Index: cc/scheduler/delay_based_time_source.cc |
diff --git a/cc/scheduler/delay_based_time_source.cc b/cc/scheduler/delay_based_time_source.cc |
index 5d2f20bee6fd41695b9bcf84d85bd2ca50138163..6038a3bfc29b3142f6d079811bc4473d78f53dee 100644 |
--- a/cc/scheduler/delay_based_time_source.cc |
+++ b/cc/scheduler/delay_based_time_source.cc |
@@ -15,10 +15,10 @@ namespace cc { |
namespace { |
-// kDoubleTickThreshold prevents ticks from running within the specified |
+// kDoubleTickDivisor prevents ticks from running within the specified |
// fraction of an interval. This helps account for jitter in the timebase as |
// well as quick timer reactivation. |
-static const double kDoubleTickThreshold = 0.25; |
+static const int kDoubleTickDivisor = 4; |
// kIntervalChangeThreshold is the fraction of the interval that will trigger an |
// immediate interval change. kPhaseChangeThreshold is the fraction of the |
@@ -40,10 +40,10 @@ scoped_refptr<DelayBasedTimeSource> DelayBasedTimeSource::Create( |
DelayBasedTimeSource::DelayBasedTimeSource( |
base::TimeDelta interval, base::SingleThreadTaskRunner* task_runner) |
: client_(NULL), |
- has_tick_target_(false), |
+ last_tick_time_(base::TimeTicks() - interval), |
current_parameters_(interval, base::TimeTicks()), |
next_parameters_(interval, base::TimeTicks()), |
- state_(STATE_INACTIVE), |
+ active_(false), |
task_runner_(task_runner), |
weak_factory_(this) {} |
@@ -51,32 +51,19 @@ DelayBasedTimeSource::~DelayBasedTimeSource() {} |
void DelayBasedTimeSource::SetActive(bool active) { |
TRACE_EVENT1("cc", "DelayBasedTimeSource::SetActive", "active", active); |
- if (!active) { |
- state_ = STATE_INACTIVE; |
- weak_factory_.InvalidateWeakPtrs(); |
+ if (active == active_) |
return; |
- } |
+ active_ = active; |
- if (state_ == STATE_STARTING || state_ == STATE_ACTIVE) |
- return; |
- |
- if (!has_tick_target_) { |
- // Becoming active the first time is deferred: we post a 0-delay task. |
- // When it runs, we use that to establish the timebase, become truly |
- // active, and fire the first tick. |
- state_ = STATE_STARTING; |
- task_runner_->PostTask(FROM_HERE, |
- base::Bind(&DelayBasedTimeSource::OnTimerFired, |
- weak_factory_.GetWeakPtr())); |
+ if (!active_) { |
+ weak_factory_.InvalidateWeakPtrs(); |
return; |
} |
- state_ = STATE_ACTIVE; |
- |
PostNextTickTask(Now()); |
} |
-bool DelayBasedTimeSource::Active() const { return state_ != STATE_INACTIVE; } |
+bool DelayBasedTimeSource::Active() const { return active_; } |
base::TimeTicks DelayBasedTimeSource::LastTickTime() { return last_tick_time_; } |
@@ -85,17 +72,11 @@ base::TimeTicks DelayBasedTimeSource::NextTickTime() { |
} |
void DelayBasedTimeSource::OnTimerFired() { |
- DCHECK(state_ != STATE_INACTIVE); |
- |
- base::TimeTicks now = this->Now(); |
- last_tick_time_ = now; |
+ DCHECK(active_); |
- if (state_ == STATE_STARTING) { |
- SetTimebaseAndInterval(now, current_parameters_.interval); |
- state_ = STATE_ACTIVE; |
- } |
+ last_tick_time_ = current_parameters_.tick_target; |
- PostNextTickTask(now); |
+ PostNextTickTask(Now()); |
// Fire the tick. |
if (client_) |
@@ -110,9 +91,8 @@ void DelayBasedTimeSource::SetTimebaseAndInterval(base::TimeTicks timebase, |
base::TimeDelta interval) { |
next_parameters_.interval = interval; |
next_parameters_.tick_target = timebase; |
