Unable to implement asynchronous polling using ScheduledExecutorService

Question

I am trying to implement a polling functionality which does this:

while (condition is false or it does not timeout):
   call another end point
   wait(x seconds)

I wrote below code:

private static CompletableFuture<Integer> asyncStatusChecker() {
    ScheduledExecutorService executor = Executors.newSingleThreadScheduledExecutor();
    CompletableFuture<Integer> completionFuture = new CompletableFuture<>();
    final ScheduledFuture<?> checkFuture = executor.scheduleAtFixedRate(() -> {
        int currentStatus = fetchStatus();
        System.out.println("current c: " + currentStatus);
        if (isStatusFinal(currentStatus)) {
            completionFuture.complete(currentStatus);
        }
    }, 5, 1, TimeUnit.SECONDS);
    completionFuture.whenComplete((result, thrown) ->
            checkFuture.cancel(true));
    completionFuture.orTimeout(10, TimeUnit.SECONDS);
    return completionFuture;
}

But it's not correct implementation as the process still remains active even after execution and also it does not look syntactically correct. Anybody know what I am doing wrong here?

Answer 1

I think you probably need to update the status, like this:

    int currentStatus = fetchStatus();
    System.out.println("current c: " + currentStatus);
    if (isStatusFinal(currentStatus)) {
        completionFuture.complete(currentStatus);
    } else {
        //update status
    }

or do the update status thing at some otherwhere.