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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 "components/scheduler/renderer/queueing_time_estimator.h" | |
6 | |
7 #include "components/scheduler/renderer/coarse_duration_timer.h" | |
8 | |
9 namespace scheduler { | |
10 | |
11 namespace { | |
12 | |
13 base::TimeDelta ExpectedQueueingTimeFromTask(base::TimeTicks task_start, | |
14 base::TimeTicks task_end, | |
15 base::TimeTicks window_start, | |
16 base::TimeTicks window_end) { | |
17 DCHECK(task_start <= task_end); | |
Lei Zhang
2016/06/08 01:05:27
DCHECK_LE() and friends are preferred, BTW. They w
tdresser
2016/06/08 14:25:05
Thanks, I'll clean this up if the overall approach
| |
18 DCHECK(task_start <= window_end); | |
19 DCHECK(window_start < window_end); | |
20 DCHECK(task_end >= window_start); | |
21 base::TimeTicks task_in_window_start_time = | |
22 std::max(task_start, window_start); | |
23 base::TimeTicks task_in_window_end_time = | |
24 std::min(task_end, window_end); | |
25 DCHECK(task_in_window_end_time <= task_in_window_end_time); | |
26 | |
27 double probability_of_this_task = | |
28 static_cast<double>((task_in_window_end_time - task_in_window_start_time) | |
29 .InMicroseconds()) / | |
30 (window_end - window_start).InMicroseconds(); | |
31 | |
32 base::TimeDelta expected_queueing_duration_within_task = | |
33 ((task_end - task_in_window_start_time) + | |
34 (task_end - task_in_window_end_time)) / | |
35 2; | |
36 | |
37 return base::TimeDelta::FromMillisecondsD( | |
38 probability_of_this_task * | |
39 expected_queueing_duration_within_task.InMillisecondsF()); | |
40 } | |
41 | |
42 } // namespace | |
43 | |
44 QueueingTimeEstimator::QueueingTimeEstimator( | |
45 QueueingTimeEstimator::Client* client, | |
46 CoarseDurationTimer* timer, | |
47 base::TimeDelta window_duration) | |
48 : client_(client), | |
49 timer_(timer), | |
50 outstanding_task_count_(0), | |
51 window_duration_(window_duration) {} | |
52 | |
53 QueueingTimeEstimator::~QueueingTimeEstimator() {} | |
54 | |
55 void QueueingTimeEstimator::WillProcessTask( | |
56 const base::PendingTask& pending_task) { | |
57 // Avoid measuring the duration in nested run loops. | |
58 if (++outstanding_task_count_ != 1) | |
59 return; | |
60 | |
61 timer_->BeginInterval(); | |
62 } | |
63 | |
64 void QueueingTimeEstimator::DidProcessTask( | |
65 const base::PendingTask& pending_task) { | |
66 if (--outstanding_task_count_ != 0) | |
67 return; | |
68 | |
69 base::TimeDelta duration = timer_->EndInterval(); | |
70 if (duration.is_zero()) | |
71 return; | |
72 | |
73 base::TimeTicks task_end_time = timer_->most_recent_time(); | |
74 base::TimeTicks task_start_time = task_end_time - duration; | |
75 | |
76 // If this is the first task, set the window start time such that the window | |
77 // and the task end at the same time. | |
78 if (window_start_time_.is_null()) | |
79 window_start_time_ = task_end_time - window_duration_; | |
80 | |
81 bool start_past_window = | |
82 task_start_time > window_start_time_ + window_duration_; | |
83 bool end_past_window = | |
84 task_end_time > window_start_time_ + window_duration_; | |
85 | |
86 while (end_past_window) { | |
87 if (!start_past_window) { | |
88 // Include the current task in this window. | |
89 current_expected_queueing_time_ += ExpectedQueueingTimeFromTask( | |
90 task_start_time, task_end_time, window_start_time_, | |
91 window_start_time_ + window_duration_); | |
92 } | |
93 client_->OnQueueingTimeForWindowEstimated(current_expected_queueing_time_); | |
94 window_start_time_ += window_duration_; | |
95 current_expected_queueing_time_ = base::TimeDelta(); | |
96 | |
97 start_past_window = | |
98 task_start_time > window_start_time_ + window_duration_; | |
99 end_past_window = | |
100 task_end_time > window_start_time_ + window_duration_; | |
101 } | |
102 | |
103 current_expected_queueing_time_ += ExpectedQueueingTimeFromTask( | |
104 task_start_time, task_end_time, window_start_time_, | |
105 window_start_time_ + window_duration_); | |
106 } | |
107 | |
108 } // namespace scheduler | |
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