Support CompletableFuture<> as return type of @Async methods [SPR-13128]

[spring-projects-issues]

Thomas Darimont opened SPR-13128 and commented

Currently @Async annotated methods support to return Future<> result wrappers via AsyncResult<> it would be great if we would support CompletableFuture here as well.

I created a small example that adds the necessary functionality to AsyncExecutionInterceptor.

Usage:

	@Async
	public <T> CompletableFuture<T> asyncOperation(T input) {

		System.out.println("working...");
		LockSupport.parkNanos(TimeUnit.SECONDS.toNanos(5));
		System.out.println("done.");
		
		return CompletableFuture.completedFuture(input);
	}

Consumer:

service.asyncOperation("test").thenAccept(System.out::println);

---

Reference URL: https://gist.github.com/thomasdarimont/197e92e537554634adbd

Issue Links:

• DATACMNS-714 Add support for CompletableFuture as query method return type on Spring 4.2 ("is depended on by")
• Support CompletableFuture as return value in @MessageMapping handlers [SPR-12207] #16821 Support CompletableFuture as return value in @MessageMapping handlers
• Support CompletableFuture as alternative to DeferredResult in MVC [SPR-12597] #17198 Support CompletableFuture as alternative to DeferredResult in MVC
• INT-3724 Please add support for CompletableFuture in Asynchronous Gateways
• DATACMNS-712 Support CompletableFuture as repository return type
• Document supported return types for @Async methods [SPR-14881] #19447 Document supported return types for @Async methods

Referenced from: commits dd4bc63, c41779f, 581ab18

0 votes, 7 watchers

[spring-projects-issues]

Juergen Hoeller commented

Good idea, and a nice fit with our existing CompletableFuture work for 4.2! Rolled into 4.2 RC2 now.

Juergen

[spring-projects-issues]

Gary Russell commented

Also see spring-projects/spring-integration#1463 for CompletableFuture return types from Spring Integration gateway (proxy) methods.

[spring-projects-issues]

Thomas Darimont commented

Thanks for adding that :)

Would it be possible to get that backported to 4.1.x?
We could add support for that to Spring Data as well but we currently test against 4.1.x.

Cheers,
Thomas

[spring-projects-issues]

Juergen Hoeller commented

I'm afraid not since it's a new feature which benefits from going through a release candidate phase... It also ties nicely into our general CompletableFuture theme in 4.2.

I talked about this with Ollie yesterday, and there seems to be nothing preventing you from shipping CompletableFuture support in Spring Data even against SPR 4.1.7...

Juergen

[spring-projects-issues]

Sam Brannen commented

Reopening since this appears to break AnnotationAsyncExecutionAspectTests.qualifiedAsyncMethodsAreRoutedToCorrectExecutor().

See failing Performance builds for details:

java.lang.ClassCastException: java.lang.ClassCastException: java.util.concurrent.FutureTask cannot be cast to java.util.concurrent.CompletableFuture
java.lang.ClassCastException: java.util.concurrent.FutureTask cannot be cast to java.util.concurrent.CompletableFuture
	at org.springframework.scheduling.aspectj.AnnotationAsyncExecutionAspectTests$ClassWithQualifiedAsyncMethods.e1OtherWork(AnnotationAsyncExecutionAspectTests.java:287)
	at org.springframework.scheduling.aspectj.AnnotationAsyncExecutionAspectTests.qualifiedAsyncMethodsAreRoutedToCorrectExecutor(AnnotationAsyncExecutionAspectTests.java:147)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:497)
(40 more lines...)

[spring-projects-issues]

Juergen Hoeller commented

Oops, I added a test for the AspectJ variant of processing here but apparently forgot to put the actual code for it into the aspect implementation... So effectively, just the interceptor-based variant worked. Fixed now, with the common CompletableFuture processing happening in a shared base class instead of just in AsyncExecutionInterceptor.

Juergen

[spring-projects-issues]

Sam Brannen commented

Aha! Glad you sorted it out with a late night coding session... just before 4.2 RC2. ;)

[spring-projects-issues]

Didier Loiseau commented

Is the support of CompletableFuture with @Async documented somewhere? I was trying to find documentation and the minimum version that supports it but I only found this ticket and a few blog posts.

[spring-projects-issues]

Oliver Drotbohm commented

Good one. I've filed #19447 to improve the documentation on that.