[GitHub] [lucene-solr] mikemccand commented on a change in pull request #854: Shared PQ Based Early Termination for Concurrent Search

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mikemccand commented on a change in pull request #854: Shared PQ Based Early Termination for Concurrent Search
URL: https://github.com/apache/lucene-solr/pull/854#discussion_r322909770
 
 

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 File path: lucene/core/src/java/org/apache/lucene/search/EarlyTerminatingFieldCollectorManager.java
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+/*
+ * 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;
+
+import java.util.Collection;
+import java.util.concurrent.ConcurrentLinkedQueue;
+import java.util.concurrent.atomic.AtomicBoolean;
+import java.util.concurrent.atomic.AtomicInteger;
+import java.util.concurrent.locks.ReentrantLock;
+
+import static org.apache.lucene.search.TopFieldCollector.EMPTY_SCOREDOCS;
+
+/**
+ * CollectorManager which allows early termination across multiple slices
+ * when the index sort key and the query sort key are the same
+ */
+public class EarlyTerminatingFieldCollectorManager implements CollectorManager<TopFieldCollector, TopFieldDocs> {
+  private final Sort sort;
+  private final int numHits;
+  private final int totalHitsThreshold;
+  private final AtomicInteger globalTotalHits;
+  private final ReentrantLock lock;
+  private int numCollectors;
+
+  private final ConcurrentLinkedQueue<TopFieldCollector.EarlyTerminatingFieldCollector> mergeableCollectors;
+  private FieldValueHitQueue globalHitQueue;
+  private FieldValueHitQueue.Entry bottom;
+  // We do not make this Atomic since it will be sought under a lock
+  private int queueSlotCounter;
+  private final AtomicBoolean mergeStarted;
+  public final AtomicBoolean mergeCompleted;
+
+  public EarlyTerminatingFieldCollectorManager(Sort sort, int numHits, int totalHitsThreshold) {
+    this.sort = sort;
+    this.numHits = numHits;
+    this.totalHitsThreshold = totalHitsThreshold;
+    this.globalTotalHits = new AtomicInteger();
+    this.lock = new ReentrantLock();
+    this.mergeStarted = new AtomicBoolean();
+    this.mergeCompleted = new AtomicBoolean();
+    this.mergeableCollectors = new ConcurrentLinkedQueue();
+    this.globalHitQueue = null;
+  }
+
+  @Override
+  public TopFieldCollector.EarlyTerminatingFieldCollector newCollector() {
+    ++numCollectors;
+
+    return new TopFieldCollector.EarlyTerminatingFieldCollector(sort, FieldValueHitQueue.create(sort.fields, numHits), numHits,
+        totalHitsThreshold, this, globalTotalHits);
+  }
+
+  @Override
+  public TopFieldDocs reduce(Collection<TopFieldCollector> collectors) {
+
+    if (globalHitQueue == null) {
+      final TopFieldDocs[] topDocs = new TopFieldDocs[collectors.size()];
+      int i = 0;
+      for (TopFieldCollector collector : collectors) {
+        topDocs[i++] = collector.topDocs();
+      }
+      return TopDocs.merge(sort, 0, numHits, topDocs);
+    }
+
+    ScoreDoc[] results = populateResults(globalHitQueue.size());
+
+    return newTopDocs(results);
+  }
+
+  public int compareAndUpdateBottom(int docBase, int doc, Object value) {
+
+    try {
+      lock.lock();
+
+      // If not enough hits are accumulated, add this hit to the global hit queue
+      if (globalHitQueue.size() < numHits) {
+        FieldValueHitQueue.Entry newEntry = new FieldValueHitQueue.Entry(queueSlotCounter++, (doc + docBase), value);
+        bottom = (FieldValueHitQueue.Entry) globalHitQueue.add(newEntry);
+        return 1;
+      }
+
+      FieldComparator[] comparators = globalHitQueue.getComparators();
+      int[] reverseMul = globalHitQueue.getReverseMul();
+      Object bottomValues = bottom.values;
+      Object[] valuesArray;
+      Object[] bottomValuesArray;
+
+      if (comparators.length > 1) {
+        assert value instanceof Object[];
+        valuesArray = (Object[]) value;
+
+        assert bottomValues instanceof Object[];
+        bottomValuesArray = (Object[]) bottomValues;
+      } else {
+        valuesArray = new Object[1];
+        valuesArray[0] = value;
+
+        bottomValuesArray = new Object[1];
 
 Review comment:
   Hmm, spooky we must allocate two `Object[]` per collected hit in this case ...

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