[Java Async] sample async #java

async-schedule.java

// https://dzone.com/articles/asynchronous-timeouts

private static final ScheduledExecutorService scheduler =
        Executors.newScheduledThreadPool(
                1,
                new ThreadFactoryBuilder()
                        .setDaemon(true)
                        .setNameFormat("failAfter-%d")
                        .build());
public static <T> CompletableFuture<T> failAfter(Duration duration) {
    final CompletableFuture<T> promise = new CompletableFuture<>();
    scheduler.schedule(() -> promise.completeExceptionally(new TimeoutException("Timeout after " + duration)), 
                       duration.toMillis(), MILLISECONDS);
    return promise;
}

public static <T> CompletableFuture<T> within(CompletableFuture<T> future, Duration duration) {
    final CompletableFuture<T> timeout = failAfter(duration);
    return future.applyToEither(timeout, Function.identity());
}

// sample usage
final CompletableFuture<Response> responseFuture = within(
        asyncCode(), Duration.ofSeconds(1));
responseFuture
        .thenAccept(this::send)
        .exceptionally(throwable -> {
            log.error("Unrecoverable error", throwable);
            return null;
        });