Add context to StaleAsyncWebRequestException to allow for better exception handling [SPR-9369]

[spring-projects-issues]

Phil Webb opened SPR-9369 and commented

The StaleAsyncWebRequestException added as part of #13162 is thrown when an async request has gone stale. Since the exception can be handled using the usual MVC semantics it might be useful to add more context to the exception. One option might be to add a get getSource() method that could return the Callable or DeferredResult object that was returned from the original @Controller method.

An example use case for this might be to send a user to a user an email if a timeout occurs.

---

Affects: 3.1.1

Issue Links:

• Support for Servlet 3.0/3.1 asynchronous request processing [SPR-8517] #13162 Support for Servlet 3.0/3.1 asynchronous request processing

[spring-projects-issues]

Rossen Stoyanchev commented

Yes, good point. That would allow removing an expired DeferredResult.

[spring-projects-issues]

Rossen Stoyanchev commented

On a second thought, by the time the exception is raised, the response is not usable. So I wonder if the HandlerExceptionResolver mechanism is the best place to deal with it since you can't really write to the response any more. With a DeferredResult I can catch the exception when I try to set it and of course I have access to the DeferredResult instance. However, with a Callable I might want some way to be notified of the exception and a HandlerExceptionResolver is still the main option. I'll leave this open for now until we get a more specific requirement.

[spring-projects-issues]

Rossen Stoyanchev commented

StaleAsyncWebRequestException was removed for M2.

If a controller method returns a Callable and doesn't complete on time, an error is logged. It's all we can do since the request/response pair is no longer usable. DeferredResult on the other hand now offers an isSetOrExpired() method that can be used to check if the instance is still usable. Also DeferredResult.setResult(Object) returns a boolean depending on whether it succeeded in handing off the result for processing or not (including the stale request issue).