/*
* 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.mina.filter.executor;
import java.util.ArrayList;
import java.util.HashSet;
import java.util.List;
import java.util.Queue;
import java.util.Set;
import java.util.concurrent.BlockingQueue;
import java.util.concurrent.ConcurrentLinkedQueue;
import java.util.concurrent.Executors;
import java.util.concurrent.LinkedBlockingQueue;
import java.util.concurrent.RejectedExecutionHandler;
import java.util.concurrent.SynchronousQueue;
import java.util.concurrent.ThreadFactory;
import java.util.concurrent.ThreadPoolExecutor;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.atomic.AtomicInteger;
import org.apache.mina.core.session.AttributeKey;
import org.apache.mina.core.session.DummySession;
import org.apache.mina.core.session.IoEvent;
import org.apache.mina.core.session.IoSession;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
/**
* A {@link ThreadPoolExecutor} that maintains the order of {@link IoEvent}s.
* <p>
* If you don't need to maintain the order of events per session, please use
* {@link UnorderedThreadPoolExecutor}.
* @author The Apache MINA Project (dev@mina.apache.org)
* @org.apache.xbean.XBean
*/
public class OrderedThreadPoolExecutor extends ThreadPoolExecutor {
/** A logger for this class (commented as it breaks MDCFlter tests) */
static Logger LOGGER = LoggerFactory.getLogger(OrderedThreadPoolExecutor.class);
/** A default value for the initial pool size */
private static final int DEFAULT_INITIAL_THREAD_POOL_SIZE = 0;
/** A default value for the maximum pool size */
private static final int DEFAULT_MAX_THREAD_POOL = 16;
/** A default value for the KeepAlive delay */
private static final int DEFAULT_KEEP_ALIVE = 30;
private static final IoSession EXIT_SIGNAL = new DummySession();
/** A key stored into the session's attribute for the event tasks being queued */
private final AttributeKey TASKS_QUEUE = new AttributeKey(getClass(), "tasksQueue");
/** A queue used to store the available sessions */
private final BlockingQueue<IoSession> waitingSessions = new LinkedBlockingQueue<IoSession>();
private final Set<Worker> workers = new HashSet<Worker>();
private volatile int largestPoolSize;
private final AtomicInteger idleWorkers = new AtomicInteger();
private long completedTaskCount;
private volatile boolean shutdown;
private final IoEventQueueHandler eventQueueHandler;
/**
* Creates a default ThreadPool, with default values :
* - minimum pool size is 0
* - maximum pool size is 16
* - keepAlive set to 30 seconds
* - A default ThreadFactory
* - All events are accepted
*/
public OrderedThreadPoolExecutor() {
this(DEFAULT_INITIAL_THREAD_POOL_SIZE, DEFAULT_MAX_THREAD_POOL,
DEFAULT_KEEP_ALIVE, TimeUnit.SECONDS, Executors.defaultThreadFactory(), null);
}
/**
* Creates a default ThreadPool, with default values :
* - minimum pool size is 0
* - keepAlive set to 30 seconds
* - A default ThreadFactory
* - All events are accepted
*
* @param maximumPoolSize The maximum pool size
*/
public OrderedThreadPoolExecutor(int maximumPoolSize) {
this(DEFAULT_INITIAL_THREAD_POOL_SIZE, maximumPoolSize, DEFAULT_KEEP_ALIVE, TimeUnit.SECONDS,
Executors.defaultThreadFactory(), null);
}
/**
* Creates a default ThreadPool, with default values :
* - keepAlive set to 30 seconds
* - A default ThreadFactory
* - All events are accepted
*
* @param corePoolSize The initial pool sizePoolSize
* @param maximumPoolSize The maximum pool size
*/
public OrderedThreadPoolExecutor(int corePoolSize, int maximumPoolSize) {
this(corePoolSize, maximumPoolSize, DEFAULT_KEEP_ALIVE, TimeUnit.SECONDS,
Executors.defaultThreadFactory(), null);
}
/**
* Creates a default ThreadPool, with default values :
* - A default ThreadFactory
* - All events are accepted
*
