| Index: cc/CCDelayBasedTimeSource.cpp
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| diff --git a/cc/CCDelayBasedTimeSource.cpp b/cc/CCDelayBasedTimeSource.cpp
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| deleted file mode 100644
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| index 6e34a074a2e824d4eb892fa7f88832083a654009..0000000000000000000000000000000000000000
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| --- a/cc/CCDelayBasedTimeSource.cpp
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| +++ /dev/null
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| @@ -1,232 +0,0 @@
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| -// Copyright 2011 The Chromium Authors. All rights reserved.
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| -// Use of this source code is governed by a BSD-style license that can be
|
| -// found in the LICENSE file.
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| -
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| -#include "config.h"
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| -
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| -#include "CCDelayBasedTimeSource.h"
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| -
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| -#include "TraceEvent.h"
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| -#include <algorithm>
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| -#include <wtf/CurrentTime.h>
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| -#include <wtf/MathExtras.h>
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| -
|
| -namespace cc {
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| -
|
| -namespace {
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| -
|
| -// doubleTickThreshold prevents ticks from running within the specified fraction of an interval.
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| -// This helps account for jitter in the timebase as well as quick timer reactivation.
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| -const double doubleTickThreshold = 0.25;
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| -
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| -// intervalChangeThreshold is the fraction of the interval that will trigger an immediate interval change.
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| -// phaseChangeThreshold is the fraction of the interval that will trigger an immediate phase change.
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| -// If the changes are within the thresholds, the change will take place on the next tick.
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| -// If either change is outside the thresholds, the next tick will be canceled and reissued immediately.
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| -const double intervalChangeThreshold = 0.25;
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| -const double phaseChangeThreshold = 0.25;
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| -
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| -}
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| -
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| -
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| -PassRefPtr<CCDelayBasedTimeSource> CCDelayBasedTimeSource::create(base::TimeDelta interval, CCThread* thread)
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| -{
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| - return adoptRef(new CCDelayBasedTimeSource(interval, thread));
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| -}
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| -
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| -CCDelayBasedTimeSource::CCDelayBasedTimeSource(base::TimeDelta interval, CCThread* thread)
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| - : m_client(0)
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| - , m_hasTickTarget(false)
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| - , m_currentParameters(interval, base::TimeTicks())
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| - , m_nextParameters(interval, base::TimeTicks())
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| - , m_state(STATE_INACTIVE)
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| - , m_timer(thread, this)
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| -{
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| - turnOffVerifier();
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| -}
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| -
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| -CCDelayBasedTimeSource::~CCDelayBasedTimeSource()
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| -{
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| -}
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| -
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| -void CCDelayBasedTimeSource::setActive(bool active)
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| -{
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| - TRACE_EVENT1("cc", "CCDelayBasedTimeSource::setActive", "active", active);
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| - if (!active) {
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| - m_state = STATE_INACTIVE;
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| - m_timer.stop();
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| - return;
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| - }
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| -
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| - if (m_state == STATE_STARTING || m_state == STATE_ACTIVE)
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| - return;
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| -
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| - if (!m_hasTickTarget) {
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| - // Becoming active the first time is deferred: we post a 0-delay task. When
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| - // it runs, we use that to establish the timebase, become truly active, and
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| - // fire the first tick.
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| - m_state = STATE_STARTING;
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| - m_timer.startOneShot(0);
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| - return;
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| - }
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| -
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| - m_state = STATE_ACTIVE;
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| -
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| - postNextTickTask(now());
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| -}
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| -
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| -bool CCDelayBasedTimeSource::active() const
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| -{
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| - return m_state != STATE_INACTIVE;
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| -}
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| -
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| -base::TimeTicks CCDelayBasedTimeSource::lastTickTime()
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| -{
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| - return m_lastTickTime;
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| -}
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| -
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| -base::TimeTicks CCDelayBasedTimeSource::nextTickTime()
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| -{
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| - return active() ? m_currentParameters.tickTarget : base::TimeTicks();
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| -}
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| -
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| -void CCDelayBasedTimeSource::onTimerFired()
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| -{
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| - ASSERT(m_state != STATE_INACTIVE);
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| -
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| - base::TimeTicks now = this->now();
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| - m_lastTickTime = now;
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| -
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| - if (m_state == STATE_STARTING) {
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| - setTimebaseAndInterval(now, m_currentParameters.interval);
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| - m_state = STATE_ACTIVE;
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| - }
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| -
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| - postNextTickTask(now);
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| -
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| - // Fire the tick
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| - if (m_client)
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| - m_client->onTimerTick();
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| -}
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| -
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| -void CCDelayBasedTimeSource::setClient(CCTimeSourceClient* client)
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| -{
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| - m_client = client;
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| -}
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| -
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| -void CCDelayBasedTimeSource::setTimebaseAndInterval(base::TimeTicks timebase, base::TimeDelta interval)
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| -{
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| - m_nextParameters.interval = interval;
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| - m_nextParameters.tickTarget = timebase;
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| - m_hasTickTarget = true;
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| -
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| - if (m_state != STATE_ACTIVE) {
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| - // If we aren't active, there's no need to reset the timer.
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| - return;
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| - }
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| -
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| - // If the change in interval is larger than the change threshold,
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| - // request an immediate reset.
