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Issue 12676029: cc: Fix capitalization style in chromified files. (Closed) Base URL: svn://svn.chromium.org/chrome/trunk/src
Patch Set: Created 7 years, 9 months ago
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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 "cc/scheduler/delay_based_time_source.h" 5 #include "cc/scheduler/delay_based_time_source.h"
6 6
7 #include <algorithm> 7 #include <algorithm>
8 #include <cmath> 8 #include <cmath>
9 9
10 #include "base/debug/trace_event.h" 10 #include "base/debug/trace_event.h"
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44 has_tick_target_(false), 44 has_tick_target_(false),
45 current_parameters_(interval, base::TimeTicks()), 45 current_parameters_(interval, base::TimeTicks()),
46 next_parameters_(interval, base::TimeTicks()), 46 next_parameters_(interval, base::TimeTicks()),
47 state_(STATE_INACTIVE), 47 state_(STATE_INACTIVE),
48 thread_(thread), 48 thread_(thread),
49 weak_factory_(ALLOW_THIS_IN_INITIALIZER_LIST(this)) {} 49 weak_factory_(ALLOW_THIS_IN_INITIALIZER_LIST(this)) {}
50 50
51 DelayBasedTimeSource::~DelayBasedTimeSource() {} 51 DelayBasedTimeSource::~DelayBasedTimeSource() {}
52 52
53 void DelayBasedTimeSource::SetActive(bool active) { 53 void DelayBasedTimeSource::SetActive(bool active) {
54 TRACE_EVENT1("cc", "DelayBasedTimeSource::setActive", "active", active); 54 TRACE_EVENT1("cc", "DelayBasedTimeSource::SetActive", "active", active);
55 if (!active) { 55 if (!active) {
56 state_ = STATE_INACTIVE; 56 state_ = STATE_INACTIVE;
57 weak_factory_.InvalidateWeakPtrs(); 57 weak_factory_.InvalidateWeakPtrs();
58 return; 58 return;
59 } 59 }
60 60
61 if (state_ == STATE_STARTING || state_ == STATE_ACTIVE) 61 if (state_ == STATE_STARTING || state_ == STATE_ACTIVE)
62 return; 62 return;
63 63
64 if (!has_tick_target_) { 64 if (!has_tick_target_) {
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145 return; 145 return;
146 } 146 }
147 } 147 }
148 148
149 base::TimeTicks DelayBasedTimeSource::Now() const { 149 base::TimeTicks DelayBasedTimeSource::Now() const {
150 return base::TimeTicks::Now(); 150 return base::TimeTicks::Now();
151 } 151 }
152 152
153 // This code tries to achieve an average tick rate as close to interval_ as 153 // This code tries to achieve an average tick rate as close to interval_ as
154 // possible. To do this, it has to deal with a few basic issues: 154 // possible. To do this, it has to deal with a few basic issues:
155 // 1. postDelayedTask can delay only at a millisecond granularity. So, 16.666 155 // 1. PostDelayedTask can delay only at a millisecond granularity. So, 16.666
156 // has to posted as 16 or 17. 156 // has to posted as 16 or 17.
157 // 2. A delayed task may come back a bit late (a few ms), or really late 157 // 2. A delayed task may come back a bit late (a few ms), or really late
158 // (frames later) 158 // (frames later)
159 // 159 //
160 // The basic idea with this scheduler here is to keep track of where we *want* 160 // The basic idea with this scheduler here is to keep track of where we *want*
161 // to run in tick_target_. We update this with the exact interval. 161 // to run in tick_target_. We update this with the exact interval.
162 // 162 //
163 // Then, when we post our task, we take the floor of (tick_target_ and Now()). 163 // Then, when we post our task, we take the floor of (tick_target_ and Now()).
164 // If we started at now=0, and 60FPs (all times in milliseconds): 164 // If we started at now=0, and 60FPs (all times in milliseconds):
165 // now=0 target=16.667 postDelayedTask(16) 165 // now=0 target=16.667 PostDelayedTask(16)
166 // 166 //
167 // When our callback runs, we figure out how far off we were from that goal. 167 // When our callback runs, we figure out how far off we were from that goal.
