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1 // Copyright 2011 The Chromium Authors. All rights reserved. | 1 // Copyright 2011 The Chromium Authors. All rights reserved. |
2 // Use of this source code is governed by a BSD-style license that can be | 2 // Use of this source code is governed by a BSD-style license that can be |
3 // found in the LICENSE file. | 3 // found in the LICENSE file. |
4 | 4 |
5 #include "config.h" | 5 #include "config.h" |
6 | 6 |
7 #include "CCDelayBasedTimeSource.h" | 7 #include "CCDelayBasedTimeSource.h" |
8 | 8 |
9 #include "base/debug/trace_event.h" | 9 #include "base/debug/trace_event.h" |
| 10 #include "base/logging.h" |
10 #include <algorithm> | 11 #include <algorithm> |
11 #include <wtf/CurrentTime.h> | 12 #include <wtf/CurrentTime.h> |
12 #include <wtf/MathExtras.h> | 13 #include <wtf/MathExtras.h> |
13 | 14 |
14 namespace cc { | 15 namespace cc { |
15 | 16 |
16 namespace { | 17 namespace { |
17 | 18 |
18 // doubleTickThreshold prevents ticks from running within the specified fraction
of an interval. | 19 // doubleTickThreshold prevents ticks from running within the specified fraction
of an interval. |
19 // This helps account for jitter in the timebase as well as quick timer reactiva
tion. | 20 // This helps account for jitter in the timebase as well as quick timer reactiva
tion. |
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83 return m_lastTickTime; | 84 return m_lastTickTime; |
84 } | 85 } |
85 | 86 |
86 base::TimeTicks CCDelayBasedTimeSource::nextTickTime() | 87 base::TimeTicks CCDelayBasedTimeSource::nextTickTime() |
87 { | 88 { |
88 return active() ? m_currentParameters.tickTarget : base::TimeTicks(); | 89 return active() ? m_currentParameters.tickTarget : base::TimeTicks(); |
89 } | 90 } |
90 | 91 |
91 void CCDelayBasedTimeSource::onTimerFired() | 92 void CCDelayBasedTimeSource::onTimerFired() |
92 { | 93 { |
93 ASSERT(m_state != STATE_INACTIVE); | 94 DCHECK(m_state != STATE_INACTIVE); |
94 | 95 |
95 base::TimeTicks now = this->now(); | 96 base::TimeTicks now = this->now(); |
96 m_lastTickTime = now; | 97 m_lastTickTime = now; |
97 | 98 |
98 if (m_state == STATE_STARTING) { | 99 if (m_state == STATE_STARTING) { |
99 setTimebaseAndInterval(now, m_currentParameters.interval); | 100 setTimebaseAndInterval(now, m_currentParameters.interval); |
100 m_state = STATE_ACTIVE; | 101 m_state = STATE_ACTIVE; |
101 } | 102 } |
102 | 103 |
103 postNextTickTask(now); | 104 postNextTickTask(now); |
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195 // This brings us back to 18+15 = 33, which was where we would have been if the
task hadn't been late. | 196 // This brings us back to 18+15 = 33, which was where we would have been if the
task hadn't been late. |
196 // | 197 // |
197 // For the really late delay, we we move to the next logical tick. The timebase
is not reset. | 198 // For the really late delay, we we move to the next logical tick. The timebase
is not reset. |
198 // now=37 tickTarget=16.667 newTarget=50.000 --> tick(), postDelayedTas
k(floor(50.000-37)) --> postDelayedTask(13) | 199 // now=37 tickTarget=16.667 newTarget=50.000 --> tick(), postDelayedTas
k(floor(50.000-37)) --> postDelayedTask(13) |
199 base::TimeTicks CCDelayBasedTimeSource::nextTickTarget(base::TimeTicks now) | 200 base::TimeTicks CCDelayBasedTimeSource::nextTickTarget(base::TimeTicks now) |
200 { | 201 { |
201 base::TimeDelta newInterval = m_nextParameters.interval; | 202 base::TimeDelta newInterval = m_nextParameters.interval; |
202 int intervalsElapsed = static_cast<int>(floor((now - m_nextParameters.tickTa
rget).InSecondsF() / newInterval.InSecondsF())); | 203 int intervalsElapsed = static_cast<int>(floor((now - m_nextParameters.tickTa
rget).InSecondsF() / newInterval.InSecondsF())); |
203 base::TimeTicks lastEffectiveTick = m_nextParameters.tickTarget + newInterva
l * intervalsElapsed; | 204 base::TimeTicks lastEffectiveTick = m_nextParameters.tickTarget + newInterva
l * intervalsElapsed; |
204 base::TimeTicks newTickTarget = lastEffectiveTick + newInterval; | 205 base::TimeTicks newTickTarget = lastEffectiveTick + newInterval; |
205 ASSERT(newTickTarget > now); | 206 DCHECK(newTickTarget > now); |
206 | 207 |
207 // Avoid double ticks when: | 208 // Avoid double ticks when: |
208 // 1) Turning off the timer and turning it right back on. | 209 // 1) Turning off the timer and turning it right back on. |
209 // 2) Jittery data is passed to setTimebaseAndInterval(). | 210 // 2) Jittery data is passed to setTimebaseAndInterval(). |
210 if (newTickTarget - m_lastTickTime <= newInterval / static_cast<int>(1.0 / d
oubleTickThreshold)) | 211 if (newTickTarget - m_lastTickTime <= newInterval / static_cast<int>(1.0 / d
oubleTickThreshold)) |
211 newTickTarget += newInterval; | 212 newTickTarget += newInterval; |
212 | 213 |
213 return newTickTarget; | 214 return newTickTarget; |
214 } | 215 } |
215 | 216 |
216 void CCDelayBasedTimeSource::postNextTickTask(base::TimeTicks now) | 217 void CCDelayBasedTimeSource::postNextTickTask(base::TimeTicks now) |
217 { | 218 { |
218 base::TimeTicks newTickTarget = nextTickTarget(now); | 219 base::TimeTicks newTickTarget = nextTickTarget(now); |
219 | 220 |
220 // Post another task *before* the tick and update state | 221 // Post another task *before* the tick and update state |
221 base::TimeDelta delay = newTickTarget - now; | 222 base::TimeDelta delay = newTickTarget - now; |
222 ASSERT(delay.InMillisecondsF() <= | 223 DCHECK(delay.InMillisecondsF() <= |
223 m_nextParameters.interval.InMillisecondsF() * (1.0 + doubleTickThresh
old)); | 224 m_nextParameters.interval.InMillisecondsF() * (1.0 + doubleTickThresh
old)); |
224 m_timer.startOneShot(delay.InSecondsF()); | 225 m_timer.startOneShot(delay.InSecondsF()); |
225 | 226 |
226 m_nextParameters.tickTarget = newTickTarget; | 227 m_nextParameters.tickTarget = newTickTarget; |
227 m_currentParameters = m_nextParameters; | 228 m_currentParameters = m_nextParameters; |
228 } | 229 } |
229 | 230 |
230 } // namespace cc | 231 } // namespace cc |
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