LUCENE-1918: fix corner cases (resulting in exceptions) when passing ParallelReader to IndexWriter.addIndexes

git-svn-id: https://svn.apache.org/repos/asf/lucene/java/trunk@816602 13f79535-47bb-0310-9956-ffa450edef68

CHANGES.txt

@@ -559,6 +559,13 @@ Bug fixes
     OpenBitSet, due to an inefficiency in how the underlying storage is
     reallocated.  (Nadav Har'El via Mike McCandless)
 
+ * LUCENE-1918: Fixed cases where a ParallelReader would
+   generate exceptions on being passed to
+   IndexWriter.addIndexes(IndexReader[]).  First case was when the
+   ParallelReader was empty.  Second case was when the ParallelReader
+   used to contain documents with TermVectors, but all such documents
+   have been deleted. (Christian Kohlschütter via Mike McCandless)
+
 New features
 
  * LUCENE-1411: Added expert API to open an IndexWriter on a prior

src/java/org/apache/lucene/index/ParallelReader.java

@@ -472,7 +472,12 @@ public class ParallelReader extends IndexReader {
     private TermEnum termEnum;
 
     public ParallelTermEnum() throws IOException {
-      field = (String)fieldToReader.firstKey();
+      try {
+        field = (String)fieldToReader.firstKey();
+      } catch(NoSuchElementException e) {
+        // No fields, so keep field == null, termEnum == null
+        return;
+      }
       if (field != null)
         termEnum = ((IndexReader)fieldToReader.get(field)).terms();
     }

src/java/org/apache/lucene/index/TermVectorsWriter.java

@@ -156,11 +156,13 @@ final class TermVectorsWriter {
       }
 
       // 2nd pass: write field pointers to tvd
-      long lastFieldPointer = fieldPointers[0];
-      for (int i=1; i<numFields; i++) {
-        final long fieldPointer = fieldPointers[i];
-        tvd.writeVLong(fieldPointer-lastFieldPointer);
-        lastFieldPointer = fieldPointer;
+      if (numFields > 1) {
+        long lastFieldPointer = fieldPointers[0];
+        for (int i=1; i<numFields; i++) {
+          final long fieldPointer = fieldPointers[i];
+          tvd.writeVLong(fieldPointer-lastFieldPointer);
+          lastFieldPointer = fieldPointer;
+        }
       }
     } else
       tvd.writeVInt(0);

src/test/org/apache/lucene/index/TestParallelReaderEmptyIndex.java

@@ -0,0 +1,136 @@
+package org.apache.lucene.index;
+
+/**
+ * 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.util.LuceneTestCase;
+import org.apache.lucene.util._TestUtil;
+
+import org.apache.lucene.analysis.SimpleAnalyzer;
+import org.apache.lucene.document.Document;
+import org.apache.lucene.document.Field;
+import org.apache.lucene.document.Field.Index;
+import org.apache.lucene.document.Field.Store;
+import org.apache.lucene.document.Field.TermVector;
+import org.apache.lucene.index.IndexWriter.MaxFieldLength;
+import org.apache.lucene.store.MockRAMDirectory;
+import org.apache.lucene.store.RAMDirectory;
+
+/**
+ * Some tests for {@link ParallelReader}s with empty indexes
+ * 
+ * @author Christian Kohlschuetter
+ */
+public class TestParallelReaderEmptyIndex extends LuceneTestCase {
+
+  /**
+   * Creates two empty indexes and wraps a ParallelReader around. Adding this
+   * reader to a new index should not throw any exception.
+   * 
+   * @throws IOException
+   */
+  public void testEmptyIndex() throws IOException {
+    RAMDirectory rd1 = new MockRAMDirectory();
+    IndexWriter iw = new IndexWriter(rd1, new SimpleAnalyzer(), true,
+                                     MaxFieldLength.UNLIMITED);
+    iw.close();
+
+    RAMDirectory rd2 = new MockRAMDirectory(rd1);
+
+    RAMDirectory rdOut = new MockRAMDirectory();
+
+    IndexWriter iwOut = new IndexWriter(rdOut, new SimpleAnalyzer(), true,
+                                        MaxFieldLength.UNLIMITED);
+    ParallelReader pr = new ParallelReader();
+    pr.add(IndexReader.open(rd1,true));
+    pr.add(IndexReader.open(rd2,true));
+		
+    // When unpatched, Lucene crashes here with a NoSuchElementException (caused by ParallelTermEnum)
+    iwOut.addIndexes(new IndexReader[] { pr });
+		
+    iwOut.optimize();
+    iwOut.close();
+    _TestUtil.checkIndex(rdOut);
+    rdOut.close();
+    rd1.close();
+    rd2.close();
+  }
+
+  /**
+   * This method creates an empty index (numFields=0, numDocs=0) but is marked
+   * to have TermVectors. Adding this index to another index should not throw
+   * any exception.
+   */
+  public void testEmptyIndexWithVectors() throws IOException {
+    RAMDirectory rd1 = new MockRAMDirectory();
+    {
+      IndexWriter iw = new IndexWriter(rd1, new SimpleAnalyzer(), true,
+                                       MaxFieldLength.UNLIMITED);
+      Document doc = new Document();
+      doc.add(new Field("test", "", Store.NO, Index.ANALYZED,
+                        TermVector.YES));
+      iw.addDocument(doc);
+      doc.add(new Field("test", "", Store.NO, Index.ANALYZED,
+                        TermVector.NO));
+      iw.addDocument(doc);
+      iw.close();
+
+      IndexReader ir = IndexReader.open(rd1,false);
+      ir.deleteDocument(0);
+      ir.close();
+
+      iw = new IndexWriter(rd1, new SimpleAnalyzer(), false,
+                           MaxFieldLength.UNLIMITED);
+      iw.optimize();
+      iw.close();
+    }
+
+    RAMDirectory rd2 = new MockRAMDirectory();
+    {
+      IndexWriter iw = new IndexWriter(rd2, new SimpleAnalyzer(), true,
+                                       MaxFieldLength.UNLIMITED);
+      Document doc = new Document();
+      iw.addDocument(doc);
+      iw.close();
+    }
+
+    RAMDirectory rdOut = new MockRAMDirectory();
+
+    IndexWriter iwOut = new IndexWriter(rdOut, new SimpleAnalyzer(), true,
+                                        MaxFieldLength.UNLIMITED);
+    ParallelReader pr = new ParallelReader();
+    pr.add(IndexReader.open(rd1,true));
+    pr.add(IndexReader.open(rd2,true));
+
+    // When unpatched, Lucene crashes here with an ArrayIndexOutOfBoundsException (caused by TermVectorsWriter)
+    iwOut.addIndexes(new IndexReader[] { pr });
+
+    // ParallelReader closes any IndexReader you added to it:
+    pr.close();
+
+    rd1.close();
+    rd2.close();
+		
+    iwOut.optimize();
+    iwOut.close();
+    
+    _TestUtil.checkIndex(rdOut);
+    rdOut.close();
+  }
+}