext getFetchSubPhaseContext(FetchSubPhase.ContextFactory<SubPhaseContext> contextFactory) {
-        return in.getFetchSubPhaseContext(contextFactory);
+    public void addSearchExt(SearchExtBuilder searchExtBuilder) {
+        in.addSearchExt(searchExtBuilder);
+    }
+
+    @Override
+    public SearchExtBuilder getSearchExt(String name) {
+        return in.getSearchExt(name);
     }
 
     @Override

core/src/main/java/org/elasticsearch/search/internal/SearchContext.java

@@ -22,9 +22,7 @@ package org.elasticsearch.search.internal;
 import org.apache.lucene.search.Collector;
 import org.apache.lucene.search.FieldDoc;
 import org.apache.lucene.search.Query;
-import org.apache.lucene.store.AlreadyClosedException;
 import org.apache.lucene.util.Counter;
-import org.apache.lucene.util.RefCount;
 import org.elasticsearch.action.search.SearchType;
 import org.elasticsearch.common.Nullable;
 import org.elasticsearch.common.ParseFieldMatcher;
@@ -43,17 +41,17 @@ import org.elasticsearch.index.mapper.MapperService;
 import org.elasticsearch.index.mapper.ObjectMapper;
 import org.elasticsearch.index.query.ParsedQuery;
 import org.elasticsearch.index.query.QueryShardContext;
-import org.elasticsearch.search.fetch.StoredFieldsContext;
 import org.elasticsearch.index.shard.IndexShard;
 import org.elasticsearch.index.similarity.SimilarityService;
 import org.elasticsearch.script.ScriptService;
+import org.elasticsearch.search.SearchExtBuilder;
 import org.elasticsearch.search.SearchShardTarget;
 import org.elasticsearch.search.aggregations.SearchContextAggregations;
 import org.elasticsearch.search.dfs.DfsSearchResult;
 import org.elasticsearch.search.fetch.FetchPhase;
 import org.elasticsearch.search.fetch.FetchSearchResult;
-import org.elasticsearch.search.fetch.FetchSubPhase;
-import org.elasticsearch.search.fetch.FetchSubPhaseContext;
+import org.elasticsearch.search.fetch.StoredFieldsContext;
+import org.elasticsearch.search.fetch.subphase.DocValueFieldsContext;
 import org.elasticsearch.search.fetch.subphase.FetchSourceContext;
 import org.elasticsearch.search.fetch.subphase.InnerHitsContext;
 import org.elasticsearch.search.fetch.subphase.ScriptFieldsContext;
@@ -187,7 +185,9 @@ public abstract class SearchContext extends AbstractRefCounted implements Releas
 
     public abstract SearchContext aggregations(SearchContextAggregations aggregations);
 
-    public abstract  <SubPhaseContext extends FetchSubPhaseContext> SubPhaseContext getFetchSubPhaseContext(FetchSubPhase.ContextFactory<SubPhaseContext> contextFactory);
+    public abstract void addSearchExt(SearchExtBuilder searchExtBuilder);
+
+    public abstract SearchExtBuilder getSearchExt(String name);
 
     public abstract SearchContextHighlight highlight();
 
@@ -226,6 +226,10 @@ public abstract class SearchContext extends AbstractRefCounted implements Releas
 
     public abstract SearchContext fetchSourceContext(FetchSourceContext fetchSourceContext);
 
+    public abstract DocValueFieldsContext docValueFieldsContext();
+
+    public abstract SearchContext docValueFieldsContext(DocValueFieldsContext docValueFieldsContext);
+
     public abstract ContextIndexSearcher searcher();
 
     public abstract IndexShard indexShard();

core/src/main/java/org/elasticsearch/search/internal/SubSearchContext.java

@@ -25,6 +25,7 @@ import org.elasticsearch.index.query.ParsedQuery;
 import org.elasticsearch.search.fetch.StoredFieldsContext;
 import org.elasticsearch.search.aggregations.SearchContextAggregations;
 import org.elasticsearch.search.fetch.FetchSearchResult;
+import org.elasticsearch.search.fetch.subphase.DocValueFieldsContext;
 import org.elasticsearch.search.fetch.subphase.FetchSourceContext;
 import org.elasticsearch.search.fetch.subphase.ScriptFieldsContext;
 import org.elasticsearch.search.fetch.subphase.highlight.SearchContextHighlight;
@@ -36,8 +37,6 @@ import org.elasticsearch.search.suggest.SuggestionSearchContext;
 
 import java.util.List;
 
-/**
- */
 public class SubSearchContext extends FilteredSearchContext {
 
     // By default return 3 hits per bucket. A higher default would make the response really large by default, since
@@ -60,6 +59,7 @@ public class SubSearchContext extends FilteredSearchContext {
     private StoredFieldsContext storedFields;
     private ScriptFieldsContext scriptFields;
     private FetchSourceContext fetchSourceContext;
+    private DocValueFieldsContext docValueFieldsContext;
     private SearchContextHighlight highlight;
 
     private boolean explain;
@@ -154,6 +154,17 @@ public class SubSearchContext extends FilteredSearchContext {
         return this;
     }
 
+    @Override
+    public DocValueFieldsContext docValueFieldsContext() {
+        return docValueFieldsContext;
+    }
+
+    @Override
+    public SearchContext docValueFieldsContext(DocValueFieldsContext docValueFieldsContext) {
+        this.docValueFieldsContext = docValueFieldsContext;
+        return this;
+    }
+
     @Override
     public void timeout(TimeValue timeout) {
         throw new UnsupportedOperationException("Not supported");

core/src/main/java/org/elasticsearch/search/query/QueryPhase.java

@@ -68,7 +68,8 @@ import java.util.List;
 import java.util.concurrent.Callable;
 
