com.hotels.bdp.circustrain.s3mapreducecp.io.ThrottledInputStream Maven / Gradle / Ivy

Go to download
/**
 * Copyright (C) 2016-2017 Expedia Inc and Apache Hadoop contributors.
 *
 * Based on {@code org.apache.hadoop.tools.util.ThrottledInputStream} from Hadoop DistCp 2.7.1:
 *
 * https://github.com/apache/hadoop/blob/release-2.7.1/hadoop-tools/hadoop-distcp/src/main/java/org/
 * apache/hadoop/tools/util/ThrottledInputStream.java
 *
 * Licensed 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 com.hotels.bdp.circustrain.s3mapreducecp.io;

import java.io.IOException;
import java.io.InputStream;

import org.apache.hadoop.fs.PositionedReadable;

/**
 * The ThrottleInputStream provides bandwidth throttling on a specified InputStream. It is implemented as a wrapper on
 * top of another InputStream instance. The throttling works by examining the number of bytes read from the underlying
 * InputStream from the beginning, and sleep()ing for a time interval if the byte-transfer is found to exceed the
 * specified tolerable maximum. (Thus, while the read-rate might exceed the maximum for a given short interval, the
 * average tends towards the specified maximum, overall.)
 */
public class ThrottledInputStream extends InputStream {

  private final InputStream rawStream;
  private final long maxBytesPerSec;
  private final long startTime = System.currentTimeMillis();

  private long bytesRead = 0;
  private long totalSleepTime = 0;

  private static final long SLEEP_DURATION_MS = 50;

  public ThrottledInputStream(InputStream rawStream) {
    this(rawStream, Long.MAX_VALUE);
  }

  public ThrottledInputStream(InputStream rawStream, long maxBytesPerSec) {
    assert maxBytesPerSec > 0 : "Bandwidth " + maxBytesPerSec + " is invalid";
    this.rawStream = rawStream;
    this.maxBytesPerSec = maxBytesPerSec;
  }

  @Override
  public void close() throws IOException {
    rawStream.close();
  }

  /** @inheritDoc */
  @Override
  public int read() throws IOException {
    throttle();
    int data = rawStream.read();
    if (data != -1) {
      bytesRead++;
    }
    return data;
  }

  /** @inheritDoc */
  @Override
  public int read(byte[] b) throws IOException {
    throttle();
    int readLen = rawStream.read(b);
    if (readLen != -1) {
      bytesRead += readLen;
    }
    return readLen;
  }

  /** @inheritDoc */
  @Override
  public int read(byte[] b, int off, int len) throws IOException {
    throttle();
    int readLen = rawStream.read(b, off, len);
    if (readLen != -1) {
      bytesRead += readLen;
    }
    return readLen;
  }

  /**
   * Read bytes starting from the specified position. This requires rawStream is an instance of
   * {@link PositionedReadable}.
   */
  public int read(long position, byte[] buffer, int offset, int length) throws IOException {
    if (!(rawStream instanceof PositionedReadable)) {
      throw new UnsupportedOperationException("positioned read is not supported by the internal stream");
    }
    throttle();
    int readLen = ((PositionedReadable) rawStream).read(position, buffer, offset, length);
    if (readLen != -1) {
      bytesRead += readLen;
    }
    return readLen;
  }

  private void throttle() throws IOException {
    if (getBytesPerSec() > maxBytesPerSec) {
      try {
        Thread.sleep(SLEEP_DURATION_MS);
        totalSleepTime += SLEEP_DURATION_MS;
      } catch (InterruptedException e) {
        throw new IOException("Thread aborted", e);
      }
    }
  }

  /**
   * Getter for the number of bytes read from this stream, since creation.
   *
   * @return The number of bytes.
   */
  public long getTotalBytesRead() {
    return bytesRead;
  }

  /**
   * Getter for the read-rate from this stream, since creation. Calculated as bytesRead/elapsedTimeSinceStart.
   *
   * @return Read rate, in bytes/sec.
   */
  public long getBytesPerSec() {
    long elapsed = (System.currentTimeMillis() - startTime) / 1000;
    if (elapsed == 0) {
      return bytesRead;
    } else {
      return bytesRead / elapsed;
    }
  }

  /**
   * Getter the total time spent in sleep.
   *
   * @return Number of milliseconds spent in sleep.
   */
  public long getTotalSleepTime() {
    return totalSleepTime;
  }

  /** @inheritDoc */
  @Override
  public String toString() {
    return "ThrottledInputStream{"
        + "bytesRead="
        + bytesRead
        + ", maxBytesPerSec="
        + maxBytesPerSec
        + ", bytesPerSec="
        + getBytesPerSec()
        + ", totalSleepTime="
        + totalSleepTime
        + '}';
  }
}