ipc/glue/BackgroundChild.h

   1 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
   2 /* vim: set ts=8 sts=2 et sw=2 tw=80: */
   3 /* This Source Code Form is subject to the terms of the Mozilla Public
   4  * License, v. 2.0. If a copy of the MPL was not distributed with this file,
   5  * You can obtain one at http://mozilla.org/MPL/2.0/. */
   6
   7 #ifndef mozilla_ipc_backgroundchild_h__
   8 #define mozilla_ipc_backgroundchild_h__
   9
  10 #include "mozilla/Attributes.h"
  11
  12 class nsIEventTarget;
  13
  14 namespace mozilla {
  15 namespace dom {
  16
  17 class BlobImpl;
  18 class ContentChild;
  19 class ContentParent;
  20 class ContentProcess;
  21
  22 }  // namespace dom
  23
  24 namespace ipc {
  25
  26 class PBackgroundChild;
  27 class PBackgroundStarterChild;
  28
  29 // This class allows access to the PBackground protocol. PBackground allows
  30 // communication between any thread (in the parent or a child process) and a
  31 // single background thread in the parent process. Each PBackgroundChild
  32 // instance is tied to the thread on which it is created and must not be shared
  33 // across threads. Each PBackgroundChild is unique and valid as long as its
  34 // designated thread lives.
  35 //
  36 // Creation of PBackground is synchronous. GetOrCreateForCurrentThread will
  37 // create the actor if it doesn't exist yet. Thereafter (assuming success)
  38 // GetForCurrentThread() will return the same actor every time.
  39 //
  40 // CloseForCurrentThread() will close the current PBackground actor.  Subsequent
  41 // calls to GetForCurrentThread will return null.  CloseForCurrentThread() may
  42 // only be called exactly once for each thread-specific actor.  Currently it is
  43 // illegal to call this before the PBackground actor has been created.
  44 //
  45 // The PBackgroundChild actor and all its sub-protocol actors will be
  46 // automatically destroyed when its designated thread completes.
  47 //
  48 // InitContentStarter must be called on the main thread
  49 // with an actor bridging to the relevant target process type before these
  50 // methods can be used.
  51 class BackgroundChild final {
  52   friend class mozilla::dom::ContentParent;
  53   friend class mozilla::dom::ContentProcess;
  54
  55  public:
  56   // See above.
  57   static PBackgroundChild* GetForCurrentThread();
  58
  59   // See above.
  60   static PBackgroundChild* GetOrCreateForCurrentThread();
  61
  62   // See above.
  63   static void CloseForCurrentThread();
  64
  65   // See above.
  66   static void InitContentStarter(mozilla::dom::ContentChild* aContent);
  67
  68  private:
  69   // Only called by this class's friends.
  70   static void Startup();
  71 };
  72
  73 }  // namespace ipc
  74 }  // namespace mozilla
  75
  76 #endif  // mozilla_ipc_backgroundchild_h__