compositing: Stop compositing unnecessarily after each animation frame. #9663
+146
−115
| @@ -0,0 +1,94 @@ | ||
| /* This Source Code Form is subject to the terms of the Mozilla Public | ||
| * License, v. 2.0. If a copy of the MPL was not distributed with this | ||
| * file, You can obtain one at http://mozilla.org/MPL/2.0/. */ | ||
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| //! A timer thread that composites near the end of the frame. | ||
| //! | ||
| //! This is useful when we need to composite next frame but we want to opportunistically give the | ||
| //! painting thread time to paint if it can. | ||
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| use compositor_thread::{CompositorProxy, Msg}; | ||
| use std::sync::mpsc::{Receiver, Sender, channel}; | ||
| use std::thread::{self, Builder}; | ||
| use time; | ||
| use util::time::duration_from_nanoseconds; | ||
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| /// The amount of time in nanoseconds that we give to the painting thread to paint. When this | ||
| /// expires, we give up and composite anyway. | ||
| static TIMEOUT: u64 = 12_000_000; | ||
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| pub struct DelayedCompositionTimerProxy { | ||
| sender: Sender<ToDelayedCompositionTimerMsg>, | ||
| } | ||
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| pub struct DelayedCompositionTimer { | ||
| compositor_proxy: Box<CompositorProxy>, | ||
| receiver: Receiver<ToDelayedCompositionTimerMsg>, | ||
| } | ||
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| enum ToDelayedCompositionTimerMsg { | ||
| Exit, | ||
| ScheduleComposite(u64), | ||
| } | ||
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| impl DelayedCompositionTimerProxy { | ||
| pub fn new(compositor_proxy: Box<CompositorProxy + Send>) -> DelayedCompositionTimerProxy { | ||
| let (to_timer_sender, to_timer_receiver) = channel(); | ||
| Builder::new().spawn(move || { | ||
| let mut timer = DelayedCompositionTimer { | ||
| compositor_proxy: compositor_proxy, | ||
| receiver: to_timer_receiver, | ||
| }; | ||
| timer.run(); | ||
| }).unwrap(); | ||
| DelayedCompositionTimerProxy { | ||
| sender: to_timer_sender, | ||
| } | ||
| } | ||
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| pub fn schedule_composite(&mut self, timestamp: u64) { | ||
| self.sender.send(ToDelayedCompositionTimerMsg::ScheduleComposite(timestamp)).unwrap() | ||
| } | ||
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| pub fn shutdown(&mut self) { | ||
| self.sender.send(ToDelayedCompositionTimerMsg::Exit).unwrap() | ||
| } | ||
| } | ||
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| impl DelayedCompositionTimer { | ||
| pub fn run(&mut self) { | ||
| 'outer: loop { | ||
| let mut timestamp; | ||
| loop { | ||
| match self.receiver.recv() { | ||
| Ok(ToDelayedCompositionTimerMsg::ScheduleComposite(this_timestamp)) => { | ||
| timestamp = this_timestamp; | ||
| break | ||
| } | ||
| Ok(ToDelayedCompositionTimerMsg::Exit) => break 'outer, | ||
| _ => break 'outer, | ||
| } | ||
| } | ||
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| // Drain all messages from the queue. | ||
| loop { | ||
| match self.receiver.try_recv() { | ||
| Ok(ToDelayedCompositionTimerMsg::ScheduleComposite(this_timestamp)) => { | ||
| timestamp = this_timestamp; | ||
| break | ||
| } | ||
| _ => break, | ||
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| } | ||
| } | ||
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| let target = timestamp + TIMEOUT; | ||
| let now = time::precise_time_ns(); | ||
| if target > now { | ||
| let delta_ns = target - now; | ||
| thread::sleep(duration_from_nanoseconds(delta_ns)); | ||
| } | ||
| self.compositor_proxy.send(Msg::DelayedCompositionTimeout(timestamp)); | ||
| } | ||
| } | ||
| } | ||
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Should this have a case for exit? e.g.