/**
* 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.hdfs.server.datanode.fsdataset.impl;
import java.io.File;
import java.util.HashMap;
import java.util.Map;
import java.util.concurrent.LinkedBlockingQueue;
import java.util.concurrent.ThreadFactory;
import java.util.concurrent.ThreadPoolExecutor;
import java.util.concurrent.TimeUnit;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.hadoop.hdfs.protocol.ExtendedBlock;
import org.apache.hadoop.hdfs.server.datanode.DataNode;
import org.apache.hadoop.hdfs.server.protocol.BlockCommand;
/**
* This class is a container of multiple thread pools, each for a volume,
* so that we can schedule async disk operations easily.
*
* Examples of async disk operations are deletion of block files.
* We don't want to create a new thread for each of the deletion request, and
* we don't want to do all deletions in the heartbeat thread since deletion
* can be slow, and we don't want to use a single thread pool because that
* is inefficient when we have more than 1 volume. AsyncDiskService is the
* solution for these.
*
* This class and {@link org.apache.hadoop.util.AsyncDiskService} are similar.
* They should be combined.
*/
class FsDatasetAsyncDiskService {
public static final Log LOG = LogFactory.getLog(FsDatasetAsyncDiskService.class);
// ThreadPool core pool size
private static final int CORE_THREADS_PER_VOLUME = 1;
// ThreadPool maximum pool size
private static final int MAXIMUM_THREADS_PER_VOLUME = 4;
// ThreadPool keep-alive time for threads over core pool size
private static final long THREADS_KEEP_ALIVE_SECONDS = 60;
private final DataNode datanode;
private Map<File, ThreadPoolExecutor> executors
= new HashMap<File, ThreadPoolExecutor>();
/**
* Create a AsyncDiskServices with a set of volumes (specified by their
* root directories).
*
* The AsyncDiskServices uses one ThreadPool per volume to do the async
* disk operations.
*
* @param volumes The roots of the data volumes.
*/
FsDatasetAsyncDiskService(DataNode datanode, File[] volumes) {
this.datanode = datanode;
final ThreadGroup threadGroup = new ThreadGroup(getClass().getSimpleName());
// Create one ThreadPool per volume
for (int v = 0 ; v < volumes.length; v++) {
final File vol = volumes[v];
ThreadFactory threadFactory = new ThreadFactory() {
int counter = 0;
@Override
public Thread newThread(Runnable r) {
int thisIndex;
synchronized (this) {
thisIndex = counter++;
}
Thread t = new Thread(threadGroup, r);
t.setName("Async disk worker #" + thisIndex +
" for volume " + vol);
return t;
}
};
ThreadPoolExecutor executor = new ThreadPoolExecutor(
CORE_THREADS_PER_VOLUME, MAXIMUM_THREADS_PER_VOLUME,
THREADS_KEEP_ALIVE_SECONDS, TimeUnit.SECONDS,
new LinkedBlockingQueue<Runnable>(), threadFactory);
// This can reduce the number of running threads
executor.allowCoreThreadTimeOut(true);
executors.put(vol, executor);
}
}
synchronized long countPendingDeletions() {
long count = 0;
for (ThreadPoolExecutor exec : executors.values()) {
count += exec.getTaskCount() - exec.getCompletedTaskCount();
}
return count;
}
/**
* Execute the task sometime in the future, using ThreadPools.
*/
synchronized void execute(File root, Runnable task) {
if (executors == null) {
throw new RuntimeException("AsyncDiskService is already shutdown");
}
ThreadPoolExecutor executor = executors.get(root);
if (executor == null) {
throw new RuntimeException("Cannot find root " + root
+ " for execution of task " + task);
} else {
executor.execute(task);
}
}
/**
* Gracefully shut down all ThreadPool. Will wait for all deletion
* tasks to finish.
*/
synchronized void shutdown() {
if (executors == null) {
LOG.warn("AsyncDiskService has already shut down.");
} else {
LOG.info("Shutting down all async disk service threads");
for (Map.Entry<File, ThreadPoolExecutor> e : executors.entrySet()) {
e.getValue().shutdown();
}
// clear the executor map so that calling execute again will fail.
executors = null;
LOG.info("All async disk service threads have been shut down");
}
}
/**
* Delete the block file and meta file from the disk asynchronously, adjust
* dfsUsed statistics accordingly.
*/
void deleteAsync(FsVolumeImpl volume, File blockFile, File metaFile,
ExtendedBlock block, String trashDirectory) {
LOG.info("Scheduling " + block.getLocalBlock()
+ " file " + blockFile + " for deletion");
ReplicaFileDeleteTask deletionTask = new ReplicaFileDeleteTask(
volume, blockFile, metaFile, block, trashDirectory);
execute(volume.getCurrentDir(), deletionTask);
}
/** A task for deleting a block file and its associated meta file, as well
* as decrement the dfs usage of the volume.
* Optionally accepts a trash directory. If one is specified then the files
* are moved to trash instead of being deleted. If none is specified then the
* files are deleted immediately.
*/
class ReplicaFileDeleteTask implements Runnable {
final FsVolumeImpl volume;
final File blockFile;
final File metaFile;
final ExtendedBlock block;
final String trashDirectory;
ReplicaFileDeleteTask(FsVolumeImpl volume, File blockFile,
File metaFile, ExtendedBlock block, String trashDirectory) {
this.volume = volume;
this.blockFile = blockFile;
this.metaFile = metaFile;
this.block = block;
this.trashDirectory = trashDirectory;
}
@Override
public String toString() {
// Called in AsyncDiskService.execute for displaying error messages.
return "deletion of block " + block.getBlockPoolId() + " "
+ block.getLocalBlock() + " with block file " + blockFile
+ " and meta file " + metaFile + " from volume " + volume;
}
private boolean deleteFiles() {
return blockFile.delete() && (metaFile.delete() || !metaFile.exists());
}
private boolean moveFiles() {
File trashDirFile = new File(trashDirectory);
if (!trashDirFile.exists() && !trashDirFile.mkdirs()) {
LOG.error("Failed to create trash directory " + trashDirectory);
return false;
}
if (LOG.isDebugEnabled()) {
LOG.debug("Moving files " + blockFile.getName() + " and " +
metaFile.getName() + " to trash.");
}
File newBlockFile = new File(trashDirectory, blockFile.getName());
File newMetaFile = new File(trashDirectory, metaFile.getName());
return (blockFile.renameTo(newBlockFile) &&
metaFile.renameTo(newMetaFile));
}
@Override
public void run() {
long dfsBytes = blockFile.length() + metaFile.length();
boolean result;
result = (trashDirectory == null) ? deleteFiles() : moveFiles();
if (!result) {
LOG.warn("Unexpected error trying to "
+ (trashDirectory == null ? "delete" : "move")
+ " block " + block.getBlockPoolId() + " " + block.getLocalBlock()
+ " at file " + blockFile + ". Ignored.");
} else {
if(block.getLocalBlock().getNumBytes() != BlockCommand.NO_ACK){
datanode.notifyNamenodeDeletedBlock(block, volume.getStorageID());
}
volume.decDfsUsed(block.getBlockPoolId(), dfsBytes);
LOG.info("Deleted " + block.getBlockPoolId() + " "
+ block.getLocalBlock() + " file " + blockFile);
}
}
}
}