Return Promise from queue.start()

[slavafomin]

Hello!

Thank you for this great module! It's very convenient.

However, it would be great to add support for Promises in queue.start().

Right now I have to wrap it like this:

function startQueue (queue) {
  return new Promise((resolve, reject) => {
    queue.start(error => {
      if (error) {
        reject(error);
      } else {
        resolve();
      }
    });
  });
}

And then:

const queue = $queue();
queue.push(…);
await startQueue(queue);
// queue is finished here

The better would be:

const queue = $queue();
queue.push(…);
await queue.start();
// queue is finished here

[jessetane]

@slavafomin feel free to send a PR

[jessetane]

@slavafomin @kwolfy anyone interested in working on a patch for this?

[sempasha]

Before returning Promise there is one ambiguous thing should be resolved. Starting queue with callback and without it has different errors handling behaviour:

1. In first case queue.start(callback), when error occurs queue will trigger error event, and stops execution;
2. While in second case queue.start(), when error occurs queue will just trigger error event and nothing more.

In my view there should be more transparent way to determine, what queue should do when error occurs - just trigger error event or stops execution next jobs with error event.

[jessetane]

@sempasha good point - I'm open to changes that break the API if we all agree they improve the design

[MaksimLavrenyuk]

@slavafomin Resolve https://github.com/jessetane/queue/pull/93