/**
* 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.tajo.storage.compress;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.io.compress.CompressionCodec;
import org.apache.hadoop.io.compress.Compressor;
import org.apache.hadoop.io.compress.Decompressor;
import org.apache.hadoop.io.compress.DoNotPool;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
/**
* A global compressor/decompressor pool used to save and reuse (possibly
* native) compression/decompression codecs.
*/
public final class CodecPool {
private static final Log LOG = LogFactory.getLog(CodecPool.class);
/**
* A global compressor pool used to save the expensive
* construction/destruction of (possibly native) decompression codecs.
*/
private static final Map<Class<Compressor>, List<Compressor>> COMPRESSOR_POOL =
new HashMap<Class<Compressor>, List<Compressor>>();
/**
* A global decompressor pool used to save the expensive
* construction/destruction of (possibly native) decompression codecs.
*/
private static final Map<Class<Decompressor>, List<Decompressor>> DECOMPRESSOR_POOL =
new HashMap<Class<Decompressor>, List<Decompressor>>();
private static <T> T borrow(Map<Class<T>, List<T>> pool,
Class<? extends T> codecClass) {
T codec = null;
// Check if an appropriate codec is available
synchronized (pool) {
if (pool.containsKey(codecClass)) {
List<T> codecList = pool.get(codecClass);
if (codecList != null) {
synchronized (codecList) {
if (!codecList.isEmpty()) {
codec = codecList.remove(codecList.size() - 1);
}
}
}
}
}
return codec;
}
private static <T> void payback(Map<Class<T>, List<T>> pool, T codec) {
if (codec != null) {
Class<T> codecClass = (Class<T>) codec.getClass();
synchronized (pool) {
if (!pool.containsKey(codecClass)) {
pool.put(codecClass, new ArrayList<T>());
}
List<T> codecList = pool.get(codecClass);
synchronized (codecList) {
codecList.add(codec);
}
}
}
}
/**
* Get a {@link Compressor} for the given {@link CompressionCodec} from the
* pool or a new one.
*
* @param codec
* the <code>CompressionCodec</code> for which to get the
* <code>Compressor</code>
* @param conf the <code>Configuration</code> object which contains confs for creating or reinit the compressor
* @return <code>Compressor</code> for the given <code>CompressionCodec</code>
* from the pool or a new one
*/
public static Compressor getCompressor(CompressionCodec codec, Configuration conf) {
Compressor compressor = borrow(COMPRESSOR_POOL, codec.getCompressorType());
if (compressor == null) {
compressor = codec.createCompressor();
LOG.info("Got brand-new compressor ["+codec.getDefaultExtension()+"]");
} else {
compressor.reinit(conf);
if(LOG.isDebugEnabled()) {
LOG.debug("Got recycled compressor");
}
}
return compressor;
}
public static Compressor getCompressor(CompressionCodec codec) {
return getCompressor(codec, null);
}
/**
* Get a {@link Decompressor} for the given {@link CompressionCodec} from the
* pool or a new one.
*
* @param codec
* the <code>CompressionCodec</code> for which to get the
* <code>Decompressor</code>
* @return <code>Decompressor</code> for the given
* <code>CompressionCodec</code> the pool or a new one
*/
public static Decompressor getDecompressor(CompressionCodec codec) {
Decompressor decompressor = borrow(DECOMPRESSOR_POOL, codec
.getDecompressorType());
if (decompressor == null) {
decompressor = codec.createDecompressor();
LOG.info("Got brand-new decompressor ["+codec.getDefaultExtension()+"]");
} else {
if(LOG.isDebugEnabled()) {
LOG.debug("Got recycled decompressor");
}
}
return decompressor;
}
/**
* Return the {@link Compressor} to the pool.
*
* @param compressor
* the <code>Compressor</code> to be returned to the pool
*/
public static void returnCompressor(Compressor compressor) {
if (compressor == null) {
return;
}
// if the compressor can't be reused, don't pool it.
if (compressor.getClass().isAnnotationPresent(DoNotPool.class)) {
return;
}
compressor.reset();
payback(COMPRESSOR_POOL, compressor);
}
/**
* Return the {@link Decompressor} to the pool.
*
* @param decompressor
* the <code>Decompressor</code> to be returned to the pool
*/
public static void returnDecompressor(Decompressor decompressor) {
if (decompressor == null) {
return;
}
// if the decompressor can't be reused, don't pool it.
if (decompressor.getClass().isAnnotationPresent(DoNotPool.class)) {
return;
}
decompressor.reset();
payback(DECOMPRESSOR_POOL, decompressor);
}
private CodecPool() {
// prevent instantiation
}
}