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| - double intervalDelta = std::abs((interval - m_currentParameters.interval).InSecondsF());
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| - double intervalChange = intervalDelta / interval.InSecondsF();
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| - if (intervalChange > intervalChangeThreshold) {
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| - setActive(false);
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| - setActive(true);
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| - return;
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| - }
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| -
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| - // If the change in phase is greater than the change threshold in either
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| - // direction, request an immediate reset. This logic might result in a false
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| - // negative if there is a simultaneous small change in the interval and the
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| - // fmod just happens to return something near zero. Assuming the timebase
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| - // is very recent though, which it should be, we'll still be ok because the
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| - // old clock and new clock just happen to line up.
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| - double targetDelta = std::abs((timebase - m_currentParameters.tickTarget).InSecondsF());
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| - double phaseChange = fmod(targetDelta, interval.InSecondsF()) / interval.InSecondsF();
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| - if (phaseChange > phaseChangeThreshold && phaseChange < (1.0 - phaseChangeThreshold)) {
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| - setActive(false);
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| - setActive(true);
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| - return;
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| - }
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| -}
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| -
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| -base::TimeTicks CCDelayBasedTimeSource::now() const
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| -{
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| - return base::TimeTicks::Now();
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| -}
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| -
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| -// This code tries to achieve an average tick rate as close to m_interval as possible.
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| -// To do this, it has to deal with a few basic issues:
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| -// 1. postDelayedTask can delay only at a millisecond granularity. So, 16.666 has to
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| -// posted as 16 or 17.
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| -// 2. A delayed task may come back a bit late (a few ms), or really late (frames later)
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| -//
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| -// The basic idea with this scheduler here is to keep track of where we *want* to run in
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| -// m_tickTarget. We update this with the exact interval.
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| -//
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| -// Then, when we post our task, we take the floor of (m_tickTarget and now()). If we
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| -// started at now=0, and 60FPs (all times in milliseconds):
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| -// now=0 target=16.667 postDelayedTask(16)
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| -//
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| -// When our callback runs, we figure out how far off we were from that goal. Because of the flooring
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| -// operation, and assuming our timer runs exactly when it should, this yields:
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| -// now=16 target=16.667
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| -//
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| -// Since we can't post a 0.667 ms task to get to now=16, we just treat this as a tick. Then,
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| -// we update target to be 33.333. We now post another task based on the difference between our target
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| -// and now:
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| -// now=16 tickTarget=16.667 newTarget=33.333 --> postDelayedTask(floor(33.333 - 16)) --> postDelayedTask(17)
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| -//
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| -// Over time, with no late tasks, this leads to us posting tasks like this:
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| -// now=0 tickTarget=0 newTarget=16.667 --> tick(), postDelayedTask(16)
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| -// now=16 tickTarget=16.667 newTarget=33.333 --> tick(), postDelayedTask(17)
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| -// now=33 tickTarget=33.333 newTarget=50.000 --> tick(), postDelayedTask(17)
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| -// now=50 tickTarget=50.000 newTarget=66.667 --> tick(), postDelayedTask(16)
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| -//
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| -// We treat delays in tasks differently depending on the amount of delay we encounter. Suppose we
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| -// posted a task with a target=16.667:
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| -// Case 1: late but not unrecoverably-so
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| -// now=18 tickTarget=16.667
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| -//
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| -// Case 2: so late we obviously missed the tick
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| -// now=25.0 tickTarget=16.667
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| -//
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| -// We treat the first case as a tick anyway, and assume the delay was
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| -// unusual. Thus, we compute the newTarget based on the old timebase:
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| -// now=18 tickTarget=16.667 newTarget=33.333 --> tick(), postDelayedTask(floor(33.333-18)) --> postDelayedTask(15)
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| -// This brings us back to 18+15 = 33, which was where we would have been if the task hadn't been late.
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| -//
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| -// For the really late delay, we we move to the next logical tick. The timebase is not reset.
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| -// now=37 tickTarget=16.667 newTarget=50.000 --> tick(), postDelayedTask(floor(50.000-37)) --> postDelayedTask(13)
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| -base::TimeTicks CCDelayBasedTimeSource::nextTickTarget(base::TimeTicks now)
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| -{
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| - base::TimeDelta newInterval = m_nextParameters.interval;
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| - int intervalsElapsed = static_cast<int>(floor((now - m_nextParameters.tickTarget).InSecondsF() / newInterval.InSecondsF()));
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| - base::TimeTicks lastEffectiveTick = m_nextParameters.tickTarget + newInterval * intervalsElapsed;
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| - base::TimeTicks newTickTarget = lastEffectiveTick + newInterval;
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| - ASSERT(newTickTarget > now);
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| -
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| - // Avoid double ticks when:
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| - // 1) Turning off the timer and turning it right back on.
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| - // 2) Jittery data is passed to setTimebaseAndInterval().
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| - if (newTickTarget - m_lastTickTime <= newInterval / static_cast<int>(1.0 / doubleTickThreshold))
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| - newTickTarget += newInterval;
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| -
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| - return newTickTarget;
|
| -}
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| -
|
| -void CCDelayBasedTimeSource::postNextTickTask(base::TimeTicks now)
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| -{
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| - base::TimeTicks newTickTarget = nextTickTarget(now);
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| -
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| - // Post another task *before* the tick and update state
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| - base::TimeDelta delay = newTickTarget - now;
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| - ASSERT(delay.InMillisecondsF() <=
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| - m_nextParameters.interval.InMillisecondsF() * (1.0 + doubleTickThreshold));
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| - m_timer.startOneShot(delay.InSecondsF());
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| -
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| - m_nextParameters.tickTarget = newTickTarget;
|
| - m_currentParameters = m_nextParameters;
|
| -}
|
| -
|
| -}
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|
|