Add interceptors for async processing

This change introduces two new interceptors with callback methods
for concurrent request handling. These interfaces are
CallableProcessingInterceptor and DeferredResultProcessingInterceptor.

Unlike a HandlerInterceptor, and its AsyncHandlerInterceptor sub-type,
which intercepts the invocation of a handler in he main request
processing thread, the two new interfaces are aimed at intercepting the
asynchronous execution of a Callable or a DeferredResult.

This allows for the registration of thread initialization logic in the
case of Callable executed with an AsyncTaskExecutor, or for centralized
tracking of the completion and/or expiration of a DeferredResult.

spring-webmvc/src/main/java/org/springframework/web/servlet/AsyncHandlerInterceptor.java

@@ -19,18 +19,19 @@ package org.springframework.web.servlet;
 import javax.servlet.http.HttpServletRequest;
 import javax.servlet.http.HttpServletResponse;
 
+import org.springframework.web.method.HandlerMethod;
+
 /**
  * Extends {@code HandlerInterceptor} with a callback method invoked during
  * asynchronous request handling.
  *
  * <p>When a handler starts asynchronous request handling, the DispatcherServlet
  * exits without invoking {@code postHandle} and {@code afterCompletion}, as it
- * normally does, since the results of request handling (e.g. ModelAndView) are
- * not available in the current thread and handling is not yet complete.
- * In such scenarios, the
+ * normally does, since the results of request handling (e.g. ModelAndView)
+ * will. be produced concurrently in another thread. In such scenarios,
  * {@link #afterConcurrentHandlingStarted(HttpServletRequest, HttpServletResponse)}
- * method is invoked instead allowing implementations to perform tasks such as
- * cleaning up thread bound attributes.
+ * is invoked instead allowing implementations to perform tasks such as cleaning
+ * up thread bound attributes.
  *
  * <p>When asynchronous handling completes, the request is dispatched to the
  * container for further processing. At this stage the DispatcherServlet invokes
@@ -40,20 +41,26 @@ import javax.servlet.http.HttpServletResponse;
  * @since 3.2
  *
  * @see org.springframework.web.context.request.async.WebAsyncManager
+ * @see org.springframework.web.context.request.async.CallableProcessingInterceptor
+ * @see org.springframework.web.context.request.async.DeferredResultProcessingInterceptor
  */
 public interface AsyncHandlerInterceptor extends HandlerInterceptor {
 
 	/**
-	 * Called instead of {@code postHandle} and {@code afterCompletion}, when the
-	 * a handler is being executed concurrently. Implementations may use the provided
-	 * request and response but should avoid modifying them in ways that would
-	 * conflict with the concurrent execution of the handler. A typical use of
-	 * this method would be to clean thread local variables.
+	 * Called instead of {@code postHandle} and {@code afterCompletion}, when
+	 * the a handler is being executed concurrently. Implementations may use the
+	 * provided request and response but should avoid modifying them in ways
+	 * that would conflict with the concurrent execution of the handler. A
+	 * typical use of this method would be to clean thread local variables.
 	 *
 	 * @param request the current request
 	 * @param response the current response
-	 * @param handler handler that started async execution, for type and/or instance examination
+	 * @param handler handler (or {@link HandlerMethod}) that started async
+	 * execution, for type and/or instance examination
+	 * @throws Exception in case of errors
 	 */
-	void afterConcurrentHandlingStarted(HttpServletRequest request, HttpServletResponse response, Object handler);
+	void afterConcurrentHandlingStarted(
+			HttpServletRequest request, HttpServletResponse response, Object handler)
+			throws Exception;
 
 }

spring-webmvc/src/main/java/org/springframework/web/servlet/FrameworkServlet.java

@@ -20,6 +20,7 @@ import java.io.IOException;
 import java.security.Principal;
 import java.util.ArrayList;
 import java.util.Collections;
+import java.util.concurrent.Callable;
 
 import javax.servlet.ServletContext;
 import javax.servlet.ServletException;
@@ -44,12 +45,13 @@ import org.springframework.util.StringUtils;
 import org.springframework.web.bind.annotation.RequestMethod;
 import org.springframework.web.context.ConfigurableWebApplicationContext;
 import org.springframework.web.context.WebApplicationContext;
+import org.springframework.web.context.request.NativeWebRequest;
 import org.springframework.web.context.request.RequestAttributes;
 import org.springframework.web.context.request.RequestContextHolder;
 import org.springframework.web.context.request.ServletRequestAttributes;
-import org.springframework.web.context.request.async.WebAsyncUtils;
+import org.springframework.web.context.request.async.CallableProcessingInterceptor;
 import org.springframework.web.context.request.async.WebAsyncManager;
-import org.springframework.web.context.request.async.WebAsyncManager.WebAsyncThreadInitializer;
+import org.springframework.web.context.request.async.WebAsyncUtils;
 import org.springframework.web.context.support.ServletRequestHandledEvent;
 import org.springframework.web.context.support.WebApplicationContextUtils;
 import org.springframework.web.context.support.XmlWebApplicationContext;
@@ -909,7 +911,7 @@ public abstract class FrameworkServlet extends HttpServletBean {
 		initContextHolders(request, localeContext, requestAttributes);
 
