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// Copyright (c) 2012 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.
#include "base/basictypes.h"
#include "base/memory/scoped_ptr.h"
#include "base/synchronization/waitable_event.h"
#include "base/threading/thread.h"
#include "content/common/content_export.h"
namespace content {
class ChildThread;
// Base class for child processes of the browser process (i.e. renderer and
// plugin host). This is a singleton object for each child process.
// During process shutdown the following sequence of actions happens in
// order.
// 1. ChildProcess::~ChildProcess() is called.
// 2. Shutdown event is fired. Background threads should stop.
// 3. ChildThread::Shutdown() is called. ChildThread is also deleted.
// 4. IO thread is stopped.
// 5. Main message loop exits.
// 6. Child process is now fully stopped.
// Note: IO thread outlives the ChildThread object.
class CONTENT_EXPORT ChildProcess {
// Child processes should have an object that derives from this class.
// Normally you would immediately call set_main_thread after construction.
virtual ~ChildProcess();
// May be NULL if the main thread hasn't been set explicitly.
ChildThread* main_thread();
// Sets the object associated with the main thread of this process.
// Takes ownership of the pointer.
void set_main_thread(ChildThread* thread);
base::MessageLoop* io_message_loop() { return io_thread_.message_loop(); }
base::MessageLoopProxy* io_message_loop_proxy() {
return io_thread_.message_loop_proxy().get();
// 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 ChildProcess object for this process. Can only be called
// on the main thread.
static ChildProcess* current();
static void WaitForDebugger(const std::string& label);
int ref_count_;
// An event that will be signalled when we shutdown.
base::WaitableEvent shutdown_event_;
// The thread that handles IO events.
base::Thread io_thread_;
// 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<ChildThread> main_thread_;
} // namespace content