Bug 1183229 - Add a way to count the number of timeline-observed docshells outside of nsDocShell, r=smaug

docshell/base/nsDocShell.cpp

@@ -2929,8 +2929,6 @@ nsDocShell::HistoryTransactionRemoved(int32_t aIndex)
   return NS_OK;
 }
 
-unsigned long nsDocShell::gProfileTimelineRecordingsCount = 0;
-
 mozilla::LinkedList<nsDocShell::ObservedDocShell>* nsDocShell::gObservedDocShells = nullptr;
 
 NS_IMETHODIMP
@@ -2939,14 +2937,14 @@ nsDocShell::SetRecordProfileTimelineMarkers(bool aValue)
   bool currentValue = nsIDocShell::GetRecordProfileTimelineMarkers();
   if (currentValue != aValue) {
     if (aValue) {
-      ++gProfileTimelineRecordingsCount;
+      TimelineConsumers::AddConsumer();
       UseEntryScriptProfiling();
 
       MOZ_ASSERT(!mObserved);
       mObserved.reset(new ObservedDocShell(this));
       GetOrCreateObservedDocShells().insertFront(mObserved.get());
     } else {
-      --gProfileTimelineRecordingsCount;
+      TimelineConsumers::RemoveConsumer();
       UnuseEntryScriptProfiling();
 
       mObserved.reset(nullptr);

docshell/base/nsDocShell.h

@@ -34,6 +34,7 @@
 #include "nsThreadUtils.h"
 #include "nsContentUtils.h"
 #include "timeline/TimelineMarker.h"
+#include "timeline/TimelineConsumers.h"
 
 // Threshold value in ms for META refresh based redirects
 #define REFRESH_REDIRECT_TIMER 15000
@@ -262,10 +263,6 @@ public:
   void AddProfileTimelineMarker(const char* aName, TracingMetadata aMetaData);
   void AddProfileTimelineMarker(mozilla::UniquePtr<TimelineMarker>&& aMarker);
 
-  // Global counter for how many docShells are currently recording profile
-  // timeline markers
-  static unsigned long gProfileTimelineRecordingsCount;
-
   class ObservedDocShell : public mozilla::LinkedListElement<ObservedDocShell>
   {
   public:

docshell/base/timeline/AutoGlobalTimelineMarker.cpp

@@ -6,6 +6,7 @@
 
 #include "mozilla/AutoGlobalTimelineMarker.h"
 
+#include "mozilla/TimelineConsumers.h"
 #include "MainThreadUtils.h"
 #include "nsDocShell.h"
 
@@ -37,7 +38,7 @@ AutoGlobalTimelineMarker::AutoGlobalTimelineMarker(const char* aName
   MOZ_GUARD_OBJECT_NOTIFIER_INIT;
   MOZ_ASSERT(NS_IsMainThread());
 
-  if (nsDocShell::gProfileTimelineRecordingsCount == 0) {
+  if (TimelineConsumers::IsEmpty()) {
     return;
   }
 

docshell/base/timeline/AutoTimelineMarker.cpp

@@ -15,7 +15,7 @@ bool
 AutoTimelineMarker::DocShellIsRecording(nsDocShell& aDocShell)
 {
   bool isRecording = false;
-  if (nsDocShell::gProfileTimelineRecordingsCount > 0) {
+  if (!TimelineConsumers::IsEmpty()) {
     aDocShell.GetRecordProfileTimelineMarkers(&isRecording);
   }
   return isRecording;

docshell/base/timeline/TimelineConsumers.cpp

@@ -0,0 +1,31 @@
+/* -*- 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 "mozilla/TimelineConsumers.h"
+
+namespace mozilla {
+
+unsigned long TimelineConsumers::sActiveConsumers = 0;
+
+void
+TimelineConsumers::AddConsumer()
+{
+  sActiveConsumers++;
+}
+
+void
+TimelineConsumers::RemoveConsumer()
+{
+  sActiveConsumers--;
+}
+
+bool
+TimelineConsumers::IsEmpty()
+{
+  return sActiveConsumers == 0;
+}
+
+} // namespace mozilla

