Migrate Q to BlueBird (or Vow)
bluebird, node.js, promise, q
Solution
Yes, Bluebird is two orders of magnitude faster than Q, and is much more debuggable. You can look at the benchmarks yourself.
As for the code:
- `Q()` maps to `Promise.resolve` in Bluebird (just like in ES6 native promises).*
- `Q.defer` maps to `Promise.defer()` although it's a better option to use the promise constructor or automatic promisification as explained in this answer. In short, the promise constructor is throw safe.
Note* - once you've cast the promise, it'll assimilate thenables from other libraries automatically - so this is perfectly fine:
this.Start = Promise.resolve(ampq.connect(url, { heartbeat: heartbeat }))
.then((connection) => {
this.Connection = connection;
return connection.createConfirmChannel());
})
.then((channel) => {
this.ConfirmChannel = channel;
channel.on('error', this.handleChannelError);
return true;
});
Problem
I'm current using the Q promise library in a Node/amqp app. I've read that the performance of Q vs libraries like BlueBird or Vow is... not so good. Unfortunately, I can't figure out how to use BlueBird (or Vow) to replace my current Q usage patterns. Here's an example: ``` this.Start = Q(ampq.connect(url, { heartbeat: heartbeat })) .then((connection) => { this.Connection = connection; return Q(connection.createConfirmChannel()); }) .then((channel) => { this.ConfirmChannel = channel; channel.on('error', this.handleChannelError); return true; }); ``` I should've mentioned - I'm using TypeScript... In this example I'm taking an amqplib promises, and creating a Q promise out of it (because I don't like the amqplib promises). How do I do that with BlueBird or Vow? Another example is: ``` public myMethod(): Q.Promise<boolean> { var ackDeferred = Q.defer<boolean>(); var handleChannelConfirm = (err, ok): void => { if (err !== null) { //message nacked! ackDeferred.resolve(false); } else { //message acked ackDeferred.resolve(true); } } ...some other code here which invokes callback above... return ackDeferred.promise; } ``` How is that pattern implemented? So my general questions is: - Are the performance differences I've read about true? - How do I migrate from Q to BlueBird or Vow, with a focus on those two patterns (but an explanation of using 'then' would be great, too)?