Bug 1413606 P1 Add ClientThing base class. r=baku

dom/clients/manager/ClientThing.h

@@ -0,0 +1,108 @@
+/* -*- 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_dom_ClientThing_h
+#define _mozilla_dom_ClientThing_h
+
+#include "nsTArray.h"
+
+namespace mozilla {
+namespace dom {
+
+// Base class representing various Client "things" such as ClientHandle,
+// ClientSource, and ClientManager.  Currently it provides a common set
+// of code for handling activation and shutdown of IPC actors.
+template <typename ActorType>
+class ClientThing
+{
+  ActorType* mActor;
+  bool mShutdown;
+
+protected:
+  ClientThing()
+    : mActor(nullptr)
+    , mShutdown(false)
+  {
+  }
+
+  ~ClientThing()
+  {
+    ShutdownThing();
+  }
+
+  // Return the current actor.
+  ActorType*
+  GetActor() const
+  {
+    return mActor;
+  }
+
+  // Returns true if ShutdownThing() has been called.
+  bool
+  IsShutdown() const
+  {
+    return mShutdown;
+  }
+
+  // Conditionally execute the given callable based on the current state.
+  template<typename Callable>
+  void
+  MaybeExecute(const Callable& aCallable)
+  {
+    if (mShutdown) {
+      return;
+    }
+    MOZ_DIAGNOSTIC_ASSERT(mActor);
+    aCallable(mActor);
+  }
+
+  // Attach activate the thing by attaching its underlying IPC actor.  This
+  // will make the thing register as the actor's owner as well.  The actor
+  // must call RevokeActor() to clear this weak back reference before its
+  // destroyed.
+  void
+  ActivateThing(ActorType* aActor)
+  {
+    MOZ_DIAGNOSTIC_ASSERT(aActor);
+    MOZ_DIAGNOSTIC_ASSERT(!mActor);
+    MOZ_DIAGNOSTIC_ASSERT(!mShutdown);
+    mActor = aActor;
+    mActor->SetOwner(this);
+  }
+
+  // Start destroying the underlying actor and disconnect the thing.
+  void
+  ShutdownThing()
+  {
+    if (mShutdown) {
+      return;
+    }
+    mShutdown = true;
+
+    // If we are shutdown before the actor, then clear the weak references
+    // between the actor and the thing.
+    if (mActor) {
+      mActor->RevokeOwner(this);
+      mActor->MaybeStartTeardown();
+      mActor = nullptr;
+    }
+  }
+
+public:
+  // Clear the weak references between the thing and its IPC actor.
+  void
+  RevokeActor(ActorType* aActor)
+  {
+    MOZ_DIAGNOSTIC_ASSERT(mActor);
+    MOZ_DIAGNOSTIC_ASSERT(mActor == aActor);
+    mActor->RevokeOwner(this);
+    mActor = nullptr;
+  }
+};
+
+} // namespace dom
+} // namespace mozilla
+
+#endif // _mozilla_dom_ClientThing_h

dom/clients/manager/moz.build

@@ -8,6 +8,7 @@ EXPORTS.mozilla.dom += [
   'ClientInfo.h',
   'ClientIPCUtils.h',
   'ClientState.h',
+  'ClientThing.h',
 ]
 
 UNIFIED_SOURCES += [