quartzschedulerthread.java

定时器开源项目, 相对于 jcrontab, Quartz 算是更完整的一个项目, 随著开发的版本上来, 他已经脱离只是写在程序里面的计时器, 在指定的时间或区间, 处理所指定的事件. 也加入了 se

/*
 * Copyright James House (c) 2001-2004
 * 
 * All rights reserved.
 * 
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met: 1.
 * Redistributions of source code must retain the above copyright notice, this
 * list of conditions and the following disclaimer. 2. Redistributions in
 * binary form must reproduce the above copyright notice, this list of
 * conditions and the following disclaimer in the documentation and/or other
 * materials provided with the distribution.
 * 
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND ANY
 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE FOR ANY
 * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */
package org.quartz.core;

import java.util.Random;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.quartz.Job;
import org.quartz.JobPersistenceException;
import org.quartz.SchedulerException;
import org.quartz.Trigger;
import org.quartz.spi.TriggerFiredBundle;

/**
 * <p>
 * The thread responsible for performing the work of firing <code>{@link Trigger}</code>
 * s that are registered with the <code>{@link QuartzScheduler}</code>.
 * </p>
 * 
 * @see QuartzScheduler
 * @see Job
 * @see Trigger
 * 
 * @author James House
 */
public class QuartzSchedulerThread extends Thread {
    /*
     * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
     * 
     * Data members.
     * 
     * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
     */
    private QuartzScheduler qs;

    private QuartzSchedulerResources qsRsrcs;

    private Object pauseLock = new Object();

    private Object idleLock = new Object();

    private boolean signaled;

    private boolean paused;

    private boolean halted;

    private SchedulingContext ctxt = null;

    private Random random = new Random(System.currentTimeMillis());

    // When the scheduler finds there is no current trigger to fire, how long
    // it should wait until checking again...
    private static long DEFAULT_IDLE_WAIT_TIME = 30L * 1000L;

    private long idleWaitTime = DEFAULT_IDLE_WAIT_TIME;

    private int idleWaitVariablness = 7 * 1000;

    private long dbFailureRetryInterval = 15L * 1000L;

    /*
     * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
     * 
     * Constructors.
     * 
     * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
     */

    /**
     * <p>
     * Construct a new <code>QuartzSchedulerThread</code> for the given
     * <code>QuartzScheduler</code> as a non-daemon <code>Thread</code>
     * with normal priority.
     * </p>
     */
    QuartzSchedulerThread(QuartzScheduler qs, QuartzSchedulerResources qsRsrcs,
            SchedulingContext ctxt) {
        this(qs, qsRsrcs, ctxt, false, Thread.NORM_PRIORITY);
    }

    /**
     * <p>
     * Construct a new <code>QuartzSchedulerThread</code> for the given
     * <code>QuartzScheduler</code> as a <code>Thread</code> with the given
     * attributes.
     * </p>
     */
    QuartzSchedulerThread(QuartzScheduler qs, QuartzSchedulerResources qsRsrcs,
            SchedulingContext ctxt, boolean setDaemon, int threadPrio) {
        super(qs.getSchedulerThreadGroup(), qsRsrcs.getThreadName());
        this.qs = qs;
        this.qsRsrcs = qsRsrcs;
        this.ctxt = ctxt;
        this.setDaemon(setDaemon);
        this.setPriority(threadPrio);

        // start the underlying thread, but put this object into the 'paused'
        // state
        // so processing doesn't start yet...
        paused = true;
        halted = false;
        this.start();
    }

    /*
     * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
     * 
     * Interface.
     * 
     * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
     */

    void setIdleWaitTime(long waitTime) {
        idleWaitTime = waitTime;
        idleWaitVariablness = (int) (waitTime * 0.2);
    }

    private long getDbFailureRetryInterval() {
        return dbFailureRetryInterval;
    }

    public void setDbFailureRetryInterval(long dbFailureRetryInterval) {
        this.dbFailureRetryInterval = dbFailureRetryInterval;
    }

    private long getRandomizedIdleWaitTime() {
        return idleWaitTime - random.nextInt(idleWaitVariablness);
    }

    /**
     * <p>
     * Signals the main processing loop to pause at the next possible point.
     * </p>
     */
    void togglePause(boolean pause) {
        synchronized (pauseLock) {
            paused = pause;

            if (paused) {
                signalSchedulingChange();
            } else {
                pauseLock.notify();
            }
        }
    }

    /**
     * <p>
     * Signals the main processing loop to pause at the next possible point.
     * </p>
     */
    void halt() {
        synchronized (pauseLock) {
            halted = true;

            if (paused) {
                pauseLock.notify();
            } else {
                signalSchedulingChange();
            }
        }
    }

    boolean isPaused() {
        return paused;
    }

    /**
     * <p>
     * Signals the main processing loop that a change in scheduling has been
     * made - in order to interrupt any sleeping that may be occuring while
     * waiting for the fire time to arrive.
     * </p>
     */
    void signalSchedulingChange() {
        signaled = true;
    }

    /**
     * <p>
     * The main processing loop of the <code>QuartzSchedulerThread</code>.
     * </p>
     */
    public void run() {
        boolean lastAcquireFailed = false;
        
        while (!halted) {
            // check if we're supposed to pause...
            synchronized (pauseLock) {
                while (paused && !halted) {
                    try {
                        // wait until togglePause(false) is called...
                        pauseLock.wait(100L);
                    } catch (InterruptedException ignore) {
                    }
                }

                if (halted) {
                    break;
                }
            }