* @param corePoolSize The initial pool sizePoolSize
* @param maximumPoolSize The maximum pool size
* @param keepAliveTime Default duration for a thread
* @param unit Time unit used for the keepAlive value
*/
public OrderedThreadPoolExecutor(
int corePoolSize, int maximumPoolSize, long keepAliveTime, TimeUnit unit) {
this(corePoolSize, maximumPoolSize, keepAliveTime, unit,
Executors.defaultThreadFactory(), null);
}
/**
* Creates a default ThreadPool, with default values :
* - A default ThreadFactory
*
* @param corePoolSize The initial pool sizePoolSize
* @param maximumPoolSize The maximum pool size
* @param keepAliveTime Default duration for a thread
* @param unit Time unit used for the keepAlive value
* @param eventQueueHandler The queue used to store events
*/
public OrderedThreadPoolExecutor(
int corePoolSize, int maximumPoolSize,
long keepAliveTime, TimeUnit unit,
IoEventQueueHandler eventQueueHandler) {
this(corePoolSize, maximumPoolSize, keepAliveTime, unit,
Executors.defaultThreadFactory(), eventQueueHandler);
}
/**
* Creates a default ThreadPool, with default values :
* - A default ThreadFactory
*
* @param corePoolSize The initial pool sizePoolSize
* @param maximumPoolSize The maximum pool size
* @param keepAliveTime Default duration for a thread
* @param unit Time unit used for the keepAlive value
* @param threadFactory The factory used to create threads
*/
public OrderedThreadPoolExecutor(
int corePoolSize, int maximumPoolSize,
long keepAliveTime, TimeUnit unit,
ThreadFactory threadFactory) {
this(corePoolSize, maximumPoolSize, keepAliveTime, unit, threadFactory, null);
}
/**
* Creates a new instance of a OrderedThreadPoolExecutor.
*
* @param corePoolSize The initial pool sizePoolSize
* @param maximumPoolSize The maximum pool size
* @param keepAliveTime Default duration for a thread
* @param unit Time unit used for the keepAlive value
* @param threadFactory The factory used to create threads
* @param eventQueueHandler The queue used to store events
*/
public OrderedThreadPoolExecutor(
int corePoolSize, int maximumPoolSize,
long keepAliveTime, TimeUnit unit,
ThreadFactory threadFactory, IoEventQueueHandler eventQueueHandler) {
// We have to initialize the pool with default values (0 and 1) in order to
// handle the exception in a better way. We can't add a try {} catch() {}
// around the super() call.
super(DEFAULT_INITIAL_THREAD_POOL_SIZE, 1, keepAliveTime, unit,
new SynchronousQueue<Runnable>(), threadFactory, new AbortPolicy());
if (corePoolSize < DEFAULT_INITIAL_THREAD_POOL_SIZE) {
throw new IllegalArgumentException("corePoolSize: " + corePoolSize);
}
if ((maximumPoolSize == 0) || (maximumPoolSize < corePoolSize)) {
throw new IllegalArgumentException("maximumPoolSize: " + maximumPoolSize);
}
// Now, we can setup the pool sizes
super.setCorePoolSize( corePoolSize );
super.setMaximumPoolSize( maximumPoolSize );
// The queueHandler might be null.
if (eventQueueHandler == null) {
this.eventQueueHandler = IoEventQueueHandler.NOOP;
} else {
this.eventQueueHandler = eventQueueHandler;
}
}
/**
* Get the session's tasks queue.
*/
private SessionTasksQueue getSessionTasksQueue(IoSession session) {
SessionTasksQueue queue = (SessionTasksQueue) session.getAttribute(TASKS_QUEUE);
if (queue == null) {
queue = new SessionTasksQueue();
SessionTasksQueue oldQueue =
(SessionTasksQueue) session.setAttributeIfAbsent(TASKS_QUEUE, queue);
if (oldQueue != null) {
queue = oldQueue;
}
}
return queue;
}
/**
* @return The associated queue handler.
*/
public IoEventQueueHandler getQueueHandler() {
return eventQueueHandler;
}
/**
* {@inheritDoc}
*/
@Override
public void setRejectedExecutionHandler(RejectedExecutionHandler handler) {
// Ignore the request. It must always be AbortPolicy.
