Bug 1363877 - Label IPC shmem messages as SystemGroup (r=dvander)

MozReview-Commit-ID: 3I5ny0wxVHI

ipc/glue/MessageChannel.cpp

@@ -774,6 +774,7 @@ MessageChannel::Open(Transport* aTransport, MessageLoop* aIOLoop, Side aSide)
     mWorkerLoop = MessageLoop::current();
     mWorkerLoopID = mWorkerLoop->id();
     mWorkerLoop->AddDestructionObserver(this);
+    mListener->SetIsMainThreadProtocol();
 
     if (!AbstractThread::GetCurrent()) {
         mWorkerLoop->AddDestructionObserver(
@@ -859,6 +860,7 @@ MessageChannel::CommonThreadOpenInit(MessageChannel *aTargetChan, Side aSide)
     mWorkerLoop = MessageLoop::current();
     mWorkerLoopID = mWorkerLoop->id();
     mWorkerLoop->AddDestructionObserver(this);
+    mListener->SetIsMainThreadProtocol();
 
     if (!AbstractThread::GetCurrent()) {
         mWorkerLoop->AddDestructionObserver(

ipc/glue/ProtocolUtils.cpp

@@ -19,6 +19,7 @@
 #include "mozilla/ipc/MessageChannel.h"
 #include "mozilla/ipc/Transport.h"
 #include "mozilla/StaticMutex.h"
+#include "mozilla/SystemGroup.h"
 #include "mozilla/Unused.h"
 #include "nsPrintfCString.h"
 
@@ -815,6 +816,13 @@ IToplevelProtocol::ShmemDestroyed(const Message& aMsg)
 already_AddRefed<nsIEventTarget>
 IToplevelProtocol::GetMessageEventTarget(const Message& aMsg)
 {
+  if (IsMainThreadProtocol() && SystemGroup::Initialized()) {
+    if (aMsg.type() == SHMEM_CREATED_MESSAGE_TYPE ||
+        aMsg.type() == SHMEM_DESTROYED_MESSAGE_TYPE) {
+      return do_AddRef(SystemGroup::EventTargetFor(TaskCategory::Other));
+    }
+  }
+
   int32_t route = aMsg.routing_id();
 
   Maybe<MutexAutoLock> lock;

ipc/glue/ProtocolUtils.h

@@ -386,6 +386,10 @@ public:
     GetActorEventTarget();
 
     virtual void OnChannelReceivedMessage(const Message& aMsg) {}
+
+    bool IsMainThreadProtocol() const { return mIsMainThreadProtocol; }
+    void SetIsMainThreadProtocol() { mIsMainThreadProtocol = NS_IsMainThread(); }
+
 protected:
     // Override this method in top-level protocols to change the event target
     // for a new actor (and its sub-actors).
@@ -413,6 +417,7 @@ protected:
     int32_t mLastRouteId;
     IDMap<Shmem::SharedMemory*> mShmemMap;
     Shmem::id_t mLastShmemId;
+    bool mIsMainThreadProtocol;
 
     Mutex mEventTargetMutex;
     IDMap<nsCOMPtr<nsIEventTarget>> mEventTargetMap;

xpcom/threads/SystemGroup.cpp

@@ -22,6 +22,8 @@ public:
   static void ShutdownStatic();
   static SystemGroupImpl* Get();
 
+  static bool Initialized() { return !!sSingleton; }
+
   NS_METHOD_(MozExternalRefCountType) AddRef(void)
   {
     return 2;
@@ -76,6 +78,12 @@ SystemGroup::Shutdown()
   SystemGroupImpl::ShutdownStatic();
 }
 
+bool
+SystemGroup::Initialized()
+{
+  return SystemGroupImpl::Initialized();
+}
+
 /* static */ nsresult
 SystemGroup::Dispatch(const char* aName,
                       TaskCategory aCategory,

xpcom/threads/SystemGroup.h

@@ -34,6 +34,9 @@ class SystemGroup
 
   static void InitStatic();
   static void Shutdown();
+
+  // Returns true if SystemGroup has been initialized.
+  static bool Initialized();
 };
 
 } // namespace mozilla