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/*
 * Copyright 2002-2014 the original author or authors.
 *
 * Licensed 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.springframework.scheduling.concurrent;

import java.util.concurrent.BlockingQueue;
import java.util.concurrent.Callable;
import java.util.concurrent.Executor;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Future;
import java.util.concurrent.LinkedBlockingQueue;
import java.util.concurrent.RejectedExecutionException;
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 org.springframework.core.task.AsyncListenableTaskExecutor;
import org.springframework.core.task.TaskRejectedException;
import org.springframework.scheduling.SchedulingTaskExecutor;
import org.springframework.util.Assert;
import org.springframework.util.concurrent.ListenableFuture;
import org.springframework.util.concurrent.ListenableFutureTask;

/**
 * JavaBean that allows for configuring a {@link java.util.concurrent.ThreadPoolExecutor}
 * in bean style (through its "corePoolSize", "maxPoolSize", "keepAliveSeconds", "queueCapacity"
 * properties) and exposing it as a Spring {@link org.springframework.core.task.TaskExecutor}.
 * This class is also well suited for management and monitoring (e.g. through JMX),
 * providing several useful attributes: "corePoolSize", "maxPoolSize", "keepAliveSeconds"
 * (all supporting updates at runtime); "poolSize", "activeCount" (for introspection only).
 *
 * 

For an alternative, you may set up a ThreadPoolExecutor instance directly using * constructor injection, or use a factory method definition that points to the * {@link java.util.concurrent.Executors} class. To expose such a raw Executor as a * Spring {@link org.springframework.core.task.TaskExecutor}, simply wrap it with a * {@link org.springframework.scheduling.concurrent.ConcurrentTaskExecutor} adapter. * *

NOTE: This class implements Spring's * {@link org.springframework.core.task.TaskExecutor} interface as well as the * {@link java.util.concurrent.Executor} interface, with the former being the primary * interface, the other just serving as secondary convenience. For this reason, the * exception handling follows the TaskExecutor contract rather than the Executor contract, * in particular regarding the {@link org.springframework.core.task.TaskRejectedException}. * *

If you prefer native {@link java.util.concurrent.ExecutorService} exposure instead, * consider {@link ThreadPoolExecutorFactoryBean} as an alternative to this class. * * @author Juergen Hoeller * @since 2.0 * @see org.springframework.core.task.TaskExecutor * @see java.util.concurrent.ThreadPoolExecutor * @see ConcurrentTaskExecutor */ @SuppressWarnings("serial") public class ThreadPoolTaskExecutor extends ExecutorConfigurationSupport implements AsyncListenableTaskExecutor, SchedulingTaskExecutor { private final Object poolSizeMonitor = new Object(); private int corePoolSize = 1; private int maxPoolSize = Integer.MAX_VALUE; private int keepAliveSeconds = 60; private int queueCapacity = Integer.MAX_VALUE; private boolean allowCoreThreadTimeOut = false; private ThreadPoolExecutor threadPoolExecutor; /** * Set the ThreadPoolExecutor's core pool size. * Default is 1. *

This setting can be modified at runtime, for example through JMX. */ public void setCorePoolSize(int corePoolSize) { synchronized (this.poolSizeMonitor) { this.corePoolSize = corePoolSize; if (this.threadPoolExecutor != null) { this.threadPoolExecutor.setCorePoolSize(corePoolSize); } } } /** * Return the ThreadPoolExecutor's core pool size. */ public int getCorePoolSize() { synchronized (this.poolSizeMonitor) { return this.corePoolSize; } } /** * Set the ThreadPoolExecutor's maximum pool size. * Default is {@code Integer.MAX_VALUE}. *

This setting can be modified at runtime, for example through JMX. */ public void setMaxPoolSize(int maxPoolSize) { synchronized (this.poolSizeMonitor) { this.maxPoolSize = maxPoolSize; if (this.threadPoolExecutor != null) { this.threadPoolExecutor.setMaximumPoolSize(maxPoolSize); } } } /** * Return the ThreadPoolExecutor's maximum pool size. */ public int getMaxPoolSize() { synchronized (this.poolSizeMonitor) { return this.maxPoolSize; } } /** * Set the ThreadPoolExecutor's keep-alive seconds. * Default is 60. *

This setting can be modified at runtime, for example through JMX. */ public void setKeepAliveSeconds(int keepAliveSeconds) { synchronized (this.poolSizeMonitor) { this.keepAliveSeconds = keepAliveSeconds; if (this.threadPoolExecutor != null) { this.threadPoolExecutor.setKeepAliveTime(keepAliveSeconds, TimeUnit.SECONDS); } } } /** * Return the ThreadPoolExecutor's keep-alive seconds. */ public int getKeepAliveSeconds() { synchronized (this.poolSizeMonitor) { return this.keepAliveSeconds; } } /** * Set the capacity for the ThreadPoolExecutor's BlockingQueue. * Default is {@code Integer.MAX_VALUE}. *

