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1 // Copyright 2016 The Chromium Authors. All rights reserved. | |
2 // Use of this source code is governed by a BSD-style license that can be | |
3 // found in the LICENSE file. | |
4 | |
5 #include "base/auto_reset.h" | |
6 #include "base/logging.h" | |
7 #include "blimp/engine/renderer/frame_scheduler.h" | |
8 | |
9 namespace blimp { | |
10 namespace engine { | |
11 namespace { | |
12 // This is the temporary frame delay to keep pages which make animation requests | |
13 // but don't mutate the state on the engine from running main frames | |
14 // back-to-back. We need smarter throttling of engine updates. See | |
15 // crbug.com/597829. | |
16 constexpr base::TimeDelta kDefaultFrameDelay = | |
17 base::TimeDelta::FromMilliseconds(30); | |
18 } // namespace | |
19 | |
20 FrameScheduler::FrameScheduler( | |
21 scoped_refptr<base::SingleThreadTaskRunner> task_runner, | |
22 FrameSchedulerClient* client) | |
23 : next_frame_time_(base::TimeTicks::Now()), | |
24 frame_delay_(kDefaultFrameDelay), | |
25 client_(client) { | |
26 DCHECK(client_); | |
27 frame_tick_timer_.SetTaskRunner(std::move(task_runner)); | |
28 } | |
29 | |
30 FrameScheduler::~FrameScheduler() = default; | |
31 | |
32 void FrameScheduler::ScheduleFrameUpdate() { | |
33 if (needs_frame_update_) | |
34 return; | |
35 | |
36 needs_frame_update_ = true; | |
37 ScheduleFrameUpdateIfNecessary(); | |
38 } | |
39 | |
40 void FrameScheduler::DidSendFrameUpdateToClient() { | |
41 DCHECK(in_frame_update_); | |
42 DCHECK(!frame_ack_pending_) << "We can have only frame update in flight"; | |
43 | |
44 frame_ack_pending_ = true; | |
45 } | |
46 | |
47 void FrameScheduler::DidReceiveFrameUpdateAck() { | |
48 DCHECK(frame_ack_pending_); | |
49 | |
50 frame_ack_pending_ = false; | |
51 ScheduleFrameUpdateIfNecessary(); | |
52 } | |
53 | |
54 void FrameScheduler::ScheduleFrameUpdateIfNecessary() { | |
55 // If we can't produce main frame updates right now, don't schedule a task. | |
56 if (!ShouldProduceFrameUpdates()) { | |
57 return; | |
58 } | |
59 | |
60 // If a task has already been scheduled, we don't need to schedule again. | |
61 if (frame_tick_timer_.IsRunning()) | |
62 return; | |
63 | |
64 base::TimeDelta delay = next_frame_time_ - base::TimeTicks::Now(); | |
65 frame_tick_timer_.Start( | |
66 FROM_HERE, delay, | |
67 base::Bind(&FrameScheduler::StartFrameUpdate, base::Unretained(this))); | |
68 } | |
69 | |
70 bool FrameScheduler::ShouldProduceFrameUpdates() const { | |
71 return needs_frame_update_ && !frame_ack_pending_; | |
72 } | |
73 | |
74 void FrameScheduler::StartFrameUpdate() { | |
75 DCHECK(!in_frame_update_); | |
76 DCHECK(needs_frame_update_); | |
77 | |
78 // If an update was sent to the client since this request, we can not start | |
79 // another frame. Early out here, we'll come back when an Ack is received from | |
80 // the client. | |
81 if (frame_ack_pending_) | |
82 return; | |
83 | |
84 needs_frame_update_ = false; | |
85 next_frame_time_ = base::TimeTicks::Now() + frame_delay_; | |
86 { | |
87 base::AutoReset<bool> in_frame_update(&in_frame_update_, true); | |
88 client_->StartFrameUpdate(); | |
89 } | |
90 } | |
91 | |
92 } // namespace engine | |
93 } // namespace blimp | |
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