base/message_pump_glib.h

   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 BASE_MESSAGE_PUMP_GLIB_H_
   6 #define BASE_MESSAGE_PUMP_GLIB_H_
   7
   8 #include "base/base_export.h"
   9 #include "base/memory/scoped_ptr.h"
  10 #include "base/message_pump.h"
  11 #include "base/observer_list.h"
  12 #include "base/time.h"
  13
  14 typedef struct _GMainContext GMainContext;
  15 typedef struct _GPollFD GPollFD;
  16 typedef struct _GSource GSource;
  17
  18 namespace base {
  19
  20 // MessagePumpObserver is notified prior to an event being dispatched. As
  21 // Observers are notified of every change, they have to be FAST! The platform
  22 // specific implementation of the class is in message_pump_gtk/message_pump_x.
  23 class MessagePumpObserver;
  24
  25 // MessagePumpDispatcher is used during a nested invocation of Run to dispatch
  26 // events. If Run is invoked with a non-NULL MessagePumpDispatcher, MessageLoop
  27 // does not dispatch events (or invoke gtk_main_do_event), rather every event is
  28 // passed to Dispatcher's Dispatch method for dispatch. It is up to the
  29 // Dispatcher to dispatch, or not, the event. The platform specific
  30 // implementation of the class is in message_pump_gtk/message_pump_x.
  31 class MessagePumpDispatcher;
  32
  33 // This class implements a base MessagePump needed for TYPE_UI MessageLoops on
  34 // platforms using GLib.
  35 class BASE_EXPORT MessagePumpGlib : public MessagePump {
  36  public:
  37   MessagePumpGlib();
  38
  39   // Like MessagePump::Run, but events are routed through dispatcher.
  40   virtual void RunWithDispatcher(Delegate* delegate,
  41                                  MessagePumpDispatcher* dispatcher);
  42
  43   // Internal methods used for processing the pump callbacks.  They are
  44   // public for simplicity but should not be used directly.  HandlePrepare
  45   // is called during the prepare step of glib, and returns a timeout that
  46   // will be passed to the poll. HandleCheck is called after the poll
  47   // has completed, and returns whether or not HandleDispatch should be called.
  48   // HandleDispatch is called if HandleCheck returned true.
  49   int HandlePrepare();
  50   bool HandleCheck();
  51   void HandleDispatch();
  52
  53   // Adds an Observer, which will start receiving notifications immediately.
  54   void AddObserver(MessagePumpObserver* observer);
  55
  56   // Removes an Observer.  It is safe to call this method while an Observer is
  57   // receiving a notification callback.
  58   void RemoveObserver(MessagePumpObserver* observer);
  59
  60   // Overridden from MessagePump:
  61   virtual void Run(Delegate* delegate) OVERRIDE;
  62   virtual void Quit() OVERRIDE;
  63   virtual void ScheduleWork() OVERRIDE;
  64   virtual void ScheduleDelayedWork(const TimeTicks& delayed_work_time) OVERRIDE;
  65
  66  protected:
  67   virtual ~MessagePumpGlib();
  68
  69   // Returns the dispatcher for the current run state (|state_->dispatcher|).
  70   MessagePumpDispatcher* GetDispatcher();
  71
  72   ObserverList<MessagePumpObserver>& observers() { return observers_; }
  73
  74  private:
  75   // We may make recursive calls to Run, so we save state that needs to be
  76   // separate between them in this structure type.
  77   struct RunState;
  78
  79   RunState* state_;
  80
  81   // This is a GLib structure that we can add event sources to.  We use the
  82   // default GLib context, which is the one to which all GTK events are
  83   // dispatched.
  84   GMainContext* context_;
  85
  86   // This is the time when we need to do delayed work.
  87   TimeTicks delayed_work_time_;
  88
  89   // The work source.  It is shared by all calls to Run and destroyed when
  90   // the message pump is destroyed.
  91   GSource* work_source_;
  92
  93   // We use a wakeup pipe to make sure we'll get out of the glib polling phase
  94   // when another thread has scheduled us to do some work.  There is a glib
  95   // mechanism g_main_context_wakeup, but this won't guarantee that our event's
  96   // Dispatch() will be called.
  97   int wakeup_pipe_read_;
  98   int wakeup_pipe_write_;
  99   // Use a scoped_ptr to avoid needing the definition of GPollFD in the header.
 100   scoped_ptr<GPollFD> wakeup_gpollfd_;
 101
 102   // List of observers.
 103   ObserverList<MessagePumpObserver> observers_;
 104
 105   DISALLOW_COPY_AND_ASSIGN(MessagePumpGlib);
 106 };
 107
 108 }  // namespace base
 109
 110 #endif  // BASE_MESSAGE_PUMP_GLIB_H_