Adds runtimeStatsTotalMetric to collect v8 metrics and bucket them based on UE.

tracing/tracing/metrics/v8/runtime_stats_metric.html

Index: tracing/tracing/metrics/v8/runtime_stats_metric.html
diff --git a/tracing/tracing/metrics/v8/runtime_stats_metric.html b/tracing/tracing/metrics/v8/runtime_stats_metric.html
index 546af9daa3034938d39d42182d0d7bbfc2018849..76d30e52f8baa64e03e61b5a0a8af497a508f915 100644
--- a/tracing/tracing/metrics/v8/runtime_stats_metric.html
+++ b/tracing/tracing/metrics/v8/runtime_stats_metric.html
@@ -81,10 +81,9 @@ tr.exportTo('tr.metrics.v8', function() {
         tr.b.UnitPrefixScale.METRIC.MICRO, tr.b.UnitPrefixScale.METRIC.MILLI);
   }
 
-  function computeRuntimeStats(values, model, endTime) {
-    var slices = [...model.getDescendantEvents()].filter(event =>
-        event instanceof tr.e.v8.V8ThreadSlice &&
-        event.start <= endTime);
+  // TODO(crbug.com/688342): Remove this function when runtimeStatsMetric is
+  // removed.
+  function computeRuntimeStats(histograms, slices) {
 
     var runtimeGroupCollection = new tr.e.v8.RuntimeStatsGroupCollection();
     runtimeGroupCollection.addSlices(slices);
@@ -96,12 +95,12 @@ tr.exportTo('tr.metrics.v8', function() {
         var durationSampleHistogram = createDurationHistogram_(entry.name);
         durationSampleHistogram.addSample(convertMicroToMilli_(entry.time));
         durationSamples.set(entry.name + ':duration', durationSampleHistogram);
-        values.addHistogram(durationSampleHistogram);
+        histograms.addHistogram(durationSampleHistogram);
 
         var countSampleHistogram = createCountHistogram_(entry.name);
         countSampleHistogram.addSample(entry.count);
         countSamples.set(entry.name + ':count', countSampleHistogram);
-        values.addHistogram(countSampleHistogram);
+        histograms.addHistogram(countSampleHistogram);
       }
 
       var durationHistogram = createDurationHistogram_(runtimeGroup.name);
@@ -113,22 +112,87 @@ tr.exportTo('tr.metrics.v8', function() {
         samples: countSamples
       });
 
-      values.addHistogram(durationHistogram);
-      values.addHistogram(countHistogram);
+      histograms.addHistogram(durationHistogram);
+      histograms.addHistogram(countHistogram);
     }
   }
 
-  function runtimeStatsMetric(values, model) {
+  // TODO(crbug.com/688342): Remove this metric and use runtimeStatsTotalMetric
+  // instead when the runtimeStatsTotalMetric is stable.
+  function runtimeStatsMetric(histograms, model) {
     var interactiveTime = computeInteractiveTime_(model);
     var domContentLoadedTime = computeDomContentLoadedTime_(model);
     var endTime = Math.max(interactiveTime, domContentLoadedTime);
-    computeRuntimeStats(values, model, endTime);
+    var slices = [...model.getDescendantEvents()].filter(event =>
+          event instanceof tr.e.v8.V8ThreadSlice && event.start <= endTime);
+    computeRuntimeStats(histograms, slices);
+  }
+
+  function computeRuntimeStatsBucketOnUE(histograms, slices,
+      histogramNamePrefix) {
+    var runtimeGroupCollection = new tr.e.v8.RuntimeStatsGroupCollection();
+    runtimeGroupCollection.addSlices(slices);
+
+    for (var runtimeGroup of runtimeGroupCollection.runtimeGroups) {
+      var histogramName = histogramNamePrefix + '_' + runtimeGroup.name;
+      var durationHistogram = createDurationHistogram_(histogramName);
+      durationHistogram.addSample(convertMicroToMilli_(runtimeGroup.time));
+      histograms.addHistogram(durationHistogram);
+
+      var countHistogram = createCountHistogram_(histogramName);
+      countHistogram.addSample(runtimeGroup.count);
+      histograms.addHistogram(countHistogram);
+    }
+  }
+
+  function runtimeStatsTotalMetric(histograms, model) {
+    var v8ThreadSlices = [...model.getDescendantEvents()].filter(event =>
+          event instanceof tr.e.v8.V8ThreadSlice).sort((e1, e2) =>
+          e1.start - e2.start);
+    var v8SlicesBucketOnUEMap = new Map();
+    // User expectations can sometime overlap. So, certain v8 slices can be
+    // included in more than one expectation. We count such slices in each
+    // of the expectations. This is done so as to minimize the noise due to
+    // the differences in the extent of overlap between the runs.
+    for (var expectation of model.userModel.expectations) {
+      var slices = expectation.range.filterArray(v8ThreadSlices,
+          event => event.start);
+      if (slices.length === 0) continue;
+      // filterArray filters the array that intersects the range inclusively.
+      // Expectations are not inclusive i.e. expectations are like [0, 1),
+      // [1, 2). v8ThreadSlices that start at 1 should be counted only in [1,2)
+      // bucket. Filter out sample at the boundary so that they are not counted
+      // twice.
+      var lastSlice = slices[slices.length - 1];
+      if (!expectation.range.intersectsRangeExclusive(lastSlice.range)) {
+        slices.pop();
+      }
+
+      if (v8SlicesBucketOnUEMap.get(expectation.stageTitle) === undefined) {
+        v8SlicesBucketOnUEMap.set(expectation.stageTitle, slices);
+      } else {
+        var totalSlices = v8SlicesBucketOnUEMap.get(expectation.stageTitle)
+                                               .concat(slices);
+        v8SlicesBucketOnUEMap.set(expectation.stageTitle, totalSlices);
+      }
+    }
+
+    // Add histograms for each UE.
+    for (var [name, slices] of v8SlicesBucketOnUEMap.entries()) {
+      computeRuntimeStatsBucketOnUE(histograms, slices, name);
+    }
+    // Also compute the metric that includes all of the samples. The values
+    // in UE buckets do not add up to the total of all samples, since we
+    // duplicate some of the samples in multiple buckets when the UEs overlap.
+    computeRuntimeStatsBucketOnUE(histograms, v8ThreadSlices, 'Any');

[benjhayden, 2017/02/13 20:40:30]

Fadi and I were looking at results_rcs_gc.html and we noticed that there are
quite a lot of Histograms.
TBMv2 has facilities to help organize Histograms so that users don't have to
deal with all of them at once.
You'll notice the RelatedHistogramBreakdown diagnostics in runtimeStatsMetric.
You probably don't want to use RelatedHistogramBreakdowns here since "breakdown"
implies exclusivity, whereas UEs can overlap here.
However, you can use RelatedHistogramMaps to encode relationships so that the
'Any' Histograms are always visible in results.html at the top level, and the
stage-specific Histograms are only visible as diagnostics.
Do you want to schedule a VC? Or try to add the RelatedHistogramMaps and see if
you have any questions?

   }
 
+  tr.metrics.MetricRegistry.register(runtimeStatsTotalMetric);
   tr.metrics.MetricRegistry.register(runtimeStatsMetric);
 
   return {
     runtimeStatsMetric,
+    runtimeStatsTotalMetric,
   };
 });
 </script>