- has_tick_target_ = true; |
- if (state_ != STATE_ACTIVE) { |
+ if (!active_) { |
// If we aren't active, there's no need to reset the timer. |
return; |
} |
@@ -123,6 +103,8 @@ void DelayBasedTimeSource::SetTimebaseAndInterval(base::TimeTicks timebase, |
std::abs((interval - current_parameters_.interval).InSecondsF()); |
double interval_change = interval_delta / interval.InSecondsF(); |
if (interval_change > kIntervalChangeThreshold) { |
+ TRACE_EVENT_INSTANT0("cc", "DelayBasedTimeSource::IntervalChanged", |
+ TRACE_EVENT_SCOPE_THREAD); |
SetActive(false); |
SetActive(true); |
return; |
@@ -140,6 +122,8 @@ void DelayBasedTimeSource::SetTimebaseAndInterval(base::TimeTicks timebase, |
fmod(target_delta, interval.InSecondsF()) / interval.InSecondsF(); |
if (phase_change > kPhaseChangeThreshold && |
phase_change < (1.0 - kPhaseChangeThreshold)) { |
+ TRACE_EVENT_INSTANT0("cc", "DelayBasedTimeSource::PhaseChanged", |
+ TRACE_EVENT_SCOPE_THREAD); |
SetActive(false); |
SetActive(true); |
return; |
@@ -205,26 +189,24 @@ base::TimeTicks DelayBasedTimeSource::Now() const { |
// now=37 tick_target=16.667 new_target=50.000 --> |
// tick(), PostDelayedTask(floor(50.000-37)) --> PostDelayedTask(13) |
base::TimeTicks DelayBasedTimeSource::NextTickTarget(base::TimeTicks now) { |
+ const base::TimeDelta epsilon(base::TimeDelta::FromMicroseconds(1)); |
base::TimeDelta new_interval = next_parameters_.interval; |
int intervals_elapsed = |
- static_cast<int>(floor((now - next_parameters_.tick_target).InSecondsF() / |
- new_interval.InSecondsF())); |
- base::TimeTicks last_effective_tick = |
+ (now - next_parameters_.tick_target + new_interval - epsilon) / |
+ new_interval; |
+ base::TimeTicks new_tick_target = |
next_parameters_.tick_target + new_interval * intervals_elapsed; |
- base::TimeTicks new_tick_target = last_effective_tick + new_interval; |
- DCHECK(now < new_tick_target) |
+ DCHECK(now <= new_tick_target) |
<< "now = " << now.ToInternalValue() |
<< "; new_tick_target = " << new_tick_target.ToInternalValue() |
<< "; new_interval = " << new_interval.InMicroseconds() |
<< "; tick_target = " << next_parameters_.tick_target.ToInternalValue() |
- << "; intervals_elapsed = " << intervals_elapsed |
- << "; last_effective_tick = " << last_effective_tick.ToInternalValue(); |
+ << "; intervals_elapsed = " << intervals_elapsed; |
// Avoid double ticks when: |
// 1) Turning off the timer and turning it right back on. |
// 2) Jittery data is passed to SetTimebaseAndInterval(). |
- if (new_tick_target - last_tick_time_ <= |
- new_interval / static_cast<int>(1.0 / kDoubleTickThreshold)) |
+ if (new_tick_target - last_tick_time_ <= new_interval / kDoubleTickDivisor) |
new_tick_target += new_interval; |
return new_tick_target; |
@@ -234,10 +216,9 @@ void DelayBasedTimeSource::PostNextTickTask(base::TimeTicks now) { |
base::TimeTicks new_tick_target = NextTickTarget(now); |
// Post another task *before* the tick and update state |
- base::TimeDelta delay = new_tick_target - now; |
- DCHECK(delay.InMillisecondsF() <= |
- next_parameters_.interval.InMillisecondsF() * |
- (1.0 + kDoubleTickThreshold)); |
+ base::TimeDelta delay; |
+ if (now <= new_tick_target) |
+ delay = new_tick_target - now; |
task_runner_->PostDelayedTask(FROM_HERE, |
base::Bind(&DelayBasedTimeSource::OnTimerFired, |
weak_factory_.GetWeakPtr()), |