1533439 - Investigate using MozPromise to simplify async control flow and cancellation

Status: NEW

(Core :: Networking: HTTP, enhancement, P3)

Description

[Andy Grover [:grover]]

Starting in nsHttpChannel::AsyncOpen, there are many time-consuming steps that are handled asynchronously. This may be a good use case for MozPromise, which could instead describe the control flow as a chain of promises. This could make control flow easier to follow at a high level, as well as making cancellation easier.

:bholley blogged about this shortly after the introduction of MozPromise in 2015 (https://bholley.net/blog/2015/mozpromise.html). MozPromise is currently used mostly in the media decoding subsystem, so we should be able to look at that code for usage examples, and maybe even ask those engineers for guidance if needed.