quartz2.x源码分析——启动过程

先简单介绍一下quartz,Quartz是一个功能丰富的开源作业调度库,可以集成到几乎任何Java应用程序中 - 从最小的独立应用程序到最大的电子商务系统。quartz可用于创建执行数十,数百甚至数十万个作业的简单或复杂的计划; 任务定义为标准Java组件的任务,可以执行任何可以对其进行编程的任何内容。Quartz Scheduler包含许多企业级功能,例如支持JTA事务和集群。
以上内容来自quartz官网

我们会针对quartz的几个主要类进行分析,看一下quartz是如何实现定时调度功能

1.1测试Demo

来自官方实例的example1

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public class SimpleExample {
public void run() throws Exception {
Logger log = LoggerFactory.getLogger(SimpleExample.class);
log.info("------- Initializing ----------------------");
// First we must get a reference to a scheduler
SchedulerFactory sf = new StdSchedulerFactory();
Scheduler sched = sf.getScheduler();
log.info("------- Initialization Complete -----------");
// computer a time that is on the next round minute
Date runTime = evenMinuteDate(new Date());
log.info("------- Scheduling Job -------------------");
// define the job and tie it to our HelloJob class
JobDetail job = newJob(HelloJob.class).withIdentity("job1", "group1").build();
// Trigger the job to run on the next round minute
Trigger trigger = newTrigger().withIdentity("trigger1", "group1").startAt(runTime).build();
// Tell quartz to schedule the job using our trigger
sched.scheduleJob(job, trigger);
log.info(job.getKey() + " will run at: " + runTime);
// Start up the scheduler (nothing can actually run until the
// scheduler has been started)
sched.start();
log.info("------- Started Scheduler -----------------");
// wait long enough so that the scheduler as an opportunity to
// run the job!
log.info("------- Waiting 65 seconds... -------------");
try {
// wait 65 seconds to show job
Thread.sleep(65L * 1000L);
// executing...
} catch (Exception e) {
//
}
// shut down the scheduler
log.info("------- Shutting Down ---------------------");
sched.shutdown(true);
log.info("------- Shutdown Complete -----------------");
}
public static void main(String[] args) throws Exception {
SimpleExample example = new SimpleExample();
example.run();
}
}
public class HelloJob implements Job {
private static Logger _log = LoggerFactory.getLogger(HelloJob.class);
public HelloJob() {
}
public void execute(JobExecutionContext context)
throws JobExecutionException {
_log.info("Hello World! - " + new Date());
}
}

1.2 quartz关键API

从上述example中我们可以看到quartz主要接口和类

  • Scheduler - 进行作业调度的主要接口.
  • Job - 作业接口,编写自己的作业需要实现,如example中的HelloJob
  • JobDetail - 作业的详细信息,除了包含作业本身,还包含一些额外的数据。
  • Trigger - 作业计划的组件-作业何时执行,执行次数,频率等。
  • JobBuilder - 建造者模式创建 JobDetail实例.
  • TriggerBuilder - 建造者模式创建 Trigger 实例.
  • QuartzSchedulerThread 继承Thread 主要的执行任务线程

从上面的几个接口,可以看到quartz设计非常精妙,将作业和触发器分开设计,同时调度器完成对作业的调度。
了解了几个关键类和接口作用,下面我们来分析整个执行过程。

