Bug 1313420 - Implement Performance.timeOrigin - part 1, r=bz

dom/performance/Performance.cpp

@@ -13,6 +13,7 @@
 #include "PerformanceMeasure.h"
 #include "PerformanceObserver.h"
 #include "PerformanceResourceTiming.h"
+#include "PerformanceService.h"
 #include "PerformanceWorker.h"
 #include "mozilla/ErrorResult.h"
 #include "mozilla/dom/PerformanceBinding.h"
@@ -141,6 +142,17 @@ Performance::Performance(nsPIDOMWindowInner* aWindow)
 Performance::~Performance()
 {}
 
+DOMHighResTimeStamp
+Performance::TimeOrigin()
+{
+  if (!mPerformanceService) {
+    mPerformanceService = PerformanceService::GetOrCreate();
+  }
+
+  MOZ_ASSERT(mPerformanceService);
+  return mPerformanceService->TimeOrigin(CreationTimeStamp());
+}
+
 JSObject*
 Performance::WrapObject(JSContext* aCx, JS::Handle<JSObject*> aGivenProto)
 {

dom/performance/Performance.h

@@ -24,6 +24,7 @@ namespace dom {
 class PerformanceEntry;
 class PerformanceNavigation;
 class PerformanceObserver;
+class PerformanceService;
 class PerformanceTiming;
 
 namespace workers {
@@ -70,6 +71,8 @@ public:
 
   virtual DOMHighResTimeStamp Now() const = 0;
 
+  DOMHighResTimeStamp TimeOrigin();
+
   void Mark(const nsAString& aName, ErrorResult& aRv);
 
   void ClearMarks(const Optional<nsAString>& aName);
@@ -154,6 +157,8 @@ private:
   uint64_t mResourceTimingBufferSize;
   static const uint64_t kDefaultResourceTimingBufferSize = 150;
   bool mPendingNotificationObserversTask;
+
+  RefPtr<PerformanceService> mPerformanceService;
 };
 
 } // namespace dom

dom/performance/PerformanceService.cpp

@@ -0,0 +1,46 @@
+/* -*- 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/. */
+
+#include "PerformanceService.h"
+
+#include "mozilla/ClearOnShutdown.h"
+#include "mozilla/StaticMutex.h"
+#include "mozilla/StaticPtr.h"
+
+namespace mozilla {
+namespace dom {
+
+static StaticRefPtr<PerformanceService> gPerformanceService;
+static StaticMutex gPerformanceServiceMutex;
+
+/* static */ PerformanceService*
+PerformanceService::GetOrCreate()
+{
+  StaticMutexAutoLock al(gPerformanceServiceMutex);
+
+  if (!gPerformanceService) {
+    gPerformanceService = new PerformanceService();
+    ClearOnShutdown(&gPerformanceService);
+  }
+
+  return gPerformanceService;
+}
+
+DOMHighResTimeStamp
+PerformanceService::TimeOrigin(const TimeStamp& aCreationTimeStamp) const
+{
+  return (aCreationTimeStamp - mCreationTimeStamp).ToMilliseconds() +
+           (mCreationEpochTime / PR_USEC_PER_MSEC);
+}
+
+PerformanceService::PerformanceService()
+{
+  mCreationTimeStamp = TimeStamp::Now();
+  mCreationEpochTime = PR_Now();
+}
+
+} // dom namespace
+} // mozilla namespace

dom/performance/PerformanceService.h

@@ -0,0 +1,48 @@
+/* -*- 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 dom_performance_PerformanceService_h
+#define dom_performance_PerformanceService_h
+
+#include "mozilla/TimeStamp.h"
+#include "nsCOMPtr.h"
+#include "nsDOMNavigationTiming.h"
+
+namespace mozilla {
+namespace dom {
+
+// This class is thread-safe.
+
+// We use this singleton for having the correct value of performance.timeOrigin.
+// This value must be calculated on top of the pair:
+// - mCreationTimeStamp (monotonic clock)
+// - mCreationEpochTime (unix epoch time)
+// These 2 values must be taken "at the same time" in order to be used
+// correctly.
+
+class PerformanceService
+{
+public:
+  NS_INLINE_DECL_THREADSAFE_REFCOUNTING(PerformanceService)
+
+  static PerformanceService*
+  GetOrCreate();
+
+  DOMHighResTimeStamp
+  TimeOrigin(const TimeStamp& aCreationTimeStamp) const;
+
+private:
+  PerformanceService();
+  ~PerformanceService() = default;
+
+  TimeStamp mCreationTimeStamp;
+  PRTime mCreationEpochTime;
+};
+
+} // dom namespace
+} // mozilla namespace
+
+#endif // dom_performance_PerformanceService_h

dom/performance/moz.build

@@ -13,6 +13,7 @@ EXPORTS.mozilla.dom += [
     'PerformanceObserver.h',
     'PerformanceObserverEntryList.h',
     'PerformanceResourceTiming.h',
+    'PerformanceService.h',
     'PerformanceTiming.h',
 ]
 
@@ -26,6 +27,7 @@ UNIFIED_SOURCES += [
     'PerformanceObserver.cpp',
     'PerformanceObserverEntryList.cpp',
     'PerformanceResourceTiming.cpp',
+    'PerformanceService.cpp',
     'PerformanceTiming.cpp',
     'PerformanceWorker.cpp',
 ]

dom/webidl/Performance.webidl

@@ -17,6 +17,9 @@ typedef sequence <PerformanceEntry> PerformanceEntryList;
 interface Performance {
   [DependsOn=DeviceState, Affects=Nothing]
   DOMHighResTimeStamp now();
+
+  [Constant]
+  readonly attribute DOMHighResTimeStamp timeOrigin;
 };
 
 [Exposed=Window]