 /**
- *
+ * Query phase of a search request, used to run the query and get back from each shard information about the matching documents
+ * (document ids and score or sort criteria) so that matches can be reduced on the coordinating node
  */
 public class QueryPhase implements SearchPhase {
 

core/src/main/java/org/elasticsearch/search/rescore/RescorePhase.java

@@ -29,6 +29,7 @@ import org.elasticsearch.search.internal.SearchContext;
 import java.io.IOException;
 
 /**
+ * Rescore phase of a search request, used to run potentially expensive scoring models against the top matching documents.
  */
 public class RescorePhase extends AbstractComponent implements SearchPhase {
 

core/src/main/java/org/elasticsearch/search/suggest/SuggestPhase.java

@@ -35,6 +35,7 @@ import java.util.List;
 import java.util.Map;
 
 /**
+ * Suggest phase of a search request, used to collect suggestions
  */
 public class SuggestPhase extends AbstractComponent implements SearchPhase {
 

core/src/test/java/org/elasticsearch/action/search/MultiSearchRequestTests.java

@@ -175,6 +175,6 @@ public class MultiSearchRequestTests extends ESTestCase {
         IndicesQueriesRegistry registry = new IndicesQueriesRegistry();
         QueryParser<MatchAllQueryBuilder> parser = MatchAllQueryBuilder::fromXContent;
         registry.register(parser, MatchAllQueryBuilder.NAME);
-        return new SearchRequestParsers(registry, null, null);
+        return new SearchRequestParsers(registry, null, null, null);
     }
 }

core/src/test/java/org/elasticsearch/search/SearchRequestTests.java

@@ -29,6 +29,7 @@ import org.elasticsearch.common.io.stream.StreamInput;
 import org.elasticsearch.common.settings.Settings;
 import org.elasticsearch.common.unit.TimeValue;
 import org.elasticsearch.indices.IndicesModule;
+import org.elasticsearch.search.fetch.FetchSubPhasePluginIT;
 import org.elasticsearch.test.ESTestCase;
 import org.junit.AfterClass;
 import org.junit.BeforeClass;
@@ -36,6 +37,7 @@ import org.junit.BeforeClass;
 import java.io.IOException;
 import java.util.ArrayList;
 import java.util.Arrays;
+import java.util.Collections;
 import java.util.List;
 
 import static java.util.Collections.emptyList;
@@ -53,7 +55,8 @@ public class SearchRequestTests extends ESTestCase {
                 bindMapperExtension();
             }
         };
-        SearchModule searchModule = new SearchModule(Settings.EMPTY, false, emptyList()) {
+        SearchModule searchModule = new SearchModule(Settings.EMPTY, false,
+                Collections.singletonList(new FetchSubPhasePluginIT.FetchTermVectorsPlugin())) {
             @Override
             protected void configureSearch() {
                 // Skip me

core/src/test/java/org/elasticsearch/search/builder/SearchSourceBuilderTests.java

@@ -59,6 +59,7 @@ import org.elasticsearch.script.ScriptService;
 import org.elasticsearch.search.SearchModule;
 import org.elasticsearch.search.SearchRequestParsers;
 import org.elasticsearch.search.aggregations.AggregationBuilders;
+import org.elasticsearch.search.fetch.FetchSubPhasePluginIT;
 import org.elasticsearch.search.fetch.subphase.FetchSourceContext;
 import org.elasticsearch.search.fetch.subphase.highlight.HighlightBuilderTests;
 import org.elasticsearch.search.rescore.QueryRescoreBuilderTests;
@@ -85,7 +86,6 @@ import java.util.ArrayList;
 import java.util.Collections;
 import java.util.List;
 
-import static java.util.Collections.emptyList;
 import static org.elasticsearch.test.ClusterServiceUtils.createClusterService;
 import static org.elasticsearch.test.ClusterServiceUtils.setState;
 import static org.hamcrest.CoreMatchers.containsString;
@@ -132,7 +132,8 @@ public class SearchSourceBuilderTests extends ESTestCase {
                 bindMapperExtension();
             }
         };
-        SearchModule searchModule = new SearchModule(settings, false, emptyList()) {
+        SearchModule searchModule = new SearchModule(settings, false,
+                Collections.singletonList(new FetchSubPhasePluginIT.FetchTermVectorsPlugin())) {
             @Override
             protected void configureSearch() {
                 // Skip me
@@ -389,11 +390,7 @@ public class SearchSourceBuilderTests extends ESTestCase {
             builder.aggregation(AggregationBuilders.avg(randomAsciiOfLengthBetween(5, 20)));
         }
         if (randomBoolean()) {
-            XContentBuilder xContentBuilder = XContentFactory.jsonBuilder();
-            xContentBuilder.startObject();
-            xContentBuilder.field("term_vectors_fetch", randomAsciiOfLengthBetween(5, 20));
-            xContentBuilder.endObject();
-            builder.ext(xContentBuilder);
+            builder.ext(Collections.singletonList(new FetchSubPhasePluginIT.TermVectorsFetchBuilder("test")));
         }
         if (randomBoolean()) {
             String field = randomBoolean() ? null : randomAsciiOfLengthBetween(5, 20);
@@ -431,15 +428,14 @@ public class SearchSourceBuilderTests extends ESTestCase {
                                 // test the embedded case
         }
         SearchSourceBuilder newBuilder = SearchSourceBuilder.fromXContent(parseContext, searchRequestParsers.aggParsers,
-            searchRequestParsers.suggesters);
+            searchRequestParsers.suggesters, searchRequestParsers.searchExtParsers);
         assertNull(parser.nextToken());
         assertEquals(testBuilder, newBuilder);
         assertEquals(testBuilder.hashCode(), newBuilder.hashCode());
     }
 
