LUCENE-6091: Fix UsageTrackingFilterCachingPolicy's handling of null DocIdSets.

git-svn-id: https://svn.apache.org/repos/asf/lucene/dev/trunk@1643085 13f79535-47bb-0310-9956-ffa450edef68

lucene/core/src/java/org/apache/lucene/search/UsageTrackingFilterCachingPolicy.java

@@ -36,18 +36,18 @@ import org.apache.lucene.util.FrequencyTrackingRingBuffer;
  */
 public final class UsageTrackingFilterCachingPolicy implements FilterCachingPolicy {
 
-  private static boolean isCostly(Filter filter) {
+  static boolean isCostly(Filter filter) {
     // This does not measure the cost of iterating over the filter (for this we
     // already have the DocIdSetIterator#cost API) but the cost to build the
     // DocIdSet in the first place
     return filter instanceof MultiTermQueryWrapperFilter;
   }
 
-  private static boolean isCheapToCache(DocIdSet set) {
+  static boolean isCheapToCache(DocIdSet set) {
     // the produced doc set is already cacheable, so caching has no
     // overhead at all. TODO: extend this to sets whose iterators have a low
     // cost?
-    return set.isCacheable();
+    return set == null || set.isCacheable();
   }
 
   private final FilterCachingPolicy.CacheOnLargeSegments segmentPolicy;

lucene/core/src/test/org/apache/lucene/search/TestFilterCachingPolicy.java

@@ -0,0 +1,55 @@
+package org.apache.lucene.search;
+
+/*
+ * 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.
+ */
+
+import java.io.IOException;
+
+import org.apache.lucene.document.Document;
+import org.apache.lucene.index.IndexReader;
+import org.apache.lucene.index.LeafReaderContext;
+import org.apache.lucene.index.RandomIndexWriter;
+import org.apache.lucene.index.Term;
+import org.apache.lucene.store.Directory;
+import org.apache.lucene.util.LuceneTestCase;
+
+public class TestFilterCachingPolicy extends LuceneTestCase {
+
+  public void testLargeSegmentDetection() throws IOException {
+    Directory dir = newDirectory();
+    RandomIndexWriter w = new RandomIndexWriter(random(), dir);
+    final int numDocs = atLeast(100);
+    for (int i = 0; i < numDocs; ++i) {
+      w.addDocument(new Document());
+    }
+    final IndexReader reader = w.getReader();
+    for (float minSizeRatio : new float[] {Float.MIN_VALUE, 0.01f, 0.1f, 0.9f}) {
+      final FilterCachingPolicy policy = new FilterCachingPolicy.CacheOnLargeSegments(minSizeRatio);
+      for (LeafReaderContext ctx : reader.leaves()) {
+        final Filter filter = new QueryWrapperFilter(new TermQuery(new Term("field", "value")));
+        final DocIdSet set = null;
+        final boolean shouldCache = policy.shouldCache(filter, ctx, set);
+        final float sizeRatio = (float) ctx.reader().maxDoc() / reader.maxDoc();
+        assertEquals(sizeRatio >= minSizeRatio, shouldCache);
+      }
+    }
+    reader.close();
+    w.close();
+    dir.close();
+  }
+
+}

lucene/core/src/test/org/apache/lucene/search/TestUsageTrackingFilterCachingPolicy.java

@@ -0,0 +1,44 @@
+package org.apache.lucene.search;
+
+/*
+ * 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.
+ */
+
+import org.apache.lucene.index.Term;
+import org.apache.lucene.util.LuceneTestCase;
+import org.apache.lucene.util.RoaringDocIdSet;
+
+public class TestUsageTrackingFilterCachingPolicy extends LuceneTestCase {
+
+  public void testCheapToCache() {
+    assertTrue(UsageTrackingFilterCachingPolicy.isCheapToCache(null));
+    assertTrue(UsageTrackingFilterCachingPolicy.isCheapToCache(DocIdSet.EMPTY));
+    assertTrue(UsageTrackingFilterCachingPolicy.isCheapToCache(new RoaringDocIdSet.Builder(5).add(3).build()));
+    assertFalse(UsageTrackingFilterCachingPolicy.isCheapToCache(new DocValuesDocIdSet(5, null) {
+      @Override
+      protected boolean matchDoc(int doc) {
+        return false;
+      }
+    }));
+  }
+
+  public void testCostlyFilter() {
+    assertTrue(UsageTrackingFilterCachingPolicy.isCostly(new PrefixFilter(new Term("field", "prefix"))));
+    assertTrue(UsageTrackingFilterCachingPolicy.isCostly(NumericRangeFilter.newIntRange("intField", 8, 1, 1000, true, true)));
+    assertFalse(UsageTrackingFilterCachingPolicy.isCostly(new QueryWrapperFilter(new TermQuery(new Term("field", "value")))));
+  }
+
+}