cc: Improve frame/commit accounting

cc/frame_rate_counter.cc

 // Copyright 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "config.h"
 
 #include "CCFrameRateCounter.h"
 
 #include <cmath>
 
 #include "CCProxy.h"
 #include <public/Platform.h>
 
 namespace cc {
 
-const double CCFrameRateCounter::kFrameTooFast = 1.0 / 70.0; // measured in seconds
-const double CCFrameRateCounter::kFrameTooSlow = 1.0 / 12.0;
-const double CCFrameRateCounter::kDroppedFrameTime = 1.0 / 50.0;
-
 // safeMod works on -1, returning m-1 in that case.
 static inline int safeMod(int number, int modulus)
 {
     return (number + modulus) % modulus;
 }
 
 // static
 scoped_ptr<CCFrameRateCounter> CCFrameRateCounter::create() {
   return make_scoped_ptr(new CCFrameRateCounter());
 }
 
+void CCFrameRateCounter::setTimebaseAndInterval(base::TimeTicks timebase, base::TimeDelta interval)
+{
+    if (interval != m_interval) {
+        base::TimeTicks now = base::TimeTicks::Now();
+        m_vsyncCount = currentVsyncCount(now);
+        m_intervalChangedTime = now;
+        m_interval = interval;
+    }
+
+    m_frameTooFastSeconds = 0.8 * interval.InSecondsF();
+    m_frameTooSlowSeconds = 1.0 / 12.0;
+}
+
 inline base::TimeDelta CCFrameRateCounter::frameInterval(int frameNumber) const
 {
     return m_timeStampHistory[frameIndex(frameNumber)] -
         m_timeStampHistory[frameIndex(frameNumber - 1)];
 }
 
 inline int CCFrameRateCounter::frameIndex(int frameNumber) const
 {
     return safeMod(frameNumber, kTimeStampHistorySize);
 }
 
 CCFrameRateCounter::CCFrameRateCounter()
-    : m_currentFrameNumber(1)
-    , m_droppedFrameCount(0)
+    : m_frameTooFastSeconds(0)
+    , m_frameTooSlowSeconds(0)
+    , m_vsyncCount(0)
+    , m_currentFrameNumber(1)
 {
     m_timeStampHistory[0] = base::TimeTicks::Now();
     m_timeStampHistory[1] = m_timeStampHistory[0];
     for (int i = 2; i < kTimeStampHistorySize; i++)
         m_timeStampHistory[i] = base::TimeTicks();
 }
 
 void CCFrameRateCounter::markBeginningOfFrame(base::TimeTicks timestamp)
 {
     m_timeStampHistory[frameIndex(m_currentFrameNumber)] = timestamp;
     base::TimeDelta frameIntervalSeconds = frameInterval(m_currentFrameNumber);
 
     if (CCProxy::hasImplThread() && m_currentFrameNumber > 0) {
         double drawDelayMs = frameIntervalSeconds.InMillisecondsF();
         WebKit::Platform::current()->histogramCustomCounts("Renderer4.CompositorThreadImplDrawDelay", static_cast<int>(drawDelayMs), 1, 120, 60);
     }
 
-    if (!isBadFrameInterval(frameIntervalSeconds) &&
-        frameIntervalSeconds.InSecondsF() > kDroppedFrameTime)
-        ++m_droppedFrameCount;
 }
 
 void CCFrameRateCounter::markEndOfFrame()
 {
     m_currentFrameNumber += 1;
 }
 
 bool CCFrameRateCounter::isBadFrameInterval(base::TimeDelta intervalBetweenConsecutiveFrames) const
 {
+    ASSERT(m_interval != base::TimeDelta());
     bool schedulerAllowsDoubleFrames = !CCProxy::hasImplThread();
-    bool intervalTooFast = schedulerAllowsDoubleFrames && intervalBetweenConsecutiveFrames.InSecondsF() < kFrameTooFast;
-    bool intervalTooSlow = intervalBetweenConsecutiveFrames.InSecondsF() > kFrameTooSlow;
+    bool intervalTooFast = schedulerAllowsDoubleFrames && intervalBetweenConsecutiveFrames.InSecondsF() < m_frameTooFastSeconds;
+    bool intervalTooSlow = intervalBetweenConsecutiveFrames.InSecondsF() > m_frameTooSlowSeconds;
     return intervalTooFast || intervalTooSlow;
 }
 
 bool CCFrameRateCounter::isBadFrame(int frameNumber) const
 {
     return isBadFrameInterval(frameInterval(frameNumber));
 }
 
+int64_t CCFrameRateCounter::currentVsyncCount(base::TimeTicks now) const
+{
+    int64_t vsyncCount = m_vsyncCount;
+    if (m_interval != base::TimeDelta())
+        vsyncCount += (now - m_intervalChangedTime + (m_interval/2)) / m_interval;
+    return vsyncCount;
+}
+
 void CCFrameRateCounter::getAverageFPSAndStandardDeviation(double& averageFPS, double& standardDeviation) const
 {
     int frame = m_currentFrameNumber - 1;
     averageFPS = 0;
     int averageFPSCount = 0;
     double fpsVarianceNumerator = 0;
 
     // Walk backwards through the samples looking for a run of good frame
     // timings from which to compute the mean and standard deviation.
     //
@@ skipping 29 matching lines @@
     standardDeviation = sqrt(fpsVarianceNumerator / averageFPSCount);
 }
 
 base::TimeTicks CCFrameRateCounter::timeStampOfRecentFrame(int n)
 {
     ASSERT(n >= 0 && n < kTimeStampHistorySize);
     int desiredIndex = (frameIndex(m_currentFrameNumber) + n) % kTimeStampHistorySize;
     return m_timeStampHistory[desiredIndex];
 }
 
+void CCFrameRateCounter::renderingStats(CCRenderingStats* stats) const
+{
+    ASSERT(m_interval != base::TimeDelta());
+
+    base::TimeTicks now = base::TimeTicks::Now();
+    stats->vsyncCount = currentVsyncCount(now);
+    stats->rendererFrameCount = m_currentFrameNumber - 1;
+    stats->droppedFrameCount = stats->vsyncCount - stats->rendererFrameCount;
+}
+
 }  // namespace cc