1662827 - Remove the need for multiple channels on some WebRender threads

Status: RESOLVED FIXED

(Core :: Graphics: WebRender, task, P3)

Description

[Nicolas Silva [:nical]]

On the render backend and scene builder threads we have multiple channels. The main reason is that the both the api (webrender_api crate) and backend/scene (webrender crate) threads need to communicate with those, and a lot of the types in webrender internal messages can't move over to the api crate without dragging pretty much all of webrender.

The issue with having multiple channels in the event loops is that it makes it very hard to reason about the ordering of messages going going to the scene builder or directly to the render backend.

If the scene builder and render backend each had a single channel to receive message on we would get useful guarantees such as if message A is sent to the render backend before sending B to the scene builder, A is processed on the render backend before the render backend processes the result of B.

Comment 1

[Nicolas Silva [:nical]]

Attachment: Bug 1662827 - Merge webrender and webrender_api. r=gw

The motivation behind this change is to simplify a number of things:

• Allow any internal webrender types in ApiMsg and SceneBuilderRequest.
• As a result be able to ahve a single channel on the render backend an scene builder event loops.
• And as a result get some ordering guarantees between messages sent to the scene builder and render backend.
• Greatly simplify the message passing logic in WebRender thanks to all of the above and unblock sending messages directly to the scene builder thread.

Comment 2

[Nicolas Silva [:nical]]

Attachment: Bug 1662827 - Move interner code out of api.rs. r=gw

Minor cleanup after merging webrender and webrender_api.

Depends on D89180

Comment 3

[Nicolas Silva [:nical]]

Attachment: Bug 1662827 - Use a single channel on the render backend thread. r=gw

Depends on D89181

Comment 4

[Nicolas Silva [:nical]]

Attachment: Bug 1662827 - Use a single channel on the scene builder thread. r=gw

Depends on D89182

Comment 5

[Nicolas Silva [:nical]]

Attachment: Bug 1662827 - Move the api senders to the webrender crate. r=gw

Comment 6

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/40366bd1a0f7
Move the api senders to the webrender crate. r=gw
https://hg.mozilla.org/integration/autoland/rev/461e4e35a0e3
Use a single channel on the render backend thread. r=gw
https://hg.mozilla.org/integration/autoland/rev/25ef3ef3c69d
Use a single channel on the scene builder thread. r=gw

Comment 7

[Nicolas Silva [:nical]]

Attachment: Bug 1662827 - Fix tileview build.

Comment 8

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/4d216f67247b
Fix tileview build.

Comment 9

[Alexandru Michis [:malexandru]]

Backed out 4 changesets (Bug 1662827) for causing webrender bustages.

Backout link: https://hg.mozilla.org/integration/autoland/rev/471729107f9e34b8dc2f31f105c314a14ff8a5fe

Push with failures: https://treeherder.mozilla.org/#/jobs?repo=autoland&group_state=expanded&searchStr=webrender&tochange=4d216f67247b18204c7fb91fe02b6d81a53596b1&fromchange=25ef3ef3c69dc423e4324b9726ef3a0bd8f45d73&selectedTaskRun=GUT1xZAqS7qox8YjlD-EiA.0

Failure log: https://treeherder.mozilla.org/logviewer.html#/jobs?job_id=315098398&repo=autoland&lineNumber=2114

Comment 10

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/b1408e54551c
Move the api senders to the webrender crate. r=gw
https://hg.mozilla.org/integration/autoland/rev/7cafd404871f
Use a single channel on the render backend thread. r=gw
https://hg.mozilla.org/integration/autoland/rev/b003f8d0a290
Use a single channel on the scene builder thread. r=gw

Comment 11

[Dorel Luca [:dluca]]

https://hg.mozilla.org/mozilla-central/rev/b1408e54551c
https://hg.mozilla.org/mozilla-central/rev/7cafd404871f
https://hg.mozilla.org/mozilla-central/rev/b003f8d0a290