Version of MessagePumpForUI optimized for GPU process

base/message_loop/message_pump_win.h

 // 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.
 
 #ifndef BASE_MESSAGE_LOOP_MESSAGE_PUMP_WIN_H_
 #define BASE_MESSAGE_LOOP_MESSAGE_PUMP_WIN_H_
 
 #include <windows.h>
 
 #include <list>
 
 #include "base/base_export.h"
 #include "base/message_loop/message_pump.h"
 #include "base/observer_list.h"
 #include "base/time/time.h"
 #include "base/win/scoped_handle.h"
 
 namespace base {
 
 // MessagePumpWin serves as the base for specialized versions of the MessagePump
 // for Windows. It provides basic functionality like handling of observers and
 // controlling the lifetime of the message pump.
 class BASE_EXPORT MessagePumpWin : public MessagePump {
  public:
-  MessagePumpWin() : have_work_(0), state_(NULL) {}
+  MessagePumpWin() : work_state_(READY), state_(NULL) {}
 
   // MessagePump methods:
   void Run(Delegate* delegate) override;
   void Quit() override;
 
  protected:
   struct RunState {
     Delegate* delegate;
 
     // Used to flag that the current Run() invocation should return ASAP.
     bool should_quit;
 
     // Used to count how many Run() invocations are on the stack.
     int run_depth;
   };
 
+  // State used with work_state_ variable.
+  enum WorkState {
+    READY = 0,      // Ready to accept new work.
+    HAVE_WORK = 1,  // New work has been signalled.
+    WORKING = 2     // Handling the work.
+  };
+
   virtual void DoRunLoop() = 0;
   int GetCurrentDelay() const;
 
   // The time at which delayed work should run.
   TimeTicks delayed_work_time_;
 
-  // A boolean value used to indicate if there is a kMsgDoWork message pending
+  // A value used to indicate if there is a kMsgDoWork message pending
   // in the Windows Message queue.  There is at most one such message, and it
   // can drive execution of tasks when a native message pump is running.
-  LONG have_work_;
+  LONG work_state_;
 
   // State for the current invocation of Run.
   RunState* state_;
 };
 
 //-----------------------------------------------------------------------------
+// MessagePumpForUIBase serves as a base class for for specialized versions of
+// MessagePump instantiated with TYPE_UI. It provides basic functionality for
+// creating a hidden window with a message queue and handling window messages,
+// including the special kMsgHaveWork message that indicates the scheduled work,
+// handling timers, etc.
+//
+class BASE_EXPORT MessagePumpForUIBase : public MessagePumpWin {
+ public:
+  // The application-defined code passed to the hook procedure.
+  static const int kMessageFilterCode = 0x5001;
+
+  MessagePumpForUIBase();
+  ~MessagePumpForUIBase() override;
+
+  // MessagePump methods:
+  void ScheduleWork() override;
+
+ protected:
+  virtual void HandleWorkMessage() = 0;
+  virtual void HandleTimerMessage() = 0;
+
+  bool IsWorkMessage(const MSG& msg) const;
+  void SetTimer(int delay_msec);
+  void KillTimer();
+
+ private:
+  static LRESULT CALLBACK WndProcThunk(HWND window_handle,
+                                       UINT message,
+                                       WPARAM wparam,
+                                       LPARAM lparam);
+  void InitMessageWnd();
+
+  // Atom representing the registered window class.
+  ATOM atom_;
+
+  // A hidden message-only window.
+  HWND message_hwnd_;
+};
+
+//-----------------------------------------------------------------------------
 // MessagePumpForUI extends MessagePumpWin with methods that are particular to a
 // MessageLoop instantiated with TYPE_UI.
 //
 // MessagePumpForUI implements a "traditional" Windows message pump. It contains
 // a nearly infinite loop that peeks out messages, and then dispatches them.
 // Intermixed with those peeks are callouts to DoWork for pending tasks, and
 // DoDelayedWork for pending timers. When there are no events to be serviced,
 // this pump goes into a wait state. In most cases, this message pump handles
 // all processing.
 //
@@ skipping 27 matching lines @@
 // kMsgHaveWork messages.  As a result, care is taken to do some peeking in
 // between the posting of each kMsgHaveWork message (i.e., after kMsgHaveWork
 // is peeked, and before a replacement kMsgHaveWork is posted).
 //
 // NOTE: Although it may seem odd that messages are used to start and stop this
 // flow (as opposed to signaling objects, etc.), it should be understood that
 // the native message pump will *only* respond to messages.  As a result, it is
 // an excellent choice.  It is also helpful that the starter messages that are
 // placed in the queue when new task arrive also awakens DoRunLoop.
 //
-class BASE_EXPORT MessagePumpForUI : public MessagePumpWin {
+class BASE_EXPORT MessagePumpForUI : public MessagePumpForUIBase {
  public:
-  // The application-defined code passed to the hook procedure.
-  static const int kMessageFilterCode = 0x5001;
-
   MessagePumpForUI();
   ~MessagePumpForUI() override;
 
