Refactor ChildProcess and related classes to create a framework outside of br...

base/mp/mp_child_process.h

+// Copyright (c) 2010 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef BASE_MP_CHILD_PROCESS_H__
+#define BASE_MP_CHILD_PROCESS_H__
+
+#include "base/basictypes.h"
+#include "base/scoped_ptr.h"
+#include "base/thread.h"
+#include "base/waitable_event.h"
+#include "base/mp/mp_child_thread.h"
+
+namespace base {
+
+// Base class for child processes of the browser process (i.e. renderer and
+// plugin host). This is a singleton object for each child process.
+class MpChildProcess {
+ public:
+  // Child processes should have an object that derives from this class.
+  MpChildProcess();
+  virtual ~MpChildProcess();
+
+  // Derived classes should override this method to return a pointer to the
+  // application IO thread.
+  virtual base::Thread* GetIOThread() = 0;
+
+  // Getter for the child process' main thread.
+  MpChildThread* main_thread() { return main_thread_.get(); }
+  void set_main_thread(MpChildThread* thread) { main_thread_.reset(thread); }
+
+  MessageLoop* io_message_loop() { return GetIOThread()->message_loop(); }
+
+  // A global event object that is signalled when the main thread's message
+  // loop exits.  This gives background threads a way to observe the main
+  // thread shutting down.  This can be useful when a background thread is
+  // waiting for some information from the browser process.  If the browser
+  // process goes away prematurely, the background thread can at least notice
+  // the child processes's main thread exiting to determine that it should give
+  // up waiting.
+  // For example, see the renderer code used to implement
+  // webkit_glue::GetCookies.
+  base::WaitableEvent* GetShutDownEvent();
+
+  // These are used for ref-counting the child process.  The process shuts
+  // itself down when the ref count reaches 0.
+  // For example, in the renderer process, generally each tab managed by this
+  // process will hold a reference to the process, and release when closed.
+  void AddRefProcess();
+  void ReleaseProcess();
+
+  // Getter for the one MpChildProcess object for this process.
+  static MpChildProcess* current() { return child_process_; }
+ private:
+  int ref_count_;
+
+  // An event that will be signalled when we shutdown.
+  base::WaitableEvent shutdown_event_;
+
+  // NOTE: make sure that main_thread_ is listed after shutdown_event_, since
+  // it depends on it (indirectly through IPC::SyncChannel).  Same for
+  // io_thread_.
+  scoped_ptr<MpChildThread> main_thread_;
+
+  // The singleton instance for this process.
+  static MpChildProcess* child_process_;
+
+  DISALLOW_COPY_AND_ASSIGN(MpChildProcess);
+};
+
+}  // namespace base
+
+#endif  // BASE_MP_CHILD_PROCESS_H__