SPR-7369: @Async support in spring-aspects with AspectJ

org.springframework.aspects/src/main/java/org/springframework/scheduling/AbstractAsynchronousExecutionAspect.aj

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+package org.springframework.scheduling;
+
+import java.util.concurrent.Callable;
+import java.util.concurrent.Executor;
+import java.util.concurrent.Future;
+
+import org.aspectj.lang.reflect.MethodSignature;
+import org.springframework.core.task.AsyncTaskExecutor;
+import org.springframework.core.task.SimpleAsyncTaskExecutor;
+import org.springframework.core.task.support.TaskExecutorAdapter;
+
+/**
+ * Abstract aspect that routes selected methods asynchronously.
+ * <p>
+ * This aspect, by default, uses {@link SimpleAsyncTaskExecutor} to route method
+ * execution. However, you may inject it with any implementation of 
+ * {@link Executor} to override the default.
+ * 
+ * @author Ramnivas Laddad
+ */
+public abstract aspect AbstractAsynchronousExecutionAspect {
+	private AsyncTaskExecutor asyncExecutor;
+	
+	public AbstractAsynchronousExecutionAspect() {
+		// Set default executor, which may be replaced by calling setExecutor(Executor)
+		setExecutor(new SimpleAsyncTaskExecutor());
+	}
+
+    public abstract pointcut asyncMethod();
+
+    Object around() : asyncMethod() {
+    		Callable<Object> callable = new Callable<Object>() {
+    			public Object call() throws Exception {
+    				Object result = proceed();
+    				if (result instanceof Future) {
+    					return ((Future<?>) result).get();
+    				}
+    				return null;
+    			}};
+    			
+    		Future<?> result = asyncExecutor.submit(callable);
+		
+    		if (Future.class.isAssignableFrom(((MethodSignature)thisJoinPointStaticPart.getSignature()).getReturnType())) {
+			return result;
+		} else {
+			return null;
+		}
+    }
+
+    public void setExecutor(Executor executor) {
+    		if (executor instanceof AsyncTaskExecutor) {
+        		this.asyncExecutor = (AsyncTaskExecutor) executor;
+    		} else {
+    			this.asyncExecutor = new TaskExecutorAdapter(asyncExecutor);
+    		}
+    }
+    
+}

org.springframework.aspects/src/main/java/org/springframework/scheduling/AnnotationDrivenAsynchronousExecutionAspect.aj

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+package org.springframework.scheduling;
+
+import java.util.concurrent.Future;
+import org.springframework.scheduling.annotation.Async;
+
+/**
+ * Aspect to route methods based on the {@link Async} annotation.
+ * <p>
+ * This aspect routes methods marked with the {@link Async} annotation
+ * as well as methods in classes marked with the same. Any method expected
+ * to be routed asynchronously must return either void, {@link Future}, 
+ * or a subtype of {@link Future}. This aspect, therefore, will produce 
+ * a compile-time error for methods that violate this constraint on the return type. 
+ * If, however, a class marked with <code>&#64;Async</code> contains a method that 
+ * violates this constraint, it produces only a warning.
+ * 
+ * @author Ramnivas Laddad
+ *
+ */
+public aspect AnnotationDrivenAsynchronousExecutionAspect extends AbstractAsynchronousExecutionAspect {
+	private pointcut asyncMarkedMethod() 
+		: execution(@Async (void || Future+) *(..));
+	private pointcut asyncTypeMarkedMethod() 
+		: execution((void || Future+) (@Async *).*(..));
+	
+	public pointcut asyncMethod() : asyncMarkedMethod() || asyncTypeMarkedMethod();
+	
+	declare error: 
+		execution(@Async !(void||Future) *(..)): 
+		"Only method that return void or Future may have @Async annotation";
+
+	declare warning: 
+		execution(!(void||Future) (@Async *).*(..)): 
+		"Method in class marked with @Async that do not return void or Future will be routed synchronously";
+}

org.springframework.aspects/src/test/java/org/springframework/scheduling/AnnotationDrivenAsynchronousExecutionAspectTest.java

