AsyncResult allows for exposing an execution exception

Issue: SPR-13076

spring-context/src/main/java/org/springframework/scheduling/annotation/AsyncResult.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2014 the original author or authors.
+ * Copyright 2002-2015 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.
@@ -16,6 +16,8 @@
 
 package org.springframework.scheduling.annotation;
 
+import java.util.concurrent.ExecutionException;
+import java.util.concurrent.Future;
 import java.util.concurrent.TimeUnit;
 
 import org.springframework.util.concurrent.FailureCallback;
@@ -31,21 +33,37 @@ import org.springframework.util.concurrent.SuccessCallback;
  * plain {@link java.util.concurrent.Future}, along with the corresponding support
  * in {@code @Async} processing.
  *
+ * <p>As of Spring 4.2, this class also supports passing execution exceptions back
+ * to the caller.
+ *
  * @author Juergen Hoeller
  * @since 3.0
  * @see Async
+ * @see #forValue(Object)
+ * @see #forExecutionException(Throwable)
  */
 public class AsyncResult<V> implements ListenableFuture<V> {
 
 	private final V value;
 
+	private final ExecutionException executionException;
+
 
 	/**
 	 * Create a new AsyncResult holder.
 	 * @param value the value to pass through
 	 */
 	public AsyncResult(V value) {
+		this(value, null);
+	}
+
+	/**
+	 * Create a new AsyncResult holder.
+	 * @param value the value to pass through
+	 */
+	private AsyncResult(V value, ExecutionException ex) {
 		this.value = value;
+		this.executionException = ex;
 	}
 
 
@@ -65,13 +83,16 @@ public class AsyncResult<V> implements ListenableFuture<V> {
 	}
 
 	@Override
-	public V get() {
+	public V get() throws ExecutionException {
+		if (this.executionException != null) {
+			throw this.executionException;
+		}
 		return this.value;
 	}
 
 	@Override
-	public V get(long timeout, TimeUnit unit) {
-		return this.value;
+	public V get(long timeout, TimeUnit unit) throws ExecutionException {
+		return get();
 	}
 
 	@Override
@@ -89,4 +110,28 @@ public class AsyncResult<V> implements ListenableFuture<V> {
 		}
 	}
 
+
+	/**
+	 * Create a new async result which exposes the given value from {@link Future#get()}.
+	 * @param value the value to expose
+	 * @since 4.2
+	 * @see Future#get()
+	 */
+	public static <V> ListenableFuture<V> forValue(V value) {
+		return new AsyncResult<V>(value, null);
+	}
+
+	/**
+	 * Create a new async result which exposes the given exception as an
+	 * {@link ExecutionException} from {@link Future#get()}.
+	 * @param ex the exception to expose (either an pre-built {@link ExecutionException}
+	 * or a cause to be wrapped in an {@link ExecutionException})
+	 * @since 4.2
+	 * @see ExecutionException
+	 */
+	public static <V> ListenableFuture<V> forExecutionException(Throwable ex) {
+		return new AsyncResult<V>(null,
+				(ex instanceof ExecutionException ? (ExecutionException) ex : new ExecutionException(ex)));
+	}
+
 }