content: /*
   * The Alluxio Open Foundation licenses this work under the Apache License, version 2.0
   * (the "License"). You may not use this work except in compliance with the License, which is
   * available at www.apache.org/licenses/LICENSE-2.0
   *
   * This software is distributed on an "AS IS" basis, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND,
   * either express or implied, as more fully set forth in the License.
   *
   * See the NOTICE file distributed with this work for information regarding copyright ownership.
   */
  
  package alluxio.proxy.s3;
  
  import com.google.common.util.concurrent.RateLimiter;
  
  import java.io.IOException;
  import java.io.InputStream;
  
  /**
   * This class is a wrapper for InputStream which limit rate when reading bytes.
   */
  public class RateLimitInputStream extends InputStream {
  
    private final InputStream mInputStream;
    private final RateLimiter[] mRateLimiters;
  
    /**
     * Constructs a new {@link RateLimitInputStream}.
     *
     * @param inputStream  Original stream to be limited
     * @param rateLimiters RateLimiters to limit Maximal reading bytes per second
     */
    public RateLimitInputStream(InputStream inputStream, RateLimiter... rateLimiters) {
      mInputStream = inputStream;
      mRateLimiters = rateLimiters;
    }
  
    @Override
    public int read() throws IOException {
      acquire(1);
      return mInputStream.read();
    }
  
    @Override
    public int read(byte[] b) throws IOException {
      return read(b, 0, b.length);
    }
  
    @Override
    public int read(byte[] b, int off, int len) throws IOException {
      acquire(Math.min(b.length - off, len));
      return mInputStream.read(b, off, len);
    }
  
    @Override
    public void close() throws IOException {
      mInputStream.close();
    }
  
    private void acquire(int permits) {
      for (RateLimiter rateLimiter : mRateLimiters) {
        if (rateLimiter == null) {
          continue;
        }
        rateLimiter.acquire(permits);
      }
    }
  }
  