| /** |
| * 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.mapred; |
| |
| import java.io.FileDescriptor; |
| import java.io.IOException; |
| import java.io.RandomAccessFile; |
| import java.nio.channels.WritableByteChannel; |
| |
| import org.apache.commons.logging.Log; |
| import org.apache.commons.logging.LogFactory; |
| import org.apache.hadoop.io.ReadaheadPool; |
| import org.apache.hadoop.io.ReadaheadPool.ReadaheadRequest; |
| import org.apache.hadoop.io.nativeio.NativeIO; |
| import org.jboss.netty.channel.DefaultFileRegion; |
| |
| public class FadvisedFileRegion extends DefaultFileRegion { |
| |
| private static final Log LOG = LogFactory.getLog(FadvisedFileRegion.class); |
| |
| private final boolean manageOsCache; |
| private final int readaheadLength; |
| private final ReadaheadPool readaheadPool; |
| private final FileDescriptor fd; |
| private final String identifier; |
| |
| private ReadaheadRequest readaheadRequest; |
| |
| public FadvisedFileRegion(RandomAccessFile file, long position, long count, |
| boolean manageOsCache, int readaheadLength, ReadaheadPool readaheadPool, |
| String identifier) throws IOException { |
| super(file.getChannel(), position, count); |
| this.manageOsCache = manageOsCache; |
| this.readaheadLength = readaheadLength; |
| this.readaheadPool = readaheadPool; |
| this.fd = file.getFD(); |
| this.identifier = identifier; |
| } |
| |
| @Override |
| public long transferTo(WritableByteChannel target, long position) |
| throws IOException { |
| if (manageOsCache && readaheadPool != null) { |
| readaheadRequest = readaheadPool.readaheadStream(identifier, fd, |
| getPosition() + position, readaheadLength, |
| getPosition() + getCount(), readaheadRequest); |
| } |
| return super.transferTo(target, position); |
| } |
| |
| @Override |
| public void releaseExternalResources() { |
| if (readaheadRequest != null) { |
| readaheadRequest.cancel(); |
| } |
| if (manageOsCache && getCount() > 0) { |
| try { |
| NativeIO.posixFadviseIfPossible(fd, getPosition(), getCount(), |
| NativeIO.POSIX_FADV_DONTNEED); |
| } catch (Throwable t) { |
| LOG.warn("Failed to manage OS cache for " + identifier, t); |
| } |
| } |
| super.releaseExternalResources(); |
| } |
| } |