码农code之路scheduler.start()是Quartz的启动方式！下面开始源码的分析!
说明：我都是分析的jobStore 方式为jdbc的SimpleTrigger！RAM的方式类似分析方式！
源码中相关sql中内容解释：
{0} ： 表的前缀 ，如表qrtz_trigger ,{0}== qrtz_
{1} ：quartz.properties 中配置的 org.quartz.scheduler.instanceName: myInstanceName ，{1} ==myInstanceName
scheduler.start() 调用 .QuartzScheduler.start();
Quartz 的启动要调用start()方法进行线程的启动，并执行需要出发的Trigger，start方法里面进行的操作：
- 启动的初始化
- 判断是否集群，对应不同的操作
- 若是非集群，首先有恢复机制，恢复任何失败或misfire的作业，并根据需要清理数据存储。
- 初始化线程管理，唤醒所有等待的线程！
线程中启动线程是调用start()方法，但是真正执行线程任务的操作在run()中！
开启 scheduler调用start();
QuartzScheduler.start();下面就是简单的源码分析：
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) {//初始化标识为null，进行初始化操作
initialStart = new Date();
this.resources.getJobStore().schedulerStarted();//1 主要分析的地方
startPlugins();
} else {
resources.getJobStore().schedulerResumed();//2 如果已经初始化过，则恢复jobStore
}
schedThread.togglePause(false);//3 唤醒所有等待的线程
getLog().info(
"Scheduler " + resources.getUniqueIdentifier() + " started.");
notifySchedulerListenersStarted();
}一、启动调度任务
this.resources.getJobStore().schedulerStarted() ;主要分析的地方,实际上 是调用 QuartzSchedulerResources中的JobStore进行启动！看下面代码：
public void schedulerStarted() throws SchedulerException {
//是集群
if (isClustered()) {
clusterManagementThread = new ClusterManager();
if(initializersLoader != null)
clusterManagementThread.setContextClassLoader(initializersLoader);
clusterManagementThread.initialize();
} else {//不是集群
try {
recoverJobs();/1、恢复job
} catch (SchedulerException se) {
throw new SchedulerConfigException(
"Failure occured during job recovery.", se);
}
}
misfireHandler = new MisfireHandler();
if(initializersLoader != null)
misfireHandler.setContextClassLoader(initializersLoader);
misfireHandler.initialize();//2、 获取ThreadExecutor 线程管理
schedulerRunning = true;
getLog().debug("JobStore background threads started (as scheduler was started).");
} 1 、恢复job recoverJobs();
//启动的时候 有一个恢复机制：
//recoverJobs ----- 将恢复任何失败或misfire的作业，并根据需要清理数据存储。
protected void recoverJobs() throws JobPersistenceException {
executeInNonManagedTXLock(
LOCK_TRIGGER_ACCESS,
new VoidTransactionCallback() {
public void executeVoid(Connection conn) throws JobPersistenceException {
recoverJobs(conn);//恢复job
}
}, null);
}
protected void recoverJobs(Connection conn) throws JobPersistenceException {
try {
（1）//更新不一致的作业状态 先修改状态，将 ACQUIRED 和 BLOCKED ---> WAITING
int rows = getDelegate().updateTriggerStatesFromOtherStates(conn,
STATE_WAITING, STATE_ACQUIRED, STATE_BLOCKED);
rows += getDelegate().updateTriggerStatesFromOtherStates(conn,
STATE_PAUSED, STATE_PAUSED_BLOCKED, STATE_PAUSED_BLOCKED);
//----更新sql---
//"UPDATE {0}TRIGGERS SET TRIGGER_STATE = ? WHERE SCHED_NAME = {1} AND (TRIGGER_STATE = ? OR TRIGGER_STATE = ?)"
