Introdue ParentIdCollector that collects only if the parent ID is non null ie. if the document has a parent.

Closes #2744

src/main/java/org/elasticsearch/index/search/child/ChildrenQuery.java

@@ -319,30 +319,25 @@ public class ChildrenQuery extends Query implements SearchContext.Rewrite {
         }
     }
 
-    static class ChildUidCollector extends NoopCollector {
+    static class ChildUidCollector extends ParentIdCollector {
 
         final TObjectFloatHashMap<HashedBytesArray> uidToScore;
         final ScoreType scoreType;
-        final SearchContext searchContext;
-        final String childType;
-
         Scorer scorer;
-        IdReaderTypeCache typeCache;
 
         ChildUidCollector(ScoreType scoreType, SearchContext searchContext, String childType, TObjectFloatHashMap<HashedBytesArray> uidToScore) {
+            super(childType, searchContext);
             this.uidToScore = uidToScore;
             this.scoreType = scoreType;
-            this.searchContext = searchContext;
-            this.childType = childType;
         }
 
         @Override
-        public void collect(int doc) throws IOException {
+        public void setScorer(Scorer scorer) throws IOException {
-            if (typeCache == null) {
+            this.scorer = scorer;
-                return;
+        }
-            }
 
-            HashedBytesArray parentUid = typeCache.parentIdByDoc(doc);
+        @Override
+        protected void collect(int doc, HashedBytesArray parentUid) throws IOException {
             float previousScore = uidToScore.get(parentUid);
             float currentScore = scorer.score();
             if (previousScore == 0) {
@@ -357,23 +352,19 @@ public class ChildrenQuery extends Query implements SearchContext.Rewrite {
                             uidToScore.put(parentUid, currentScore);
                         }
                         break;
+                    case AVG:
+                        assert false : "AVG has it's own collector";
+                        
+                    default:
+                        assert false : "Are we missing a sore type here? -- " + scoreType;
+                        break;
                 }
             }
         }
 
-        @Override
-        public void setScorer(Scorer scorer) throws IOException {
-            this.scorer = scorer;
-        }
-
-        @Override
-        public void setNextReader(AtomicReaderContext context) throws IOException {
-            typeCache = searchContext.idCache().reader(context.reader()).type(childType);
-        }
-
     }
 
-    static class AvgChildUidCollector extends ChildUidCollector {
+    final static class AvgChildUidCollector extends ChildUidCollector {
 
         final TObjectIntHashMap<HashedBytesArray> uidToCount;
 
@@ -384,12 +375,7 @@ public class ChildrenQuery extends Query implements SearchContext.Rewrite {
         }
 
         @Override
-        public void collect(int doc) throws IOException {
+        protected void collect(int doc, HashedBytesArray parentUid) throws IOException {
-            if (typeCache == null) {
-                return;
-            }
-
-            HashedBytesArray parentUid = typeCache.parentIdByDoc(doc);
             float previousScore = uidToScore.get(parentUid);
             float currentScore = scorer.score();
             if (previousScore == 0) {

src/main/java/org/elasticsearch/index/search/child/HasChildFilter.java

@@ -102,7 +102,7 @@ public abstract class HasChildFilter extends Filter implements SearchContext.Rew
             collectedUids = null;
         }
 
-        static class ParentDocSet extends MatchDocIdSet {
+        final static class ParentDocSet extends MatchDocIdSet {
 
             final IndexReader reader;
             final THashSet<HashedBytesArray> parents;
@@ -121,33 +121,19 @@ public abstract class HasChildFilter extends Filter implements SearchContext.Rew
             }
         }
 
-        static class UidCollector extends NoopCollector {
+        final static class UidCollector extends ParentIdCollector {
-
+            private final THashSet<HashedBytesArray> collectedUids;
-            final String parentType;
-            final SearchContext context;
-            final THashSet<HashedBytesArray> collectedUids;
-
-            private IdReaderTypeCache typeCache;
 
             UidCollector(String parentType, SearchContext context, THashSet<HashedBytesArray> collectedUids) {
-                this.parentType = parentType;
+                super(parentType, context);
-                this.context = context;
                 this.collectedUids = collectedUids;
             }
 
             @Override
-            public void collect(int doc) throws IOException {
+            public void collect(int doc, HashedBytesArray parentIdByDoc){
-                // It can happen that for particular segment no document exist for an specific type. This prevents NPE
+                collectedUids.add(parentIdByDoc);
-                if (typeCache != null) {
-                    collectedUids.add(typeCache.parentIdByDoc(doc));
-                }
-
             }
 
