blob: ff74b6191e4b65ee63a1e1096d7ea5e7959c19dd [file] [log] [blame]
// 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 <memory>
#include <vector>
#include "base/macros.h"
#include "base/synchronization/waitable_event.h"
#include "base/task/task_scheduler/task_scheduler.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.
// 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. Main message loop exits.
// 6. Child process is now fully stopped.
// Note: IO thread outlives the ChildThreadImpl 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.
// |io_thread_priority| is the priority of the IO thread.
// |task_scheduler_name| and |task_scheduler_init_params| are used to
// initialize TaskScheduler. Default params are used if
// |task_scheduler_init_params| is nullptr.
base::ThreadPriority io_thread_priority = base::ThreadPriority::NORMAL,
const std::string& task_scheduler_name = "ContentChild",
task_scheduler_init_params = nullptr);
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);
base::SingleThreadTaskRunner* io_task_runner() {
return io_thread_.task_runner().get();
base::PlatformThreadId io_thread_id() { return io_thread_.GetThreadId(); }
// 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();
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_.
std::unique_ptr<ChildThreadImpl> main_thread_;
// Whether this ChildProcess initialized TaskScheduler.
bool initialized_task_scheduler_ = false;
} // namespace content