/**
* 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.nfs.nfs3;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.Map.Entry;
import java.util.concurrent.ConcurrentMap;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.nfs.nfs3.FileHandle;
import org.apache.hadoop.nfs.nfs3.Nfs3Constant;
import org.apache.hadoop.util.Daemon;
import com.google.common.annotations.VisibleForTesting;
import com.google.common.base.Preconditions;
import com.google.common.collect.Maps;
/**
* A cache saves OpenFileCtx objects for different users. Each cache entry is
* used to maintain the writing context for a single file.
*/
class OpenFileCtxCache {
private static final Log LOG = LogFactory.getLog(OpenFileCtxCache.class);
// Insert and delete with openFileMap are synced
private final ConcurrentMap<FileHandle, OpenFileCtx> openFileMap = Maps
.newConcurrentMap();
private final int maxStreams;
private final long streamTimeout;
private final StreamMonitor streamMonitor;
OpenFileCtxCache(Configuration config, long streamTimeout) {
maxStreams = config.getInt(Nfs3Constant.MAX_OPEN_FILES,
Nfs3Constant.MAX_OPEN_FILES_DEFAULT);
LOG.info("Maximum open streams is " + maxStreams);
this.streamTimeout = streamTimeout;
streamMonitor = new StreamMonitor();
}
/**
* The entry to be evicted is based on the following rules:<br>
* 1. if the OpenFileCtx has any pending task, it will not be chosen.<br>
* 2. if there is inactive OpenFileCtx, the first found one is to evict. <br>
* 3. For OpenFileCtx entries don't belong to group 1 or 2, the idlest one
* is select. If it's idle longer than OUTPUT_STREAM_TIMEOUT_MIN_DEFAULT, it
* will be evicted. Otherwise, the whole eviction request is failed.
*/
@VisibleForTesting
Entry<FileHandle, OpenFileCtx> getEntryToEvict() {
Iterator<Entry<FileHandle, OpenFileCtx>> it = openFileMap.entrySet()
.iterator();
if (LOG.isTraceEnabled()) {
LOG.trace("openFileMap size:" + openFileMap.size());
}
Entry<FileHandle, OpenFileCtx> idlest = null;
while (it.hasNext()) {
Entry<FileHandle, OpenFileCtx> pairs = it.next();
OpenFileCtx ctx = pairs.getValue();
if (!ctx.getActiveState()) {
if (LOG.isDebugEnabled()) {
LOG.debug("Got one inactive stream: " + ctx);
}
return pairs;
}
if (ctx.hasPendingWork()) {
// Always skip files with pending work.
continue;
}
if (idlest == null) {
idlest = pairs;
} else {
if (ctx.getLastAccessTime() < idlest.getValue().getLastAccessTime()) {
idlest = pairs;
}
}
}
if (idlest == null) {
LOG.warn("No eviction candidate. All streams have pending work.");
return null;
} else {
long idleTime = System.currentTimeMillis()
- idlest.getValue().getLastAccessTime();
if (idleTime < Nfs3Constant.OUTPUT_STREAM_TIMEOUT_MIN_DEFAULT) {
if (LOG.isDebugEnabled()) {
LOG.debug("idlest stream's idle time:" + idleTime);
}
LOG.warn("All opened streams are busy, can't remove any from cache.");
return null;
} else {
return idlest;
}
}
}
boolean put(FileHandle h, OpenFileCtx context) {
OpenFileCtx toEvict = null;
synchronized (this) {
Preconditions.checkState(openFileMap.size() <= this.maxStreams,
"stream cache size " + openFileMap.size()
+ " is larger than maximum" + this.maxStreams);
if (openFileMap.size() == this.maxStreams) {
Entry<FileHandle, OpenFileCtx> pairs = getEntryToEvict();
if (pairs ==null) {
return false;
} else {
if (LOG.isDebugEnabled()) {
LOG.debug("Evict stream ctx: " + pairs.getValue());
}
toEvict = openFileMap.remove(pairs.getKey());
Preconditions.checkState(toEvict == pairs.getValue(),
"The deleted entry is not the same as odlest found.");
}
}
openFileMap.put(h, context);
}
// Cleanup the old stream outside the lock
if (toEvict != null) {
toEvict.cleanup();
}
return true;
}
@VisibleForTesting
void scan(long streamTimeout) {
ArrayList<OpenFileCtx> ctxToRemove = new ArrayList<OpenFileCtx>();
Iterator<Entry<FileHandle, OpenFileCtx>> it = openFileMap.entrySet()
.iterator();
if (LOG.isTraceEnabled()) {
LOG.trace("openFileMap size:" + openFileMap.size());
}
while (it.hasNext()) {
Entry<FileHandle, OpenFileCtx> pairs = it.next();
FileHandle handle = pairs.getKey();
OpenFileCtx ctx = pairs.getValue();
if (!ctx.streamCleanup(handle.getFileId(), streamTimeout)) {
continue;
}
// Check it again inside lock before removing
synchronized (this) {
OpenFileCtx ctx2 = openFileMap.get(handle);
if (ctx2 != null) {
if (ctx2.streamCleanup(handle.getFileId(), streamTimeout)) {
openFileMap.remove(handle);
if (LOG.isDebugEnabled()) {
LOG.debug("After remove stream " + handle.getFileId()
+ ", the stream number:" + openFileMap.size());
}
ctxToRemove.add(ctx2);
}
}
}
}
// Invoke the cleanup outside the lock
for (OpenFileCtx ofc : ctxToRemove) {
ofc.cleanup();
}
}
OpenFileCtx get(FileHandle key) {
return openFileMap.get(key);
}
int size() {
return openFileMap.size();
}
void start() {
streamMonitor.start();
}
// Evict all entries
void cleanAll() {
ArrayList<OpenFileCtx> cleanedContext = new ArrayList<OpenFileCtx>();
synchronized (this) {
Iterator<Entry<FileHandle, OpenFileCtx>> it = openFileMap.entrySet()
.iterator();
if (LOG.isTraceEnabled()) {
LOG.trace("openFileMap size:" + openFileMap.size());
}
while (it.hasNext()) {
Entry<FileHandle, OpenFileCtx> pairs = it.next();
OpenFileCtx ctx = pairs.getValue();
it.remove();
cleanedContext.add(ctx);
}
}
// Invoke the cleanup outside the lock
for (OpenFileCtx ofc : cleanedContext) {
ofc.cleanup();
}
}
void shutdown() {
// stop the dump thread
if (streamMonitor != null && streamMonitor.isAlive()) {
streamMonitor.shouldRun(false);
streamMonitor.interrupt();
try {
streamMonitor.join(3000);
} catch (InterruptedException e) {
}
}
cleanAll();
}
/**
* StreamMonitor wakes up periodically to find and closes idle streams.
*/
class StreamMonitor extends Daemon {
private final static int rotation = 5 * 1000; // 5 seconds
private long lastWakeupTime = 0;
private boolean shouldRun = true;
void shouldRun(boolean shouldRun) {
this.shouldRun = shouldRun;
}
@Override
public void run() {
while (shouldRun) {
scan(streamTimeout);
// Check if it can sleep
try {
long workedTime = System.currentTimeMillis() - lastWakeupTime;
if (workedTime < rotation) {
if (LOG.isTraceEnabled()) {
LOG.trace("StreamMonitor can still have a sleep:"
+ ((rotation - workedTime) / 1000));
}
Thread.sleep(rotation - workedTime);
}
lastWakeupTime = System.currentTimeMillis();
} catch (InterruptedException e) {
LOG.info("StreamMonitor got interrupted");
return;
}
}
}
}
}