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package org.frameworkset.web.request.async;
import java.util.concurrent.Callable;
import org.frameworkset.web.servlet.mvc.NativeWebRequest;
/**
* Intercepts concurrent request handling, where the concurrent result is
* obtained by executing a {@link Callable} on behalf of the application with
* an {@link AsyncTaskExecutor}.
*
* A {@code CallableProcessingInterceptor} is invoked before and after the
* invocation of the {@code Callable} task in the asynchronous thread, as well
* as on timeout from a container thread, 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 {@code HandlerExceptionResolver} mechanism.
*
*
The {@link #handleTimeout(NativeWebRequest, Callable) afterTimeout} method
* can select a value to be used to resume processing.
*
* @author Rossen Stoyanchev
* @author Rob Winch
* @since 3.2
*/
public interface CallableProcessingInterceptor {
static final Object RESULT_NONE = new Object();
static final Object RESPONSE_HANDLED = new Object();
/**
* Invoked before the start of concurrent handling in the original
* thread in which the {@code Callable} is submitted for concurrent handling.
*
This is useful for capturing the state of the current thread just prior to
* invoking the {@link Callable}. Once the state is captured, it can then be
* transferred to the new {@link Thread} in
* {@link #preProcess(NativeWebRequest, Callable)}. Capturing the state of
* Spring Security's SecurityContextHolder and migrating it to the new Thread
* is a concrete example of where this is useful.
* @param request the current request
* @param task the task for the current async request
* @throws Exception in case of errors
*/
void beforeConcurrentHandling(NativeWebRequest request, Callable task) throws Exception;
/**
* Invoked after the start of concurrent handling in the async
* thread in which the {@code Callable} is executed and before the
* actual invocation of the {@code Callable}.
* @param request the current request
* @param task the task for the current async request
* @throws Exception in case of errors
*/
void preProcess(NativeWebRequest request, Callable task) throws Exception;
/**
* Invoked after the {@code Callable} has produced a result in the
* async thread in which the {@code Callable} is executed. This method may
* be invoked later than {@code afterTimeout} or {@code afterCompletion}
* depending on when the {@code Callable} finishes processing.
* @param request the current request
* @param task the task for the current async request
* @param concurrentResult the result of concurrent processing, which could
* be a {@link Throwable} if the {@code Callable} raised an exception
* @throws Exception in case of errors
*/
void postProcess(NativeWebRequest request, Callable task, Object concurrentResult) throws Exception;
/**
* Invoked from a container thread when the async request times out before
* the {@code Callable} task completes. Implementations may return a value,
* including an {@link Exception}, to use instead of the value the
* {@link Callable} did not return in time.
* @param request the current request
* @param task the task for the current async request
* @return a concurrent result value; if the value is anything other than
* {@link #RESULT_NONE} or {@link #RESPONSE_HANDLED}, concurrent processing
* is resumed and subsequent interceptors are not invoked
* @throws Exception in case of errors
*/
Object handleTimeout(NativeWebRequest request, Callable task) throws Exception;
/**
* Invoked from a container thread when async processing completes for any
* reason including timeout or network error.
* @param request the current request
* @param task the task for the current async request
* @throws Exception in case of errors
*/
void afterCompletion(NativeWebRequest request, Callable task) throws Exception;
}