001 /*
002 * Licensed to the Apache Software Foundation (ASF) under one
003 * or more contributor license agreements. See the NOTICE file
004 * distributed with this work for additional information
005 * regarding copyright ownership. The ASF licenses this file
006 * to you under the Apache License, Version 2.0 (the
007 * "License"); you may not use this file except in compliance
008 * with the License. You may obtain a copy of the License at
009 *
010 * http://www.apache.org/licenses/LICENSE-2.0
011 *
012 * Unless required by applicable law or agreed to in writing, software
013 * distributed under the License is distributed on an "AS IS" BASIS,
014 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
015 * See the License for the specific language governing permissions and
016 * limitations under the License.
017 */
018
019 package org.apache.hadoop.io.compress;
020
021 import java.io.IOException;
022 import java.io.InputStream;
023 import java.io.OutputStream;
024
025 import org.apache.hadoop.conf.Configurable;
026 import org.apache.hadoop.conf.Configuration;
027 import org.apache.hadoop.io.compress.snappy.SnappyCompressor;
028 import org.apache.hadoop.io.compress.snappy.SnappyDecompressor;
029 import org.apache.hadoop.fs.CommonConfigurationKeys;
030 import org.apache.hadoop.util.NativeCodeLoader;
031
032 /**
033 * This class creates snappy compressors/decompressors.
034 */
035 public class SnappyCodec implements Configurable, CompressionCodec {
036 Configuration conf;
037
038 /**
039 * Set the configuration to be used by this object.
040 *
041 * @param conf the configuration object.
042 */
043 @Override
044 public void setConf(Configuration conf) {
045 this.conf = conf;
046 }
047
048 /**
049 * Return the configuration used by this object.
050 *
051 * @return the configuration object used by this objec.
052 */
053 @Override
054 public Configuration getConf() {
055 return conf;
056 }
057
058 /**
059 * Are the native snappy libraries loaded & initialized?
060 */
061 public static void checkNativeCodeLoaded() {
062 if (!NativeCodeLoader.buildSupportsSnappy()) {
063 throw new RuntimeException("native snappy library not available: " +
064 "this version of libhadoop was built without " +
065 "snappy support.");
066 }
067 if (!SnappyCompressor.isNativeCodeLoaded()) {
068 throw new RuntimeException("native snappy library not available: " +
069 "SnappyCompressor has not been loaded.");
070 }
071 if (!SnappyDecompressor.isNativeCodeLoaded()) {
072 throw new RuntimeException("native snappy library not available: " +
073 "SnappyDecompressor has not been loaded.");
074 }
075 }
076
077 public static boolean isNativeCodeLoaded() {
078 return SnappyCompressor.isNativeCodeLoaded() &&
079 SnappyDecompressor.isNativeCodeLoaded();
080 }
081
082 /**
083 * Create a {@link CompressionOutputStream} that will write to the given
084 * {@link OutputStream}.
085 *
086 * @param out the location for the final output stream
087 * @return a stream the user can write uncompressed data to have it compressed
088 * @throws IOException
089 */
090 @Override
091 public CompressionOutputStream createOutputStream(OutputStream out)
092 throws IOException {
093 return createOutputStream(out, createCompressor());
094 }
095
096 /**
097 * Create a {@link CompressionOutputStream} that will write to the given
098 * {@link OutputStream} with the given {@link Compressor}.
099 *
100 * @param out the location for the final output stream
101 * @param compressor compressor to use
102 * @return a stream the user can write uncompressed data to have it compressed
103 * @throws IOException
104 */
105 @Override
106 public CompressionOutputStream createOutputStream(OutputStream out,
107 Compressor compressor)
108 throws IOException {
109 checkNativeCodeLoaded();
110 int bufferSize = conf.getInt(
111 CommonConfigurationKeys.IO_COMPRESSION_CODEC_SNAPPY_BUFFERSIZE_KEY,
112 CommonConfigurationKeys.IO_COMPRESSION_CODEC_SNAPPY_BUFFERSIZE_DEFAULT);
113
114 int compressionOverhead = (bufferSize / 6) + 32;
115
116 return new BlockCompressorStream(out, compressor, bufferSize,
117 compressionOverhead);
118 }
119
120 /**
121 * Get the type of {@link Compressor} needed by this {@link CompressionCodec}.
122 *
123 * @return the type of compressor needed by this codec.
124 */
125 @Override
126 public Class<? extends Compressor> getCompressorType() {
127 checkNativeCodeLoaded();
128 return SnappyCompressor.class;
129 }
130
131 /**
132 * Create a new {@link Compressor} for use by this {@link CompressionCodec}.
133 *
134 * @return a new compressor for use by this codec
135 */
136 @Override
137 public Compressor createCompressor() {
138 checkNativeCodeLoaded();
139 int bufferSize = conf.getInt(
140 CommonConfigurationKeys.IO_COMPRESSION_CODEC_SNAPPY_BUFFERSIZE_KEY,
141 CommonConfigurationKeys.IO_COMPRESSION_CODEC_SNAPPY_BUFFERSIZE_DEFAULT);
142 return new SnappyCompressor(bufferSize);
143 }
144
145 /**
146 * Create a {@link CompressionInputStream} that will read from the given
147 * input stream.
148 *
149 * @param in the stream to read compressed bytes from
150 * @return a stream to read uncompressed bytes from
151 * @throws IOException
152 */
153 @Override
154 public CompressionInputStream createInputStream(InputStream in)
155 throws IOException {
156 return createInputStream(in, createDecompressor());
157 }
158
159 /**
160 * Create a {@link CompressionInputStream} that will read from the given
161 * {@link InputStream} with the given {@link Decompressor}.
162 *
163 * @param in the stream to read compressed bytes from
164 * @param decompressor decompressor to use
165 * @return a stream to read uncompressed bytes from
166 * @throws IOException
167 */
168 @Override
169 public CompressionInputStream createInputStream(InputStream in,
170 Decompressor decompressor)
171 throws IOException {
172 checkNativeCodeLoaded();
173 return new BlockDecompressorStream(in, decompressor, conf.getInt(
174 CommonConfigurationKeys.IO_COMPRESSION_CODEC_SNAPPY_BUFFERSIZE_KEY,
175 CommonConfigurationKeys.IO_COMPRESSION_CODEC_SNAPPY_BUFFERSIZE_DEFAULT));
176 }
177
178 /**
179 * Get the type of {@link Decompressor} needed by this {@link CompressionCodec}.
180 *
181 * @return the type of decompressor needed by this codec.
182 */
183 @Override
184 public Class<? extends Decompressor> getDecompressorType() {
185 checkNativeCodeLoaded();
186 return SnappyDecompressor.class;
187 }
188
189 /**
190 * Create a new {@link Decompressor} for use by this {@link CompressionCodec}.
191 *
192 * @return a new decompressor for use by this codec
193 */
194 @Override
195 public Decompressor createDecompressor() {
196 checkNativeCodeLoaded();
197 int bufferSize = conf.getInt(
198 CommonConfigurationKeys.IO_COMPRESSION_CODEC_SNAPPY_BUFFERSIZE_KEY,
199 CommonConfigurationKeys.IO_COMPRESSION_CODEC_SNAPPY_BUFFERSIZE_DEFAULT);
200 return new SnappyDecompressor(bufferSize);
201 }
202
203 /**
204 * Get the default filename extension for this kind of compression.
205 *
206 * @return <code>.snappy</code>.
207 */
208 @Override
209 public String getDefaultExtension() {
210 return ".snappy";
211 }
212 }