org.springframework.web.context.request.async

Interface DeferredResultProcessingInterceptor

All Known Implementing Classes:

AsyncRequestInterceptor, AsyncRequestInterceptor, AsyncRequestInterceptor, AsyncRequestInterceptor, DeferredResultProcessingInterceptorAdapter, TimeoutDeferredResultProcessingInterceptor

public interface DeferredResultProcessingInterceptor

Intercepts concurrent request handling, where the concurrent result is obtained by waiting for a DeferredResult to be set from a thread chosen by the application (e.g. in response to some external event).

A DeferredResultProcessingInterceptor is invoked before the start of async processing, after the DeferredResult is set as well as on timeout, or or after completing for any reason including a timeout or network error.

As a general rule exceptions raised by interceptor methods will cause async processing to resume by dispatching back to the container and using the Exception instance as the concurrent result. Such exceptions will then be processed through the HandlerExceptionResolver mechanism.

The afterTimeout method can set the DeferredResult in order to resume processing.

Since:

3.2

Author:

Rossen Stoyanchev, Rob Winch

Method Summary

Modifier and Type	Method and Description
<T> void	afterCompletion(NativeWebRequest request, DeferredResult<T> deferredResult) Invoked from a container thread when an async request completed for any reason including timeout and network error.
<T> void	beforeConcurrentHandling(NativeWebRequest request, DeferredResult<T> deferredResult) Invoked immediately before the start of concurrent handling, in the same thread that started it.
<T> boolean	handleTimeout(NativeWebRequest request, DeferredResult<T> deferredResult) Invoked from a container thread when an async request times out before the DeferredResult has been set.
<T> void	postProcess(NativeWebRequest request, DeferredResult<T> deferredResult, java.lang.Object concurrentResult) Invoked after a DeferredResult has been set, via DeferredResult.setResult(Object) or DeferredResult.setErrorResult(Object), and is also ready to handle the concurrent result.
<T> void	preProcess(NativeWebRequest request, DeferredResult<T> deferredResult) Invoked immediately after the start of concurrent handling, in the same thread that started it.

Method Detail

beforeConcurrentHandling

<T> void beforeConcurrentHandling(NativeWebRequest request,
                                  DeferredResult<T> deferredResult)
                           throws java.lang.Exception

Invoked immediately before the start of concurrent handling, in the same thread that started it. This method may be used to capture state just prior to the start of concurrent processing with the given DeferredResult.

Parameters:

request - the current request

deferredResult - the DeferredResult for the current request

Throws:

java.lang.Exception - in case of errors

preProcess

<T> void preProcess(NativeWebRequest request,
                    DeferredResult<T> deferredResult)
             throws java.lang.Exception

Invoked immediately after the start of concurrent handling, in the same thread that started it. This method may be used to detect the start of concurrent processing with the given DeferredResult.

The DeferredResult may have already been set, for example at the time of its creation or by another thread.

Parameters:

request - the current request

deferredResult - the DeferredResult for the current request

Throws:

java.lang.Exception - in case of errors

postProcess

<T> void postProcess(NativeWebRequest request,
                     DeferredResult<T> deferredResult,
                     java.lang.Object concurrentResult)
              throws java.lang.Exception

Invoked after a DeferredResult has been set, via DeferredResult.setResult(Object) or DeferredResult.setErrorResult(Object), and is also ready to handle the concurrent result.

This method may also be invoked after a timeout when the DeferredResult was created with a constructor accepting a default timeout result.

Parameters:

request - the current request

deferredResult - the DeferredResult for the current request

concurrentResult - the result to which the DeferredResult

Throws:

java.lang.Exception - in case of errors

handleTimeout

<T> boolean handleTimeout(NativeWebRequest request,
                          DeferredResult<T> deferredResult)
                   throws java.lang.Exception

Invoked from a container thread when an async request times out before the DeferredResult has been set. Implementations may invoke setResult or setErrorResult to resume processing.

Parameters:

request - the current request

deferredResult - the DeferredResult for the current request; if the DeferredResult is set, then concurrent processing is resumed and subsequent interceptors are not invoked

Returns:

true if processing should continue, or false if other interceptors should not be invoked

Throws:

java.lang.Exception - in case of errors

afterCompletion

<T> void afterCompletion(NativeWebRequest request,
                         DeferredResult<T> deferredResult)
                  throws java.lang.Exception

Invoked from a container thread when an async request completed for any reason including timeout and network error. This method is useful for detecting that a DeferredResult instance is no longer usable.

Parameters:

request - the current request

deferredResult - the DeferredResult for the current request

Throws:

java.lang.Exception - in case of errors