     private static QueryParseContext createParseContext(XContentParser parser) {
-        QueryParseContext context = new QueryParseContext(searchRequestParsers.queryParsers, parser, parseFieldMatcher);
-        return context;
+        return new QueryParseContext(searchRequestParsers.queryParsers, parser, parseFieldMatcher);
     }
 
     public void testSerialization() throws IOException {
@@ -497,7 +493,7 @@ public class SearchSourceBuilderTests extends ESTestCase {
             String restContent = " { \"_source\": { \"includes\": \"include\", \"excludes\": \"*.field2\"}}";
             try (XContentParser parser = XContentFactory.xContent(restContent).createParser(restContent)) {
                 SearchSourceBuilder searchSourceBuilder = SearchSourceBuilder.fromXContent(createParseContext(parser),
-                        searchRequestParsers.aggParsers, searchRequestParsers.suggesters);
+                        searchRequestParsers.aggParsers, searchRequestParsers.suggesters, searchRequestParsers.searchExtParsers);
                 assertArrayEquals(new String[]{"*.field2"}, searchSourceBuilder.fetchSource().excludes());
                 assertArrayEquals(new String[]{"include"}, searchSourceBuilder.fetchSource().includes());
             }
@@ -506,7 +502,7 @@ public class SearchSourceBuilderTests extends ESTestCase {
             String restContent = " { \"_source\": false}";
             try (XContentParser parser = XContentFactory.xContent(restContent).createParser(restContent)) {
                 SearchSourceBuilder searchSourceBuilder = SearchSourceBuilder.fromXContent(createParseContext(parser),
-                    searchRequestParsers.aggParsers, searchRequestParsers.suggesters);
+                    searchRequestParsers.aggParsers, searchRequestParsers.suggesters, searchRequestParsers.searchExtParsers);
                 assertArrayEquals(new String[]{}, searchSourceBuilder.fetchSource().excludes());
                 assertArrayEquals(new String[]{}, searchSourceBuilder.fetchSource().includes());
                 assertFalse(searchSourceBuilder.fetchSource().fetchSource());
@@ -519,7 +515,7 @@ public class SearchSourceBuilderTests extends ESTestCase {
             String restContent = " { \"sort\": \"foo\"}";
             try (XContentParser parser = XContentFactory.xContent(restContent).createParser(restContent)) {
                 SearchSourceBuilder searchSourceBuilder = SearchSourceBuilder.fromXContent(createParseContext(parser),
-                    searchRequestParsers.aggParsers, searchRequestParsers.suggesters);
+                    searchRequestParsers.aggParsers, searchRequestParsers.suggesters, searchRequestParsers.searchExtParsers);
                 assertEquals(1, searchSourceBuilder.sorts().size());
                 assertEquals(new FieldSortBuilder("foo"), searchSourceBuilder.sorts().get(0));
             }
@@ -535,7 +531,7 @@ public class SearchSourceBuilderTests extends ESTestCase {
                     "    ]}";
             try (XContentParser parser = XContentFactory.xContent(restContent).createParser(restContent)) {
                 SearchSourceBuilder searchSourceBuilder = SearchSourceBuilder.fromXContent(createParseContext(parser),
-                    searchRequestParsers.aggParsers, searchRequestParsers.suggesters);
+                    searchRequestParsers.aggParsers, searchRequestParsers.suggesters, searchRequestParsers.searchExtParsers);
                 assertEquals(5, searchSourceBuilder.sorts().size());
                 assertEquals(new FieldSortBuilder("post_date"), searchSourceBuilder.sorts().get(0));
                 assertEquals(new FieldSortBuilder("user"), searchSourceBuilder.sorts().get(1));
@@ -559,7 +555,7 @@ public class SearchSourceBuilderTests extends ESTestCase {
                     "}\n";
             try (XContentParser parser = XContentFactory.xContent(restContent).createParser(restContent)) {
                 SearchSourceBuilder searchSourceBuilder = SearchSourceBuilder.fromXContent(createParseContext(parser),
-                    searchRequestParsers.aggParsers, searchRequestParsers.suggesters);
+                    searchRequestParsers.aggParsers, searchRequestParsers.suggesters, searchRequestParsers.searchExtParsers);
                 assertEquals(1, searchSourceBuilder.aggregations().count());
             }
         }
@@ -575,7 +571,7 @@ public class SearchSourceBuilderTests extends ESTestCase {
                     "}\n";
             try (XContentParser parser = XContentFactory.xContent(restContent).createParser(restContent)) {
                 SearchSourceBuilder searchSourceBuilder = SearchSourceBuilder.fromXContent(createParseContext(parser),
-                    searchRequestParsers.aggParsers, searchRequestParsers.suggesters);
+                    searchRequestParsers.aggParsers, searchRequestParsers.suggesters, searchRequestParsers.searchExtParsers);
                 assertEquals(1, searchSourceBuilder.aggregations().count());
             }
         }
@@ -601,7 +597,7 @@ public class SearchSourceBuilderTests extends ESTestCase {
                 "}\n";
             try (XContentParser parser = XContentFactory.xContent(restContent).createParser(restContent)) {
                 SearchSourceBuilder searchSourceBuilder = SearchSourceBuilder.fromXContent(createParseContext(parser),
-                    searchRequestParsers.aggParsers, searchRequestParsers.suggesters);
+                    searchRequestParsers.aggParsers, searchRequestParsers.suggesters, searchRequestParsers.searchExtParsers);
                 assertEquals(1, searchSourceBuilder.rescores().size());
                 assertEquals(new QueryRescorerBuilder(QueryBuilders.matchQuery("content", "baz")).windowSize(50),
                         searchSourceBuilder.rescores().get(0));
@@ -624,7 +620,7 @@ public class SearchSourceBuilderTests extends ESTestCase {
                 "}\n";
             try (XContentParser parser = XContentFactory.xContent(restContent).createParser(restContent)) {
                 SearchSourceBuilder searchSourceBuilder = SearchSourceBuilder.fromXContent(createParseContext(parser),
-                    searchRequestParsers.aggParsers, searchRequestParsers.suggesters);
+                    searchRequestParsers.aggParsers, searchRequestParsers.suggesters, searchRequestParsers.searchExtParsers);
                 assertEquals(1, searchSourceBuilder.rescores().size());
                 assertEquals(new QueryRescorerBuilder(QueryBuilders.matchQuery("content", "baz")).windowSize(50),
                         searchSourceBuilder.rescores().get(0));
@@ -637,7 +633,7 @@ public class SearchSourceBuilderTests extends ESTestCase {
         final String query = "{ \"query\": { \"match_all\": {}}, \"timeout\": \"" + timeout + "\"}";
         try (XContentParser parser = XContentFactory.xContent(query).createParser(query)) {
             final SearchSourceBuilder builder = SearchSourceBuilder.fromXContent(createParseContext(parser),
-                searchRequestParsers.aggParsers, searchRequestParsers.suggesters);
+                searchRequestParsers.aggParsers, searchRequestParsers.suggesters, searchRequestParsers.searchExtParsers);
             assertThat(builder.timeout(), equalTo(TimeValue.parseTimeValue(timeout, null, "timeout")));
         }
     }
@@ -650,7 +646,7 @@ public class SearchSourceBuilderTests extends ESTestCase {
                     expectThrows(
                             ElasticsearchParseException.class,
                             () -> SearchSourceBuilder.fromXContent(createParseContext(parser),
-                                searchRequestParsers.aggParsers, searchRequestParsers.suggesters));
+                                searchRequestParsers.aggParsers, searchRequestParsers.suggesters, searchRequestParsers.searchExtParsers));
             assertThat(e, hasToString(containsString("unit is missing or unrecognized")));
         }
     }

