chemosphere的影响因子（聊聊cheddar的PendingResult）

本文主要研究一下cheddar的PendingResult

Cheddar/cheddar/cheddar-application/src/main/java/com/clicktravel/cheddar/application/pending/result/PendingResult.java

classPendingResult{ privatestaticfinallongTIMEOUT_SECONDS=30; privatefinalCountDownLatchcountdownLatch=newCountDownLatch(1); privateResultresult; /** *Offersa{@linkResult},returningimmediately. *@paramresult{@linkResult}tooffer */ publicvoidofferResult(finalResultresult){ this.result=result; countdownLatch.countDown(); } /** *Pollsfora{@linkResult},blockinguntilitisofferedbysomeotherthread.Iftheresulthasalreadybeen *offered,theresultisreturnedimmediately. *@return{@linkResult}obtained,potentiallyafterblocking *@throwsInterruptedexception,PendingResultTimeoutException */ publicResultpollResult()throwsInterruptedException,PendingResultTimeoutException{ if(!countdownLatch.await(TIMEOUT_SECONDS,TimeUnit.SECONDS)){ thrownewPendingResultTimeoutException(); } returnresult; } }

PendingResult定义了offerResult、pollResult方法；offerResult方法设置result，然后通过countdownLatch通过pollResult；pollResult方法等待TIMEOUT_SECONDS，若还没有结果抛出PendingResultTimeoutException

PendingResultHandler

Cheddar/cheddar/cheddar-application/src/main/java/com/clicktravel/cheddar/application/pending/result/PendingResultHandler.java

@Component publicclassPendingResultHandler{ privatefinalPendingResultsHolderpendingResultsHolder; privatefinalStringapplicationName; privatefinalXStreamxStream=newXStream(); @Autowired publicPendingResultHandler(finalPendingResultsHolderpendingResultsHolder, @Value("${server.application.name}")finalStringapplicationName){ this.pendingResultsHolder=pendingResultsHolder; this.applicationName=applicationName; } /** *Createsa{@linkPendingResult}storedonthelocalapplicationinstance *@returnpendingResultIdUniqueidentifierofcreated{@PendingResult} */ publicStringcreatePendingResult(){ returnpendingResultsHolder.create(); } /** *Removesa{@linkPendingResult}storedonthelocalapplicationinstance *@parampendingResultIdIDof{@linkPendingResult}toremove */ publicvoidremovePendingResult(finalStringpendingResultId){ pendingResultsHolder.remove(pendingResultId); } /** *Pollsa{@linkPendingResult}storedonthelocalapplicationinstanceforareturnedvalue,blockinguntila *valueisofferedoranExceptionisthrown *@parampendingResultIdIDoflocallystored{@linkPendingResult} *@returnValuefromreturnedresult *@throwsExceptionIfexceptionwasthrown */ publicObjectpollValue(finalStringpendingResultId)throwsException{ finalPendingResultpendingResult=pendingResultsHolder.get(pendingResultId); returnpendingResult.pollResult().getValue(); } /** *Offersareturnvaluefora{@linkPendingResult},whichispossiblystoredonadifferent(remote)application *instance *@parampendingResultIdIDof{@linkPendingResult}tooffervalueto *@paramvalueValuetooffer */ publicvoidofferValue(finalStringpendingResultId,finalObjectvalue){ offerResult(pendingResultId,newSimpleResult(value)); } /** *Offersathrownexceptionfora{@linkPendingResult},whichispossiblystoredonadifferent(remote) *applicationinstance *@parampendingResultIdof{@linkPendingResult}toofferthrownexceptionto *@paramexceptionThrownexceptiontooffer */ publicvoidofferException(finalStringpendingResultId,finalExceptionexception){ offerResult(pendingResultId,newExceptionResult(exception)); } privatevoidofferResult(finalStringpendingResultId,finalResultresult){ finalPendingResultOfferedEventevent=newPendingResultOfferedEvent(); event.setTargetApplicationName(applicationName); event.setPendingResultId(pendingResultId); event.setResultXml(toCompactXml(result)); SystemEventPublisher.instance().publishEvent(event); } privateStringtoCompactXml(finalObjectobject){ finalStringWriterstringWriter=newStringWriter(); xStream.marshal(object,newCompactWriter(stringWriter)); returnstringWriter.toString(); } }

PendingResultHandler提供了removePendingResult、pollValue、offerValue、offerException方法；offerResult方法创建并发布PendingResultOfferedEvent

小结

cheddar的PendingResult定义了offerResult、pollResult方法；PendingResultHandler提供了removePendingResult、pollValue、offerValue、offerException方法。

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