getLog().info(
"Freed " + rows
+ " triggers from 'acquired' / 'blocked' state.");
// clean up misfired jobs
//1.1 清理misfire的jobs
recoverMisfiredJobs(conn, true);
// recover jobs marked for recovery that were not fully executed
//1.2 恢复未完全执行的标记为恢复的作业 --查询 qrtz_fire_trigger
List<OperableTrigger> recoveringJobTriggers = getDelegate()
.selectTriggersForRecoveringJobs(conn);
getLog()
.info(
"Recovering "
+ recoveringJobTriggers.size()
+ " jobs that were in-progress at the time of the last shut-down.");
for (OperableTrigger recoveringJobTrigger: recoveringJobTriggers) {
if (jobExists(conn, recoveringJobTrigger.getJobKey())) {
recoveringJobTrigger.computeFirstFireTime(null);
storeTrigger(conn, recoveringJobTrigger, null, false,
STATE_WAITING, false, true);
}
}
getLog().info("Recovery complete.");
// remove lingering 'complete' triggers...
//1.3 移除state == complete
List<TriggerKey> cts = getDelegate().selectTriggersInState(conn, STATE_COMPLETE);
for(TriggerKey ct: cts) {
removeTrigger(conn, ct);
}
getLog().info(
"Removed " + cts.size() + " 'complete' triggers.");
// clean up any fired trigger entries
//1.4 清理任何已触发的触发器条目
int n = getDelegate().deleteFiredTriggers(conn);
getLog().info("Removed " + n + " stale fired job entries.");
} catch (JobPersistenceException e) {
throw e;
} catch (Exception e) {
throw new JobPersistenceException("Couldn't recover jobs: "
+ e.getMessage(), e);
}
}1.1 清理misfire的jobs recoverMisfiredJobs(conn, true);
//是否有misfire的Trigger
//我们必须仍然寻找MISFIRED状态，以防触发器被遗忘
//在此状态下升级到此版本不支持
（a1）hasMisfiredTriggersInState(conn, STATE_WAITING, getMisfireTime(),
maxMisfiresToHandleAtATime, misfiredTriggers);
////getMisfireTime() 当前时间 -(减去) 一分钟 ,maxMisfiresToHandleAtATime == -1 ,misfiredTriggers== null
"SELECT TRIGGER_NAME, TRIGGER_GROUP FROM {0}TRIGGERS WHERE SCHED_NAME = {1} AND NOT (MISFIRE_INSTR = -1) AND NEXT_FIRE_TIME < ? AND TRIGGER_STATE = ? ORDER BY NEXT_FIRE_TIME ASC, PRIORITY DESC"
上面sql查询出来结果是个list
(aa1)若resultList.size() == count 返回 TRUE！！ 否则 返回false！
(aa2)不等于 count ，封装数据，到resultList中，triggername TriggerGroup
//查询出来有misfire 的 Trigger
（b2） misfiredTriggers.size() > 0
(bb1)输出日志信息 ：getLog().info(
"Handling " + misfiredTriggers.size() +
" trigger(s) that missed their scheduled fire-time.");
（bb2）循环 misfiredTriggers List集合
for (TriggerKey triggerKey: misfiredTriggers) {
//retrieveTrigger ，检索Trigger，检索到进行数据封装
OperableTrigger trig =
retrieveTrigger(conn, triggerKey);
//retrieveTrigger 执行的操作
（1）"SELECT * FROM {0}TRIGGERS WHERE SCHED_NAME = {1} AND TRIGGER_NAME = ? AND TRIGGER_GROUP = ?"
（2）关联Trigger对应的类型，如simpleTrigger等
if (trig == null) {
continue;
}
//do 更新misfire的触发器
doUpdateOfMisfiredTrigger(conn, trig, false, STATE_WAITING, recovering); //recovering===TRUE
（1）cal = retrieveCalendar(conn, trig.getCalendarName()); 搞这个表，qrtz_calendar
（2）trig.updateAfterMisfire(cal); //simpleTrigger默认的misfire 机制
setNextFireTime(new Date()); //设置下次执行的时间（next_fire_time）为当前时间！这里比较重要！！！
（3） getNextFireTime != null
if (trig.getNextFireTime() == null) {
storeTrigger(conn, trig,
null, true, STATE_COMPLETE, forceState, recovering);
schedSignaler.notifySchedulerListenersFinalized(trig);
} else {
storeTrigger(conn, trig, null, true, newStateIfNotComplete,
forceState, false);
// job == null replaceExisting ==true state==waitting forceState==false recovering==false
storeTrigger(Connection conn,
OperableTrigger newTrigger, JobDetail job, boolean replaceExisting, String state,
boolean forceState, boolean recovering)
//Insert or update a trigger.
