How to integrate Spring Retry with AsyncRestTemplate

Question

How can you integrate Spring Retry with external calls with AsyncRestTemplate? If it's not possible, is there another framework that supports it?

My use case:

public void doSomething() throws ExecutionException, InterruptedException {

    ListenableFuture<ResponseEntity<String>> future = asyncRestTemplate.getForEntity("http://localhost/foo", String.class);

    // do some tasks here

    ResponseEntity<String> stringResponseEntity = future.get(); // <-- How do you retry just this call?

}

How do you retry this future.get() call? If the external service returns a 404, I want to avoid calling those tasks in between again and just retry the external call? I can't just wrap future.get() with a retryTemplate.execute() because it won't actually make another call to the external service.

Answer 1

You have to wrap the entire doSomething (or at least the template operation and get) in a retry template.

EDIT

Instead of calling get() you could add a ListenableFutureCallback to the future; something like this...

final AtomicReference<ListenableFuture<ResponseEntity<String>>> future = 
    new AtomicReference<>(asyncRestTemplate.getForEntity("http://localhost/foo", String.class));

final CountDownLatch latch = new CountDownLatch(1);
future.addCallback(new ListenableFutureCallback<String>() {

    int retries;

    @Override
    public void onSuccess(String result) {

         if (notTheResultIWant) {
             future.set(asyncTemplate.getFor (...));
             future.get().addCallback(this);    
             retries++;        
         }
         else {
              latch.countDown();
         }
    }

    @Override
    public void onFailure(Throwable ex) {
         latch.countDown();
    }

});


if (latch.await(10, Timeunit.SECONDS) {
    ...
    future.get().get();
}