Any positive value will lead to a LinkedBlockingQueue instance; * any other value will lead to a SynchronousQueue instance. * @see java.util.concurrent.LinkedBlockingQueue * @see java.util.concurrent.SynchronousQueue */ public void setQueueCapacity(int queueCapacity) { this.queueCapacity = queueCapacity; } /** * Specify whether to allow core threads to time out. This enables dynamic * growing and shrinking even in combination with a non-zero queue (since * the max pool size will only grow once the queue is full). *

Default is "false". * @see java.util.concurrent.ThreadPoolExecutor#allowCoreThreadTimeOut(boolean) */ public void setAllowCoreThreadTimeOut(boolean allowCoreThreadTimeOut) { this.allowCoreThreadTimeOut = allowCoreThreadTimeOut; } @Override protected ExecutorService initializeExecutor( ThreadFactory threadFactory, RejectedExecutionHandler rejectedExecutionHandler) { BlockingQueue queue = createQueue(this.queueCapacity); ThreadPoolExecutor executor = new ThreadPoolExecutor( this.corePoolSize, this.maxPoolSize, this.keepAliveSeconds, TimeUnit.SECONDS, queue, threadFactory, rejectedExecutionHandler); if (this.allowCoreThreadTimeOut) { executor.allowCoreThreadTimeOut(true); } this.threadPoolExecutor = executor; return executor; } /** * Create the BlockingQueue to use for the ThreadPoolExecutor. *

A LinkedBlockingQueue instance will be created for a positive * capacity value; a SynchronousQueue else. * @param queueCapacity the specified queue capacity * @return the BlockingQueue instance * @see java.util.concurrent.LinkedBlockingQueue * @see java.util.concurrent.SynchronousQueue */ protected BlockingQueue createQueue(int queueCapacity) { if (queueCapacity > 0) { return new LinkedBlockingQueue(queueCapacity); } else { return new SynchronousQueue(); } } /** * Return the underlying ThreadPoolExecutor for native access. * @return the underlying ThreadPoolExecutor (never {@code null}) * @throws IllegalStateException if the ThreadPoolTaskExecutor hasn't been initialized yet */ public ThreadPoolExecutor getThreadPoolExecutor() throws IllegalStateException { Assert.state(this.threadPoolExecutor != null, "ThreadPoolTaskExecutor not initialized"); return this.threadPoolExecutor; } /** * Return the current pool size. * @see java.util.concurrent.ThreadPoolExecutor#getPoolSize() */ public int getPoolSize() { if (this.threadPoolExecutor == null) { // Not initialized yet: assume core pool size. return this.corePoolSize; } return this.threadPoolExecutor.getPoolSize(); } /** * Return the number of currently active threads. * @see java.util.concurrent.ThreadPoolExecutor#getActiveCount() */ public int getActiveCount() { if (this.threadPoolExecutor == null) { // Not initialized yet: assume no active threads. return 0; } return this.threadPoolExecutor.getActiveCount(); } @Override public void execute(Runnable task) { Executor executor = getThreadPoolExecutor(); try { executor.execute(task); } catch (RejectedExecutionException ex) { throw new TaskRejectedException("Executor [" + executor + "] did not accept task: " + task, ex); } } @Override public void execute(Runnable task, long startTimeout) { execute(task); } @Override public Future submit(Runnable task) { ExecutorService executor = getThreadPoolExecutor(); try { return executor.submit(task); } catch (RejectedExecutionException ex) { throw new TaskRejectedException("Executor [" + executor + "] did not accept task: " + task, ex); } } @Override public Future submit(Callable task) { ExecutorService executor = getThreadPoolExecutor(); try { return executor.submit(task); } catch (RejectedExecutionException ex) { throw new TaskRejectedException("Executor [" + executor + "] did not accept task: " + task, ex); } } @Override public ListenableFuture submitListenable(Runnable task) { ExecutorService executor = getThreadPoolExecutor(); try { ListenableFutureTask future = new ListenableFutureTask(task, null); executor.execute(future); return future; } catch (RejectedExecutionException ex) { throw new TaskRejectedException("Executor [" + executor + "] did not accept task: " + task, ex); } } @Override public ListenableFuture submitListenable(Callable task) { ExecutorService executor = getThreadPoolExecutor(); try { ListenableFutureTask future = new ListenableFutureTask(task); executor.execute(future); return future; } catch (RejectedExecutionException ex) { throw new TaskRejectedException("Executor [" + executor + "] did not accept task: " + task, ex); } } /** * This task executor prefers short-lived work units. */ @Override public boolean prefersShortLivedTasks() { return true; } }