bug 1468099, Add a way to check if all the tabs in a process can be throttled, r=farre

dom/base/TabGroup.cpp

@@ -9,6 +9,7 @@
 #include "mozilla/dom/ContentChild.h"
 #include "mozilla/dom/TabChild.h"
 #include "mozilla/dom/DocGroup.h"
+#include "mozilla/dom/TimeoutManager.h"
 #include "mozilla/AbstractThread.h"
 #include "mozilla/ClearOnShutdown.h"
 #include "mozilla/StaticPtr.h"
@@ -23,6 +24,8 @@ namespace dom {
 
 static StaticRefPtr<TabGroup> sChromeTabGroup;
 
+LinkedList<TabGroup>* TabGroup::sTabGroups = nullptr;
+
 TabGroup::TabGroup(bool aIsChrome)
  : mLastWindowLeft(false)
  , mThrottledQueuesInitialized(false)
@@ -31,6 +34,11 @@ TabGroup::TabGroup(bool aIsChrome)
  , mIsChrome(aIsChrome)
  , mForegroundCount(0)
 {
+  if (!sTabGroups) {
+    sTabGroups = new LinkedList<TabGroup>();
+  }
+  sTabGroups->insertBack(this);
+
   CreateEventTargets(/* aNeedValidation = */ !aIsChrome);
 
   // Do not throttle runnables from chrome windows.  In theory we should
@@ -54,6 +62,15 @@ TabGroup::~TabGroup()
   MOZ_ASSERT(mDocGroups.IsEmpty());
   MOZ_ASSERT(mWindows.IsEmpty());
   MOZ_RELEASE_ASSERT(mLastWindowLeft || mIsChrome);
+
+  LinkedListElement<TabGroup>* listElement =
+    static_cast<LinkedListElement<TabGroup>*>(this);
+  listElement->remove();
+
+  if (sTabGroups->isEmpty()) {
+    delete sTabGroups;
+    sTabGroups = nullptr;
+  }
 }
 
 void
@@ -323,5 +340,37 @@ TabGroup::Count(bool aActiveOnly) const
   return count;
 }
 
+/*static*/ bool
+TabGroup::HasOnlyThrottableTabs()
+{
+  if (!sTabGroups) {
+    return false;
+  }
+
+  for (TabGroup* tabGroup = sTabGroups->getFirst(); tabGroup;
+       tabGroup =
+         static_cast<LinkedListElement<TabGroup>*>(tabGroup)->getNext()) {
+    for (auto iter = tabGroup->Iter(); !iter.Done(); iter.Next()) {
+      DocGroup* docGroup = iter.Get()->mDocGroup;
+      for (auto* documentInDocGroup : *docGroup) {
+        if (documentInDocGroup->IsCurrentActiveDocument()) {
+          nsPIDOMWindowInner* win =
+            documentInDocGroup->GetInnerWindow();
+          if (win && win->IsCurrentInnerWindow()) {
+            nsPIDOMWindowOuter* outer = win->GetOuterWindow();
+            if (outer) {
+              TimeoutManager& tm = win->TimeoutManager();
+              if (!tm.BudgetThrottlingEnabled(outer->IsBackground())) {
+                return false;
+              }
+            }
+          }
+        }
+      }
+    }
+  }
+  return true;
+}
+
 } // namespace dom
 } // namespace mozilla

dom/base/TabGroup.h

@@ -46,7 +46,8 @@ class TabChild;
 class DocGroup;
 class TabChild;
 
-class TabGroup final : public SchedulerGroup
+class TabGroup final : public SchedulerGroup,
+                       public LinkedListElement<TabGroup>
 {
 private:
   class HashEntry : public nsCStringHashKey
@@ -146,6 +147,16 @@ public:
     return mNumOfIndexedDBDatabases;
   }
 
+  static LinkedList<TabGroup>* GetTabGroupList()
+  {
+    return sTabGroups;
+  }
+
+  // This returns true if all the window objects in all the TabGroups are
+  // either inactive (for example in bfcache) or are in background tabs which
+  // can be throttled.
+  static bool HasOnlyThrottableTabs();
+
 private:
   virtual AbstractThread*
   AbstractMainThreadForImpl(TaskCategory aCategory) override;
@@ -167,6 +178,8 @@ private:
   DocGroupMap mDocGroups;
   nsTArray<nsPIDOMWindowOuter*> mWindows;
   uint32_t mForegroundCount;
+
+  static LinkedList<TabGroup>* sTabGroups;
 };
 
 } // namespace dom

dom/base/TimeoutManager.h

@@ -111,6 +111,8 @@ public:
   nsIEventTarget*
   EventTarget();
 
+  bool BudgetThrottlingEnabled(bool aIsBackground) const;
+
   static const uint32_t InvalidFiringId;
 
 private:
@@ -149,8 +151,6 @@ private:
   void UpdateBudget(const TimeStamp& aNow,
                     const TimeDuration& aDuration = TimeDuration());
 
-  bool BudgetThrottlingEnabled(bool aIsBackground) const;
-
 private:
   struct Timeouts {
     explicit Timeouts(const TimeoutManager& aManager)