-            @Override
-            public void setNextReader(AtomicReaderContext readerContext) throws IOException {
-                typeCache = context.idCache().reader(readerContext.reader()).type(parentType);
-            }
         }
     }
 }

src/main/java/org/elasticsearch/index/search/child/ParentIdCollector.java

@@ -0,0 +1,59 @@
+/*
+ * Licensed to ElasticSearch and Shay Banon 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.index.search.child;
+
+import java.io.IOException;
+
+import org.apache.lucene.index.AtomicReaderContext;
+import org.elasticsearch.common.bytes.HashedBytesArray;
+import org.elasticsearch.common.lucene.search.NoopCollector;
+import org.elasticsearch.index.cache.id.IdReaderTypeCache;
+import org.elasticsearch.search.internal.SearchContext;
+
+/**
+ * A simple collector that only collects if the docs parent ID is not
+ * <code>null</code>
+ */
+abstract class ParentIdCollector extends NoopCollector {
+    protected final String type;
+    protected final SearchContext context;
+    private IdReaderTypeCache typeCache;
+
+    protected ParentIdCollector(String parentType, SearchContext context) {
+        this.type = parentType;
+        this.context = context;
+    }
+
+    @Override
+    public final void collect(int doc) throws IOException {
+        if (typeCache != null) {
+            HashedBytesArray parentIdByDoc = typeCache.parentIdByDoc(doc);
+            if (parentIdByDoc != null) {
+               collect(doc, parentIdByDoc);
+            }
+        }
+    }
+    
+    protected abstract void collect(int doc, HashedBytesArray parentId) throws IOException;
+
+    @Override
+    public void setNextReader(AtomicReaderContext readerContext) throws IOException {
+        typeCache = context.idCache().reader(readerContext.reader()).type(type);
+    }
+}

src/test/java/org/elasticsearch/test/integration/search/child/SimpleChildQuerySearchTests.java

@@ -19,6 +19,7 @@
 
 package org.elasticsearch.test.integration.search.child;
 
+import org.elasticsearch.ElasticSearchException;
 import org.elasticsearch.action.count.CountResponse;
 import org.elasticsearch.action.search.SearchResponse;
 import org.elasticsearch.action.search.SearchType;
@@ -35,6 +36,7 @@ import org.testng.annotations.AfterClass;
 import org.testng.annotations.BeforeClass;
 import org.testng.annotations.Test;
 
+import java.io.IOException;
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.List;
@@ -110,6 +112,33 @@ public class SimpleChildQuerySearchTests extends AbstractNodesTests {
         assertThat("Failures " + Arrays.toString(searchResponse.getShardFailures()), searchResponse.getShardFailures().length, equalTo(0));
         assertThat(searchResponse.getHits().totalHits(), equalTo(1l));
     }
+    
+    
+    @Test // see #2744
+    public void test2744() throws ElasticSearchException, IOException {
+        client.admin().indices().prepareDelete().execute().actionGet();
+
+        client.admin().indices().prepareCreate("test")
+                .setSettings(
+                        ImmutableSettings.settingsBuilder()
+                                .put("index.number_of_shards", 1)
+                                .put("index.number_of_replicas", 0)
+                ).execute().actionGet();
+        client.admin().cluster().prepareHealth().setWaitForEvents(Priority.LANGUID).setWaitForGreenStatus().execute().actionGet();
+        client.admin().indices().preparePutMapping("test").setType("test").setSource(jsonBuilder().startObject().startObject("type")
+                .startObject("_parent").field("type", "foo").endObject()
+                .endObject().endObject()).execute().actionGet();
+
+        // index simple data
+        client.prepareIndex("test", "foo", "1").setSource("foo", 1).execute().actionGet();
+        client.prepareIndex("test", "test").setSource("foo", 1).setParent("1").execute().actionGet();
+        client.admin().indices().prepareRefresh().execute().actionGet();
+        SearchResponse searchResponse =  client.prepareSearch("test").setQuery(hasChildQuery("test", matchQuery("foo", 1))).execute().actionGet();
+        assertThat(searchResponse.getFailedShards(), equalTo(0));
+        assertThat(searchResponse.getHits().totalHits(), equalTo(1l));
+        assertThat(searchResponse.getHits().getAt(0).id(), equalTo("1"));
+
+    }
 
     @Test
     public void simpleChildQuery() throws Exception {