Service platform tasks due within a frame early - #29
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Both run loops slept a full frame period whenever the next engine task was due sooner, adding up to a frame of latency. Wake at the task's due time instead, with a 1ms floor. Idle behaviour (empty queue) is unchanged, and vsync is still aligned to frame boundaries by the embedder. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01F1bgmVQVQTHUQpQtBbFw6t
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Both
FlutterWindowrun loops (theTimerpath andrun() async) slept for at least a full frame period, even whenprocessMessages()said the next engine task was due sooner. That delayed such tasks by up to one frame, about 16.7 ms at 60 Hz. The C++ reference runner in flutter-embedded-linux sleeps onlywait_durationin that case.This change wakes the loop when that task is due, with a 1 ms floor.
CPU impact should be negligible:
processMessages()returnsInt64.maxand both loops still wake once per frame, as before.TaskRunner::ProcessTasks(), thendispatchEvent(), which doesn't block (Waylandpollwith timeout 0,XPendingon X11,sd_event_run/uv_runwith no wait on DRM).dispatchEvent()also delivers vsync, butVsyncWaiter::NotifyVsynconly fires if the engine requested a frame, and the frame start is still aligned to the next vsync boundary. Frames can't render faster than the refresh rate.Timer path: the timer callback already sets
fireDateto delay the next fire. CFRunLoop honours anyfireDateset during the callout that's later than the fire that just happened, so setting an earlier one (now + max(wait, 1 ms)) works the same way.The existing behaviour of sleeping longer than a frame when the next task is further out is unchanged.
Independent of #28 and merges cleanly with it. Built with
swift build --target FlutterSwift; not yet tested on target hardware.🤖 Generated with Claude Code
https://claude.ai/code/session_01F1bgmVQVQTHUQpQtBbFw6t