Lucene example source code file (ThrottledIndexOutput.java)

This example Lucene source code file (ThrottledIndexOutput.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

default_min_written_bytes, indexoutput, indexoutput, interruptedexception, io, ioexception, ioexception, override, override, threadinterruptedexception, throttledindexoutput, throttledindexoutput

The Lucene ThrottledIndexOutput.java source code

package org.apache.lucene.util;

/**
 * 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.store.IndexInput;
import org.apache.lucene.store.IndexOutput;

public class ThrottledIndexOutput extends IndexOutput {
  public static final int DEFAULT_MIN_WRITTEN_BYTES = 1024;
  private final int bytesPerSecond;
  private IndexOutput delegate;
  private long flushDelayMillis;
  private long closeDelayMillis;
  private long seekDelayMillis;
  private long pendingBytes;
  private long minBytesWritten;
  private long timeElapsed;
  private final byte[] bytes = new byte[1];

  public ThrottledIndexOutput newFromDelegate(IndexOutput output) {
    return new ThrottledIndexOutput(bytesPerSecond, flushDelayMillis,
        closeDelayMillis, seekDelayMillis, minBytesWritten, output);
  }

  public ThrottledIndexOutput(int bytesPerSecond, long delayInMillis,
      IndexOutput delegate) {
    this(bytesPerSecond, delayInMillis, delayInMillis, delayInMillis,
        DEFAULT_MIN_WRITTEN_BYTES, delegate);
  }

  public ThrottledIndexOutput(int bytesPerSecond, long delays,
      int minBytesWritten, IndexOutput delegate) {
    this(bytesPerSecond, delays, delays, delays, minBytesWritten, delegate);
  }

  public static final int mBitsToBytes(int mbits) {
    return mbits * 125000;
  }

  public ThrottledIndexOutput(int bytesPerSecond, long flushDelayMillis,
      long closeDelayMillis, long seekDelayMillis, long minBytesWritten,
      IndexOutput delegate) {
    assert bytesPerSecond > 0;
    this.delegate = delegate;
    this.bytesPerSecond = bytesPerSecond;
    this.flushDelayMillis = flushDelayMillis;
    this.closeDelayMillis = closeDelayMillis;
    this.seekDelayMillis = seekDelayMillis;
    this.minBytesWritten = minBytesWritten;
  }

  @Override
  public void flush() throws IOException {
    sleep(flushDelayMillis);
    delegate.flush();
  }

  @Override
  public void close() throws IOException {
    sleep(closeDelayMillis + getDelay(true));
    delegate.close();

  }

  @Override
  public long getFilePointer() {
    return delegate.getFilePointer();
  }

  @Override
  public void seek(long pos) throws IOException {
    sleep(seekDelayMillis);
    delegate.seek(pos);
  }

  @Override
  public long length() throws IOException {
    return delegate.length();
  }

  @Override
  public void writeByte(byte b) throws IOException {
    bytes[0] = b;
    writeBytes(bytes, 0, 1);
  }

  @Override
  public void writeBytes(byte[] b, int offset, int length) throws IOException {
    final long before = System.nanoTime();
    delegate.writeBytes(b, offset, length);
    timeElapsed += System.nanoTime() - before;
    pendingBytes += length;
    sleep(getDelay(false));

  }

  protected long getDelay(boolean closing) {
    if (pendingBytes > 0 && (closing || pendingBytes > minBytesWritten)) {
      long actualBps = (timeElapsed / pendingBytes) * 1000000000l; // nano to sec
      if (actualBps > bytesPerSecond) {
        long expected = (pendingBytes * 1000l / bytesPerSecond) ;
        final long delay = expected - (timeElapsed / 1000000l) ;
        pendingBytes = 0;
        timeElapsed = 0;
        return delay;
      }
    }
    return 0;

  }

  private static final void sleep(long ms) {
    if (ms <= 0)
      return;
    try {
      Thread.sleep(ms);
    } catch (InterruptedException e) {
      throw new ThreadInterruptedException(e);
    }
  }
  
  @Override
  public void setLength(long length) throws IOException {
    delegate.setLength(length);
  }

  @Override
  public void copyBytes(IndexInput input, long numBytes) throws IOException {
    delegate.copyBytes(input, numBytes);
  }
}