1 // Copyright (c) 2012 The Chromium Authors. All rights reserved. 2 // Use of this source code is governed by a BSD-style license that can be 3 // found in the LICENSE file. 4 5 #ifndef CONTENT_CHILD_CHILD_PROCESS_H_ 6 #define CONTENT_CHILD_CHILD_PROCESS_H_ 7 8 #include "base/basictypes.h" 9 #include "base/memory/scoped_ptr.h" 10 #include "base/synchronization/waitable_event.h" 11 #include "base/threading/thread.h" 12 #include "content/common/content_export.h" 13 14 namespace content { 15 class ChildThread; 16 17 // Base class for child processes of the browser process (i.e. renderer and 18 // plugin host). This is a singleton object for each child process. 19 // 20 // During process shutdown the following sequence of actions happens in 21 // order. 22 // 23 // 1. ChildProcess::~ChildProcess() is called. 24 // 2. Shutdown event is fired. Background threads should stop. 25 // 3. ChildThread::Shutdown() is called. ChildThread is also deleted. 26 // 4. IO thread is stopped. 27 // 5. Main message loop exits. 28 // 6. Child process is now fully stopped. 29 // 30 // Note: IO thread outlives the ChildThread object. 31 class CONTENT_EXPORT ChildProcess { 32 public: 33 // Child processes should have an object that derives from this class. 34 // Normally you would immediately call set_main_thread after construction. 35 ChildProcess(); 36 virtual ~ChildProcess(); 37 38 // May be NULL if the main thread hasn't been set explicitly. 39 ChildThread* main_thread(); 40 41 // Sets the object associated with the main thread of this process. 42 // Takes ownership of the pointer. 43 void set_main_thread(ChildThread* thread); 44 45 base::MessageLoop* io_message_loop() { return io_thread_.message_loop(); } 46 base::MessageLoopProxy* io_message_loop_proxy() { 47 return io_thread_.message_loop_proxy().get(); 48 } 49 50 // A global event object that is signalled when the main thread's message 51 // loop exits. This gives background threads a way to observe the main 52 // thread shutting down. This can be useful when a background thread is 53 // waiting for some information from the browser process. If the browser 54 // process goes away prematurely, the background thread can at least notice 55 // the child processes's main thread exiting to determine that it should give 56 // up waiting. 57 // For example, see the renderer code used to implement GetCookies(). 58 base::WaitableEvent* GetShutDownEvent(); 59 60 // These are used for ref-counting the child process. The process shuts 61 // itself down when the ref count reaches 0. 62 // For example, in the renderer process, generally each tab managed by this 63 // process will hold a reference to the process, and release when closed. 64 void AddRefProcess(); 65 void ReleaseProcess(); 66 67 // Getter for the one ChildProcess object for this process. Can only be called 68 // on the main thread. 69 static ChildProcess* current(); 70 71 static void WaitForDebugger(const std::string& label); 72 private: 73 int ref_count_; 74 75 // An event that will be signalled when we shutdown. 76 base::WaitableEvent shutdown_event_; 77 78 // The thread that handles IO events. 79 base::Thread io_thread_; 80 81 // NOTE: make sure that main_thread_ is listed after shutdown_event_, since 82 // it depends on it (indirectly through IPC::SyncChannel). Same for 83 // io_thread_. 84 scoped_ptr<ChildThread> main_thread_; 85 86 DISALLOW_COPY_AND_ASSIGN(ChildProcess); 87 }; 88 89 } // namespace content 90 91 #endif // CONTENT_CHILD_CHILD_PROCESS_H_ 92
