/tags/release-0.0.0-rc0/hive/external/ql/src/java/org/apache/hadoop/hive/ql/io/CodecPool.java
Java | 164 lines | 85 code | 16 blank | 63 comment | 17 complexity | 3630c900fb7658f18adb6be2e6808c95 MD5 | raw file
Possible License(s): Apache-2.0, BSD-3-Clause, JSON, CPL-1.0
- /**
- * 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.hive.ql.io;
- import java.util.ArrayList;
- import java.util.HashMap;
- import java.util.List;
- import java.util.Map;
- import org.apache.commons.logging.Log;
- import org.apache.commons.logging.LogFactory;
- import org.apache.hadoop.io.compress.CompressionCodec;
- import org.apache.hadoop.io.compress.Compressor;
- import org.apache.hadoop.io.compress.Decompressor;
- /**
- * 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>
- * @return <code>Compressor</code> for the given <code>CompressionCodec</code>
- * from the pool or a new one
- */
- public static Compressor getCompressor(CompressionCodec codec) {
- Compressor compressor = borrow(COMPRESSOR_POOL, codec.getCompressorType());
- if (compressor == null) {
- compressor = codec.createCompressor();
- LOG.info("Got brand-new compressor");
- } else {
- LOG.debug("Got recycled compressor");
- }
- return compressor;
- }
- /**
- * 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");
- } else {
- 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;
- }
- 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;
- }
- decompressor.reset();
- payback(DECOMPRESSOR_POOL, decompressor);
- }
- private CodecPool() {
- // prevent instantiation
- }
- }