168 // Because of the flooring operation, and assuming our timer runs exactly when 168 // Because of the flooring operation, and assuming our timer runs exactly when
169 // it should, this yields: 169 // it should, this yields:
170 // now=16 target=16.667 170 // now=16 target=16.667
171 // 171 //
172 // Since we can't post a 0.667 ms task to get to now=16, we just treat this as a 172 // Since we can't post a 0.667 ms task to get to now=16, we just treat this as a
173 // tick. Then, we update target to be 33.333. We now post another task based on 173 // tick. Then, we update target to be 33.333. We now post another task based on
174 // the difference between our target and now: 174 // the difference between our target and now:
175 // now=16 tick_target=16.667 newTarget=33.333 --> 175 // now=16 tick_target=16.667 new_target=33.333 -->
176 // postDelayedTask(floor(33.333 - 16)) --> postDelayedTask(17) 176 // PostDelayedTask(floor(33.333 - 16)) --> PostDelayedTask(17)
177 // 177 //
178 // Over time, with no late tasks, this leads to us posting tasks like this: 178 // Over time, with no late tasks, this leads to us posting tasks like this:
179 // now=0 tick_target=0 newTarget=16.667 --> 179 // now=0 tick_target=0 new_target=16.667 -->
180 // tick(), postDelayedTask(16) 180 // tick(), PostDelayedTask(16)
181 // now=16 tick_target=16.667 newTarget=33.333 --> 181 // now=16 tick_target=16.667 new_target=33.333 -->
182 // tick(), postDelayedTask(17) 182 // tick(), PostDelayedTask(17)
183 // now=33 tick_target=33.333 newTarget=50.000 --> 183 // now=33 tick_target=33.333 new_target=50.000 -->
184 // tick(), postDelayedTask(17) 184 // tick(), PostDelayedTask(17)
185 // now=50 tick_target=50.000 newTarget=66.667 --> 185 // now=50 tick_target=50.000 new_target=66.667 -->
186 // tick(), postDelayedTask(16) 186 // tick(), PostDelayedTask(16)
187 // 187 //
188 // We treat delays in tasks differently depending on the amount of delay we 188 // We treat delays in tasks differently depending on the amount of delay we
189 // encounter. Suppose we posted a task with a target=16.667: 189 // encounter. Suppose we posted a task with a target=16.667:
190 // Case 1: late but not unrecoverably-so 190 // Case 1: late but not unrecoverably-so
191 // now=18 tick_target=16.667 191 // now=18 tick_target=16.667
192 // 192 //
193 // Case 2: so late we obviously missed the tick 193 // Case 2: so late we obviously missed the tick
194 // now=25.0 tick_target=16.667 194 // now=25.0 tick_target=16.667
195 // 195 //
196 // We treat the first case as a tick anyway, and assume the delay was unusual. 196 // We treat the first case as a tick anyway, and assume the delay was unusual.
197 // Thus, we compute the newTarget based on the old timebase: 197 // Thus, we compute the new_target based on the old timebase:
198 // now=18 tick_target=16.667 newTarget=33.333 --> 198 // now=18 tick_target=16.667 new_target=33.333 -->
199 // tick(), postDelayedTask(floor(33.333-18)) --> postDelayedTask(15) 199 // tick(), PostDelayedTask(floor(33.333-18)) --> PostDelayedTask(15)
200 // This brings us back to 18+15 = 33, which was where we would have been if the 200 // This brings us back to 18+15 = 33, which was where we would have been if the
201 // task hadn't been late. 201 // task hadn't been late.
202 // 202 //
203 // For the really late delay, we we move to the next logical tick. The timebase 203 // For the really late delay, we we move to the next logical tick. The timebase
204 // is not reset. 204 // is not reset.
205 // now=37 tick_target=16.667 newTarget=50.000 --> 205 // now=37 tick_target=16.667 new_target=50.000 -->
206 // tick(), postDelayedTask(floor(50.000-37)) --> postDelayedTask(13) 206 // tick(), PostDelayedTask(floor(50.000-37)) --> PostDelayedTask(13)
207 base::TimeTicks DelayBasedTimeSource::NextTickTarget(base::TimeTicks now) { 207 base::TimeTicks DelayBasedTimeSource::NextTickTarget(base::TimeTicks now) {
208 base::TimeDelta new_interval = next_parameters_.interval; 208 base::TimeDelta new_interval = next_parameters_.interval;
209 int intervals_elapsed = 209 int intervals_elapsed =
210 static_cast<int>(floor((now - next_parameters_.tick_target).InSecondsF() / 210 static_cast<int>(floor((now - next_parameters_.tick_target).InSecondsF() /
211 new_interval.InSecondsF())); 211 new_interval.InSecondsF()));
212 base::TimeTicks last_effective_tick = 212 base::TimeTicks last_effective_tick =
213 next_parameters_.tick_target + new_interval * intervals_elapsed; 213 next_parameters_.tick_target + new_interval * intervals_elapsed;
214 base::TimeTicks new_tick_target = last_effective_tick + new_interval; 214 base::TimeTicks new_tick_target = last_effective_tick + new_interval;
215 DCHECK(new_tick_target > now); 215 DCHECK(new_tick_target > now);
216 216
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234 (1.0 + kDoubleTickThreshold)); 234 (1.0 + kDoubleTickThreshold));
235 thread_->PostDelayedTask(base::Bind(&DelayBasedTimeSource::OnTimerFired, 235 thread_->PostDelayedTask(base::Bind(&DelayBasedTimeSource::OnTimerFired,
236 weak_factory_.GetWeakPtr()), 236 weak_factory_.GetWeakPtr()),
237 delay); 237 delay);
238 238
239 next_parameters_.tick_target = new_tick_target; 239 next_parameters_.tick_target = new_tick_target;
240 current_parameters_ = next_parameters_; 240 current_parameters_ = next_parameters_;
241 } 241 }
242 242
243 } // namespace cc 243 } // namespace cc
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