+ private:
   // MessagePump methods:
-  void ScheduleWork() override;
+  void DoRunLoop() override;
   void ScheduleDelayedWork(const TimeTicks& delayed_work_time) override;
 
- private:
-  static LRESULT CALLBACK WndProcThunk(HWND window_handle,
-                                       UINT message,
-                                       WPARAM wparam,
-                                       LPARAM lparam);
-  void DoRunLoop() override;
-  void InitMessageWnd();
+  void HandleWorkMessage() override;
+  void HandleTimerMessage() override;
+
+  bool ProcessNextWindowsMessage();
   void WaitForWork();
-  void HandleWorkMessage();
-  void HandleTimerMessage();
-  void RescheduleTimer();
-  bool ProcessNextWindowsMessage();
+
   bool ProcessMessageHelper(const MSG& msg);
   bool ProcessPumpReplacementMessage();
-
-  // Atom representing the registered window class.
-  ATOM atom_;
-
-  // A hidden message-only window.
-  HWND message_hwnd_;
+  void RescheduleTimer();
 };
 
 //-----------------------------------------------------------------------------
+// MessagePumpForGpu is a simplified version of MessagePumpForUI that is
+// optimized for the GPU process. Unlike MessagePumpForUI it doesn't handle a
+// situation where a native message pump might be used by modal dialogs and
+// message boxes. That allows to skip some system calls like setting and killing
+// timers, getting status of the message queue, etc.
+
+class BASE_EXPORT MessagePumpForGpu : public MessagePumpForUIBase {
+ public:
+  MessagePumpForGpu();
+  ~MessagePumpForGpu() override;
+
+  // Factory methods.
+  static void InitFactory();
+  static scoped_ptr<MessagePump> CreateMessagePumpForGpu();
+
+ private:
+  // MessagePump methods:
+  void DoRunLoop() override;
+  void ScheduleDelayedWork(const TimeTicks& delayed_work_time) override;
+
+  void HandleWorkMessage() override;
+  void HandleTimerMessage() override;
+
+  void ProcessWindowsMessages();
+  void WaitForWork();
+};
+
+//-----------------------------------------------------------------------------
 // MessagePumpForIO extends MessagePumpWin with methods that are particular to a
 // MessageLoop instantiated with TYPE_IO. This version of MessagePump does not
 // deal with Windows mesagges, and instead has a Run loop based on Completion
 // Ports so it is better suited for IO operations.
 //
 class BASE_EXPORT MessagePumpForIO : public MessagePumpWin {
  public:
   struct IOContext;
 
   // Clients interested in receiving OS notifications when asynchronous IO
@@ skipping 176 matching lines @@
   // This list will be empty almost always. It stores IO completions that have
   // not been delivered yet because somebody was doing cleanup.
   std::list<IOItem> completed_io_;
 
   ObserverList<IOObserver> io_observers_;
 };
 
 }  // namespace base
 
 #endif  // BASE_MESSAGE_LOOP_MESSAGE_PUMP_WIN_H_