Adds unit test for sampler aggregation

core/src/main/java/org/elasticsearch/search/aggregations/bucket/DeferringBucketCollector.java

@@ -54,6 +54,16 @@ public Aggregator wrap(final Aggregator in) {
         return new WrappedAggregator(in);
     }
 
+    /**
+     * Unwrap an aggregator. Used for testing.
+     */
+    public static Aggregator unwrap(Aggregator in) {
+        if (in instanceof WrappedAggregator) {
+            return ((WrappedAggregator) in).in;
+        }
+        return in;
+    }
+
     protected class WrappedAggregator extends Aggregator {
         private Aggregator in;
 

core/src/test/java/org/elasticsearch/search/aggregations/AggregatorTestCase.java

@@ -34,14 +34,14 @@
 import org.elasticsearch.index.IndexSettings;
 import org.elasticsearch.index.cache.query.DisabledQueryCache;
 import org.elasticsearch.index.engine.Engine;
-import org.elasticsearch.index.fielddata.IndexFieldData;
 import org.elasticsearch.index.fielddata.IndexFieldDataCache;
 import org.elasticsearch.index.fielddata.IndexFieldDataService;
 import org.elasticsearch.index.mapper.MappedFieldType;
 import org.elasticsearch.index.mapper.MapperService;
 import org.elasticsearch.index.query.QueryShardContext;
 import org.elasticsearch.indices.breaker.CircuitBreakerService;
 import org.elasticsearch.indices.breaker.NoneCircuitBreakerService;
+import org.elasticsearch.search.aggregations.bucket.DeferringBucketCollector;
 import org.elasticsearch.search.fetch.FetchPhase;
 import org.elasticsearch.search.fetch.subphase.DocValueFieldsFetchSubPhase;
 import org.elasticsearch.search.fetch.subphase.FetchSourceSubPhase;
@@ -110,10 +110,9 @@ public boolean shouldCache(Query query) throws IOException {
 
         QueryShardContext queryShardContext = mock(QueryShardContext.class);
         for (MappedFieldType fieldType : fieldTypes) {
-            IndexFieldData<?> fieldData = fieldType.fielddataBuilder().build(indexSettings, fieldType,
-                new IndexFieldDataCache.None(), circuitBreakerService, mock(MapperService.class));
             when(queryShardContext.fieldMapper(fieldType.name())).thenReturn(fieldType);
-            when(queryShardContext.getForField(fieldType)).thenReturn(fieldData);
+            when(queryShardContext.getForField(fieldType)).then(invocation -> fieldType.fielddataBuilder().build(
+                    indexSettings, fieldType, new IndexFieldDataCache.None(), circuitBreakerService, mock(MapperService.class)));
             when(searchContext.getQueryShardContext()).thenReturn(queryShardContext);
         }
 
@@ -126,13 +125,16 @@ protected <A extends InternalAggregation, C extends Aggregator> A search(IndexSe
                                                                              Query query,
                                                                              AggregationBuilder builder,
                                                                              MappedFieldType... fieldTypes) throws IOException {
-        try (C a = createAggregator(builder, searcher, fieldTypes)) {
+        C a = createAggregator(builder, searcher, fieldTypes);
+        try {
             a.preCollection();
             searcher.search(query, a);
             a.postCollection();
             @SuppressWarnings("unchecked")
             A internalAgg = (A) a.buildAggregation(0L);
             return internalAgg;
+        } finally {
+            closeAgg(a);
         }
     }
 
@@ -190,6 +192,7 @@ protected <A extends InternalAggregation, C extends Aggregator> A searchAndReduc
     }
 
     private void closeAgg(Aggregator agg) {
+        agg = DeferringBucketCollector.unwrap(agg);
         agg.close();
         for (Aggregator sub : ((AggregatorBase) agg).subAggregators) {
             closeAgg(sub);

core/src/test/java/org/elasticsearch/search/aggregations/bucket/sampler/SamplerAggregatorTests.java

@@ -0,0 +1,79 @@
+/*
+ * 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.aggregations.bucket.sampler;
+
+import org.apache.lucene.analysis.standard.StandardAnalyzer;
+import org.apache.lucene.document.Document;
+import org.apache.lucene.document.Field;
+import org.apache.lucene.document.SortedNumericDocValuesField;
+import org.apache.lucene.index.IndexReader;
+import org.apache.lucene.index.RandomIndexWriter;
+import org.apache.lucene.index.Term;
+import org.apache.lucene.search.IndexSearcher;
+import org.apache.lucene.search.TermQuery;
+import org.apache.lucene.store.Directory;
+import org.elasticsearch.index.analysis.AnalyzerScope;
+import org.elasticsearch.index.analysis.NamedAnalyzer;
+import org.elasticsearch.index.mapper.MappedFieldType;
+import org.elasticsearch.index.mapper.NumberFieldMapper;
+import org.elasticsearch.index.mapper.TextFieldMapper.TextFieldType;
+import org.elasticsearch.search.aggregations.AggregatorTestCase;
+import org.elasticsearch.search.aggregations.metrics.min.Min;
+import org.elasticsearch.search.aggregations.metrics.min.MinAggregationBuilder;
+
+import java.io.IOException;
+
+public class SamplerAggregatorTests extends AggregatorTestCase {
+    /**
+     * Uses the sampler aggregation to find the minimum value of a field out of the top 3 scoring documents in a search.
+     */
+    public void testSampler() throws IOException {
+        TextFieldType textFieldType = new TextFieldType();
+        textFieldType.setIndexAnalyzer(new NamedAnalyzer("foo", AnalyzerScope.GLOBAL, new StandardAnalyzer()));
+        MappedFieldType numericFieldType = new NumberFieldMapper.NumberFieldType(NumberFieldMapper.NumberType.LONG);
+        numericFieldType.setName("int");
+
+        try (Directory dir = newDirectory();
+                RandomIndexWriter w = new RandomIndexWriter(random(), dir)) {
+            for (long value : new long[] {7, 3, -10, -6, 5, 50}) {
+                Document doc = new Document();
+                StringBuilder text = new StringBuilder();
+                for (int i = 0; i < value; i++) {
+                    text.append("good ");
+                }
+                doc.add(new Field("text", text.toString(), textFieldType));
+                doc.add(new SortedNumericDocValuesField("int", value));
+                w.addDocument(doc);
+            }
+
+            SamplerAggregationBuilder aggBuilder = new SamplerAggregationBuilder("sampler")
+                    .shardSize(3)
+                    .subAggregation(new MinAggregationBuilder("min")
+                            .field("int"));
+            try (IndexReader reader = w.getReader()) {
+                IndexSearcher searcher = new IndexSearcher(reader);
+                Sampler sampler = searchAndReduce(searcher, new TermQuery(new Term("text", "good")), aggBuilder, textFieldType,
+                        numericFieldType);
+                Min min = sampler.getAggregations().get("min");
+                assertEquals(5.0, min.getValue(), Double.MIN_NORMAL);
+            }
+        }
+    }
+}