[WIP] Add WebCore.UseCounter UMA to supercede FeatureObserver

third_party/WebKit/Source/core/frame/UseCounter.cpp

Index: third_party/WebKit/Source/core/frame/UseCounter.cpp
diff --git a/third_party/WebKit/Source/core/frame/UseCounter.cpp b/third_party/WebKit/Source/core/frame/UseCounter.cpp
index f7795822618707a81251a9c02d3516ced8d92409..820dd15885b577e0aeb8d155bfb7d58a3cc21c0a 100644
--- a/third_party/WebKit/Source/core/frame/UseCounter.cpp
+++ b/third_party/WebKit/Source/core/frame/UseCounter.cpp
@@ -43,10 +43,8 @@ static int totalPagesMeasuredCSSSampleId() { return 1; }
 
 int UseCounter::m_muteCount = 0;
 
-int UseCounter::mapCSSPropertyIdToCSSSampleIdForHistogram(int id)
+int UseCounter::mapCSSPropertyIdToCSSSampleIdForHistogram(CSSPropertyID cssPropertyID)
 {
-    CSSPropertyID cssPropertyID = static_cast<CSSPropertyID>(id);
-
     switch (cssPropertyID) {
     // Begin at 2, because 1 is reserved for totalPagesMeasuredCSSSampleId.
     case CSSPropertyColor: return 2;
@@ -580,12 +578,17 @@ int UseCounter::mapCSSPropertyIdToCSSSampleIdForHistogram(int id)
     return 0;
 }
 
-
 static int maximumCSSSampleId() { return 535; }
 
-static EnumerationHistogram& featureObserverHistogram()
+static EnumerationHistogram& useCounterHistogram()
 {
-    DEFINE_STATIC_LOCAL(EnumerationHistogram, histogram, ("WebCore.FeatureObserver", UseCounter::NumberOfFeatures));
+    DEFINE_STATIC_LOCAL(EnumerationHistogram, histogram, ("WebCore.UseCounter", UseCounter::NumberOfFeatures));
+    return histogram;
+}
+
+static EnumerationHistogram& CSSUseCounterHistogram()
+{
+    DEFINE_STATIC_LOCAL(EnumerationHistogram, histogram, ("WebCore.UseCounter.CSSProperties", maximumCSSSampleId()));
     return histogram;
 }
 
@@ -599,60 +602,6 @@ void UseCounter::unmuteForInspector()
     UseCounter::m_muteCount--;
 }
 
-UseCounter::UseCounter()
-{
-    m_CSSFeatureBits.ensureSize(lastUnresolvedCSSProperty + 1);
-    m_CSSFeatureBits.clearAll();
-}
-
-UseCounter::~UseCounter()
-{
-    // We always log PageDestruction so that we have a scale for the rest of the features.
-    featureObserverHistogram().count(PageDestruction);
-
-    updateMeasurements();
-}
-
-void UseCounter::CountBits::updateMeasurements()
-{
-    EnumerationHistogram& featureHistogram = featureObserverHistogram();
-    for (unsigned i = 0; i < NumberOfFeatures; ++i) {
-        if (m_bits.quickGet(i))
-            featureHistogram.count(i);
-    }
-    // Clearing count bits is timing sensitive.
-    m_bits.clearAll();
-}
-
-void UseCounter::updateMeasurements()
-{
-    featureObserverHistogram().count(PageVisits);
-    m_countBits.updateMeasurements();
-
-    // FIXME: Sometimes this function is called more than once per page. The following
-    //        bool guards against incrementing the page count when there are no CSS
-    //        bits set. https://crbug.com/236262.
-    DEFINE_STATIC_LOCAL(EnumerationHistogram, cssPropertiesHistogram, ("WebCore.FeatureObserver.CSSProperties", maximumCSSSampleId()));
-    bool needsPagesMeasuredUpdate = false;
-    for (int i = firstCSSProperty; i <= lastUnresolvedCSSProperty; ++i) {
-        if (m_CSSFeatureBits.quickGet(i)) {
-            int cssSampleId = mapCSSPropertyIdToCSSSampleIdForHistogram(i);
-            cssPropertiesHistogram.count(cssSampleId);
-            needsPagesMeasuredUpdate = true;
-        }
-    }
-
-    if (needsPagesMeasuredUpdate)
-        cssPropertiesHistogram.count(totalPagesMeasuredCSSSampleId());
-
-    m_CSSFeatureBits.clearAll();
-}
-
-void UseCounter::didCommitLoad()
-{
-    updateMeasurements();
-}
-
 void UseCounter::count(const Frame* frame, Feature feature)
 {
     if (!frame)
@@ -683,9 +632,29 @@ bool UseCounter::isCounted(Document& document, Feature feature)
 
 bool UseCounter::isCounted(CSSPropertyID unresolvedProperty)
 {
-    return m_CSSFeatureBits.quickGet(unresolvedProperty);
+    return m_CSSFeaturesReported.quickGet(unresolvedProperty);
 }
 
+void UseCounter::didCommitLoad()
+{
+    m_featuresReported.clearAll();
+    useCounterHistogram().count(PageVisits);

[dtapuska, 2016/05/31 01:10:51]

Are you explicitly counting here even though muted count is >0 ? I expect so.
But it could probably use a comment. 