}
/**
* Add a new thread to execute a task, if needed and possible.
* It depends on the current pool size. If it's full, we do nothing.
*/
private void addWorker() {
synchronized (workers) {
if (workers.size() >= super.getMaximumPoolSize()) {
return;
}
// Create a new worker, and add it to the thread pool
Worker worker = new Worker( workers.size());
Thread thread = getThreadFactory().newThread(worker);
// As we have added a new thread, it's considered as idle.
idleWorkers.incrementAndGet();
// Now, we can start it.
thread.start();
workers.add(worker);
if (workers.size() > largestPoolSize) {
largestPoolSize = workers.size();
}
}
}
/**
* Add a new Worker only if there are no idle worker.
*/
private void addWorkerIfNecessary() {
if (idleWorkers.get() == 0) {
synchronized (workers) {
if (workers.isEmpty() || (idleWorkers.get() == 0)) {
addWorker();
}
}
}
}
private void removeWorker() {
synchronized (workers) {
if (workers.size() <= super.getCorePoolSize()) {
return;
}
waitingSessions.offer(EXIT_SIGNAL);
}
}
/**
* {@inheritDoc}
*/
@Override
public int getMaximumPoolSize() {
return super.getMaximumPoolSize();
}
/**
* {@inheritDoc}
*/
@Override
public void setMaximumPoolSize(int maximumPoolSize) {
if ((maximumPoolSize <= 0) || (maximumPoolSize < super.getCorePoolSize())) {
throw new IllegalArgumentException("maximumPoolSize: "
+ maximumPoolSize);
}
synchronized (workers) {
super.setMaximumPoolSize( maximumPoolSize );
int difference = workers.size() - maximumPoolSize;
while (difference > 0) {
removeWorker();
--difference;
}
}
}
/**
* {@inheritDoc}
*/
@Override
public boolean awaitTermination(long timeout, TimeUnit unit)
throws InterruptedException {
long deadline = System.currentTimeMillis() + unit.toMillis(timeout);
synchronized (workers) {
while (!isTerminated()) {
long waitTime = deadline - System.currentTimeMillis();
if (waitTime <= 0) {
break;
}
workers.wait(waitTime);
}
}
return isTerminated();
}
/**
* {@inheritDoc}
*/
@Override
public boolean isShutdown() {
return shutdown;
}
/**
* {@inheritDoc}
*/
@Override
public boolean isTerminated() {
if (!shutdown) {
return false;
}
synchronized (workers) {
return workers.isEmpty();
}
}
/**
* {@inheritDoc}
*/
@Override
public void shutdown() {
if (shutdown) {
return;
}
shutdown = true;
synchronized (workers) {
for (int i = workers.size(); i > 0; i --) {
waitingSessions.offer(EXIT_SIGNAL);
}
}
}
/**
* {@inheritDoc}
*/
@Override
public List<Runnable> shutdownNow() {
shutdown();
List<Runnable> answer = new ArrayList<Runnable>();
IoSession session;
while ((session = waitingSessions.poll()) != null) {
if (session == EXIT_SIGNAL) {
waitingSessions.offer(EXIT_SIGNAL);
Thread.yield(); // Let others take the signal.
continue;
}
SessionTasksQueue sessionTasksQueue = (SessionTasksQueue) session.getAttribute(TASKS_QUEUE);
synchronized (sessionTasksQueue.tasksQueue) {
for (Runnable task: sessionTasksQueue.tasksQueue) {
getQueueHandler().polled(this, (IoEvent) task);
answer.add(task);
}
sessionTasksQueue.tasksQueue.clear();
}
}
return answer;
}
/**
* A Helper class used to print the list of events being queued.
