| // Copyright (c) 2006-2009 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_THREAD_H_ |
| #define BASE_THREAD_H_ |
| |
| #include <string> |
| |
| #include "base/message_loop.h" |
| #include "base/platform_thread.h" |
| |
| namespace base { |
| |
| // A simple thread abstraction that establishes a MessageLoop on a new thread. |
| // The consumer uses the MessageLoop of the thread to cause code to execute on |
| // the thread. When this object is destroyed the thread is terminated. All |
| // pending tasks queued on the thread's message loop will run to completion |
| // before the thread is terminated. |
| // |
| // After the thread is stopped, the destruction sequence is: |
| // |
| // (1) Thread::CleanUp() |
| // (2) MessageLoop::~MessageLoop |
| // (3.b) MessageLoop::DestructionObserver::WillDestroyCurrentMessageLoop |
| // (4) Thread::CleanUpAfterMessageLoopDestruction() |
| class Thread : PlatformThread::Delegate { |
| public: |
| struct Options { |
| // Specifies the type of message loop that will be allocated on the thread. |
| MessageLoop::Type message_loop_type; |
| |
| // Specifies the maximum stack size that the thread is allowed to use. |
| // This does not necessarily correspond to the thread's initial stack size. |
| // A value of 0 indicates that the default maximum should be used. |
| size_t stack_size; |
| |
| Options() : message_loop_type(MessageLoop::TYPE_DEFAULT), stack_size(0) {} |
| Options(MessageLoop::Type type, size_t size) |
| : message_loop_type(type), stack_size(size) {} |
| }; |
| |
| // Constructor. |
| // name is a display string to identify the thread. |
| explicit Thread(const char* name); |
| |
| // Destroys the thread, stopping it if necessary. |
| // |
| // NOTE: If you are subclassing from Thread, and you wish for your CleanUp |
| // method to be called, then you need to call Stop() from your destructor. |
| // |
| virtual ~Thread(); |
| |
| // Starts the thread. Returns true if the thread was successfully started; |
| // otherwise, returns false. Upon successful return, the message_loop() |
| // getter will return non-null. |
| // |
| // Note: This function can't be called on Windows with the loader lock held; |
| // i.e. during a DllMain, global object construction or destruction, atexit() |
| // callback. |
| bool Start(); |
| |
| // Starts the thread. Behaves exactly like Start in addition to allow to |
| // override the default options. |
| // |
| // Note: This function can't be called on Windows with the loader lock held; |
| // i.e. during a DllMain, global object construction or destruction, atexit() |
| // callback. |
| bool StartWithOptions(const Options& options); |
| |
| // Signals the thread to exit and returns once the thread has exited. After |
| // this method returns, the Thread object is completely reset and may be used |
| // as if it were newly constructed (i.e., Start may be called again). |
| // |
| // Stop may be called multiple times and is simply ignored if the thread is |
| // already stopped. |
| // |
| // NOTE: This method is optional. It is not strictly necessary to call this |
| // method as the Thread's destructor will take care of stopping the thread if |
| // necessary. |
| // |
| void Stop(); |
| |
| // Signals the thread to exit in the near future. |
| // |
| // WARNING: This function is not meant to be commonly used. Use at your own |
| // risk. Calling this function will cause message_loop() to become invalid in |
| // the near future. This function was created to workaround a specific |
| // deadlock on Windows with printer worker thread. In any other case, Stop() |
| // should be used. |
| // |
| // StopSoon should not be called multiple times as it is risky to do so. It |
| // could cause a timing issue in message_loop() access. Call Stop() to reset |
| // the thread object once it is known that the thread has quit. |
| void StopSoon(); |
| |
| // Returns the message loop for this thread. Use the MessageLoop's |
| // PostTask methods to execute code on the thread. This only returns |
| // non-null after a successful call to Start. After Stop has been called, |
| // this will return NULL. |
| // |
| // NOTE: You must not call this MessageLoop's Quit method directly. Use |
| // the Thread's Stop method instead. |
| // |
| MessageLoop* message_loop() const { return message_loop_; } |
| |
| // Set the name of this thread (for display in debugger too). |
| const std::string &thread_name() { return name_; } |
| |
| // The native thread handle. |
| PlatformThreadHandle thread_handle() { return thread_; } |
| |
| // The thread ID. |
| PlatformThreadId thread_id() const { return thread_id_; } |
| |
| // Returns true if the thread has been started, and not yet stopped. |
| // When a thread is running, the thread_id_ is non-zero. |
| bool IsRunning() const { return thread_id_ != 0; } |
| |
| protected: |
| // Called just prior to starting the message loop |
| virtual void Init() {} |
| |
| // Called to start the message loop |
| virtual void Run(MessageLoop* message_loop); |
| |
| // Called just after the message loop ends |
| virtual void CleanUp() {} |
| |
| // Called after the message loop has been deleted. In general clients |
| // should prefer to use CleanUp(). This method is used when code needs to |
| // be run after all of the MessageLoop::DestructionObservers have completed. |
| virtual void CleanUpAfterMessageLoopDestruction() {} |
| |
| static void SetThreadWasQuitProperly(bool flag); |
| static bool GetThreadWasQuitProperly(); |
| |
| void set_message_loop(MessageLoop* message_loop) { |
| message_loop_ = message_loop; |
| } |
| |
| private: |
| // PlatformThread::Delegate methods: |
| virtual void ThreadMain(); |
| |
| // We piggy-back on the startup_data_ member to know if we successfully |
| // started the thread. This way we know that we need to call Join. |
| bool thread_was_started() const { return startup_data_ != NULL; } |
| |
| // If true, we're in the middle of stopping, and shouldn't access |
| // |message_loop_|. It may non-NULL and invalid. |
| bool stopping_; |
| |
| // Used to pass data to ThreadMain. |
| struct StartupData; |
| StartupData* startup_data_; |
| |
| // The thread's handle. |
| PlatformThreadHandle thread_; |
| |
| // The thread's message loop. Valid only while the thread is alive. Set |
| // by the created thread. |
| MessageLoop* message_loop_; |
| |
| // Our thread's ID. |
| PlatformThreadId thread_id_; |
| |
| // The name of the thread. Used for debugging purposes. |
| std::string name_; |
| |
| friend class ThreadQuitTask; |
| |
| DISALLOW_COPY_AND_ASSIGN(Thread); |
| }; |
| |
| } // namespace base |
| |
| #endif // BASE_THREAD_H_ |