docshell/base/timeline/TimelineConsumers.h

@@ -0,0 +1,32 @@
+/* -*- 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 mozilla_TimelineConsumers_h_
+#define mozilla_TimelineConsumers_h_
+
+class nsDocShell;
+
+namespace mozilla {
+
+// # TimelineConsumers
+//
+// A class to trace how many frontends are interested in markers. Whenever
+// interest is expressed in markers, these fields will keep track of that.
+class TimelineConsumers
+{
+private:
+  // Counter for how many timelines are currently interested in markers.
+  static unsigned long sActiveConsumers;
+
+public:
+  static void AddConsumer();
+  static void RemoveConsumer();
+  static bool IsEmpty();
+};
+
+} // namespace mozilla
+
+#endif /* mozilla_TimelineConsumers_h_ */

docshell/base/timeline/moz.build

@@ -7,11 +7,13 @@
 EXPORTS.mozilla += [
     'AutoGlobalTimelineMarker.h',
     'AutoTimelineMarker.h',
+    'TimelineConsumers.h',
 ]
 
 UNIFIED_SOURCES += [
     'AutoGlobalTimelineMarker.cpp',
     'AutoTimelineMarker.cpp',
+    'TimelineConsumers.cpp',
     'TimelineMarker.cpp',
 ]
 

dom/events/EventListenerManager.cpp

@@ -23,6 +23,7 @@
 #include "mozilla/dom/BindingUtils.h"
 #include "mozilla/dom/Element.h"
 #include "mozilla/dom/Event.h"
+#include "mozilla/TimelineConsumers.h"
 
 #include "EventListenerService.h"
 #include "nsCOMArray.h"
@@ -1124,7 +1125,7 @@ EventListenerManager::HandleEventInternal(nsPresContext* aPresContext,
           nsCOMPtr<nsIDocShell> docShell;
           bool isTimelineRecording = false;
           if (mIsMainThreadELM &&
-              nsDocShell::gProfileTimelineRecordingsCount > 0 &&
+              !TimelineConsumers::IsEmpty() &&
               listener->mListenerType != Listener::eNativeListener) {
             docShell = GetDocShellForTarget();
             if (docShell) {

layout/base/nsRefreshDriver.cpp

@@ -64,6 +64,7 @@
 #include "mozilla/VsyncDispatcher.h"
 #include "nsThreadUtils.h"
 #include "mozilla/unused.h"
+#include "mozilla/TimelineConsumers.h"
 
 #ifdef MOZ_NUWA_PROCESS
 #include "ipc/Nuwa.h"
@@ -993,7 +994,7 @@ RefreshDriverTimer*
 nsRefreshDriver::ChooseTimer() const
 {
   if (mThrottled) {
-    if (!sThrottledRateTimer) 
+    if (!sThrottledRateTimer)
       sThrottledRateTimer = new InactiveRefreshDriverTimer(GetThrottledTimerInterval(),
                                                            DEFAULT_INACTIVE_TIMER_DISABLE_SECONDS * 1000.0);
     return sThrottledRateTimer;
@@ -1051,7 +1052,7 @@ nsRefreshDriver::~nsRefreshDriver()
   MOZ_ASSERT(ObserverCount() == 0,
              "observers should have unregistered");
   MOZ_ASSERT(!mActiveTimer, "timer should be gone");
-  
+
   if (mRootRefresh) {
     mRootRefresh->RemoveRefreshObserver(this, Flush_Style);
     mRootRefresh = nullptr;
@@ -1436,7 +1437,7 @@ HasPendingAnimations(nsIPresShell* aShell)
 static void GetProfileTimelineSubDocShells(nsDocShell* aRootDocShell,
                                            nsTArray<nsDocShell*>& aShells)
 {
-  if (!aRootDocShell || nsDocShell::gProfileTimelineRecordingsCount == 0) {
+  if (!aRootDocShell || TimelineConsumers::IsEmpty()) {
     return;
   }