SOLR-2564: add pollLast to deal with performance regression due to Java5/Java6 difference between modules and Solr

git-svn-id: https://svn.apache.org/repos/asf/lucene/dev/trunk@1138735 13f79535-47bb-0310-9956-ffa450edef68

modules/grouping/src/java/org/apache/lucene/search/grouping/AbstractFirstPassGroupingCollector.java

@@ -43,7 +43,8 @@ abstract public class AbstractFirstPassGroupingCollector<GROUP_VALUE_TYPE> exten
   private final int compIDXEnd;
 
   // Set once we reach topNGroups unique groups:
-  private TreeSet<CollectedSearchGroup<GROUP_VALUE_TYPE>> orderedGroups;
+  /** @lucene.internal */
+  protected TreeSet<CollectedSearchGroup<GROUP_VALUE_TYPE>> orderedGroups;
   private int docBase;
   private int spareSlot;
 
@@ -214,8 +215,7 @@ abstract public class AbstractFirstPassGroupingCollector<GROUP_VALUE_TYPE> exten
       // the bottom group with this new group.
 
       // java 6-only: final CollectedSearchGroup bottomGroup = orderedGroups.pollLast();
-      final CollectedSearchGroup<GROUP_VALUE_TYPE> bottomGroup = orderedGroups.last();
+      final CollectedSearchGroup<GROUP_VALUE_TYPE> bottomGroup = pollLast();
-      orderedGroups.remove(bottomGroup);
       assert orderedGroups.size() == topNGroups -1;
 
       groupMap.remove(bottomGroup.groupValue);
@@ -350,9 +350,14 @@ abstract public class AbstractFirstPassGroupingCollector<GROUP_VALUE_TYPE> exten
    * @return a copy of the specified group value
    */
   protected abstract GROUP_VALUE_TYPE copyDocGroupValue(GROUP_VALUE_TYPE groupValue, GROUP_VALUE_TYPE reuse);
+
+
+
+  protected CollectedSearchGroup<GROUP_VALUE_TYPE> pollLast() {
+    // java 6-only: final CollectedSearchGroup bottomGroup = orderedGroups.pollLast();
+    final CollectedSearchGroup<GROUP_VALUE_TYPE> bottomGroup = orderedGroups.last();
+    orderedGroups.remove(bottomGroup);
+    return bottomGroup;
+  }
 }
 
-class CollectedSearchGroup<T> extends SearchGroup<T> {
-  int topDoc;
-  int comparatorSlot;
-}

modules/grouping/src/java/org/apache/lucene/search/grouping/CollectedSearchGroup.java

@@ -0,0 +1,24 @@
+/**
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF 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.apache.lucene.search.grouping;
+
+/** @lucene.internal */
+public class CollectedSearchGroup<T> extends SearchGroup<T> {
+  int topDoc;
+  int comparatorSlot;
+}

solr/src/java/org/apache/solr/search/Grouping.java

@@ -628,7 +628,7 @@ public class Grouping {
       }
 
       sort = sort == null ? Sort.RELEVANCE : sort;
-      firstPass = new TermFirstPassGroupingCollector(groupBy, sort, actualGroupsToFind);
+      firstPass = new TermFirstPassGroupingCollectorJava6(groupBy, sort, actualGroupsToFind);
       return firstPass;
     }
 
@@ -996,6 +996,22 @@ public class Grouping {
       filler = docValues.getValueFiller();
       mval = filler.getValue();
     }
+
+    @Override
+    protected CollectedSearchGroup<MutableValue> pollLast() {
+      return orderedGroups.pollLast();
+    }
+  }
+
+  static class TermFirstPassGroupingCollectorJava6 extends TermFirstPassGroupingCollector {
+    public TermFirstPassGroupingCollectorJava6(String groupField, Sort groupSort, int topNGroups) throws IOException {
+      super(groupField, groupSort, topNGroups);
+    }
+
+    @Override
+    protected CollectedSearchGroup<BytesRef> pollLast() {
+      return orderedGroups.pollLast();
+    }
   }
 
   static class FunctionSecondPassGroupingCollector extends AbstractSecondPassGroupingCollector<MutableValue> {