*/
private void print( Queue<Runnable> queue, IoEvent event) {
StringBuilder sb = new StringBuilder();
sb.append( "Adding event " ).append( event.getType() ).append( " to session " ).append(event.getSession().getId() );
boolean first = true;
sb.append( "\nQueue : [" );
for (Runnable elem:queue) {
if ( first ) {
first = false;
} else {
sb.append( ", " );
}
sb.append(((IoEvent)elem).getType()).append(", ");
}
sb.append( "]\n" );
LOGGER.debug( sb.toString() );
}
/**
* {@inheritDoc}
*/
@Override
public void execute(Runnable task) {
if (shutdown) {
rejectTask(task);
}
// Check that it's a IoEvent task
checkTaskType(task);
IoEvent event = (IoEvent) task;
// Get the associated session
IoSession session = event.getSession();
// Get the session's queue of events
SessionTasksQueue sessionTasksQueue = getSessionTasksQueue(session);
Queue<Runnable> tasksQueue = sessionTasksQueue.tasksQueue;
boolean offerSession;
// propose the new event to the event queue handler. If we
// use a throttle queue handler, the message may be rejected
// if the maximum size has been reached.
boolean offerEvent = eventQueueHandler.accept(this, event);
if (offerEvent) {
// Ok, the message has been accepted
synchronized (tasksQueue) {
// Inject the event into the executor taskQueue
tasksQueue.offer(event);
if (sessionTasksQueue.processingCompleted) {
sessionTasksQueue.processingCompleted = false;
offerSession = true;
} else {
offerSession = false;
}
if (LOGGER.isDebugEnabled()) {
print(tasksQueue, event);
}
}
} else {
offerSession = false;
}
if (offerSession) {
// As the tasksQueue was empty, the task has been executed
// immediately, so we can move the session to the queue
// of sessions waiting for completion.
waitingSessions.offer(session);
}
addWorkerIfNecessary();
if (offerEvent) {
eventQueueHandler.offered(this, event);
}
}
private void rejectTask(Runnable task) {
getRejectedExecutionHandler().rejectedExecution(task, this);
}
private void checkTaskType(Runnable task) {
if (!(task instanceof IoEvent)) {
throw new IllegalArgumentException("task must be an IoEvent or its subclass.");
}
}
/**
* {@inheritDoc}
*/
@Override
public int getActiveCount() {
synchronized (workers) {
return workers.size() - idleWorkers.get();
}
}
/**
* {@inheritDoc}
*/
@Override
public long getCompletedTaskCount() {
synchronized (workers) {
long answer = completedTaskCount;
for (Worker w: workers) {
answer += w.completedTaskCount;
}
return answer;
}
}
/**
* {@inheritDoc}
*/
@Override
public int getLargestPoolSize() {
return largestPoolSize;
}
/**
* {@inheritDoc}
*/
@Override
public int getPoolSize() {
synchronized (workers) {
return workers.size();
}
}
/**
* {@inheritDoc}
*/
@Override
public long getTaskCount() {
return getCompletedTaskCount();
}
/**
* {@inheritDoc}
*/
@Override
public boolean isTerminating() {
synchronized (workers) {
return isShutdown() && !isTerminated();
}
}
/**
* {@inheritDoc}
*/
@Override
public int prestartAllCoreThreads() {
int answer = 0;
synchronized (workers) {
for (int i = super.getCorePoolSize() - workers.size() ; i > 0; i --) {
addWorker();
answer ++;
}
}
return answer;
}
/**
* {@inheritDoc}
*/
@Override
public boolean prestartCoreThread() {
synchronized (workers) {
if (workers.size() < super.getCorePoolSize()) {
addWorker();
return true;
} else {
return false;
}
}
}
/**
* {@inheritDoc}
*/
@Override
public BlockingQueue<Runnable> getQueue() {
throw new UnsupportedOperationException();
}
/**
* {@inheritDoc}
*/
@Override
public void purge() {
// Nothing to purge in this implementation.