boolean existingTrigger = triggerExists(conn, newTrigger.getKey());
if (existingTrigger) {
//state == waitting
getDelegate().updateTrigger(conn, newTrigger, state, job);
//更新sql
/*
"UPDATE {0}TRIGGERS SET JOB_NAME = ?, JOB_GROUP = ?, DESCRIPTION = ?, NEXT_FIRE_TIME = ?, PREV_FIRE_TIME = ?, TRIGGER_STATE = ?, TRIGGER_TYPE = ?, START_TIME = ?, END_TIME = ?, CALENDAR_NAME = ?, MISFIRE_INSTR = ?, PRIORITY = ? WHERE SCHED_NAME = {1} AND TRIGGER_NAME = ? AND TRIGGER_GROUP = ?"*/
} else {
getDelegate().insertTrigger(conn, newTrigger, state, job);
//插入sql
/*"INSERT INTO {0}TRIGGERS (SCHED_NAME, TRIGGER_NAME, TRIGGER_GROUP, JOB_NAME, JOB_GROUP, DESCRIPTION, NEXT_FIRE_TIME, PREV_FIRE_TIME, TRIGGER_STATE, TRIGGER_TYPE, START_TIME, END_TIME, CALENDAR_NAME, MISFIRE_INSTR, JOB_DATA, PRIORITY) VALUES({1}, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?)"*/
}
}
（c3） long earliestNewTime = Long.MAX_VALUE; // long earliestNewTime = Long.MAX_VALUE; === 9223372036854775807
if(trig.getNextFireTime() != null && trig.getNextFireTime().getTime() < earliestNewTime){
earliestNewTime = trig.getNextFireTime().getTime();
}1.2、 恢复未完全执行的标记为恢复的作业
List<OperableTrigger> recoveringJobTriggers = getDelegate()
.selectTriggersForRecoveringJobs(conn);
// INSTANCE_NAME == dufy_test REQUESTS_RECOVERY == true 实际封装到数据库查询是 REQUESTS_RECOVERY== 1
"SELECT * FROM {0}FIRED_TRIGGERS WHERE SCHED_NAME = {1} AND INSTANCE_NAME = ? AND REQUESTS_RECOVERY = ?"
//具体怎么是 truｅ是怎么转换成为 1的见附1图片！
Recovery complete.恢复完成！！ 附1：true 是如何转换为 1 的：
1.3 移除state == complete
List<TriggerKey> cts = getDelegate().selectTriggersInState(conn, STATE_COMPLETE);
-----------------------------------------------------------------------------
"SELECT TRIGGER_NAME, TRIGGER_GROUP FROM {0}TRIGGERS WHERE SCHED_NAME = {1} AND TRIGGER_STATE = ?"
-----------------------------------------------------------------------------
for(TriggerKey ct: cts) {
removeTrigger(conn, ct);
---------------------------------------------------------------------
（a）删除前，先查询jobDetail
JobDetail job = getDelegate().selectJobForTrigger(conn,getClassLoadHelper(), key, false);
"SELECT J.JOB_NAME, J.JOB_GROUP, J.IS_DURABLE, J.JOB_CLASS_NAME, J.REQUESTS_RECOVERY FROM {0}TRIGGERS T, {0}JOB_DETAILS J WHERE T.SCHED_NAME = {1} AND J.SCHED_NAME = {1} AND T.TRIGGER_NAME = ? AND T.TRIGGER_GROUP = ? AND T.JOB_NAME = J.JOB_NAME AND T.JOB_GROUP = J.JOB_GROUP"
（b）删除触发器，其侦听器及其Simple / Cron / BLOB子表条目。
boolean removedTrigger = deleteTriggerAndChildren(conn, key);
deleteTrigger(Connection conn, TriggerKey triggerKey)
（b1）deleteTriggerExtension
"DELETE FROM {0}SIMPLE_TRIGGERS WHERE SCHED_NAME = {1} AND TRIGGER_NAME = ? AND TRIGGER_GROUP = ?"