1.3 执行过程分析

1.3.1 从StdSchedulerFactory获取scheduler

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public Scheduler getScheduler() throws SchedulerException {
if (cfg == null) {
initialize();
}
SchedulerRepository schedRep = SchedulerRepository.getInstance();
Scheduler sched = schedRep.lookup(getSchedulerName());
if (sched != null) {
if (sched.isShutdown()) {
schedRep.remove(getSchedulerName());
} else {
return sched;
}
}
sched = instantiate();
return sched;
}
  1. cfg变量为PropertiesParser实例————是quartz的配置信息(主要是quartz.properties),如果为空,就初始化读取quartz的配置信息。
  2. SchedulerRepository是一个HashMap,用于存储Scheduler。如果有重名的,判断是否已经停止,是从hashMap删掉,否直接返回已保存实例
  3. SchedulerRepository未找到,实例化一个scheduler
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private Scheduler instantiate() throws SchedulerException {
if (cfg == null) {
initialize();
}
if (initException != null) {
throw initException;
}
.....
.....
SchedulerRepository schedRep = SchedulerRepository.getInstance();
// Get Scheduler Properties
// ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
String schedName = cfg.getStringProperty(PROP_SCHED_INSTANCE_NAME,
"QuartzScheduler");
String threadName = cfg.getStringProperty(PROP_SCHED_THREAD_NAME,
schedName + "_QuartzSchedulerThread");
.....
.....
String managementRESTServiceHostAndPort = cfg.getStringProperty(MANAGEMENT_REST_SERVICE_HOST_PORT, "0.0.0.0:9889");
Properties schedCtxtProps = cfg.getPropertyGroup(PROP_SCHED_CONTEXT_PREFIX, true);
// If Proxying to remote scheduler, short-circuit here...
// ~~~~~~~~~~~~~~~~~~
if (rmiProxy) {
....
....
schedRep.bind(remoteScheduler);
return remoteScheduler;
}
// Create class load helper
ClassLoadHelper loadHelper = null;
try {
loadHelper = (ClassLoadHelper) loadClass(classLoadHelperClass)
.newInstance();
} catch (Exception e) {
throw new SchedulerConfigException(
"Unable to instantiate class load helper class: "
+ e.getMessage(), e);
}
loadHelper.initialize();
// If Proxying to remote JMX scheduler, short-circuit here...
// ~~~~~~~~~~~~~~~~~~
if (jmxProxy) {
if (autoId) {
schedInstId = DEFAULT_INSTANCE_ID;
}
....
....
jmxScheduler.initialize();
schedRep.bind(jmxScheduler);
return jmxScheduler;
}
JobFactory jobFactory = null;
if(jobFactoryClass != null) {
....
....
}
InstanceIdGenerator instanceIdGenerator = null;
if(instanceIdGeneratorClass != null) {
.....
.....
}
// Get ThreadPool Properties
// ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
String tpClass = cfg.getStringProperty(PROP_THREAD_POOL_CLASS, SimpleThreadPool.class.getName());
....
....
// Get JobStore Properties
// ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
String jsClass = cfg.getStringProperty(PROP_JOB_STORE_CLASS,
RAMJobStore.class.getName());
if (jsClass == null) {
}
....
....
....
// Set up any DataSources
// ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
String[] dsNames = cfg.getPropertyGroups(PROP_DATASOURCE_PREFIX);
for (int i = 0; i < dsNames.length; i++) {
PropertiesParser pp = new PropertiesParser(cfg.getPropertyGroup(
PROP_DATASOURCE_PREFIX + "." + dsNames[i], true));
String cpClass = pp.getStringProperty(PROP_CONNECTION_PROVIDER_CLASS, null);
// custom connectionProvider...
....
....
....
}
// Set up any SchedulerPlugins
// ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
String[] pluginNames = cfg.getPropertyGroups(PROP_PLUGIN_PREFIX);
SchedulerPlugin[] plugins = new SchedulerPlugin[pluginNames.length];
for (int i = 0; i < pluginNames.length; i++) {
Properties pp = cfg.getPropertyGroup(PROP_PLUGIN_PREFIX + "."
+ pluginNames[i], true);
....
....
plugins[i] = plugin;
}
// Set up any JobListeners
// ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Class<?>[] strArg = new Class[] { String.class };
String[] jobListenerNames = cfg.getPropertyGroups(PROP_JOB_LISTENER_PREFIX);
JobListener[] jobListeners = new JobListener[jobListenerNames.length];
for (int i = 0; i < jobListenerNames.length; i++) {
Properties lp = cfg.getPropertyGroup(PROP_JOB_LISTENER_PREFIX + "."
+ jobListenerNames[i], true);
.....
.....
jobListeners[i] = listener;
}
// Set up any TriggerListeners
// ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
String[] triggerListenerNames = cfg.getPropertyGroups(PROP_TRIGGER_LISTENER_PREFIX);
TriggerListener[] triggerListeners = new TriggerListener[triggerListenerNames.length];
for (int i = 0; i < triggerListenerNames.length; i++) {
Properties lp = cfg.getPropertyGroup(PROP_TRIGGER_LISTENER_PREFIX + "."
+ triggerListenerNames[i], true);
String listenerClass = lp.getProperty(PROP_LISTENER_CLASS, null);
.....
.....
.....
triggerListeners[i] = listener;
}
boolean tpInited = false;
boolean qsInited = false;
// Get ThreadExecutor Properties
// ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
String threadExecutorClass = cfg.getStringProperty(PROP_THREAD_EXECUTOR_CLASS);
if (threadExecutorClass != null) {
tProps = cfg.getPropertyGroup(PROP_THREAD_EXECUTOR, true);
.....
.....
}
// Fire everything up
// ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
try {
JobRunShellFactory jrsf = null; // Create correct run-shell factory...
......
......
schedRep.bind(scheduler);
return scheduler;
}
catch(SchedulerException e) {
shutdownFromInstantiateException(tp, qs, tpInited, qsInited);
throw e;
}
catch(RuntimeException re) {
shutdownFromInstantiateException(tp, qs, tpInited, qsInited);
throw re;
}
catch(Error re) {
shutdownFromInstantiateException(tp, qs, tpInited, qsInited);
throw re;
}
}

