content: /**
   * 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.
   */
  package org.littleshoot.proxy;
  
  import java.io.IOException;
  import java.io.InputStream;
  
  /**
   * 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 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;
    }
  
    /** @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;
    }
  
    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 +
          '}';
    }
  }