@@ -0,0 +1,161 @@
+package org.springframework.scheduling;
+
+import java.util.concurrent.Callable;
+import java.util.concurrent.ExecutionException;
+import java.util.concurrent.Future;
+
+import junit.framework.Assert;
+
+import static junit.framework.Assert.*;
+
+import org.junit.Before;
+import org.junit.Test;
+import org.springframework.core.task.SimpleAsyncTaskExecutor;
+import org.springframework.scheduling.annotation.Async;
+import org.springframework.scheduling.annotation.AsyncResult;
+
+/**
+ * Test for AnnotationDrivenAsynchronousExecutionAspect
+ * 
+ * @author Ramnivas Laddad
+ */
+public class AnnotationDrivenAsynchronousExecutionAspectTest {
+	private static final long WAIT_TIME = 1000; //milli seconds
+	private CountingExecutor executor;
+	
+	@Before
+	public void setUp() {
+		executor = new CountingExecutor();
+		AnnotationDrivenAsynchronousExecutionAspect.aspectOf().setExecutor(executor);
+	}
+	
+	@Test
+	public void asyncMethodGetsRoutedAsynchronously() {
+		ClassWithoutAsyncAnnotation obj = new ClassWithoutAsyncAnnotation();
+		obj.incrementAsync();
+		executor.waitForCompletion();
+		assertEquals(1, obj.counter);
+		assertEquals(1, executor.submitStartCounter);
+		assertEquals(1, executor.submitCompleteCounter);
+	}
+	
+	@Test
+	public void asyncMethodReturningFutureGetsRoutedAsynchronouslyAndReturnsAFuture() throws InterruptedException, ExecutionException {
+		ClassWithoutAsyncAnnotation obj = new ClassWithoutAsyncAnnotation();
+		Future<Integer> future = obj.incrementReturningAFuture();
+		// No need to executor.waitForCompletion() as future.get() will have the same effect
+		assertEquals(5, future.get().intValue());
+		assertEquals(1, obj.counter);
+		assertEquals(1, executor.submitStartCounter);
+		assertEquals(1, executor.submitCompleteCounter);
+	}
+
+	@Test
+	public void syncMethodGetsRoutedSynchronously() {
+		ClassWithoutAsyncAnnotation obj = new ClassWithoutAsyncAnnotation();
+		obj.increment();
+		assertEquals(1, obj.counter);
+		assertEquals(0, executor.submitStartCounter);
+		assertEquals(0, executor.submitCompleteCounter);
+	}	
+	
+	@Test
+	public void voidMethodInAsyncClassGetsRoutedAsynchronously() {
+		ClassWithAsyncAnnotation obj = new ClassWithAsyncAnnotation();
+		obj.increment();
+		executor.waitForCompletion();
+		assertEquals(1, obj.counter);
+		assertEquals(1, executor.submitStartCounter);
+		assertEquals(1, executor.submitCompleteCounter);
+	}
+
+	@Test
+	public void methodReturningFutureInAsyncClassGetsRoutedAsynchronouslyAndReturnsAFuture() throws InterruptedException, ExecutionException {
+		ClassWithAsyncAnnotation obj = new ClassWithAsyncAnnotation();
+		Future<Integer> future = obj.incrementReturningAFuture();
+		assertEquals(5, future.get().intValue());
+		assertEquals(1, obj.counter);
+		assertEquals(1, executor.submitStartCounter);
+		assertEquals(1, executor.submitCompleteCounter);
+	}
+
+	@Test
+	public void methodReturningNonVoidNonFutureInAsyncClassGetsRoutedSynchronously() {
+		ClassWithAsyncAnnotation obj = new ClassWithAsyncAnnotation();
+		int returnValue = obj.return5();
+		assertEquals(5, returnValue);
+		assertEquals(0, executor.submitStartCounter);
+		assertEquals(0, executor.submitCompleteCounter);
+	}	
+
+	@SuppressWarnings("serial")
+	private static class CountingExecutor extends SimpleAsyncTaskExecutor {
+		int submitStartCounter;
+		int submitCompleteCounter;
+		
+		@Override
+		public <T> Future<T> submit(Callable<T> task) {
+			submitStartCounter++;
+			Future<T> future = super.submit(task);
+			submitCompleteCounter++;
+			synchronized (this) {
+				notifyAll();
+			}
+			return future;
+		}
+		
+		public synchronized void waitForCompletion() {
+			try {
+				wait(WAIT_TIME);
+			} catch (InterruptedException e) {
+				Assert.fail("Didn't finish the async job in " + WAIT_TIME + " milliseconds");
+			}
+		}
+	}
+	
+	static class ClassWithoutAsyncAnnotation {
+		int counter;
+		
+		@Async public void incrementAsync() {
+			counter++;
+		}
+		
+		public void increment() {
+			counter++;
+		}
+		
+		@Async public Future<Integer> incrementReturningAFuture() {
+			counter++;
+			return new AsyncResult<Integer>(5);
+		}
+		
+		// It should be an error to attach @Async to a method that returns a non-void
+		// or non-Future.
+		// We need to keep this commented out, otherwise there will be a compile-time error. 
+		// Please uncomment and re-comment this periodically to check that the compiler 
+		// produces an error message due to the 'declare error' statement 
+		// in AnnotationDrivenAsynchronousExecutionAspect
+//		@Async public int getInt() {
+//			return 0;
+//		}
+	}
+	
+	@Async
+	static class ClassWithAsyncAnnotation {
+		int counter;
+		
+		public void increment() {
+			counter++;
+		}
+		
+		// Manually check that there is a warning from the 'declare warning' statement in AnnotationDrivenAsynchronousExecutionAspect
+		public int return5() {
+			return 5;
+		}
+
+		public Future<Integer> incrementReturningAFuture() {
+			counter++;
+			return new AsyncResult<Integer>(5);
+		}
+	}
+}