"DELETE FROM {0}BLOB_TRIGGERS WHERE SCHED_NAME = {1} AND TRIGGER_NAME = ? AND TRIGGER_GROUP = ?"
（b2）"DELETE FROM {0}TRIGGERS WHERE SCHED_NAME = {1} AND TRIGGER_NAME = ? AND TRIGGER_GROUP = ?"
（c）是否删除jobdetail ，判断 isDurable 默认 为false。
if (null != job && !job.isDurable()) {
int numTriggers = getDelegate().selectNumTriggersForJob(conn,
job.getKey());
---------------------------------------------------------
"SELECT COUNT(TRIGGER_NAME) FROM {0}TRIGGERS WHERE SCHED_NAME = {1} AND JOB_NAME = ? AND JOB_GROUP = ?"
---------------------------------------------------------
if (numTriggers == 0) {
// Don't call removeJob() because we don't want to check for
// triggers again.
//不要调用removeJob（），因为我们不想再次检查触发器。
deleteJobAndChildren(conn, job.getKey()); //删除作业及其侦听器。
-----------------------------------------------------
//deleteJobDetail(Connection conn, JobKey jobKey) 删除给定作业的作业明细记录。
"DELETE FROM {0}JOB_DETAILS WHERE SCHED_NAME = {1} AND JOB_NAME = ? AND JOB_GROUP = ?"
-----------------------------------------------------
}
}
}1.4 清理任何已触发的触发器条目
int n = getDelegate().deleteFiredTriggers(conn);
----------------------------------------------------------------------------
"DELETE FROM {0}FIRED_TRIGGERS WHERE SCHED_NAME = {1}"
----------------------------------------------------------------------------2、获取ThreadExecutor 线程管理 misfireHandler.initialize();
public void initialize() {
ThreadExecutor executor = getThreadExecutor();
//getThreadExecutor == private ThreadExecutor threadExecutor = new DefaultThreadExecutor();
executor.execute(MisfireHandler.this); //启动线程执行 对应job的 execute方法
//MisfireHandler == class MisfireHandler extends Thread 继承了Thread
}二、 如果已经初始化过，则恢复
jobStoreresources.getJobStore().schedulerResumed();.如果已经初始化过，则恢复调度器运行 !
private volatile boolean schedulerRunning = false;//默认schedulerRunning = false
public void schedulerResumed() {
schedulerRunning = true;
}三、 唤醒所有等待的线程
schedThread.togglePause(false);
schedThread.togglePause(false);
//指示主处理循环在下一个可能的点暂停。
void togglePause(boolean pause) {
synchronized (sigLock) {
paused = pause;
if (paused) {
signalSchedulingChange(0);
------------------------------------------
//发信号通知主要处理循环，已经进行了调度的改变 - 以便中断在等待misfire时间到达时可能发生的任何睡眠。
public void signalSchedulingChange(long candidateNewNextFireTime) {
synchronized(sigLock) {
signaled = true;
signaledNextFireTime = candidateNewNextFireTime;
sigLock.notifyAll(); // private final Object sigLock = new Object();
}
}
------------------------------------------
} else {
sigLock.notifyAll();//唤醒所有等待的线程
}
}
} 四、总结
在看源码的时候最好要自己能够结合源码，通过文章在debug一下，可以加深印象和理解！
作者：阿飞云 | 来源：https://blog.csdn.net/u010648555/column/info/14251
