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Lucene example source code file (TestMergeSchedulerExternal.java)

This example Lucene source code file (TestMergeSchedulerExternal.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Java - Lucene tags/keywords

corruptindexexception, document, document, failonlyonmerge, indexwriter, indexwriter, io, ioexception, ioexception, logmergepolicy, mergethread, mymergescheduler, mymergethread, override, override

The Lucene TestMergeSchedulerExternal.java source code

package org.apache.lucene;

/**
 * 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.store.Directory;
import org.apache.lucene.store.MockDirectoryWrapper;
import org.apache.lucene.store.RAMDirectory;
import org.apache.lucene.index.CorruptIndexException;
import org.apache.lucene.index.IndexWriter;
import org.apache.lucene.index.IndexWriterConfig;
import org.apache.lucene.index.LogMergePolicy;
import org.apache.lucene.index.MergePolicy;
import org.apache.lucene.index.ConcurrentMergeScheduler;
import org.apache.lucene.index.MergeScheduler;
import org.apache.lucene.index.MergePolicy.OneMerge;
import org.apache.lucene.analysis.MockAnalyzer;
import org.apache.lucene.document.Document;
import org.apache.lucene.document.Field;

/**
 * Holds tests cases to verify external APIs are accessible
 * while not being in org.apache.lucene.index package.
 */
public class TestMergeSchedulerExternal extends LuceneTestCase {

  volatile boolean mergeCalled;
  volatile boolean mergeThreadCreated;
  volatile boolean excCalled;

  private class MyMergeScheduler extends ConcurrentMergeScheduler {

    private class MyMergeThread extends ConcurrentMergeScheduler.MergeThread {
      public MyMergeThread(IndexWriter writer, MergePolicy.OneMerge merge) throws IOException {
        super(writer, merge);
        mergeThreadCreated = true;
      }
    }

    @Override
    protected MergeThread getMergeThread(IndexWriter writer, MergePolicy.OneMerge merge) throws IOException {
      MergeThread thread = new MyMergeThread(writer, merge);
      thread.setThreadPriority(getMergeThreadPriority());
      thread.setDaemon(true);
      thread.setName("MyMergeThread");
      return thread;
    }

    @Override
    protected void handleMergeException(Throwable t) {
      excCalled = true;
    }

    @Override
    protected void doMerge(MergePolicy.OneMerge merge) throws IOException {
      mergeCalled = true;
      super.doMerge(merge);
    }
  }

  private static class FailOnlyOnMerge extends MockDirectoryWrapper.Failure {
    @Override
    public void eval(MockDirectoryWrapper dir)  throws IOException {
      StackTraceElement[] trace = new Exception().getStackTrace();
      for (int i = 0; i < trace.length; i++) {
        if ("doMerge".equals(trace[i].getMethodName()))
          throw new IOException("now failing during merge");
      }
    }
  }

  public void testSubclassConcurrentMergeScheduler() throws IOException {
    MockDirectoryWrapper dir = newDirectory();
    dir.failOn(new FailOnlyOnMerge());

    Document doc = new Document();
    Field idField = newField("id", "", Field.Store.YES, Field.Index.NOT_ANALYZED);
    doc.add(idField);
    
    IndexWriter writer = new IndexWriter(dir, newIndexWriterConfig(
        TEST_VERSION_CURRENT, new MockAnalyzer(random)).setMergeScheduler(new MyMergeScheduler())
        .setMaxBufferedDocs(2).setRAMBufferSizeMB(IndexWriterConfig.DISABLE_AUTO_FLUSH)
        .setMergePolicy(newLogMergePolicy()));
    LogMergePolicy logMP = (LogMergePolicy) writer.getConfig().getMergePolicy();
    logMP.setMergeFactor(10);
    for(int i=0;i<20;i++)
      writer.addDocument(doc);

    ((MyMergeScheduler) writer.getConfig().getMergeScheduler()).sync();
    writer.close();
    
    assertTrue(mergeThreadCreated);
    assertTrue(mergeCalled);
    assertTrue(excCalled);
    dir.close();
  }
  
  private static class ReportingMergeScheduler extends MergeScheduler {

    @Override
    public void merge(IndexWriter writer) throws CorruptIndexException, IOException {
      OneMerge merge = null;
      while ((merge = writer.getNextMerge()) != null) {
        if (VERBOSE) {
          System.out.println("executing merge " + merge.segString(writer.getDirectory()));
        }
        writer.merge(merge);
      }
    }

    @Override
    public void close() throws CorruptIndexException, IOException {}
    
  }

  public void testCustomMergeScheduler() throws Exception {
    // we don't really need to execute anything, just to make sure the custom MS
    // compiles. But ensure that it can be used as well, e.g., no other hidden
    // dependencies or something. Therefore, don't use any random API !
    Directory dir = new RAMDirectory();
    IndexWriterConfig conf = new IndexWriterConfig(TEST_VERSION_CURRENT, null);
    conf.setMergeScheduler(new ReportingMergeScheduler());
    IndexWriter writer = new IndexWriter(dir, conf);
    writer.addDocument(new Document());
    writer.commit(); // trigger flush
    writer.addDocument(new Document());
    writer.commit(); // trigger flush
    writer.optimize();
    writer.close();
    dir.close();
  }
  
}

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