Add ability to handle a timeout to DeferredResult

When a controller returns a DeferredResult, the underlying async
request will eventually time out. Until now the default behavior was
to send a 503 (SERVICE_UNAVAILABLE). However, this is not desirable
in all cases. For example if waiting on an event, a timeout simply
means there is no new information to send.

To handle those cases a DeferredResult now accespts a timeout result
Object in its constructor. If the timeout occurs before the
DeferredResult is set, the timeout result provided to the constructor
is used instead.

Issue: SPR-8617

spring-web/src/test/java/org/springframework/web/context/request/async/AsyncExecutionChainTests.java

@@ -123,7 +123,7 @@ public class AsyncExecutionChainTests {
 			fail("Expected exception");
 		}
 		catch (IllegalStateException ex) {
-			assertThat(ex.getMessage(), containsString("The callable field is required"));
+			assertThat(ex.getMessage(), containsString("last callable is required"));
 		}
 	}
 
@@ -171,7 +171,7 @@ public class AsyncExecutionChainTests {
 			fail("Expected exception");
 		}
 		catch (IllegalArgumentException ex) {
-			assertThat(ex.getMessage(), containsString("A DeferredResult is required"));
+			assertThat(ex.getMessage(), containsString("DeferredResult is required"));
 		}
 	}
 
@@ -186,6 +186,10 @@ public class AsyncExecutionChainTests {
 			super(request, response);
 		}
 
+		public void setTimeout(Long timeout) { }
+
+		public void setTimeoutHandler(Runnable runnable) { }
+
 		public void startAsync() {
 			this.asyncStarted = true;
 		}
@@ -194,8 +198,6 @@ public class AsyncExecutionChainTests {
 			return this.asyncStarted;
 		}
 
-		public void setTimeout(Long timeout) { }
-
 		public void complete() {
 			this.asyncStarted = false;
 			this.asyncCompleted = true;

spring-web/src/test/java/org/springframework/web/context/request/async/DeferredResultTests.java

@@ -0,0 +1,119 @@
+/*
+ * 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.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.web.context.request.async;
+
+import static org.easymock.EasyMock.createMock;
+import static org.easymock.EasyMock.replay;
+import static org.easymock.EasyMock.reset;
+import static org.easymock.EasyMock.verify;
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertTrue;
+import static org.junit.Assert.fail;
+
+import org.junit.Test;
+import org.springframework.web.context.request.async.DeferredResult.DeferredResultHandler;
+
+/**
+ * DeferredResult tests.
+ *
+ * @author Rossen Stoyanchev
+ */
+public class DeferredResultTests {
+
+	@Test
+	public void canHandleTimeout() {
+		assertFalse(new DeferredResult().canHandleTimeout());
+		assertTrue(new DeferredResult("foo").canHandleTimeout());
+	}
+
+	@Test
+	public void set() {
+		DeferredResultHandler resultHandler = createMock(DeferredResultHandler.class);
+		DeferredResult deferredResult = new DeferredResult();
+		deferredResult.init(resultHandler);
+
+		resultHandler.handle("foo");
+		replay(resultHandler);
+
+		deferredResult.set("foo");
+
+		verify(resultHandler);
+	}
+
+	@Test
+	public void handleTimeout() {
+		DeferredResultHandler resultHandler = createMock(DeferredResultHandler.class);
+		DeferredResult deferredResult = new DeferredResult("foo");
+		deferredResult.init(resultHandler);
+
+		resultHandler.handle("foo");
+		replay(resultHandler);
+
+		deferredResult.handleTimeout();
+
+		verify(resultHandler);
+	}
+
+	@Test(expected=IllegalStateException.class)
+	public void handleTimeout_timeoutResultNone() {
+		new DeferredResult().handleTimeout();
+	}
+
+	@Test
+	public void setAfterHandleTimeout() {
+		DeferredResultHandler resultHandler = createMock(DeferredResultHandler.class);
+		DeferredResult deferredResult = new DeferredResult("foo");
+		deferredResult.init(resultHandler);
+
+		resultHandler.handle("foo");
+		replay(resultHandler);
+
+		deferredResult.handleTimeout();
+
+		verify(resultHandler);
+
+		try {
+			deferredResult.set("foo");
+			fail("Expected exception");
+		}
+		catch (StaleAsyncWebRequestException ex) {
+			// expected
+		}
+	}
+
+	@Test
+	public void setBeforeHandleTimeout() {
+		DeferredResultHandler resultHandler = createMock(DeferredResultHandler.class);
+		DeferredResult deferredResult = new DeferredResult("foo");
+		deferredResult.init(resultHandler);
+
+		resultHandler.handle("foo");
+		replay(resultHandler);
+
+		deferredResult.set("foo");
+
+		verify(resultHandler);
+
+		reset(resultHandler);
+		replay(resultHandler);
+
+		deferredResult.handleTimeout();
+
+		verify(resultHandler);
+	}
+
+}