/* 
 * Copyright 2004-2005 OpenSymphony 
 * 
 * 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.
 * 
 */

/*
 * Previously Copyright (c) 2001-2004 James House
 */
package org.quartz.core;

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

import java.util.Random;

/**
 * <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 org.quartz.Job
 * @see Trigger
 * 
 * @author James House
 */
public class QuartzSchedulerThread extends Thread {
    /*
     * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
     * 
     * Data members.
     * 
     * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
     */
    private QuartzScheduler qs;

    private QuartzSchedulerResources qsRsrcs;

    private Object sigLock = new Object();

    private boolean signaled;
    private long signaledNextFireTime;
    
    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;

    private final Log log = LogFactory.getLog(getClass());

    /*
     * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
     * 
     * 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, qsRsrcs.getMakeSchedulerThreadDaemon(), 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);
        if(qsRsrcs.isThreadsInheritInitializersClassLoadContext()) {
        	log.info("QuartzSchedulerThread Inheriting ContextClassLoader of thread: " + Thread.currentThread().getName());
        	this.setContextClassLoader(Thread.currentThread().getContextClassLoader());
        }
        
        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 (sigLock) {
            paused = pause;

            if (paused) {
                signalSchedulingChange(0);
            } else {
                sigLock.notifyAll();
            }
        }
    }

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

            if (paused) {
                sigLock.notifyAll();
            } else {
                signalSchedulingChange(0);
            }
        }
    }

    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>
     *
     * @param newNextTime the time (in millis) when the newly scheduled trigger
     * will fire.  If this method is being called do to some other even (rather
     * than scheduling a trigger), the caller should pass zero (0).
     */
    public void signalSchedulingChange(long candidateNewNextFireTime) {
        synchronized(sigLock) {
            signaled = true;
            signaledNextFireTime = candidateNewNextFireTime;
            sigLock.notifyAll();
        }
    }

    public void clearSignaledSchedulingChange() {
        synchronized(sigLock) {
            signaled = false;
            signaledNextFireTime = 0;
        }
    }

    public boolean isScheduleChanged() {
        synchronized(sigLock) {
            return signaled;
        }
    }

    public long getSignaledNextFireTime() {
        synchronized(sigLock) {
            return signaledNextFireTime;
        }
    }

    /**
     * <p>
     * The main processing loop of the <code>QuartzSchedulerThread</code>.
     * </p>
     */
    public void run() {
        boolean lastAcquireFailed = false;
        
        while (!halted) {
            try {
                // check if we're supposed to pause...
                synchronized (sigLock) {
                    while (paused && !halted) {
                        try {
                            // wait until togglePause(false) is called...
                            sigLock.wait(1000L);
                        } catch (InterruptedException ignore) {
                        }
                    }
    
                    if (halted) {
                        break;
                    }
                }

                int availTreadCount = qsRsrcs.getThreadPool().blockForAvailableThreads();
                if(availTreadCount > 0) { // will always be true, due to semantics of blockForAvailableThreads...

                    Trigger trigger = null;

                    long now = System.currentTimeMillis();

                    clearSignaledSchedulingChange();
                    try {
                        trigger = qsRsrcs.getJobStore().acquireNextTrigger(
                                ctxt, now + idleWaitTime);
                        lastAcquireFailed = false;
                    } catch (JobPersistenceException jpe) {
                        if(!lastAcquireFailed) {
                            qs.notifySchedulerListenersError(
                                "An error occured while scanning for the next trigger to fire.",
                                jpe);
                        }
                        lastAcquireFailed = true;
                    } catch (RuntimeException e) {
                        if(!lastAcquireFailed) {
                            getLog().error("quartzSchedulerThreadLoop: RuntimeException "
                                    +e.getMessage(), e);
                        }
                        lastAcquireFailed = true;