Java tutorial
/* * 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.InputStream; import java.io.OutputStream; import org.apache.hadoop.conf.Configurable; import org.apache.hadoop.conf.Configuration; import org.apache.hadoop.io.compress.lz4.Lz4Compressor; import org.apache.hadoop.io.compress.lz4.Lz4Decompressor; import org.apache.hadoop.fs.CommonConfigurationKeys; import org.apache.hadoop.util.NativeCodeLoader; /** * This class creates lz4 compressors/decompressors. */ public class Lz4Codec implements Configurable, CompressionCodec { static { NativeCodeLoader.isNativeCodeLoaded(); } Configuration conf; /** * Set the configuration to be used by this object. * * @param conf the configuration object. */ @Override public void setConf(Configuration conf) { this.conf = conf; } /** * Return the configuration used by this object. * * @return the configuration object used by this objec. */ @Override public Configuration getConf() { return conf; } /** * Are the native lz4 libraries loaded & initialized? * * @return true if loaded & initialized, otherwise false */ public static boolean isNativeCodeLoaded() { return NativeCodeLoader.isNativeCodeLoaded(); } public static String getLibraryName() { return Lz4Compressor.getLibraryName(); } /** * Create a {@link CompressionOutputStream} that will write to the given * {@link OutputStream}. * * @param out the location for the final output stream * @return a stream the user can write uncompressed data to have it compressed * @throws IOException */ @Override public CompressionOutputStream createOutputStream(OutputStream out) throws IOException { return CompressionCodec.Util.createOutputStreamWithCodecPool(this, conf, out); } /** * Create a {@link CompressionOutputStream} that will write to the given * {@link OutputStream} with the given {@link Compressor}. * * @param out the location for the final output stream * @param compressor compressor to use * @return a stream the user can write uncompressed data to have it compressed * @throws IOException */ @Override public CompressionOutputStream createOutputStream(OutputStream out, Compressor compressor) throws IOException { if (!isNativeCodeLoaded()) { throw new RuntimeException("native lz4 library not available"); } int bufferSize = conf.getInt(CommonConfigurationKeys.IO_COMPRESSION_CODEC_LZ4_BUFFERSIZE_KEY, CommonConfigurationKeys.IO_COMPRESSION_CODEC_LZ4_BUFFERSIZE_DEFAULT); int compressionOverhead = bufferSize / 255 + 16; return new BlockCompressorStream(out, compressor, bufferSize, compressionOverhead); } /** * Get the type of {@link Compressor} needed by this {@link CompressionCodec}. * * @return the type of compressor needed by this codec. */ @Override public Class<? extends Compressor> getCompressorType() { if (!isNativeCodeLoaded()) { throw new RuntimeException("native lz4 library not available"); } return Lz4Compressor.class; } /** * Create a new {@link Compressor} for use by this {@link CompressionCodec}. * * @return a new compressor for use by this codec */ @Override public Compressor createCompressor() { if (!isNativeCodeLoaded()) { throw new RuntimeException("native lz4 library not available"); } int bufferSize = conf.getInt(CommonConfigurationKeys.IO_COMPRESSION_CODEC_LZ4_BUFFERSIZE_KEY, CommonConfigurationKeys.IO_COMPRESSION_CODEC_LZ4_BUFFERSIZE_DEFAULT); boolean useLz4HC = conf.getBoolean(CommonConfigurationKeys.IO_COMPRESSION_CODEC_LZ4_USELZ4HC_KEY, CommonConfigurationKeys.IO_COMPRESSION_CODEC_LZ4_USELZ4HC_DEFAULT); return new Lz4Compressor(bufferSize, useLz4HC); } /** * Create a {@link CompressionInputStream} that will read from the given * input stream. * * @param in the stream to read compressed bytes from * @return a stream to read uncompressed bytes from * @throws IOException */ @Override public CompressionInputStream createInputStream(InputStream in) throws IOException { return CompressionCodec.Util.createInputStreamWithCodecPool(this, conf, in); } /** * Create a {@link CompressionInputStream} that will read from the given * {@link InputStream} with the given {@link Decompressor}. * * @param in the stream to read compressed bytes from * @param decompressor decompressor to use * @return a stream to read uncompressed bytes from * @throws IOException */ @Override public CompressionInputStream createInputStream(InputStream in, Decompressor decompressor) throws IOException { if (!isNativeCodeLoaded()) { throw new RuntimeException("native lz4 library not available"); } return new BlockDecompressorStream(in, decompressor, conf.getInt(CommonConfigurationKeys.IO_COMPRESSION_CODEC_LZ4_BUFFERSIZE_KEY, CommonConfigurationKeys.IO_COMPRESSION_CODEC_LZ4_BUFFERSIZE_DEFAULT)); } /** * Get the type of {@link Decompressor} needed by this {@link CompressionCodec}. * * @return the type of decompressor needed by this codec. */ @Override public Class<? extends Decompressor> getDecompressorType() { if (!isNativeCodeLoaded()) { throw new RuntimeException("native lz4 library not available"); } return Lz4Decompressor.class; } /** * Create a new {@link Decompressor} for use by this {@link CompressionCodec}. * * @return a new decompressor for use by this codec */ @Override public Decompressor createDecompressor() { if (!isNativeCodeLoaded()) { throw new RuntimeException("native lz4 library not available"); } int bufferSize = conf.getInt(CommonConfigurationKeys.IO_COMPRESSION_CODEC_LZ4_BUFFERSIZE_KEY, CommonConfigurationKeys.IO_COMPRESSION_CODEC_LZ4_BUFFERSIZE_DEFAULT); return new Lz4Decompressor(bufferSize); } /** * Get the default filename extension for this kind of compression. * * @return <code>.lz4</code>. */ @Override public String getDefaultExtension() { return ".lz4"; } }