core/src/test/java/org/elasticsearch/search/fetch/FetchSubPhasePluginIT.java

@@ -26,14 +26,18 @@ import org.apache.lucene.util.BytesRef;
 import org.elasticsearch.action.search.SearchResponse;
 import org.elasticsearch.action.termvectors.TermVectorsRequest;
 import org.elasticsearch.action.termvectors.TermVectorsResponse;
+import org.elasticsearch.common.ParsingException;
+import org.elasticsearch.common.io.stream.StreamInput;
+import org.elasticsearch.common.io.stream.StreamOutput;
 import org.elasticsearch.common.logging.ESLoggerFactory;
 import org.elasticsearch.common.xcontent.XContentBuilder;
 import org.elasticsearch.common.xcontent.XContentParser;
 import org.elasticsearch.index.termvectors.TermVectorsService;
 import org.elasticsearch.plugins.Plugin;
 import org.elasticsearch.plugins.SearchPlugin;
+import org.elasticsearch.search.SearchExtBuilder;
+import org.elasticsearch.search.SearchExtParser;
 import org.elasticsearch.search.SearchHitField;
-import org.elasticsearch.search.SearchParseElement;
 import org.elasticsearch.search.builder.SearchSourceBuilder;
 import org.elasticsearch.search.internal.InternalSearchHitField;
 import org.elasticsearch.search.internal.SearchContext;
@@ -48,21 +52,27 @@ import java.util.Collections;
 import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
+import java.util.Objects;
 
 import static java.util.Collections.singletonList;
-import static java.util.Collections.singletonMap;
 import static org.elasticsearch.client.Requests.indexRequest;
 import static org.elasticsearch.common.xcontent.XContentFactory.jsonBuilder;
 import static org.elasticsearch.test.hamcrest.ElasticsearchAssertions.assertSearchResponse;
 import static org.hamcrest.CoreMatchers.equalTo;
 
-@ClusterScope(scope = Scope.SUITE, supportsDedicatedMasters = false, numDataNodes = 1)
+@ClusterScope(scope = Scope.SUITE, supportsDedicatedMasters = false, numDataNodes = 2)
 public class FetchSubPhasePluginIT extends ESIntegTestCase {
     @Override
     protected Collection<Class<? extends Plugin>> nodePlugins() {
         return Collections.singletonList(FetchTermVectorsPlugin.class);
     }
 
+    @Override
+    protected Collection<Class<? extends Plugin>> transportClientPlugins() {
+        return nodePlugins();
+    }
+
+    @SuppressWarnings("unchecked")
     public void testPlugin() throws Exception {
         client().admin()
                 .indices()
@@ -84,12 +94,11 @@ public class FetchSubPhasePluginIT extends ESIntegTestCase {
 
         client().admin().indices().prepareRefresh().execute().actionGet();
 
