TimerTaskExecutor.java

/*
 * Copyright 2002-2009 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.timer;

import java.util.Timer;
import java.util.concurrent.Callable;
import java.util.concurrent.Future;
import java.util.concurrent.FutureTask;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

import org.springframework.beans.factory.BeanNameAware;
import org.springframework.beans.factory.DisposableBean;
import org.springframework.beans.factory.InitializingBean;
import org.springframework.scheduling.SchedulingTaskExecutor;
import org.springframework.util.Assert;
import org.springframework.util.StringUtils;

/**
 * {@link org.springframework.core.task.TaskExecutor} implementation that uses a
 * single {@link Timer} for executing all tasks, effectively resulting in
 * serialized asynchronous execution on a single thread.
 *
 * @author Juergen Hoeller
 * @since 2.0
 * @see java.util.Timer
 * @deprecated as of Spring 3.0, in favor of the <code>scheduling.concurrent</code>
 * package which is based on Java 5's <code>java.util.concurrent.ExecutorService</code>
 */
@Deprecated
public class TimerTaskExecutor implements SchedulingTaskExecutor, BeanNameAware, InitializingBean, DisposableBean {

	protected final Log logger = LogFactory.getLog(getClass());

	private Timer timer;

	private long delay = 0;

	private String beanName;

	private boolean timerInternal = false;


	/**
	 * Create a new TimerTaskExecutor that needs to be further configured and initialized.
	 * @see #setTimer
	 * @see #afterPropertiesSet
	 */
	public TimerTaskExecutor() {
	}

	/**
	 * Create a new TimerTaskExecutor for the given {@link Timer}.
	 * @param timer the {@link Timer} to wrap
	 */
	public TimerTaskExecutor(Timer timer) {
		Assert.notNull(timer, "Timer must not be null");
		this.timer = timer;
	}


	/**
	 * Set the {@link Timer} to use for this {@link TimerTaskExecutor}, for example
	 * a shared {@link Timer} instance defined by a {@link TimerFactoryBean}.
	 * <p>If not specified, a default internal {@link Timer} instance will be used.
	 * @param timer the {@link Timer} to use for this {@link TimerTaskExecutor}
	 * @see TimerFactoryBean
	 */
	public void setTimer(Timer timer) {
		this.timer = timer;
	}

	/**
	 * Set the delay to use for scheduling tasks passed into the plain
	 * {@link #execute(Runnable)} method. Default is 0.
	 * <p>Note that calls to {@link #execute(Runnable, long)} will use the
	 * given timeout as delay if it is lower than the general delay.
	 * @param delay the delay in milliseconds before the task is to be executed
	 */
	public void setDelay(long delay) {
		this.delay = delay;
	}

	public void setBeanName(String beanName) {
		this.beanName = beanName;
	}


	public void afterPropertiesSet() {
		if (this.timer == null) {
			logger.info("Initializing Timer");
			this.timer = createTimer();
			this.timerInternal = true;
		}
	}

	/**
	 * Create a new {@link Timer} instance. Called by <code>afterPropertiesSet</code>
	 * if no {@link Timer} has been specified explicitly.
	 * <p>The default implementation creates a plain non-daemon {@link Timer}.
	 * If overridden, subclasses must take care to ensure that a non-null
	 * {@link Timer} is returned from the execution of this method.
	 * @see #afterPropertiesSet
	 * @see java.util.Timer#Timer(String, boolean)
	 */
	protected Timer createTimer() {
		if (StringUtils.hasText(this.beanName)) {
			return new Timer(this.beanName);
		}
		else {
			return new Timer();
		}
	}

	/**
	 * Return the underlying Timer behind this TimerTaskExecutor.
	 */
	protected final Timer getTimer() {
		Assert.notNull(this.timer, "Timer not initialized yet");
		return this.timer;
	}


	/**
	 * Schedules the given {@link Runnable} on this executor's {@link Timer} instance,
	 * wrapping it in a {@link DelegatingTimerTask}.
	 * @param task the task to be executed
	 */
	public void execute(Runnable task) {
		getTimer().schedule(new DelegatingTimerTask(task), this.delay);
	}

	public void execute(Runnable task, long startTimeout) {
		long actualDelay = (startTimeout < this.delay ? startTimeout : this.delay);
		getTimer().schedule(new DelegatingTimerTask(task), actualDelay);
	}

	public Future<?> submit(Runnable task) {
		FutureTask<Object> future = new FutureTask<Object>(task, null);
		execute(future);
		return future;
	}

	public <T> Future<T> submit(Callable<T> task) {
		FutureTask<T> future = new FutureTask<T>(task);
		execute(future);
		return future;
	}

	/**
	 * This task executor prefers short-lived work units.
	 */
	public boolean prefersShortLivedTasks() {
		return true;
	}


	/**
	 * Cancel the {@link Timer} on bean factory shutdown, stopping all scheduled tasks.
	 * @see java.util.Timer#cancel()
	 */
	public void destroy() {
		if (this.timerInternal) {
			logger.info("Cancelling Timer");
			this.timer.cancel();
		}
	}

}