| /** |
| * 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.hadoop.tools.rumen; |
| |
| import java.io.BufferedInputStream; |
| import java.io.IOException; |
| import java.io.InputStream; |
| |
| /** |
| * A simple wrapper class to make any input stream "rewindable". It could be |
| * made more memory efficient by grow the internal buffer adaptively. |
| */ |
| public class RewindableInputStream extends InputStream { |
| private InputStream input; |
| |
| /** |
| * Constructor. |
| * |
| * @param input |
| */ |
| public RewindableInputStream(InputStream input) { |
| this(input, 1024 * 1024); |
| } |
| |
| /** |
| * Constructor |
| * |
| * @param input |
| * input stream. |
| * @param maxBytesToRemember |
| * Maximum number of bytes we need to remember at the beginning of |
| * the stream. If {@link #rewind()} is called after so many bytes are |
| * read from the stream, {@link #rewind()} would fail. |
| */ |
| public RewindableInputStream(InputStream input, int maxBytesToRemember) { |
| this.input = new BufferedInputStream(input, maxBytesToRemember); |
| this.input.mark(maxBytesToRemember); |
| } |
| |
| @Override |
| public int read() throws IOException { |
| return input.read(); |
| } |
| |
| @Override |
| public int read(byte[] buffer, int offset, int length) throws IOException { |
| return input.read(buffer, offset, length); |
| } |
| |
| @Override |
| public void close() throws IOException { |
| input.close(); |
| } |
| |
| public InputStream rewind() throws IOException { |
| try { |
| input.reset(); |
| return this; |
| } catch (IOException e) { |
| throw new IOException("Unable to rewind the stream", e); |
| } |
| } |
| } |