1 files changed, 91 insertions, 0 deletions
diff --git a/tools/performance/PerfStats.h b/tools/performance/PerfStats.h
new file mode 100644
index 0000000000..68ebfc3a57
--- /dev/null
+++ b/tools/performance/PerfStats.h
@@ -0,0 +1,91 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef PerfStats_h
+#define PerfStats_h
+
+#include "mozilla/TimeStamp.h"
+#include "mozilla/StaticMutex.h"
+#include "mozilla/StaticPtr.h"
+#include "mozilla/MozPromise.h"
+#include <memory>
+#include <string>
+#include <limits>
+
+namespace mozilla {
+
+class PerfStats {
+ public:
+  typedef MozPromise<nsCString, bool, true> PerfStatsPromise;
+
+  enum class Metric : uint32_t {
+    DisplayListBuilding = 0,
+    Rasterizing,
+    LayerBuilding,
+    LayerTransactions,
+    Compositing,
+    Reflowing,
+    Styling,
+    Max
+  };
+
+  // MetricMask is a bitmask based on 'Metric', i.e. Metric::LayerBuilding (2)
+  // is synonymous to 1 << 2 in MetricMask.
+  using MetricMask = uint64_t;
+
+  static void RecordMeasurementStart(Metric aMetric) {
+    if (!(sCollectionMask & (1 << static_cast<uint64_t>(aMetric)))) {
+      return;
+    }
+    RecordMeasurementStartInternal(aMetric);
+  }
+
+  static void RecordMeasurementEnd(Metric aMetric) {
+    if (!(sCollectionMask & (1 << static_cast<uint64_t>(aMetric)))) {
+      return;
+    }
+    RecordMeasurementEndInternal(aMetric);
+  }
+
+  template <Metric N>
+  class AutoMetricRecording {
+   public:
+    AutoMetricRecording() { PerfStats::RecordMeasurementStart(N); }
+    ~AutoMetricRecording() { PerfStats::RecordMeasurementEnd(N); }
+  };
+
+  static void SetCollectionMask(MetricMask aMask);
+
+  static RefPtr<PerfStatsPromise> CollectPerfStatsJSON() {
+    return GetSingleton()->CollectPerfStatsJSONInternal();
+  }
+
+  static nsCString CollectLocalPerfStatsJSON() {
+    return GetSingleton()->CollectLocalPerfStatsJSONInternal();
+  }
+
+ private:
+  static PerfStats* GetSingleton();
+  static void RecordMeasurementStartInternal(Metric aMetric);
+  static void RecordMeasurementEndInternal(Metric aMetric);
+
+  RefPtr<PerfStatsPromise> CollectPerfStatsJSONInternal();
+  nsCString CollectLocalPerfStatsJSONInternal();
+
+  static MetricMask sCollectionMask;
+  static StaticMutex sMutex;
+  static StaticAutoPtr<PerfStats> sSingleton;
+  TimeStamp mRecordedStarts[static_cast<size_t>(Metric::Max)];
+  double mRecordedTimes[static_cast<size_t>(Metric::Max)];
+};
+
+static_assert(1 << (static_cast<uint64_t>(PerfStats::Metric::Max) - 1) <=
+                  std::numeric_limits<PerfStats::MetricMask>::max(),
+              "More metrics than can fit into sCollectionMask bitmask");
+
+}  // namespace mozilla
+
+#endif  // PerfStats_h