}
/**
* {@inheritDoc}
*/
@Override
public boolean remove(Runnable task) {
checkTaskType(task);
IoEvent event = (IoEvent) task;
IoSession session = event.getSession();
SessionTasksQueue sessionTasksQueue = (SessionTasksQueue)session.getAttribute( TASKS_QUEUE );
Queue<Runnable> tasksQueue = sessionTasksQueue.tasksQueue;
if (sessionTasksQueue == null) {
return false;
}
boolean removed;
synchronized (tasksQueue) {
removed = tasksQueue.remove(task);
}
if (removed) {
getQueueHandler().polled(this, event);
}
return removed;
}
/**
* {@inheritDoc}
*/
@Override
public int getCorePoolSize() {
return super.getCorePoolSize();
}
/**
* {@inheritDoc}
*/
@Override
public void setCorePoolSize(int corePoolSize) {
if (corePoolSize < 0) {
throw new IllegalArgumentException("corePoolSize: " + corePoolSize);
}
if (corePoolSize > super.getMaximumPoolSize()) {
throw new IllegalArgumentException("corePoolSize exceeds maximumPoolSize");
}
synchronized (workers) {
if (super.getCorePoolSize()> corePoolSize) {
for (int i = super.getCorePoolSize() - corePoolSize; i > 0; i --) {
removeWorker();
}
}
super.setCorePoolSize(corePoolSize);
}
}
private Queue<Runnable> getTasksQueue(IoSession session) {
Queue<Runnable> tasksQueue = (Queue<Runnable>) session.getAttribute(TASKS_QUEUE);
if (tasksQueue == null) {
tasksQueue = new ConcurrentLinkedQueue<Runnable>();
Queue<Runnable> oldTasksQueue = (Queue<Runnable>) session.setAttributeIfAbsent(TASKS_QUEUE, tasksQueue);
if (oldTasksQueue != null) {
tasksQueue = oldTasksQueue;
}
}
return tasksQueue;
}
private class Worker implements Runnable {
private volatile long completedTaskCount;
private Thread thread;
private int id;
public Worker( int id ) {
this.id = id;
}
public void run() {
thread = Thread.currentThread();
try {
for (;;) {
IoSession session = fetchSession();
idleWorkers.decrementAndGet();
if (session == null) {
synchronized (workers) {
if (workers.size() > getCorePoolSize()) {
// Remove now to prevent duplicate exit.
workers.remove(this);
break;
}
}
}
if (session == EXIT_SIGNAL) {
break;
}
try {
if (session != null) {
runTasks(getSessionTasksQueue(session));
}
} finally {
idleWorkers.incrementAndGet();
}
}
} finally {
synchronized (workers) {
workers.remove(this);
OrderedThreadPoolExecutor.this.completedTaskCount += completedTaskCount;
workers.notifyAll();
}
}
}
private IoSession fetchSession() {
IoSession session = null;
long currentTime = System.currentTimeMillis();
long deadline = currentTime + getKeepAliveTime(TimeUnit.MILLISECONDS);
for (;;) {
try {
long waitTime = deadline - currentTime;
if (waitTime <= 0) {
break;
}
try {
session = waitingSessions.poll(waitTime, TimeUnit.MILLISECONDS);
break;
} finally {
if (session == null) {
currentTime = System.currentTimeMillis();
}
}
} catch (InterruptedException e) {
// Ignore.
continue;
}
}
return session;
}
private void runTasks(SessionTasksQueue sessionTasksQueue) {
for (;;) {
Runnable task;
Queue<Runnable> tasksQueue = sessionTasksQueue.tasksQueue;
synchronized (tasksQueue) {
task = tasksQueue.poll();
if (task == null) {
sessionTasksQueue.processingCompleted = true;
break;
}
}
eventQueueHandler.polled(OrderedThreadPoolExecutor.this, (IoEvent) task);
runTask(task);
}
}
private void runTask(Runnable task) {
beforeExecute(thread, task);
boolean ran = false;
try {
task.run();
ran = true;
afterExecute(task, null);
completedTaskCount ++;
} catch (RuntimeException e) {
if (!ran) {
afterExecute(task, e);
}
throw e;
}
}
}
/**
* A class used to store the ordered list of events to be processed by the
* session, and the current task state.
*/
private class SessionTasksQueue {
/** A queue of ordered event waiting to be processed */
private final Queue<Runnable> tasksQueue = new ConcurrentLinkedQueue<Runnable>();
/** The current task state */
private boolean processingCompleted = true;
}
}