base/message_pump_glib.h

   1 // Copyright (c) 2011 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 #pragma once
   8
   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 MessagePumpGlib : public MessagePump {
  36  public:
  37   MessagePumpGlib();
  38   virtual ~MessagePumpGlib();
  39
  40   // Like MessagePump::Run, but events are routed through dispatcher.
  41   virtual void RunWithDispatcher(Delegate* delegate,
  42                                  MessagePumpDispatcher* dispatcher);
  43
  44   // Run a single iteration of the mainloop. A return value of true indicates
  45   // that an event was handled. |block| indicates if it should wait if no event
  46   // is ready for processing.
  47   virtual bool RunOnce(GMainContext* context, bool block) = 0;
  48
  49   // Internal methods used for processing the pump callbacks.  They are
  50   // public for simplicity but should not be used directly.  HandlePrepare
  51   // is called during the prepare step of glib, and returns a timeout that
  52   // will be passed to the poll. HandleCheck is called after the poll
  53   // has completed, and returns whether or not HandleDispatch should be called.
  54   // HandleDispatch is called if HandleCheck returned true.
  55   int HandlePrepare();
  56   bool HandleCheck();
  57   void HandleDispatch();
  58
  59   // Adds an Observer, which will start receiving notifications immediately.
  60   void AddObserver(MessagePumpObserver* observer);
  61
  62   // Removes an Observer.  It is safe to call this method while an Observer is
  63   // receiving a notification callback.
  64   void RemoveObserver(MessagePumpObserver* observer);
  65
  66   // Overridden from MessagePump:
  67   virtual void Run(Delegate* delegate);
  68   virtual void Quit();
  69   virtual void ScheduleWork();
  70   virtual void ScheduleDelayedWork(const TimeTicks& delayed_work_time);
  71
  72  protected:
  73   // Returns the dispatcher for the current run state (|state_->dispatcher|).
  74   MessagePumpDispatcher* GetDispatcher();
  75
  76   ObserverList<MessagePumpObserver>& observers() { return observers_; }
  77
  78  private:
  79   // We may make recursive calls to Run, so we save state that needs to be
  80   // separate between them in this structure type.
  81   struct RunState;
  82
  83   RunState* state_;
  84
  85   // This is a GLib structure that we can add event sources to.  We use the
  86   // default GLib context, which is the one to which all GTK events are
  87   // dispatched.
  88   GMainContext* context_;
  89
  90   // This is the time when we need to do delayed work.
  91   TimeTicks delayed_work_time_;
  92
  93   // The work source.  It is shared by all calls to Run and destroyed when
  94   // the message pump is destroyed.
  95   GSource* work_source_;
  96
  97   // We use a wakeup pipe to make sure we'll get out of the glib polling phase
  98   // when another thread has scheduled us to do some work.  There is a glib
  99   // mechanism g_main_context_wakeup, but this won't guarantee that our event's
 100   // Dispatch() will be called.
 101   int wakeup_pipe_read_;
 102   int wakeup_pipe_write_;
 103   // Use a scoped_ptr to avoid needing the definition of GPollFD in the header.
 104   scoped_ptr<GPollFD> wakeup_gpollfd_;
 105
 106   // List of observers.
 107   ObserverList<MessagePumpObserver> observers_;
 108
 109   DISALLOW_COPY_AND_ASSIGN(MessagePumpGlib);
 110 };
 111
 112 }  // namespace base
 113
 114 #endif  // BASE_MESSAGE_PUMP_GLIB_H_