-        XContentBuilder extSource = jsonBuilder().startObject()
-                .field("term_vectors_fetch", "test")
-                .endObject();
-         SearchResponse response = client().prepareSearch().setSource(new SearchSourceBuilder().ext(extSource)).get();
+         SearchResponse response = client().prepareSearch().setSource(new SearchSourceBuilder()
+                 .ext(Collections.singletonList(new TermVectorsFetchBuilder("test")))).get();
         assertSearchResponse(response);
-        assertThat(((Map<String, Integer>) response.getHits().getAt(0).field("term_vectors_fetch").getValues().get(0)).get("i"), equalTo(2));
+        assertThat(((Map<String, Integer>) response.getHits().getAt(0).field("term_vectors_fetch").getValues().get(0)).get("i"),
+                equalTo(2));
         assertThat(((Map<String, Integer>) response.getHits().getAt(0).field("term_vectors_fetch").getValues().get(0)).get("am"),
                 equalTo(2));
         assertThat(((Map<String, Integer>) response.getHits().getAt(0).field("term_vectors_fetch").getValues().get(0)).get("sam"),
@@ -101,46 +110,35 @@ public class FetchSubPhasePluginIT extends ESIntegTestCase {
         public List<FetchSubPhase> getFetchSubPhases(FetchPhaseConstructionContext context) {
             return singletonList(new TermVectorsFetchSubPhase());
         }
-    }
-
-    public static final class TermVectorsFetchSubPhase implements FetchSubPhase {
-
-        public static final ContextFactory<TermVectorsFetchContext> CONTEXT_FACTORY = new ContextFactory<TermVectorsFetchContext>() {
-
-            @Override
-            public String getName() {
-                return NAMES[0];
-            }
-
-            @Override
-            public TermVectorsFetchContext newContextInstance() {
-                return new TermVectorsFetchContext();
-            }
-        };
-
-        public static final String[] NAMES = {"term_vectors_fetch"};
 
         @Override
-        public Map<String, ? extends SearchParseElement> parseElements() {
-            return singletonMap("term_vectors_fetch", new TermVectorsFetchParseElement());
+        public List<SearchExtSpec<?>> getSearchExts() {
+            return Collections.singletonList(new SearchExtSpec<>(TermVectorsFetchSubPhase.NAME,
+                    TermVectorsFetchBuilder::new, TermVectorsFetchParser.INSTANCE));
         }
+    }
+
+    public static final class TermVectorsFetchSubPhase implements FetchSubPhase {
+        private static final String NAME = "term_vectors_fetch";
 
         @Override
         public void hitExecute(SearchContext context, HitContext hitContext) {
-            if (context.getFetchSubPhaseContext(CONTEXT_FACTORY).hitExecutionNeeded() == false) {
+            TermVectorsFetchBuilder fetchSubPhaseBuilder = (TermVectorsFetchBuilder)context.getSearchExt(NAME);
+            if (fetchSubPhaseBuilder == null) {
                 return;
             }
-            String field = context.getFetchSubPhaseContext(CONTEXT_FACTORY).getField();
-
+            String field = fetchSubPhaseBuilder.getField();
             if (hitContext.hit().fieldsOrNull() == null) {
                 hitContext.hit().fields(new HashMap<>());
             }
-            SearchHitField hitField = hitContext.hit().fields().get(NAMES[0]);
+            SearchHitField hitField = hitContext.hit().fields().get(NAME);
             if (hitField == null) {
-                hitField = new InternalSearchHitField(NAMES[0], new ArrayList<>(1));
-                hitContext.hit().fields().put(NAMES[0], hitField);
+                hitField = new InternalSearchHitField(NAME, new ArrayList<>(1));
+                hitContext.hit().fields().put(NAME, hitField);
             }
-            TermVectorsResponse termVector = TermVectorsService.getTermVectors(context.indexShard(), new TermVectorsRequest(context.indexShard().shardId().getIndex().getName(), hitContext.hit().type(), hitContext.hit().id()));
+            TermVectorsRequest termVectorsRequest = new TermVectorsRequest(context.indexShard().shardId().getIndex().getName(),
+                    hitContext.hit().type(), hitContext.hit().id());
+            TermVectorsResponse termVector = TermVectorsService.getTermVectors(context.indexShard(), termVectorsRequest);
             try {
                 Map<String, Integer> tv = new HashMap<>();
                 TermsEnum terms = termVector.getFields().terms(field).iterator();
@@ -155,36 +153,74 @@ public class FetchSubPhasePluginIT extends ESIntegTestCase {
         }
     }
 
-    public static class TermVectorsFetchParseElement implements SearchParseElement {
+    public static final class TermVectorsFetchParser implements SearchExtParser<TermVectorsFetchBuilder> {
+
+        private static final TermVectorsFetchParser INSTANCE = new TermVectorsFetchParser();
+
+        private TermVectorsFetchParser() {
+        }
 
         @Override
-        public void parse(XContentParser parser, SearchContext context) throws Exception {
-            TermVectorsFetchContext fetchSubPhaseContext = context.getFetchSubPhaseContext(TermVectorsFetchSubPhase.CONTEXT_FACTORY);
-            // this is to make sure that the SubFetchPhase knows it should execute
-            fetchSubPhaseContext.setHitExecutionNeeded(true);
+        public TermVectorsFetchBuilder fromXContent(XContentParser parser) throws IOException {
+            String field;
             XContentParser.Token token = parser.currentToken();
             if (token == XContentParser.Token.VALUE_STRING) {
-                String fieldName = parser.text();
-                fetchSubPhaseContext.setField(fieldName);
+                field = parser.text();
             } else {
-                throw new IllegalStateException("Expected a VALUE_STRING but got " + token);
+                throw new ParsingException(parser.getTokenLocation(), "Expected a VALUE_STRING but got " + token);
+            }
+            if (field == null) {
+                throw new ParsingException(parser.getTokenLocation(), "no fields specified for " + TermVectorsFetchSubPhase.NAME);
             }
+            return new TermVectorsFetchBuilder(field);
         }
     }
 
-    public static class TermVectorsFetchContext extends FetchSubPhaseContext {
+    public static final class TermVectorsFetchBuilder extends SearchExtBuilder {
+        private final String field;
 