 		WebAsyncManager asyncManager = WebAsyncUtils.getAsyncManager(request);
-		asyncManager.registerAsyncThreadInitializer(this.getClass().getName(), createAsyncThreadInitializer(request));
+		asyncManager.registerCallableInterceptor(this.getClass().getName(), createRequestBindingInterceptor(request));
 
 		try {
 			doService(request, response);
@@ -992,13 +994,15 @@ public abstract class FrameworkServlet extends HttpServletBean {
 		}
 	}
 
-	private WebAsyncThreadInitializer createAsyncThreadInitializer(final HttpServletRequest request) {
+	private CallableProcessingInterceptor createRequestBindingInterceptor(final HttpServletRequest request) {
 
-		return new WebAsyncThreadInitializer() {
-			public void initialize() {
+		return new CallableProcessingInterceptor() {
+
+			public void preProcess(NativeWebRequest webRequest, Callable<?> task) {
 				initContextHolders(request, buildLocaleContext(request), new ServletRequestAttributes(request));
 			}
-			public void reset() {
+
+			public void postProcess(NativeWebRequest webRequest, Callable<?> task, Object concurrentResult) {
 				resetContextHolders(request, null, null);
 			}
 		};

spring-webmvc/src/main/java/org/springframework/web/servlet/HandlerInterceptor.java

@@ -19,6 +19,8 @@ package org.springframework.web.servlet;
 import javax.servlet.http.HttpServletRequest;
 import javax.servlet.http.HttpServletResponse;
 
+import org.springframework.web.method.HandlerMethod;
+
 /**
  * Workflow interface that allows for customized handler execution chains.
  * Applications can register any number of existing or custom interceptors
@@ -36,8 +38,8 @@ import javax.servlet.http.HttpServletResponse;
  * {@code postHandle} and {@code afterCompletion} callbacks. When concurrent
  * handler execution completes, the request is dispatched back in order to
  * proceed with rendering the model and all methods of this contract are invoked
- * again. For further options and comments see
- * {@code org.springframework.web.servlet.HandlerInterceptor}
+ * again. For further options and details see
+ * {@code org.springframework.web.servlet.AsyncHandlerInterceptor}
  *
  * <p>Typically an interceptor chain is defined per HandlerMapping bean,
  * sharing its granularity. To be able to apply a certain interceptor chain
@@ -100,7 +102,8 @@ public interface HandlerInterceptor {
 	 * getting applied in inverse order of the execution chain.
 	 * @param request current HTTP request
 	 * @param response current HTTP response
-	 * @param handler chosen handler to execute, for type and/or instance examination
+	 * @param handler handler (or {@link HandlerMethod}) that started async
+	 * execution, for type and/or instance examination
 	 * @param modelAndView the <code>ModelAndView</code> that the handler returned
 	 * (can also be <code>null</code>)
 	 * @throws Exception in case of errors
@@ -120,7 +123,8 @@ public interface HandlerInterceptor {
 	 * the last to be invoked.
 	 * @param request current HTTP request
 	 * @param response current HTTP response
-	 * @param handler chosen handler to execute, for type and/or instance examination
+	 * @param handler handler (or {@link HandlerMethod}) that started async
+	 * execution, for type and/or instance examination
 	 * @param ex exception thrown on handler execution, if any
 	 * @throws Exception in case of errors
 	 */

spring-webmvc/src/main/java/org/springframework/web/servlet/handler/HandlerInterceptorAdapter.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2006 the original author or authors.
+ * Copyright 2002-2012 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -19,7 +19,7 @@ package org.springframework.web.servlet.handler;
 import javax.servlet.http.HttpServletRequest;
 import javax.servlet.http.HttpServletResponse;
 
-import org.springframework.web.servlet.HandlerInterceptor;
+import org.springframework.web.servlet.AsyncHandlerInterceptor;
 import org.springframework.web.servlet.ModelAndView;
 
 /**
@@ -29,7 +29,7 @@ import org.springframework.web.servlet.ModelAndView;
  * @author Juergen Hoeller
  * @since 05.12.2003
  */
-public abstract class HandlerInterceptorAdapter implements HandlerInterceptor {
+public abstract class HandlerInterceptorAdapter implements AsyncHandlerInterceptor {
 
 	/**
 	 * This implementation always returns <code>true</code>.
@@ -55,4 +55,12 @@ public abstract class HandlerInterceptorAdapter implements HandlerInterceptor {
 			throws Exception {
 	}
 
+	/**
+	 * This implementation is empty.
+	 */
+	public void afterConcurrentHandlingStarted(
+			HttpServletRequest request, HttpServletResponse response, Object handler)
+			throws Exception {
+	}
+
 }