org.apache.hadoop.io.compress.CompressionOutputStream.java Source code

Introduction

Here is the source code for org.apache.hadoop.io.compress.CompressionOutputStream.java

Source

/*
 * 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.io.compress;

import java.io.IOException;
import java.io.OutputStream;

import org.apache.hadoop.classification.InterfaceAudience;
import org.apache.hadoop.classification.InterfaceStability;

/**
 * A compression output stream.
 */
@InterfaceAudience.Public
@InterfaceStability.Evolving
public abstract class CompressionOutputStream extends OutputStream {
    /**
     * The output stream to be compressed. 
     */
    protected final OutputStream out;

    /**
     * If non-null, this is the Compressor object that we should call
     * CodecPool#returnCompressor on when this stream is closed.
     */
    private Compressor trackedCompressor;

    /**
     * Create a compression output stream that writes
     * the compressed bytes to the given stream.
     * @param out
     */
    protected CompressionOutputStream(OutputStream out) {
        this.out = out;
    }

    void setTrackedCompressor(Compressor compressor) {
        trackedCompressor = compressor;
    }

    @Override
    public void close() throws IOException {
        try {
            finish();
        } finally {
            try {
                out.close();
            } finally {
                if (trackedCompressor != null) {
                    CodecPool.returnCompressor(trackedCompressor);
                    trackedCompressor = null;
                }
            }
        }
    }

    @Override
    public void flush() throws IOException {
        out.flush();
    }

    /**
     * Write compressed bytes to the stream.
     * Made abstract to prevent leakage to underlying stream.
     */
    @Override
    public abstract void write(byte[] b, int off, int len) throws IOException;

    /**
     * Finishes writing compressed data to the output stream 
     * without closing the underlying stream.
     */
    public abstract void finish() throws IOException;

    /**
     * Reset the compression to the initial state. 
     * Does not reset the underlying stream.
     */
    public abstract void resetState() throws IOException;

}