+
+    m_CSSFeaturesReported.clearAll();
+    CSSUseCounterHistogram().count(totalPagesMeasuredCSSSampleId());
+}
+
+void UseCounter::recordMeasurement(Feature feature)
+{
+    if (UseCounter::m_muteCount)
+        return;
+
+    if (!m_featuresReported.quickGet(feature)) {
+        m_featuresReported.quickSet(feature);
+        useCounterHistogram().count(feature);
+    }
+    m_legacyCounter.recordMeasurement(feature);
+}
 
 bool UseCounter::isCounted(Document& document, const String& string)
 {
@@ -750,7 +719,11 @@ void UseCounter::count(CSSParserMode cssParserMode, CSSPropertyID feature)
     if (!isUseCounterEnabledForMode(cssParserMode))
         return;
 
-    m_CSSFeatureBits.quickSet(feature);
+    if (!m_CSSFeaturesReported.quickGet(feature)) {
+        m_CSSFeaturesReported.quickSet(feature);
+        CSSUseCounterHistogram().count(mapCSSPropertyIdToCSSSampleIdForHistogram(feature));
+    }
+    m_legacyCounter.countCSS(feature);
 }
 
 void UseCounter::count(Feature feature)
@@ -782,4 +755,83 @@ UseCounter* UseCounter::getFrom(const StyleSheetContents* sheetContents)
     return 0;
 }
 
+/*
+ *
+ * LEGACY metrics support - WebCore.FeatureObserver is to be superceded by WebCore.UseCounter
+ *
+ */
+
+static EnumerationHistogram& featureObserverHistogram()
+{
+    DEFINE_STATIC_LOCAL(EnumerationHistogram, histogram, ("WebCore.FeatureObserver", UseCounter::NumberOfFeatures));
+    return histogram;
+}
+
+UseCounter::LegacyCounter::LegacyCounter()
+    : m_countBits(NumberOfFeatures)
+    , m_CSSFeatureBits(lastUnresolvedCSSProperty + 1)
+{
+}
+
+UseCounter::LegacyCounter::~LegacyCounter()
+{
+    // We always log PageDestruction so that we have a scale for the rest of the features.
+    featureObserverHistogram().count(PageDestruction);
+    updateMeasurements();
+}
+
+void UseCounter::LegacyCounter::recordMeasurement(Feature feature)
+{
+    DCHECK(feature != PageDestruction); // PageDestruction is reserved as a scaling factor.
+    DCHECK(feature < NumberOfFeatures);
+
+    m_countBits.quickSet(feature);
+}
+
+void UseCounter::LegacyCounter::updateMeasurements()
+{
+    EnumerationHistogram& featureHistogram = featureObserverHistogram();
+    featureHistogram.count(PageVisits);
+    for (unsigned i = 0; i < NumberOfFeatures; ++i) {
+        if (m_countBits.quickGet(i))
+            featureHistogram.count(i);
+    }
+    // Clearing count bits is timing sensitive.
+    m_countBits.clearAll();
+
+    // FIXME: Sometimes this function is called more than once per page. The following
+    //        bool guards against incrementing the page count when there are no CSS
+    //        bits set. https://crbug.com/236262.
+    DEFINE_STATIC_LOCAL(EnumerationHistogram, cssPropertiesHistogram, ("WebCore.FeatureObserver.CSSProperties", maximumCSSSampleId()));
+    bool needsPagesMeasuredUpdate = false;
+    for (int i = firstCSSProperty; i <= lastUnresolvedCSSProperty; ++i) {
+        if (m_CSSFeatureBits.quickGet(i)) {
+            int cssSampleId = mapCSSPropertyIdToCSSSampleIdForHistogram(static_cast<CSSPropertyID>(i));
+            cssPropertiesHistogram.count(cssSampleId);
+            needsPagesMeasuredUpdate = true;
+        }
+    }
+
+    if (needsPagesMeasuredUpdate)
+        cssPropertiesHistogram.count(totalPagesMeasuredCSSSampleId());
+
+    m_CSSFeatureBits.clearAll();
+}
+
+bool UseCounter::LegacyCounter::hasRecordedMeasurement(Feature feature) const
+{
+    if (UseCounter::m_muteCount)
+        return false;
+    DCHECK(feature != PageDestruction); // PageDestruction is reserved as a scaling factor.
+    DCHECK(feature < NumberOfFeatures);
+
+    return m_countBits.quickGet(feature);
+}
+
+void UseCounter::LegacyCounter::countCSS(CSSPropertyID feature)
+{
+    m_CSSFeatureBits.quickSet(feature);
+}
+
+
 } // namespace blink