Matej Knopp 94cd4b14c9
[Embedder] Implement merged platform and UI thread (#162944)
Fixes https://github.com/flutter/flutter/issues/152337

Introduces `ui_task_runner` field on `FlutterCustomTaskRunners`. This
lets the embedder to specify task runner for UI isolate tasks, allowing
for merging platform and UI threads.

With custom UI task runner there is no `MessageLoop` anymore for the UI
thread, so the message loop task observer can no longer be used to flush
microtask queue. Instead the microtask queue is flushed at the end of
each `FlutterEngineRunTask` invocation if needed. This is handled
internally by the embedder.

## Pre-launch Checklist

- [x] I read the [Contributor Guide] and followed the process outlined
there for submitting PRs.
- [x] I read the [Tree Hygiene] wiki page, which explains my
responsibilities.
- [x] I read and followed the [Flutter Style Guide], including [Features
we expect every widget to implement].
- [x] I signed the [CLA].
- [x] I listed at least one issue that this PR fixes in the description
above.
- [x] I updated/added relevant documentation (doc comments with `///`).
- [x] I added new tests to check the change I am making, or this PR is
[test-exempt].
- [x] I followed the [breaking change policy] and added [Data Driven
Fixes] where supported.
- [x] All existing and new tests are passing.

If you need help, consider asking for advice on the #hackers-new channel
on [Discord].

<!-- Links -->
[Contributor Guide]:
https://github.com/flutter/flutter/blob/main/docs/contributing/Tree-hygiene.md#overview
[Tree Hygiene]:
https://github.com/flutter/flutter/blob/main/docs/contributing/Tree-hygiene.md
[test-exempt]:
https://github.com/flutter/flutter/blob/main/docs/contributing/Tree-hygiene.md#tests
[Flutter Style Guide]:
https://github.com/flutter/flutter/blob/main/docs/contributing/Style-guide-for-Flutter-repo.md
[Features we expect every widget to implement]:
https://github.com/flutter/flutter/blob/main/docs/contributing/Style-guide-for-Flutter-repo.md#features-we-expect-every-widget-to-implement
[CLA]: https://cla.developers.google.com/
[flutter/tests]: https://github.com/flutter/tests
[breaking change policy]:
https://github.com/flutter/flutter/blob/main/docs/contributing/Tree-hygiene.md#handling-breaking-changes
[Discord]:
https://github.com/flutter/flutter/blob/main/docs/contributing/Chat.md
[Data Driven Fixes]:
https://github.com/flutter/flutter/blob/main/docs/contributing/Data-driven-Fixes.md

---------

Co-authored-by: Jonah Williams <jonahwilliams@google.com>
Co-authored-by: Loïc Sharma <737941+loic-sharma@users.noreply.github.com>
2025-02-11 12:24:13 +00:00
..

Flutter Engine

Setting up the Engine development environment

See here

gclient bootstrap

Flutter engine uses gclient to manage dependencies.

If you've already cloned the flutter repository:

  1. Copy one of the engine/scripts/*.gclient to the root folder as .gclient:
    1. Googlers: copy rbe.gclient to enable faster builds with RBE
    2. Everyone else: copy standard.gclient
  2. run gclient sync from the root folder