Day 45: Dear Promise, please promise me you'll be complete one day. Love, jam

Yesterday was Labor Day, so we celebrated it by not working! Woohoo! Malisa is traveling back today, so I (Jeena) worked alone today.

Things we did:

• Promise in Fetch
  • jdm is back! He rebased his promises branch! The rust compiler still panics instead of throwing error as it uses the older rust version, but that’s ok! I can work around it.
  • It turns out there’s a lot more to do with implementing promise in fetch so I spent the day trying to understand what I need to do. Roughly, there are two things I can do:
    1. figure out how to reject/resolve Promise in fetch. Promise::maybe_resolve_native is probably a better choice than Promise::maybe_resolve because they take regular DOM objects. This seems partially dependent on the next thing.
    2. implement FetchResponseListener in fetch.rs. This turns out to have a lot more pre-requisite infrastructure! fetch.rs needs a FetchContext struct that will store the intermediate fetch. XMLHttpRequest is done very similarly to fetch, so I should look into how XHR is implemented in Servo. How XHR implements FetchResponseListener is here.

Things we learned:

• jdm drew a great diagram describing how XMLHttpRequest interacts with resource thread and XHRContext
• Promise doesn’t have to be rooted! Whaaaat. jdm says “Rc would usually be unsafe but Promise is designed in such a way that it's safe, whereas Rooted would be incorrect." Whaaaat? I don't even understand! We'll find out the reason later...

TODO:

• Promise in Fetch
  • make FetchContext struct
  • Impl FetchResponseListener for FetchContext (may require helper functions)
  • resolve/reject promise in fetch