Re: [whatwg/streams] Align WritableStream structure with ReadableStream structure (#488)

Draft commit message:

Add locking and precise flow control to WritableStream

This fixes #319 (by adding locking and the concept of a writable stream writer) and fixes #318 (by adding precise flow control via the writer.desiredSize property). The structure parallels that introduced for ReadableStream, including the introduction of a controller class.

The infrastructure is set up to allow the future introduction of different types of writable streams (with corresponding new controllers and writers).

With this in place, the public API for writable streams is almost stable; the remaining issue is whether writers should have a ready promise, or a waitForDesiredSize() method which could in the future be customized by passing an argument (see discussions in #318).

The reference implementation's pipeTo and transform stream code has been updated, and all the tests pass, but they haven't been put in the spec yet, as their design is not yet finalized (but is much closer to now that they have a more stable WritableStream foundation).

Merge at will!

---
You are receiving this because you are subscribed to this thread.
Reply to this email directly or view it on GitHub:
https://github.com/whatwg/streams/pull/488#issuecomment-237454642