Use native Promises

[jryans]

All of our supported browsers (as well as Node.js) have supported native Promises for a while. We should remove userland Promise libs (like bluebird) and convert to native instead.

[t3chguy]

benchmarks still tend to show bluebird as performing better than native promises: https://gist.github.com/joseluisq/a87adfd46d86d82ba787919a062f6e36

[jryans]

benchmarks still tend to show bluebird as performing better than native promises: https://gist.github.com/joseluisq/a87adfd46d86d82ba787919a062f6e36

The recent comments there seem to say native is fastest...?

[t3chguy]

I somehow completely missed that, also stated in the bluebird README:

Promises in Node.js 10 are significantly faster than before. Bluebird still includes a lot of features like cancellation, iteration methods and warnings that native promises don't. If you are using Bluebird for performance rather than for those - please consider giving native promises a shot and running the benchmarks yourself.

[turt2live]

fwiw we do use the cancellation features of bluebird in the js-sdk

[ara4n]

yup, cancellation features are used for cancelling file uploads iirc

[jryans]

Hmm, I don't think I am seeing obvious calls to cancel on promises so far... Could someone link to an example of where it's being used?

[t3chguy]

Cancellations are the least of what we use.

Things like Deferreds, mapSeries etc are simple to transition
Things like .value() (a sync way of getting the fulfilled value) and isFulfilled() which the code claims we use for performance (to save it being thrown onto the next event loop when it is already done) are much harder. This is a gargantuan task.

[t3chguy]

react-sdk changes have landed, js-sdk and riot-web due.

[t3chguy]

Fixxxxxed :D