How to interrupt underlying execution of CompletableFuture

Question

I know that CompletableFuture design does not control its execution with interruptions, but I suppose some of you might have this problem. CompletableFutu

Answer 1

What about this?

public static  CompletableFuture supplyAsync(final Supplier supplier) {

    final ExecutorService executorService = Executors.newFixedThreadPool(1);

    final CompletableFuture cf = new CompletableFuture() {
        @Override
        public boolean complete(T value) {
            if (isDone()) {
                return false;
            }
            executorService.shutdownNow();
            return super.complete(value);
        }

        @Override
        public boolean completeExceptionally(Throwable ex) {
            if (isDone()) {
                return false;
            }
            executorService.shutdownNow();
            return super.completeExceptionally(ex);
        }
    };

    // submit task
    executorService.submit(() -> {
        try {
            cf.complete(supplier.get());
        } catch (Throwable ex) {
            cf.completeExceptionally(ex);
        }
    });

    return cf;
}

Simple Test:

    CompletableFuture cf = supplyAsync(() -> {
        try {
            Thread.sleep(1000L);
        } catch (Exception e) {
            System.out.println("got interrupted");
            return "got interrupted";
        }
        System.out.println("normal complete");
        return "normal complete";
    });

    cf.complete("manual complete");
    System.out.println(cf.get());

I don't like the idea of having to create an Executor service every time, but maybe you can find a way to reuse the ForkJoinPool.