runtime/executor/src/main/java/org/apache/nemo/runtime/executor/data/LimitedInputStream.java

/*
 * 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.apache.nemo.runtime.executor.data;

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

/**
 * This class provide functionality to limit bytes read from {@link InputStream}.
 * You need to wrap chained compression stream with this stream to prevent overreading
 * inner stream.
 */
public final class LimitedInputStream extends InputStream {
  private final InputStream in;
  private long limit;

  /**
   * Constructor.
   *
   * @param in    {@link InputStream} that should be limited.
   * @param limit bytes to limit.
   */
  public LimitedInputStream(final InputStream in, final long limit) {
    this.in = in;
    this.limit = limit;
  }

  @Override
  public int read() throws IOException {
    if (limit > 0) {
      limit--;
      return in.read();
    } else {
      return -1;
    }
  }
}