-        private String field = null;
-
-        public TermVectorsFetchContext() {
+        public TermVectorsFetchBuilder(String field) {
+            this.field = field;
         }
 
-        public void setField(String field) {
-            this.field = field;
+        public TermVectorsFetchBuilder(StreamInput in) throws IOException {
+            this.field = in.readString();
         }
 
         public String getField() {
             return field;
         }
+
+        @Override
+        public boolean equals(Object o) {
+            if (this == o) {
+                return true;
+            }
+            if (o == null || getClass() != o.getClass()) {
+                return false;
+            }
+            TermVectorsFetchBuilder that = (TermVectorsFetchBuilder) o;
+            return Objects.equals(field, that.field);
+        }
+
+        @Override
+        public int hashCode() {
+            return Objects.hash(field);
+        }
+
+        @Override
+        public String getWriteableName() {
+            return TermVectorsFetchSubPhase.NAME;
+        }
+
+        @Override
+        public void writeTo(StreamOutput out) throws IOException {
+            out.writeString(field);
+        }
+
+        @Override
+        public XContentBuilder toXContent(XContentBuilder builder, Params params) throws IOException {
+            return builder.field(TermVectorsFetchSubPhase.NAME, field);
+        }
     }
 }

core/src/test/java/org/elasticsearch/search/internal/ShardSearchTransportRequestTests.java

@@ -34,12 +34,14 @@ import org.elasticsearch.index.shard.ShardId;
 import org.elasticsearch.indices.IndicesModule;
 import org.elasticsearch.search.SearchModule;
 import org.elasticsearch.search.SearchRequestTests;
+import org.elasticsearch.search.fetch.FetchSubPhasePluginIT;
 import org.elasticsearch.test.ESTestCase;
 import org.junit.AfterClass;
 import org.junit.BeforeClass;
 
 import java.io.IOException;
 import java.util.ArrayList;
+import java.util.Collections;
 import java.util.List;
 
 import static java.util.Collections.emptyList;
@@ -56,7 +58,8 @@ public class ShardSearchTransportRequestTests extends ESTestCase {
                 bindMapperExtension();
             }
         };
-        SearchModule searchModule = new SearchModule(Settings.EMPTY, false, emptyList()) {
+        SearchModule searchModule = new SearchModule(Settings.EMPTY, false,
+                Collections.singletonList(new FetchSubPhasePluginIT.FetchTermVectorsPlugin())) {
             @Override
             protected void configureSearch() {
                 // Skip me

modules/lang-mustache/src/main/java/org/elasticsearch/script/mustache/TransportSearchTemplateAction.java

@@ -32,14 +32,11 @@ import org.elasticsearch.common.settings.Settings;
 import org.elasticsearch.common.xcontent.XContentFactory;
 import org.elasticsearch.common.xcontent.XContentParser;
 import org.elasticsearch.index.query.QueryParseContext;
-import org.elasticsearch.indices.query.IndicesQueriesRegistry;
 import org.elasticsearch.script.ExecutableScript;
 import org.elasticsearch.script.Script;
 import org.elasticsearch.script.ScriptService;
 import org.elasticsearch.search.SearchRequestParsers;
-import org.elasticsearch.search.aggregations.AggregatorParsers;
 import org.elasticsearch.search.builder.SearchSourceBuilder;
-import org.elasticsearch.search.suggest.Suggesters;
 import org.elasticsearch.threadpool.ThreadPool;
 import org.elasticsearch.transport.TransportService;
 
@@ -86,7 +83,7 @@ public class TransportSearchTemplateAction extends HandledTransportAction<Search
             try (XContentParser parser = XContentFactory.xContent(source).createParser(source)) {
                 SearchSourceBuilder builder = SearchSourceBuilder.searchSource();
                 builder.parseXContent(new QueryParseContext(searchRequestParsers.queryParsers, parser, parseFieldMatcher),
-                    searchRequestParsers.aggParsers, searchRequestParsers.suggesters);
+                    searchRequestParsers.aggParsers, searchRequestParsers.suggesters, searchRequestParsers.searchExtParsers);
                 searchRequest.source(builder);
 
                 searchAction.execute(searchRequest, new ActionListener<SearchResponse>() {

modules/percolator/src/main/java/org/elasticsearch/percolator/TransportMultiPercolateAction.java

@@ -37,9 +37,7 @@ import org.elasticsearch.common.bytes.BytesReference;
 import org.elasticsearch.common.collect.Tuple;
 import org.elasticsearch.common.inject.Inject;
 import org.elasticsearch.common.settings.Settings;
-import org.elasticsearch.indices.query.IndicesQueriesRegistry;
 import org.elasticsearch.search.SearchRequestParsers;
-import org.elasticsearch.search.aggregations.AggregatorParsers;
 import org.elasticsearch.threadpool.ThreadPool;
 import org.elasticsearch.transport.TransportService;
 
@@ -160,8 +158,7 @@ public class TransportMultiPercolateAction extends HandledTransportAction<MultiP
             try {
                 SearchRequest searchRequest = TransportPercolateAction.createSearchRequest(
                     percolateRequest, docSource, searchRequestParsers.queryParsers,
-                    searchRequestParsers.aggParsers, parseFieldMatcher
-                );
+                    searchRequestParsers.aggParsers, searchRequestParsers.searchExtParsers, parseFieldMatcher);
                 multiSearchRequest.add(searchRequest);
             } catch (Exception e) {
                 preFailures.put(i, new MultiPercolateResponse.Item(e));

modules/percolator/src/main/java/org/elasticsearch/percolator/TransportPercolateAction.java

