Bug 977819 - 'Allow PBackgroundChild implementors to hook into the threadlocal space'. r=mrbkap.

dom/ipc/ContentParent.cpp

@@ -150,6 +150,7 @@ using namespace mozilla::system;
 #endif
 
 #ifdef ENABLE_TESTS
+#include "BackgroundChildImpl.h"
 #include "mozilla/ipc/PBackgroundChild.h"
 #include "nsIIPCBackgroundChildCreateCallback.h"
 #endif
@@ -241,6 +242,10 @@ private:
                 bool ok = BackgroundChild::GetOrCreateForCurrentThread(this);
                 MOZ_RELEASE_ASSERT(ok);
 
+                BackgroundChildImpl::ThreadLocal* threadLocal =
+                  BackgroundChildImpl::GetThreadLocalForCurrentThread();
+                MOZ_RELEASE_ASSERT(threadLocal);
+
                 // Callback 2.
                 ok = BackgroundChild::GetOrCreateForCurrentThread(this);
                 MOZ_RELEASE_ASSERT(ok);

dom/ipc/moz.build

@@ -132,6 +132,9 @@ for var in ('MOZ_PERMISSIONS', 'MOZ_CHILD_PERMISSIONS'):
 
 if CONFIG['ENABLE_TESTS']:
     DEFINES['ENABLE_TESTS'] = 1
+    LOCAL_INCLUDES += [
+      'ipc/glue',
+    ]
 
 JAR_MANIFESTS += ['jar.mn']
 

ipc/glue/BackgroundChildImpl.cpp

@@ -35,6 +35,28 @@ class TestChild MOZ_FINAL : public mozilla::ipc::PBackgroundTestChild
 namespace mozilla {
 namespace ipc {
 
+// -----------------------------------------------------------------------------
+// BackgroundChildImpl::ThreadLocal
+// -----------------------------------------------------------------------------
+
+BackgroundChildImpl::
+ThreadLocal::ThreadLocal()
+{
+  // May happen on any thread!
+  MOZ_COUNT_CTOR(mozilla::ipc::BackgroundChildImpl::ThreadLocal);
+}
+
+BackgroundChildImpl::
+ThreadLocal::~ThreadLocal()
+{
+  // May happen on any thread!
+  MOZ_COUNT_DTOR(mozilla::ipc::BackgroundChildImpl::ThreadLocal);
+}
+
+// -----------------------------------------------------------------------------
+// BackgroundChildImpl
+// -----------------------------------------------------------------------------
+
 BackgroundChildImpl::BackgroundChildImpl()
 {
   // May happen on any thread!

ipc/glue/BackgroundChildImpl.h

@@ -8,6 +8,8 @@
 #include "mozilla/Attributes.h"
 #include "mozilla/ipc/PBackgroundChild.h"
 
+template <class> class nsAutoPtr;
+
 namespace mozilla {
 namespace ipc {
 
@@ -15,6 +17,17 @@ namespace ipc {
 // to be inherited in BackgroundImpl.
 class BackgroundChildImpl : public PBackgroundChild
 {
+public:
+  class ThreadLocal;
+
+  // Get the ThreadLocal for the current thread if
+  // BackgroundChild::GetOrCreateForCurrentThread() has been called and true was
+  // returned (e.g. a valid PBackgroundChild actor has been created or is in the
+  // process of being created). Otherwise this function returns null.
+  // This functions is implemented in BackgroundImpl.cpp.
+  static ThreadLocal*
+  GetThreadLocalForCurrentThread();
+
 protected:
   BackgroundChildImpl();
   virtual ~BackgroundChildImpl();
@@ -29,6 +42,20 @@ protected:
   DeallocPBackgroundTestChild(PBackgroundTestChild* aActor) MOZ_OVERRIDE;
 };
 
+class BackgroundChildImpl::ThreadLocal
+{
+  friend class nsAutoPtr<ThreadLocal>;
+
+  // Add any members needed here.
+
+public:
+  ThreadLocal();
+
+private:
+  // Only destroyed by nsAutoPtr<ThreadLocal>.
+  ~ThreadLocal();
+};
+
 } // namespace ipc
 } // namespace mozilla
 

ipc/glue/BackgroundImpl.cpp

@@ -302,6 +302,7 @@ private:
 class ChildImpl MOZ_FINAL : public BackgroundChildImpl
 {
   friend class mozilla::ipc::BackgroundChild;
+  friend class mozilla::ipc::BackgroundChildImpl;
 
   typedef base::ProcessId ProcessId;
   typedef mozilla::ipc::Transport Transport;
@@ -330,6 +331,7 @@ class ChildImpl MOZ_FINAL : public BackgroundChildImpl
 
     nsRefPtr<ChildImpl> mActor;
     nsTArray<nsCOMPtr<nsIIPCBackgroundChildCreateCallback>> mCallbacks;
+    nsAutoPtr<BackgroundChildImpl::ThreadLocal> mConsumerThreadLocal;
   };
 
   // This is only modified on the main thread. It is a FIFO queue for actors
@@ -393,6 +395,10 @@ private:
   static bool
   GetOrCreateForCurrentThread(nsIIPCBackgroundChildCreateCallback* aCallback);
 
+  // Forwarded from BackgroundChildImpl.
+  static BackgroundChildImpl::ThreadLocal*
+  GetThreadLocalForCurrentThread();
+
   static void
   ThreadLocalDestructor(void* aThreadLocal)
   {
@@ -827,6 +833,17 @@ BackgroundChild::GetOrCreateForCurrentThread(
   return ChildImpl::GetOrCreateForCurrentThread(aCallback);
 }
 
+// -----------------------------------------------------------------------------
+// BackgroundChildImpl Public Methods
+// -----------------------------------------------------------------------------
+
+// static
+BackgroundChildImpl::ThreadLocal*
+BackgroundChildImpl::GetThreadLocalForCurrentThread()
+{
+  return ChildImpl::GetThreadLocalForCurrentThread();
+}
+
 // -----------------------------------------------------------------------------
 // ParentImpl Static Members
 // -----------------------------------------------------------------------------
@@ -1623,6 +1640,28 @@ ChildImpl::GetOrCreateForCurrentThread(
   return true;
 }
 
+// static
+BackgroundChildImpl::ThreadLocal*
+ChildImpl::GetThreadLocalForCurrentThread()
+{
+  MOZ_ASSERT(sThreadLocalIndex != kBadThreadLocalIndex,
+             "BackgroundChild::Startup() was never called!");
+
+  auto threadLocalInfo =
+    static_cast<ThreadLocalInfo*>(PR_GetThreadPrivate(sThreadLocalIndex));
+
+  if (!threadLocalInfo) {
+    return nullptr;
+  }
+
+  if (!threadLocalInfo->mConsumerThreadLocal) {
+    threadLocalInfo->mConsumerThreadLocal =
+      new BackgroundChildImpl::ThreadLocal();
+  }
+
+  return threadLocalInfo->mConsumerThreadLocal;
+}
+
 ChildImpl::CreateCallbackRunnable::~CreateCallbackRunnable()
 {
   if (mActor) {