instantiate()是一个比较重要的方法,主要从上一段代码介绍的PropertiesParser获取Scheduler配置信息

  1. 获取Scheduler Properties
  2. 如果是rmi代理sheduler,则创建RemoteScheduler,并通过scheRep.bind放入SchedulerRepository中,返回scheduler,结束
  3. 创建class load helper 加载类提供帮助
  4. 如果是jmx scheduler 则进行对应操作,并通过scheRep.bind放入SchedulerRepository中,返回scheduler,结束

    往下是本地调度,不是远程调度,因此需要获取和本地调度相关的信息

6.获取线程池配置
7.获取Job存储设置,(分为内存存储和数据库存储作业还有一个不太了解的方式,默认是内存存储)
8.设置数据库连接池
9.安装Scheduler插件
10.安装JobListener ,监听作业启动前,作业呗否决执行,作业已经执行,参见[JobListener.class]
11.安装TriggerListener,监听触发器被触发工作将要执行时,触发错过,否决工作执行,工作完成,参见[TriggerListener.class]
12.获取ThreadExecutor配置
13.初始化JobRunShellFactory,这个工厂类很重要,后面会介绍
14.创建标准StdScheduler,返回。

1.3.2 创建JobDetail

JobDeatil包含jobDataMap和jobClass,以及一些描述,名称等等,采用Build模式建造,jobDataMap主要存储一些额外信息。

1.3.3 创建Trigger

Trigger主要包含了一些计划信息,详细可参考接口

准备工作做完了,开始进行调度

1.3.3 scheduler.scheduleJob()

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public Date scheduleJob(JobDetail jobDetail, Trigger trigger)
throws SchedulerException {
return sched.scheduleJob(jobDetail, trigger);
}

sched是StdScheduler的一个成员,是QuartzScheduler的实例,在上面的instantiate()方法中实例化过并且用它构造StdScheduler;看一下QuartzScheduler的scheduleJob

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public Date scheduleJob(JobDetail jobDetail,
Trigger trigger) throws SchedulerException {
validateState();
if (jobDetail == null) {
throw new SchedulerException("JobDetail cannot be null");
}
if (trigger == null) {
throw new SchedulerException("Trigger cannot be null");
}
if (jobDetail.getKey() == null) {
throw new SchedulerException("Job's key cannot be null");
}
if (jobDetail.getJobClass() == null) {
throw new SchedulerException("Job's class cannot be null");
}
OperableTrigger trig = (OperableTrigger)trigger;
if (trigger.getJobKey() == null) {
trig.setJobKey(jobDetail.getKey());
} else if (!trigger.getJobKey().equals(jobDetail.getKey())) {
throw new SchedulerException(
"Trigger does not reference given job!");
}
trig.validate();
Calendar cal = null;
if (trigger.getCalendarName() != null) {
cal = resources.getJobStore().retrieveCalendar(trigger.getCalendarName());
}
Date ft = trig.computeFirstFireTime(cal);
if (ft == null) {
throw new SchedulerException(
"Based on configured schedule, the given trigger '" + trigger.getKey() + "' will never fire.");
}
resources.getJobStore().storeJobAndTrigger(jobDetail, trig);
notifySchedulerListenersJobAdded(jobDetail);
notifySchedulerThread(trigger.getNextFireTime().getTime());
notifySchedulerListenersSchduled(trigger);
return ft;
}

