1 files changed, 69 insertions, 0 deletions
diff --git a/xpcom/base/CycleCollectedJSContext.h b/xpcom/base/CycleCollectedJSContext.h
index ac4cf4361..4cd1479ed 100644
--- a/xpcom/base/CycleCollectedJSContext.h
+++ b/xpcom/base/CycleCollectedJSContext.h
@@ -33,6 +33,7 @@ struct Class;
 } // namespace js
 
 namespace mozilla {
+class AutoSlowOperation;
 
 class JSGCThingParticipant: public nsCycleCollectionParticipant
 {
@@ -134,6 +135,17 @@ struct CycleCollectorResults
   uint32_t mNumSlices;
 };
 
+class MicroTaskRunnable
+{
+public:
+  MicroTaskRunnable() {}
+  NS_INLINE_DECL_REFCOUNTING(MicroTaskRunnable)
+  virtual void Run(AutoSlowOperation& aAso) = 0;
+  virtual bool Suppressed() { return false; }
+protected:
+  virtual ~MicroTaskRunnable() {}
+};
+
 class CycleCollectedJSContext
 {
   friend class JSGCThingParticipant;
@@ -402,6 +414,39 @@ public:
   // Queue an async microtask to the current main or worker thread.
   virtual void DispatchToMicroTask(already_AddRefed<nsIRunnable> aRunnable);
 
+  // Call EnterMicroTask when you're entering JS execution.
+  // Usually the best way to do this is to use nsAutoMicroTask.
+  void EnterMicroTask()
+  {
+    ++mMicroTaskLevel;
+  }
+
+  void LeaveMicroTask()
+  {
+    if (--mMicroTaskLevel == 0) {
+      PerformMicroTaskCheckPoint();
+    }
+  }
+
+  bool IsInMicroTask()
+  {
+    return mMicroTaskLevel != 0;
+  }
+
+  uint32_t MicroTaskLevel()
+  {
+    return mMicroTaskLevel;
+  }
+
+  void SetMicroTaskLevel(uint32_t aLevel)
+  {
+    mMicroTaskLevel = aLevel;
+  }
+
+  void PerformMicroTaskCheckPoint();
+
+  void DispatchMicroTaskRunnable(already_AddRefed<MicroTaskRunnable> aRunnable);
+
   // Storage for watching rejected promises waiting for some client to
   // consume their rejection.
 
@@ -452,6 +497,11 @@ private:
 
   bool mDisableMicroTaskCheckpoint;
 
+  uint32_t mMicroTaskLevel;
+  std::queue<RefPtr<MicroTaskRunnable>> mPendingMicroTaskRunnables;
+
+  uint32_t mMicroTaskRecursionDepth;
+
   OOMState mOutOfMemoryState;
   OOMState mLargeAllocationFailureState;
 
@@ -470,6 +520,25 @@ private:
   EnvironmentPreparer mEnvironmentPreparer;
 };
 
+class MOZ_STACK_CLASS nsAutoMicroTask
+{
+public:
+  nsAutoMicroTask()
+  {
+    CycleCollectedJSContext* ccjs = CycleCollectedJSContext::Get();
+    if (ccjs) {
+      ccjs->EnterMicroTask();
+    }
+  }
+  ~nsAutoMicroTask()
+  {
+    CycleCollectedJSContext* ccjs = CycleCollectedJSContext::Get();
+    if (ccjs) {
+      ccjs->LeaveMicroTask();
+    }
+  }
+};
+
 void TraceScriptHolder(nsISupports* aHolder, JSTracer* aTracer);
 
 // Returns true if the JS::TraceKind is one the cycle collector cares about.