FetchSubPhase to support a single parser that extends SearchExtParser

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

@@ -63,7 +63,7 @@ import org.elasticsearch.search.dfs.DfsPhase;
 import org.elasticsearch.search.dfs.DfsSearchResult;
 import org.elasticsearch.search.fetch.FetchPhase;
 import org.elasticsearch.search.fetch.FetchSearchResult;
-import org.elasticsearch.search.fetch.FetchSubPhaseParser;
+import org.elasticsearch.search.fetch.SearchExtParser;
 import org.elasticsearch.search.fetch.QueryFetchSearchResult;
 import org.elasticsearch.search.fetch.ScrollQueryFetchSearchResult;
 import org.elasticsearch.search.fetch.ShardFetchRequest;
@@ -144,7 +144,7 @@ public class SearchService extends AbstractLifecycleComponent implements IndexEv
 
     private final ConcurrentMapLong<SearchContext> activeContexts = ConcurrentCollections.newConcurrentMapLongWithAggressiveConcurrency();
 
-    private final Map<String, FetchSubPhaseParser> fetchPhaseParsers;
+    private final Map<String, SearchExtParser> fetchPhaseParsers;
 
     private final ParseFieldMatcher parseFieldMatcher;
 
@@ -763,8 +763,8 @@ public class SearchService extends AbstractLifecycleComponent implements IndexEv
                     if (token == XContentParser.Token.FIELD_NAME) {
                         currentFieldName = extParser.currentName();
                     } else {
-                        FetchSubPhaseParser fetchSubPhaseParser = this.fetchPhaseParsers.get(currentFieldName);
+                        SearchExtParser searchExtParser = this.fetchPhaseParsers.get(currentFieldName);
-                        if (fetchSubPhaseParser == null) {
+                        if (searchExtParser == null) {
                             if (currentFieldName != null && currentFieldName.equals("suggest")) {
                                 throw new SearchParseException(context,
                                     "suggest is not supported in [ext], please use SearchSourceBuilder#suggest(SuggestBuilder) instead",
@@ -773,7 +773,7 @@ public class SearchService extends AbstractLifecycleComponent implements IndexEv
                             throw new SearchParseException(context, "Unknown element [" + currentFieldName + "] in [ext]",
                                     extParser.getTokenLocation());
                         } else {
-                            Object fetchSubPhaseBuilder = fetchSubPhaseParser.parse(extParser);
+                            Object fetchSubPhaseBuilder = searchExtParser.parse(extParser);
                             context.putFetchSubPhaseBuilder(currentFieldName, fetchSubPhaseBuilder);
                         }
                     }

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

@@ -77,10 +77,12 @@ public class FetchPhase implements SearchPhase {
         this.fetchSubPhases[fetchSubPhases.size()] = new InnerHitsFetchSubPhase(this);
     }
 
-    public Map<String, ? extends FetchSubPhaseParser> parsers() {
+    public Map<String, ? extends SearchExtParser> parsers() {
-        Map<String, FetchSubPhaseParser> parsers = new HashMap<>();
+        Map<String, SearchExtParser> parsers = new HashMap<>();
         for (FetchSubPhase fetchSubPhase : fetchSubPhases) {
-            parsers.putAll(fetchSubPhase.parsers());
+            if (fetchSubPhase.parser() != null) {
+                parsers.put(fetchSubPhase.parser().getName(), fetchSubPhase.parser());
+            }
         }
         return unmodifiableMap(parsers);
     }

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

@@ -25,7 +25,6 @@ import org.apache.lucene.search.IndexSearcher;
 import org.elasticsearch.search.internal.InternalSearchHit;
 import org.elasticsearch.search.internal.SearchContext;
 
-import java.util.Collections;
 import java.util.HashMap;
 import java.util.Map;
 
@@ -77,8 +76,11 @@ public interface FetchSubPhase {
 
     }
 
-    default Map<String, ? extends FetchSubPhaseParser> parsers() {
+    /**
-        return Collections.emptyMap();
+     * Returns the parser for the optional config to be put in the ext section of the search request
+     */
+    default SearchExtParser parser() {
+        return null;
     }
 
     /**

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

@@ -22,9 +22,17 @@ package org.elasticsearch.search.fetch;
 import org.elasticsearch.common.xcontent.XContentParser;
 
 /**
- * Parser for the ext section of a search request, which can hold custom fetch sub phase
+ * Parser for the ext section of a search request, which can hold custom fetch sub phases config
  */
-public interface FetchSubPhaseParser {
+public interface SearchExtParser {
 
+    /**
+     * Returns the name of the element that this parser is able to parse
+     */
+    String getName();
+
+    /**
+     * Parses the element whose name is returned by {@link #getName()}
+     */
     Object parse(XContentParser parser) throws Exception;
 }

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

@@ -50,7 +50,6 @@ import java.util.List;
 import java.util.Map;
 
 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;
@@ -109,8 +108,8 @@ public class FetchSubPhasePluginIT extends ESIntegTestCase {
         private static final String NAME = "term_vectors_fetch";
 
         @Override
-        public Map<String, ? extends FetchSubPhaseParser> parsers() {
+        public SearchExtParser parser() {
-            return singletonMap(NAME, new TermVectorsFetchParser());
+            return TermVectorsFetchParser.INSTANCE;
         }
 
         @Override
@@ -145,7 +144,18 @@ public class FetchSubPhasePluginIT extends ESIntegTestCase {
         }
     }
 
-    public static class TermVectorsFetchParser implements FetchSubPhaseParser {
+    public static final class TermVectorsFetchParser implements SearchExtParser {
+
+        private static final TermVectorsFetchParser INSTANCE = new TermVectorsFetchParser();
+
+        private TermVectorsFetchParser() {
+        }
+
+        @Override
+        public String getName() {
+            return TermVectorsFetchSubPhase.NAME;
+        }
+
         @Override
         public TermVectorsFetchBuilder parse(XContentParser parser) throws Exception {
             String field;
@@ -162,7 +172,7 @@ public class FetchSubPhasePluginIT extends ESIntegTestCase {
         }
     }
 
-    public static class TermVectorsFetchBuilder {
+    public static final class TermVectorsFetchBuilder {
         private final String field;
 
         private TermVectorsFetchBuilder(String field) {