让我们来看一下schedule()方法

  1. 一些校验,jobDetail,trigger,jobClass判空
  2. 计算第一次执行的日期,计算日期为空,则抛出异常,job永远不会被调度
  3. 如果上述通过,通过jobStore存储jobDetail和trigger
  4. 通知监听器程序:工作加入通知、
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public void notifySchedulerListenersJobAdded(JobDetail jobDetail) {
// build a list of all scheduler listeners that are to be notified...
List<SchedulerListener> schedListeners = buildSchedulerListenerList();
// notify all scheduler listeners
for(SchedulerListener sl: schedListeners) {
try {
sl.jobAdded(jobDetail);
} catch (Exception e) {
getLog().error(
"Error while notifying SchedulerListener of JobAdded.",
e);
}
}
}

5.通知监听器程序:通知正在休眠(工作可能都执行完,主线程sigLock.wait())的主执行线程,有工作加入,唤醒主线程

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protected void notifySchedulerThread(long candidateNewNextFireTime) {
if (isSignalOnSchedulingChange()) {
signaler.signalSchedulingChange(candidateNewNextFireTime);
}
}
public void signalSchedulingChange(long candidateNewNextFireTime) {
synchronized(sigLock) {
signaled = true;
signaledNextFireTime = candidateNewNextFireTime;
sigLock.notifyAll();
}
}

6.通知调度器job被调度了

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public void notifySchedulerListenersSchduled(Trigger trigger) {
// build a list of all scheduler listeners that are to be notified...
List<SchedulerListener> schedListeners = buildSchedulerListenerList();
// notify all scheduler listeners
for(SchedulerListener sl: schedListeners) {
try {
sl.jobScheduled(trigger);
} catch (Exception e) {
getLog().error(
"Error while notifying SchedulerListener of scheduled job."
+ " Triger=" + trigger.getKey(), e);
}
}
}

此时scheduler.scheduleJob()执行完毕

1.3.4 scheduler.start() 未执行此函数,没有什么会真正执行,主线程loop循环一直被wait。

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public void start() throws SchedulerException {
sched.start();
}
//sched.start()
public void start() throws SchedulerException {
if (shuttingDown|| closed) {
throw new SchedulerException(
"The Scheduler cannot be restarted after shutdown() has been called.");
}
// QTZ-212 : calling new schedulerStarting() method on the listeners
// right after entering start()
notifySchedulerListenersStarting();
if (initialStart == null) {
initialStart = new Date();
this.resources.getJobStore().schedulerStarted();
startPlugins();
} else {
resources.getJobStore().schedulerResumed();
}
schedThread.togglePause(false);
getLog().info(
"Scheduler " + resources.getUniqueIdentifier() + " started.");
notifySchedulerListenersStarted();
}
  1. 判断调度器是否关掉或停止(因为可能开始之前已经将调度器停止或关闭),是则直接抛异常
  2. 通知监听器,马上就要执行
  3. 启动一些通知jobStore和一些插件开始执行,如果initial不为空,说明曾经启动过,则重新恢复
  4. 切换线程开始执行togglePause(false)。此时开始执行, 下面的run()方法选取了一部分,未设置开始之前,while里面还有一个while (paused && !halted.get()) 一直等待变量改变,否则,就一直wait这也就是sche.scheduleJob()未真正启动工作的原因
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void togglePause(boolean pause) {
synchronized (sigLock) {
paused = pause;
if (paused) {
signalSchedulingChange(0);
} else {
sigLock.notifyAll();
}
}
}
public void run() {
boolean lastAcquireFailed = false;
while (!halted.get()) {
try {
// check if we're supposed to pause...
synchronized (sigLock) {
while (paused && !halted.get()) {
try {
// wait until togglePause(false) is called...
sigLock.wait(1000L);
} catch (InterruptedException ignore) {
}
}
if (halted.get()) {
break;
}
}
}

5.通知任务已经开始执行

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public void notifySchedulerListenersStarted() {
// build a list of all scheduler listeners that are to be notified...
List<SchedulerListener> schedListeners = buildSchedulerListenerList();
// notify all scheduler listeners
for(SchedulerListener sl: schedListeners) {
try {
sl.schedulerStarted();
} catch (Exception e) {
getLog().error(
"Error while notifying SchedulerListener of startup.",
e);
}
}
}

至此,整个流程大约完成了。
具体执行的(run)细节看看有空再讲一下。

参考文档