cc: Improve frame/commit accounting

cc/frame_rate_counter.cc

Index: cc/frame_rate_counter.cc
diff --git a/cc/frame_rate_counter.cc b/cc/frame_rate_counter.cc
index a02486bd0ec026e84e0d85f985f0d12ed7f3b15d..6bff0dd112b29fff7ba9f9a1b65775addb31f1e4 100644
--- a/cc/frame_rate_counter.cc
+++ b/cc/frame_rate_counter.cc
@@ -13,10 +13,6 @@
 
 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)
 {
@@ -28,6 +24,20 @@ 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();
+        if (m_interval != base::TimeDelta())
+            m_vsyncCount += (now - m_intervalChangedTime + (m_interval/2)) / m_interval;
+        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)] -
@@ -40,9 +50,12 @@ inline int CCFrameRateCounter::frameIndex(int frameNumber) const
 }
 
 CCFrameRateCounter::CCFrameRateCounter()
-    : m_currentFrameNumber(1)
-    , m_droppedFrameCount(0)
+    : m_vsyncCount(0)
+    , m_currentFrameNumber(1)
 {
+    setTimebaseAndInterval(
+        base::TimeTicks(), base::TimeDelta::FromMicroseconds(base::Time::kMicrosecondsPerSecond / 60));

[reveman, 2012/10/17 19:32:30]

this assumes that 60FPS is the initial frame rate, right? can you instead pass
timebase and interval to the constructor so we don't have to worry about keeping
this in sync with thread_proxy.cc?

or if you know that setTimebaseAndInterval will always be called before these
values are used you can just initialize them to some unique values and ASSERT if
that condition is not met.

[brianderson, 2012/10/17 22:34:48]

Done.

+
     m_timeStampHistory[0] = base::TimeTicks::Now();
     m_timeStampHistory[1] = m_timeStampHistory[0];
     for (int i = 2; i < kTimeStampHistorySize; i++)
@@ -59,9 +72,6 @@ void CCFrameRateCounter::markBeginningOfFrame(base::TimeTicks timestamp)
         WebKit::Platform::current()->histogramCustomCounts("Renderer4.CompositorThreadImplDrawDelay", static_cast<int>(drawDelayMs), 1, 120, 60);
     }
 
-    if (!isBadFrameInterval(frameIntervalSeconds) &&
-        frameIntervalSeconds.InSecondsF() > kDroppedFrameTime)
-        ++m_droppedFrameCount;
 }
 
 void CCFrameRateCounter::markEndOfFrame()
@@ -72,8 +82,8 @@ void CCFrameRateCounter::markEndOfFrame()
 bool CCFrameRateCounter::isBadFrameInterval(base::TimeDelta intervalBetweenConsecutiveFrames) const
 {
     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;
 }
 
@@ -131,5 +141,17 @@ base::TimeTicks CCFrameRateCounter::timeStampOfRecentFrame(int n)
     return m_timeStampHistory[desiredIndex];
 }
 
+void CCFrameRateCounter::renderingStats(CCRenderingStats* stats) const
+{
+    base::TimeTicks now = base::TimeTicks::Now();
+
+    stats->vsyncCount = m_vsyncCount;
+    if (m_interval != base::TimeDelta())
+        stats->vsyncCount += (now - m_intervalChangedTime + (m_interval/2)) / m_interval;

[reveman, 2012/10/17 19:32:30]

this same logic is used in setTimebaseAndInterval. can you move this into
utility function rather than duplicating it.

[brianderson, 2012/10/17 22:34:48]

Done.

+
+    stats->rendererFrameCount = m_currentFrameNumber - 1;
+    stats->droppedFrameCount = stats->vsyncCount - (m_currentFrameNumber - 1);

[reveman, 2012/10/17 19:32:30]

Looks like droppedFrameCount is unnecessary. Should we remove this field and
have our test code compute it instead?

[brianderson, 2012/10/17 22:34:48]

I think it would be nice to keep it as a separate field in case we ever want to
calculate it in a different way.

+}
+
 }  // namespace cc