All Known Implementing Classes:
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/error, 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 handleTimeout method can set the DeferredResult in order to resume processing.
Since:
3.2
Author:
Rossen Stoyanchev, Rob Winch

Method Summary

All Methods Instance Methods Default Methods
Modifier and Type	Method	Description
`default <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.
`default <T> void`	`beforeConcurrentHandling(NativeWebRequest request, DeferredResult<T> deferredResult)`	Invoked immediately before the start of concurrent handling, in the same thread that started it.
`default <T> boolean`	`handleError(NativeWebRequest request, DeferredResult<T> deferredResult, Throwable t)`	Invoked from a container thread when an error occurred while processing an async request before the `DeferredResult` has been set.
`default <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.
`default <T> void`	`postProcess(NativeWebRequest request, DeferredResult<T> deferredResult, 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.
`default <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
```
default <T> void beforeConcurrentHandling(NativeWebRequest request,
                                          DeferredResult<T> deferredResult)
                                   throws 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:
    Exception - in case of errors
  - preProcess
```
default <T> void preProcess(NativeWebRequest request,
                            DeferredResult<T> deferredResult)
                     throws 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:
    Exception - in case of errors
  - postProcess
```
default <T> void postProcess(NativeWebRequest request,
                             DeferredResult<T> deferredResult,
                             Object concurrentResult)
                      throws 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:
    Exception - in case of errors
  - handleTimeout
```
default <T> boolean handleTimeout(NativeWebRequest request,
                                  DeferredResult<T> deferredResult)
                           throws 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:
    Exception - in case of errors
  - handleError
```
default <T> boolean handleError(NativeWebRequest request,
                                DeferredResult<T> deferredResult,
                                Throwable t)
                         throws Exception
```
    Invoked from a container thread when an error occurred while processing an async request 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
    t - the error that occurred while request processing
    Returns:
    true if error handling should continue, or false if other interceptors should by bypassed and not be invoked
    Throws:
    Exception - in case of errors
  - afterCompletion
```
default <T> void afterCompletion(NativeWebRequest request,
                                 DeferredResult<T> deferredResult)
                          throws 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:
    Exception - in case of errors

Interface DeferredResultProcessingInterceptor

Method Summary

Method Detail

beforeConcurrentHandling

preProcess

postProcess

handleTimeout

handleError

afterCompletion