我是石英新手。我發(fā)現(xiàn)了@DisallowConcurrentExecutionquartz庫(kù)提供的注釋，文檔說(shuō)：'An annotation that marks a {@link Job} class as one that must not have multiple instances executed concurrently (where instance is based-upon a {@link JobDetail} definition - or in other words based upon a {@link JobKey}).'則DisallowConcurrentExecution.java寫為：@Documented@Retention(RetentionPolicy.RUNTIME)@Target(ElementType.TYPE)public @interface DisallowConcurrentExecution {}但是，我找不到實(shí)際處理同一作業(yè)不并發(fā)執(zhí)行的實(shí)現(xiàn)。這對(duì)我來(lái)說(shuō)是新的，所以有人可以幫助我解釋內(nèi)部實(shí)現(xiàn)邏輯。我試圖查找用法，但只在課堂上找到了它MethodInvokingJobDetailFactoryBean.java
1 回答
泛舟湖上清波郎朗
TA貢獻(xiàn)1818條經(jīng)驗(yàn) 獲得超3個(gè)贊
我不參與石英項(xiàng)目。我在這里的所有評(píng)論都來(lái)自我出于好奇而對(duì)此事的調(diào)查，可能會(huì)遺漏一些信息。
首先要知道的是，JobDetailImpl 將檢查注釋是否存在并在方法中提供此信息。
/**
* @return whether the associated Job class carries the {@link DisallowConcurrentExecution} annotation.
*/
public boolean isConcurrentExectionDisallowed() {
return ClassUtils.isAnnotationPresent(jobClass, DisallowConcurrentExecution.class);
}
然后你可以看到這個(gè)方法在系統(tǒng)的不同部分被檢查。
例如，JobStoreSupport 在此處檢查它，如果存在注釋，則它會(huì)檢查塊狀態(tài)：
if (job.isConcurrentExectionDisallowed() && !recovering) {
state = checkBlockedState(conn, job.getKey(), state);
}
這里是實(shí)際驗(yàn)證發(fā)生的地方，并讓 Quartz 決定在該實(shí)例上運(yùn)行或不運(yùn)行作業(yè)。
org.quartz.impl.jdbcjobstore.JobStoreSupport#checkBlockedState
/**
* Determines if a Trigger for the given job should be blocked.
* State can only transition to STATE_PAUSED_BLOCKED/BLOCKED from
* PAUSED/STATE_WAITING respectively.
*
* @return STATE_PAUSED_BLOCKED, BLOCKED, or the currentState.
*/
protected String checkBlockedState(
Connection conn, JobKey jobKey, String currentState)
throws JobPersistenceException {
// State can only transition to BLOCKED from PAUSED or WAITING.
if ((!currentState.equals(STATE_WAITING)) &&
(!currentState.equals(STATE_PAUSED))) {
return currentState;
}
try {
List<FiredTriggerRecord> lst = getDelegate().selectFiredTriggerRecordsByJob(conn,
jobKey.getName(), jobKey.getGroup());
if (lst.size() > 0) {
FiredTriggerRecord rec = lst.get(0);
if (rec.isJobDisallowsConcurrentExecution()) { // OLD_TODO: worry about failed/recovering/volatile job states?
return (STATE_PAUSED.equals(currentState)) ? STATE_PAUSED_BLOCKED : STATE_BLOCKED;
}
}
return currentState;
} catch (SQLException e) {
throw new JobPersistenceException(
"Couldn't determine if trigger should be in a blocked state '"
+ jobKey + "': "
+ e.getMessage(), e);
}
}
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