ClassCastException from PollSkipAdvice

[cdombroski]

Affects Version(s): 5.1.2

---

When using a PollSkipAdvice that is set to skipPolls, it causes a ClassCastException in AbstractPollingEndpoint. This is caused by the return Boolean.FALSE; on line 56 when the AbstractPollingEndpoint expects a Message or null.

2019-01-24 09:08:09.814 ERROR 8732 --- [ask-scheduler-1] o.s.integration.handler.LoggingHandler : org.springframework.messaging.MessagingException: nested exception is java.lang.ClassCastException: java.lang.Boolean cannot be cast to org.springframework.messaging.Message
at org.springframework.integration.endpoint.AbstractPollingEndpoint.pollForMessage(AbstractPollingEndpoint.java:343)
at org.springframework.integration.endpoint.AbstractPollingEndpoint.lambda$null$1(AbstractPollingEndpoint.java:277)
at org.springframework.integration.util.ErrorHandlingTaskExecutor.lambda$execute$0(ErrorHandlingTaskExecutor.java:57)
at org.springframework.core.task.SyncTaskExecutor.execute(SyncTaskExecutor.java:50)
at org.springframework.integration.util.ErrorHandlingTaskExecutor.execute(ErrorHandlingTaskExecutor.java:55)
at org.springframework.integration.endpoint.AbstractPollingEndpoint.lambda$createPoller$2(AbstractPollingEndpoint.java:274)
at org.springframework.scheduling.support.DelegatingErrorHandlingRunnable.run(DelegatingErrorHandlingRunnable.java:54)
at org.springframework.scheduling.concurrent.ReschedulingRunnable.run(ReschedulingRunnable.java:93)
at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)
at java.util.concurrent.FutureTask.run$$$capture(FutureTask.java:266)
at java.util.concurrent.FutureTask.run(FutureTask.java)
at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.access$201(ScheduledThreadPoolExecutor.java:180)
at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:293)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
at java.lang.Thread.run(Thread.java:748)
Caused by: java.lang.ClassCastException: java.lang.Boolean cannot be cast to org.springframework.messaging.Message
at org.springframework.integration.endpoint.AbstractPollingEndpoint.pollForMessage(AbstractPollingEndpoint.java:329)
... 15 more

[garyrussell]

Thanks - strange that nobody reported this in 5 years - I guess people aren't using it (or are using a smart poller, which really superseded this functionality).

[cdombroski]

It looks like a change in AbstractPollingEndpoint occurred about 4 months ago might have introduced this.

If you don't mind, could you point me to the documentation for the smart polling you mentioned? I'm using this to only poll a database when the process has leadership.

[garyrussell]

Ah - ok; thanks; yes, it's a regression.

See "Smart" Polling.

Version 4.2 introduced the AbstractMessageSourceAdvice. Any Advice objects in the advice-chain that subclass this class are applied only to the receive operation. Such classes implement the following methods:

• beforeReceive(MessageSource<?> source) This method is called before the MessageSource.receive() method. It lets you examine and reconfigure the source. Returning false cancels this poll (similar to the PollSkipAdvice mentioned earlier).

[cdombroski]

So, it looks like there's nothing out of the box to provide the functionality of PollSkipAdvice as a AbstractMessageSourceAdvice. It wouldn't take much to refactor the current class to do so, is this something that should/will be done in the future?

[garyrussell]

Good point; yes, we should do that.