82cdf90a71
The new CLUTTER_FRAME_CLOCK_STATE_SCHEDULED_NOW state is almost identical to CLUTTER_FRAME_CLOCK_STATE_SCHEDULED, with one important difference being that it avoids updates from being repeatedly rescheduled "now" when multiple calls to clutter_frame_clock_schedule_update_now() are done before the source is actually dispatched. Such repeated calls to schedule an update "now" may actually postpone the dispatch if the CPU is very busy and the source dispatch is delayed, defeating the purpose of scheduling a frame "now". It also allows rescheduling "now" when the frame clock is uninhibited after being inhibited while an update was scheduled "now". This may be important in cases where the frame clock is inhibited for very short periods in which it would otherwise lose the state of being scheduled "now". Scenarios such as this would become more common with the introduction of variable refresh rate since it makes scheduling "now" a commonplace occurrence. Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/3561>
14 lines
537 B
Markdown
14 lines
537 B
Markdown
# Clutter Frame scheduling
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`ClutterFrameClock` state diagram.
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```mermaid
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stateDiagram
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Init --> Scheduled/ScheduledNow : schedule update() -> now
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Idle --> Scheduled/ScheduledNow : schedule update() -> given presentation time
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Scheduled/ScheduledNow --> Dispatching : target time hit
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Dispatching --> PendingPresented : queued page flip
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Dispatching --> Idle : no queued page flip
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PendingPresented --> Scheduled/ScheduledNow : page flipped, if recent schedule update
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PendingPresented --> Idle : page flipped
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```
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