@@ -45,6 +45,7 @@ import org.elasticsearch.index.query.ConstantScoreQueryBuilder;
 import org.elasticsearch.index.query.QueryBuilders;
 import org.elasticsearch.index.query.QueryParseContext;
 import org.elasticsearch.indices.query.IndicesQueriesRegistry;
+import org.elasticsearch.search.SearchExtRegistry;
 import org.elasticsearch.search.SearchHit;
 import org.elasticsearch.search.SearchHits;
 import org.elasticsearch.search.SearchRequestParsers;
@@ -69,7 +70,8 @@ public class TransportPercolateAction extends HandledTransportAction<PercolateRe
     public TransportPercolateAction(Settings settings, ThreadPool threadPool, TransportService transportService,
                                     ActionFilters actionFilters, IndexNameExpressionResolver indexNameExpressionResolver,
                                     Client client, SearchRequestParsers searchRequestParsers) {
-        super(settings, PercolateAction.NAME, threadPool, transportService, actionFilters, indexNameExpressionResolver, PercolateRequest::new);
+        super(settings, PercolateAction.NAME, threadPool, transportService, actionFilters,
+                indexNameExpressionResolver, PercolateRequest::new);
         this.client = client;
         this.searchRequestParsers = searchRequestParsers;
         this.parseFieldMatcher = new ParseFieldMatcher(settings);
@@ -84,7 +86,8 @@ public class TransportPercolateAction extends HandledTransportAction<PercolateRe
                     if (getResponse.isExists()) {
                         innerDoExecute(request, getResponse.getSourceAsBytesRef(), listener);
                     } else {
-                        onFailure(new ResourceNotFoundException("percolate document [{}/{}/{}] doesn't exist", request.getRequest().index(), request.getRequest().type(), request.getRequest().id()));
+                        onFailure(new ResourceNotFoundException("percolate document [{}/{}/{}] doesn't exist",
+                                request.getRequest().index(), request.getRequest().type(), request.getRequest().id()));
                     }
                 }
 
@@ -102,7 +105,7 @@ public class TransportPercolateAction extends HandledTransportAction<PercolateRe
         SearchRequest searchRequest;
         try {
             searchRequest = createSearchRequest(request, docSource, searchRequestParsers.queryParsers,
-                searchRequestParsers.aggParsers, parseFieldMatcher);
+                searchRequestParsers.aggParsers, searchRequestParsers.searchExtParsers, parseFieldMatcher);
         } catch (IOException e) {
             listener.onFailure(e);
             return;
@@ -124,7 +127,10 @@ public class TransportPercolateAction extends HandledTransportAction<PercolateRe
         });
     }
 
-    public static SearchRequest createSearchRequest(PercolateRequest percolateRequest, BytesReference documentSource, IndicesQueriesRegistry queryRegistry, AggregatorParsers aggParsers, ParseFieldMatcher parseFieldMatcher) throws IOException {
+    public static SearchRequest createSearchRequest(PercolateRequest percolateRequest, BytesReference documentSource,
+                                                    IndicesQueriesRegistry queryRegistry, AggregatorParsers aggParsers,
+                                                    SearchExtRegistry searchExtRegistry, ParseFieldMatcher parseFieldMatcher)
+            throws IOException {
         SearchRequest searchRequest = new SearchRequest();
         if (percolateRequest.indices() != null) {
             searchRequest.indices(percolateRequest.indices());
@@ -220,7 +226,7 @@ public class TransportPercolateAction extends HandledTransportAction<PercolateRe
         SearchSourceBuilder searchSourceBuilder = new SearchSourceBuilder();
         try (XContentParser parser = XContentFactory.xContent(XContentType.JSON).createParser(source)) {
             QueryParseContext context = new QueryParseContext(queryRegistry, parser, parseFieldMatcher);
-            searchSourceBuilder.parseXContent(context, aggParsers, null);
+            searchSourceBuilder.parseXContent(context, aggParsers, null, searchExtRegistry);
             searchRequest.source(searchSourceBuilder);
             return searchRequest;
         }
@@ -235,7 +241,8 @@ public class TransportPercolateAction extends HandledTransportAction<PercolateRe
             matches = new PercolateResponse.Match[hits.getHits().length];
             for (int i = 0; i < hits.getHits().length; i++) {
                 SearchHit hit = hits.getHits()[i];
-                matches[i] = new PercolateResponse.Match(new Text(hit.getIndex()), new Text(hit.getId()), hit.getScore(), hit.getHighlightFields());
+                matches[i] = new PercolateResponse.Match(new Text(hit.getIndex()),
+                        new Text(hit.getId()), hit.getScore(), hit.getHighlightFields());
             }
         }
 
@@ -246,8 +253,8 @@ public class TransportPercolateAction extends HandledTransportAction<PercolateRe
         }
 
         return new PercolateResponse(
-            searchResponse.getTotalShards(), searchResponse.getSuccessfulShards(), searchResponse.getFailedShards(),
-            shardFailures, matches, hits.getTotalHits(), searchResponse.getTookInMillis(), (InternalAggregations) searchResponse.getAggregations()
+            searchResponse.getTotalShards(), searchResponse.getSuccessfulShards(), searchResponse.getFailedShards(), shardFailures,
+                matches, hits.getTotalHits(), searchResponse.getTookInMillis(), (InternalAggregations) searchResponse.getAggregations()
         );
     }
 

modules/reindex/src/main/java/org/elasticsearch/index/reindex/RestReindexAction.java

