Handle errors via AsyncListener

This is a limited backport of commit #e0678b mainly providing the fix without
exposing the onError callbacks.

Issue: SPR-16058

spring-web/src/main/java/org/springframework/web/context/request/async/StandardServletAsyncWebRequest.java

@@ -50,6 +50,8 @@ public class StandardServletAsyncWebRequest extends ServletWebRequest implements
 
 	private final List<Runnable> timeoutHandlers = new ArrayList<Runnable>();
 
+	private ErrorHandler errorHandler;
+
 	private final List<Runnable> completionHandlers = new ArrayList<Runnable>();
 
 
@@ -78,6 +80,10 @@ public class StandardServletAsyncWebRequest extends ServletWebRequest implements
 		this.timeoutHandlers.add(timeoutHandler);
 	}
 
+	void setErrorHandler(ErrorHandler errorHandler) {
+		this.errorHandler = errorHandler;
+	}
+
 	@Override
 	public void addCompletionHandler(Runnable runnable) {
 		this.completionHandlers.add(runnable);
@@ -134,7 +140,9 @@ public class StandardServletAsyncWebRequest extends ServletWebRequest implements
 
 	@Override
 	public void onError(AsyncEvent event) throws IOException {
-		onComplete(event);
+		if (this.errorHandler != null) {
+			this.errorHandler.handle(event.getThrowable());
+		}
 	}
 
 	@Override
@@ -153,4 +161,11 @@ public class StandardServletAsyncWebRequest extends ServletWebRequest implements
 		this.asyncCompleted.set(true);
 	}
 
+
+	interface ErrorHandler {
+
+		void handle(Throwable ex);
+
+	}
+
 }

spring-web/src/main/java/org/springframework/web/context/request/async/WebAsyncManager.java

@@ -298,6 +298,16 @@ public final class WebAsyncManager {
 			}
 		});
 
+		if (this.asyncWebRequest instanceof StandardServletAsyncWebRequest) {
+			((StandardServletAsyncWebRequest) this.asyncWebRequest).setErrorHandler(
+					new StandardServletAsyncWebRequest.ErrorHandler() {
+						@Override
+						public void handle(Throwable ex) {
+							setConcurrentResultAndDispatch(ex);
+						}
+					});
+		}
+
 		this.asyncWebRequest.addCompletionHandler(new Runnable() {
 			@Override
 			public void run() {
@@ -399,6 +409,16 @@ public final class WebAsyncManager {
 			}
 		});
 
+		if (this.asyncWebRequest instanceof StandardServletAsyncWebRequest) {
+			((StandardServletAsyncWebRequest) this.asyncWebRequest).setErrorHandler(
+					new StandardServletAsyncWebRequest.ErrorHandler() {
+						@Override
+						public void handle(Throwable ex) {
+							deferredResult.setErrorResult(ex);
+						}
+					});
+		}
+
 		this.asyncWebRequest.addCompletionHandler(new Runnable() {
 			@Override
 			public void run() {