MvcResult returns asyncResult after asyncDispatch

Issue: SPR-16648

Author: rstoyanchev

spring-test/src/main/java/org/springframework/mock/web/MockAsyncContext.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2017 the original author or authors.
+ * Copyright 2002-2018 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.
@@ -62,7 +62,14 @@ public MockAsyncContext(ServletRequest request, ServletResponse response) {
 
 	public void addDispatchHandler(Runnable handler) {
 		Assert.notNull(handler, "Dispatch handler must not be null");
-		this.dispatchHandlers.add(handler);
+		synchronized (this) {
+			if (this.dispatchedPath == null) {
+				this.dispatchHandlers.add(handler);
+			}
+			else {
+				handler.run();
+			}
+		}
 	}
 
 	@Override
@@ -92,9 +99,11 @@ public void dispatch(String path) {
 
 	@Override
 	public void dispatch(ServletContext context, String path) {
-		this.dispatchedPath = path;
-		for (Runnable r : this.dispatchHandlers) {
-			r.run();
+		synchronized (this) {
+			this.dispatchedPath = path;
+			for (Runnable r : this.dispatchHandlers) {
+				r.run();
+			}
 		}
 	}
 

spring-test/src/main/java/org/springframework/test/web/servlet/DefaultMvcResult.java

@@ -16,10 +16,13 @@
 
 package org.springframework.test.web.servlet;
 
+import java.util.concurrent.CountDownLatch;
+import java.util.concurrent.TimeUnit;
 import java.util.concurrent.atomic.AtomicReference;
 
 import org.springframework.mock.web.MockHttpServletRequest;
 import org.springframework.mock.web.MockHttpServletResponse;
+import org.springframework.util.Assert;
 import org.springframework.web.servlet.FlashMap;
 import org.springframework.web.servlet.HandlerInterceptor;
 import org.springframework.web.servlet.ModelAndView;
@@ -51,6 +54,8 @@ class DefaultMvcResult implements MvcResult {
 
 	private final AtomicReference<Object> asyncResult = new AtomicReference<Object>(RESULT_NONE);
 
+	private CountDownLatch asyncDispatchLatch;
+
 
 	/**
 	 * Create a new instance with the given request and response.
@@ -126,27 +131,31 @@ public Object getAsyncResult(long timeToWait) {
 		if (this.mockRequest.getAsyncContext() != null) {
 			timeToWait = (timeToWait == -1 ? this.mockRequest.getAsyncContext().getTimeout() : timeToWait);
 		}
-
-		if (timeToWait > 0) {
-			long endTime = System.currentTimeMillis() + timeToWait;
-			while (System.currentTimeMillis() < endTime && this.asyncResult.get() == RESULT_NONE) {
-				try {
-					Thread.sleep(100);
-				}
-				catch (InterruptedException ex) {
-					Thread.currentThread().interrupt();
-					throw new IllegalStateException("Interrupted while waiting for " +
-							"async result to be set for handler [" + this.handler + "]", ex);
-				}
-			}
+		if (!awaitAsyncDispatch(timeToWait)) {
+			throw new IllegalStateException("Async result for handler [" + this.handler + "]" +
+					" was not set during the specified timeToWait=" + timeToWait);
 		}
-
 		Object result = this.asyncResult.get();
-		if (result == RESULT_NONE) {
-			throw new IllegalStateException("Async result for handler [" + this.handler + "] " +
-					"was not set during the specified timeToWait=" + timeToWait);
+		Assert.state(result != RESULT_NONE, "Async result for handler [" + this.handler + "] was not set");
+		return this.asyncResult.get();
+	}
+
+	/**
+	 * True if is there a latch was not set, or the latch count reached 0.
+	 */
+	private boolean awaitAsyncDispatch(long timeout) {
+		Assert.state(this.asyncDispatchLatch != null,
+				"The asynDispatch CountDownLatch was not set by the TestDispatcherServlet.\n");
+		try {
+			return this.asyncDispatchLatch.await(timeout, TimeUnit.MILLISECONDS);
+		}
+		catch (InterruptedException e) {
+			return false;
 		}
-		return result;
+	}
+
+	void setAsyncDispatchLatch(CountDownLatch asyncDispatchLatch) {
+		this.asyncDispatchLatch = asyncDispatchLatch;
 	}
 