@@ -42,14 +42,11 @@ import org.elasticsearch.common.xcontent.json.JsonXContent;
 import org.elasticsearch.index.VersionType;
 import org.elasticsearch.index.query.QueryParseContext;
 import org.elasticsearch.index.reindex.remote.RemoteInfo;
-import org.elasticsearch.indices.query.IndicesQueriesRegistry;
 import org.elasticsearch.rest.RestChannel;
 import org.elasticsearch.rest.RestController;
 import org.elasticsearch.rest.RestRequest;
 import org.elasticsearch.script.Script;
 import org.elasticsearch.search.SearchRequestParsers;
-import org.elasticsearch.search.aggregations.AggregatorParsers;
-import org.elasticsearch.search.suggest.Suggesters;
 
 import java.io.IOException;
 import java.util.List;
@@ -87,7 +84,8 @@ public class RestReindexAction extends AbstractBaseReindexRestHandler<ReindexReq
             builder.map(source);
             try (XContentParser innerParser = parser.contentType().xContent().createParser(builder.bytes())) {
                 request.getSearchRequest().source().parseXContent(context.queryParseContext(innerParser),
-                    context.searchRequestParsers.aggParsers, context.searchRequestParsers.suggesters);
+                        context.searchRequestParsers.aggParsers, context.searchRequestParsers.suggesters,
+                        context.searchRequestParsers.searchExtParsers);
             }
         };
 

modules/reindex/src/test/java/org/elasticsearch/index/reindex/RestReindexActionTests.java

@@ -110,7 +110,7 @@ public class RestReindexActionTests extends ESTestCase {
         }
         try (XContentParser p = JsonXContent.jsonXContent.createParser(request)) {
             ReindexRequest r = new ReindexRequest(new SearchRequest(), new IndexRequest());
-            SearchRequestParsers searchParsers = new SearchRequestParsers(new IndicesQueriesRegistry(), null, null);
+            SearchRequestParsers searchParsers = new SearchRequestParsers(new IndicesQueriesRegistry(), null, null, null);
             RestReindexAction.PARSER.parse(p, r, new ReindexParseContext(searchParsers, ParseFieldMatcher.STRICT));
             assertEquals("localhost", r.getRemoteInfo().getHost());
             assertArrayEquals(new String[] {"source"}, r.getSearchRequest().indices());

test/framework/src/main/java/org/elasticsearch/test/TestSearchContext.java

@@ -36,17 +36,17 @@ import org.elasticsearch.index.mapper.MapperService;
 import org.elasticsearch.index.mapper.ObjectMapper;
 import org.elasticsearch.index.query.ParsedQuery;
 import org.elasticsearch.index.query.QueryShardContext;
-import org.elasticsearch.search.fetch.StoredFieldsContext;
 import org.elasticsearch.index.shard.IndexShard;
 import org.elasticsearch.index.similarity.SimilarityService;
 import org.elasticsearch.script.ScriptService;
+import org.elasticsearch.search.SearchExtBuilder;
 import org.elasticsearch.search.SearchShardTarget;
 import org.elasticsearch.search.aggregations.SearchContextAggregations;
 import org.elasticsearch.search.dfs.DfsSearchResult;
 import org.elasticsearch.search.fetch.FetchPhase;
 import org.elasticsearch.search.fetch.FetchSearchResult;
-import org.elasticsearch.search.fetch.FetchSubPhase;
-import org.elasticsearch.search.fetch.FetchSubPhaseContext;
+import org.elasticsearch.search.fetch.StoredFieldsContext;
+import org.elasticsearch.search.fetch.subphase.DocValueFieldsContext;
 import org.elasticsearch.search.fetch.subphase.FetchSourceContext;
 import org.elasticsearch.search.fetch.subphase.ScriptFieldsContext;
 import org.elasticsearch.search.fetch.subphase.highlight.SearchContextHighlight;
@@ -90,7 +90,7 @@ public class TestSearchContext extends SearchContext {
     private SearchContextAggregations aggregations;
 
     private final long originNanoTime = System.nanoTime();
-    private final Map<String, FetchSubPhaseContext> subPhaseContexts = new HashMap<>();
+    private final Map<String, SearchExtBuilder> searchExtBuilders = new HashMap<>();
 
     public TestSearchContext(ThreadPool threadPool, BigArrays bigArrays, ScriptService scriptService, IndexService indexService) {
         super(ParseFieldMatcher.STRICT);
@@ -197,12 +197,13 @@ public class TestSearchContext extends SearchContext {
     }
 
     @Override
-    public <SubPhaseContext extends FetchSubPhaseContext> SubPhaseContext getFetchSubPhaseContext(FetchSubPhase.ContextFactory<SubPhaseContext> contextFactory) {
-        String subPhaseName = contextFactory.getName();
-        if (subPhaseContexts.get(subPhaseName) == null) {
-            subPhaseContexts.put(subPhaseName, contextFactory.newContextInstance());
-        }
-        return (SubPhaseContext) subPhaseContexts.get(subPhaseName);
+    public void addSearchExt(SearchExtBuilder searchExtBuilder) {
+        searchExtBuilders.put(searchExtBuilder.getWriteableName(), searchExtBuilder);
+    }
+
+    @Override
+    public SearchExtBuilder getSearchExt(String name) {
+        return searchExtBuilders.get(name);
     }
 
     @Override
@@ -262,6 +263,16 @@ public class TestSearchContext extends SearchContext {
         return null;
     }
 
+    @Override
+    public DocValueFieldsContext docValueFieldsContext() {
+        return null;
+    }
+
+    @Override
+    public SearchContext docValueFieldsContext(DocValueFieldsContext docValueFieldsContext) {
+        return null;
+    }
+
     @Override
     public ContextIndexSearcher searcher() {
         return searcher;