Trace-based benchmarking via a mojo app.

apps/benchmark/measurements.cc

Index: apps/benchmark/measurements.cc
diff --git a/apps/benchmark/measurements.cc b/apps/benchmark/measurements.cc
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+++ b/apps/benchmark/measurements.cc
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+// Copyright 2015 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 "apps/benchmark/measurements.h"
+
+namespace benchmark {
+
+bool Match(const Event& event, const EventSpec& spec) {
+  return event.name == spec.name && event.category == spec.category;
+}
+
+Measurements::Measurements(std::vector<Event> events, EventSpec reference_spec)
+    : events_(events), reference_spec_(reference_spec) {}
+
+Measurements::~Measurements() {}
+
+double Measurements::Measure(const Measurement& measurement) {
+  switch (measurement.type) {
+    case Measurement::TIME_UNTIL:
+      return TimeUntil(measurement.target_event);
+    case Measurement::AVG_DURATION:
+      return AvgDuration(measurement.target_event);
+    default:
+      return -1.0;
+  }
+}
+
+double Measurements::TimeUntil(const EventSpec& event_spec) {
+  base::TimeTicks target = FindEarliest(event_spec);
+  base::TimeTicks reference = FindEarliest(reference_spec_);
+  return (target - reference).InMillisecondsF();
+}
+
+double Measurements::AvgDuration(const EventSpec& event_spec) {
+  double sum = 0.0;
+  int count = 0;
+  for (const Event& event : events_) {
+    if (event.category == "__metadata")
+      continue;
+
+    if (!Match(event, event_spec))
+      continue;
+
+    sum += event.duration.InMillisecondsF();
+    count += 1;
+  }
+
+  if (!count)
+    return -1.0;
+  return sum / count;
+}
+
+base::TimeTicks Measurements::FindEarliest(const EventSpec& spec) {
+  base::TimeTicks earliest;
+  bool found = false;
+  for (const Event& event : events_) {
+    if (event.category == "__metadata")
+      continue;
+
+    if (!Match(event, spec))
+      continue;
+
+    if (found) {
+      earliest = std::min(earliest, event.timestamp);
+    } else {
+      earliest = event.timestamp;
+      found = true;
+    }
+  }
+  return earliest;
+}
+
+}  // namespace benchmark