| // Copyright 2012 The Chromium Authors |
| // Use of this source code is governed by a BSD-style license that can be |
| // found in the LICENSE file. |
| |
| #ifndef CONTENT_CHILD_CHILD_PROCESS_H_ |
| #define CONTENT_CHILD_CHILD_PROCESS_H_ |
| |
| #include <memory> |
| #include <vector> |
| |
| #include "base/auto_reset.h" |
| #include "base/synchronization/waitable_event.h" |
| #include "base/task/single_thread_task_runner.h" |
| #include "base/task/thread_pool/thread_pool_instance.h" |
| #include "base/threading/platform_thread.h" |
| #include "base/threading/thread.h" |
| #include "content/common/content_export.h" |
| |
| namespace content { |
| class ChildThreadImpl; |
| |
| // Base class for child processes of the browser process (i.e. renderer and |
| // plugin host). This is a singleton object for each child process. |
| // |
| // The constructor will call ThreadPoolInstance::Start() unless a ThreadPool is |
| // already running, which can happen when the ChildProcess object is |
| // instantiated in the browser process or in tests. |
| // |
| // 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. ChildThreadImpl::Shutdown() is called. ChildThread is also deleted. |
| // 4. IO thread is stopped. |
| // 5. ThreadPoolInstance::Shutdown() is called if the constructor called |
| // ThreadPoolInstance::Start(). |
| // 6. Main message loop exits. |
| // 7. Child process is now fully stopped. |
| // |
| // Note: IO thread outlives the ChildThreadImpl object. |
| class CONTENT_EXPORT ChildProcess { |
| public: |
| // Child processes should have an object that derives from this class. |
| // Normally you would immediately call set_main_thread after construction. |
| // |io_thread_type| is the type of the IO thread. |
| // |thread_pool_init_params| is used to start the ThreadPool. Default params |
| // are used if |thread_pool_init_params| is nullptr. It is ignored if a |
| // ThreadPool is already running. |
| explicit ChildProcess( |
| base::ThreadType io_thread_type = base::ThreadType::kDefault, |
| std::unique_ptr<base::ThreadPoolInstance::InitParams> |
| thread_pool_init_params = nullptr); |
| |
| // This constructor can be used to create a ChildProcess within the browser |
| // process which shares the IO thread. `io_thread_runner` passes an existing |
| // task runner to use for the child IO thread instead of creating a new |
| // thread. |
| explicit ChildProcess( |
| scoped_refptr<base::SingleThreadTaskRunner> io_thread_runner); |
| |
| ChildProcess(const ChildProcess&) = delete; |
| ChildProcess& operator=(const ChildProcess&) = delete; |
| |
| virtual ~ChildProcess(); |
| |
| // May be NULL if the main thread hasn't been set explicitly. |
| ChildThreadImpl* main_thread(); |
| |
| // Sets the object associated with the main thread of this process. |
| // Takes ownership of the pointer. |
| void set_main_thread(ChildThreadImpl* thread); |
| |
| // We need to stop the IO thread here instead of just flushing it, so that it |
| // can no longer post tasks back to the main thread. |
| void StopIOThreadForTesting() { io_thread_->Stop(); } |
| |
| base::SingleThreadTaskRunner* io_task_runner() { |
| return io_thread_runner_.get(); |
| } |
| |
| #if BUILDFLAG(IS_LINUX) || BUILDFLAG(IS_CHROMEOS) |
| // Changes the thread type of the child process IO thread. |
| void SetIOThreadType(base::ThreadType thread_type); |
| #endif |
| |
| // 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 GetCookies(). |
| base::WaitableEvent* GetShutDownEvent(); |
| |
| // These are used for ref-counting the child process. The process shuts |
| // itself down when the ref count reaches 0. |
| // |
| // This is not used for renderer processes. The browser process is the only |
| // one responsible for shutting them down. See mojo::KeepAliveHandle and more |
| // generally the RenderProcessHostImpl class if you want to keep the renderer |
| // process alive longer. |
| virtual void AddRefProcess(); |
| virtual void ReleaseProcess(); |
| |
| // Getter for the one ChildProcess object for this process. Can only be called |
| // on the main thread. |
| static ChildProcess* current(); |
| |
| private: |
| const base::AutoReset<ChildProcess*> resetter_; |
| |
| int ref_count_ = 0; |
| |
| // An event that will be signalled when we shutdown. |
| base::WaitableEvent shutdown_event_{ |
| base::WaitableEvent::ResetPolicy::MANUAL, |
| base::WaitableEvent::InitialState::NOT_SIGNALED}; |
| |
| // The thread that handles IO events. May be null if `io_thread_runner` was |
| // passed to the constructor. |
| std::unique_ptr<base::Thread> io_thread_; |
| |
| // The task runner to use for IO thread tasks. |
| scoped_refptr<base::SingleThreadTaskRunner> io_thread_runner_; |
| |
| // NOTE: make sure that main_thread_ is listed after shutdown_event_, since |
| // it depends on it (indirectly through IPC::SyncChannel). Same for |
| // io_thread_. |
| std::unique_ptr<ChildThreadImpl> main_thread_; |
| |
| // Whether this ChildProcess initialized ThreadPoolInstance. |
| bool initialized_thread_pool_ = false; |
| }; |
| |
| } // namespace content |
| |
| #endif // CONTENT_CHILD_CHILD_PROCESS_H_ |