How to use

Threads

in

com.gofore.aws.workshop.common.async

  private void operate() {
    while (true) {
      if (overloading) {
        for (double d = 0.0; d < Math.PI; d += 0.01) {
          Math.tan(d);
        }
      } else {
        Threads.sleep(1000);
      }
    }
  }
}

public CompletableFuture<Stack> getStackWhen(String stackName, String... statuses) {
  DescribeStacksRequest request = new DescribeStacksRequest().withStackName(stackName);
  return describeStacks(request).thenApply(firstStack()).thenComposeAsync(stack -> {
    if (ImmutableSet.copyOf(statuses).contains(stack.getStackStatus()) && !stack.getOutputs().isEmpty()) {
      return CompletableFuture.completedFuture(stack);
    } else {
      Threads.sleep(1000);
      return getStackWhen(stackName, statuses);
    }
  }, executor);
}

@Override
public synchronized void start() throws Exception {
  if (isEnabled() && thread == null) {
    super.start();
    this.thread = new Thread(() -> {
      // loop that polls new messages with maximum long poll time
      while (isStarted()) {
        try {
          ReceiveMessageRequest request = new ReceiveMessageRequest(queueUrl)
              .withWaitTimeSeconds(LONG_POLL_SECONDS);
          ReceiveMessageResult result = sqsClient.getSqs().receiveMessage(request);
          
          // apply the message handle chain and finally delete message if
          // everything else succeeds
          Stream<CompletableFuture<Message>> messages = result.getMessages().stream()
              .map(this::handleMessage)
              .map(this::completeMessage)
              .map(this::deleteMessage);
          sequence(messages).join();
          // artificial slow down to allow scaling to happen
          Threads.sleep(10000);
        } catch (RuntimeException ex) {
          LOGGER.warn("SQS receive or message handling failed", ex);
          Threads.sleep(WAIT_AFTER_FAILURE_MILLIS);
        }
      }
    });
    this.thread.start();
  }
}