 }

spring-test/src/main/java/org/springframework/test/web/servlet/TestDispatcherServlet.java

@@ -18,11 +18,13 @@
 
 import java.io.IOException;
 import java.util.concurrent.Callable;
+import java.util.concurrent.CountDownLatch;
 import javax.servlet.ServletException;
 import javax.servlet.ServletRequest;
 import javax.servlet.http.HttpServletRequest;
 import javax.servlet.http.HttpServletResponse;
 
+import org.springframework.mock.web.MockAsyncContext;
 import org.springframework.web.context.WebApplicationContext;
 import org.springframework.web.context.request.NativeWebRequest;
 import org.springframework.web.context.request.async.CallableProcessingInterceptorAdapter;
@@ -63,6 +65,7 @@ protected void service(HttpServletRequest request, HttpServletResponse response)
 
 		registerAsyncResultInterceptors(request);
 		super.service(request, response);
+		initAsyncDispatchLatch(request);
 	}
 
 	private void registerAsyncResultInterceptors(final HttpServletRequest request) {
@@ -81,6 +84,19 @@ public <T> void postProcess(NativeWebRequest r, DeferredResult<T> result, Object
 		});
 	}
 
+	private void initAsyncDispatchLatch(HttpServletRequest request) {
+		if (request.getAsyncContext() != null) {
+			final CountDownLatch dispatchLatch = new CountDownLatch(1);
+			((MockAsyncContext) request.getAsyncContext()).addDispatchHandler(new Runnable() {
+				@Override
+				public void run() {
+					dispatchLatch.countDown();
+				}
+			});
+			getMvcResult(request).setAsyncDispatchLatch(dispatchLatch);
+		}
+	}
+
 	protected DefaultMvcResult getMvcResult(ServletRequest request) {
 		return (DefaultMvcResult) request.getAttribute(MockMvc.MVC_RESULT_ATTRIBUTE);
 	}

spring-test/src/test/java/org/springframework/test/web/servlet/DefaultMvcResultTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2014 the original author or authors.
+ * Copyright 2002-2018 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.
@@ -15,6 +15,8 @@
  */
 package org.springframework.test.web.servlet;
 
+import java.util.concurrent.CountDownLatch;
+
 import org.junit.Before;
 import org.junit.Test;
 
@@ -40,6 +42,7 @@ public void setup() {
 	@Test
 	public void getAsyncResultSuccess() throws Exception {
 		this.mvcResult.setAsyncResult("Foo");
+		this.mvcResult.setAsyncDispatchLatch(new CountDownLatch(0));
 		assertEquals("Foo", this.mvcResult.getAsyncResult());
 	}
 

spring-web/src/test/java/org/springframework/mock/web/test/MockAsyncContext.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2017 the original author or authors.
+ * Copyright 2002-2018 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.
@@ -62,7 +62,14 @@ public MockAsyncContext(ServletRequest request, ServletResponse response) {
 
 	public void addDispatchHandler(Runnable handler) {
 		Assert.notNull(handler, "Dispatch handler must not be null");
-		this.dispatchHandlers.add(handler);
+		synchronized (this) {
+			if (this.dispatchedPath == null) {
+				this.dispatchHandlers.add(handler);
+			}
+			else {
+				handler.run();
+			}
+		}
 	}
 
 	@Override
@@ -92,9 +99,11 @@ public void dispatch(String path) {
 
 	@Override
 	public void dispatch(ServletContext context, String path) {
-		this.dispatchedPath = path;
-		for (Runnable r : this.dispatchHandlers) {
-			r.run();
+		synchronized (this) {
+			this.dispatchedPath = path;
+			for (Runnable r : this.dispatchHandlers) {
+				r.run();
+			}
 		}
 	}