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      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_LOOP_MESSAGE_PUMP_GLIB_H_
      6 #define BASE_MESSAGE_LOOP_MESSAGE_PUMP_GLIB_H_
      7 
      8 #include "base/base_export.h"
      9 #include "base/memory/scoped_ptr.h"
     10 #include "base/message_loop/message_pump.h"
     11 #include "base/observer_list.h"
     12 #include "base/time/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   virtual ~MessagePumpGlib();
     39 
     40   // Like MessagePump::Run, but events are routed through dispatcher.
     41   virtual void RunWithDispatcher(Delegate* delegate,
     42                                  MessagePumpDispatcher* dispatcher);
     43 
     44   // Internal methods used for processing the pump callbacks.  They are
     45   // public for simplicity but should not be used directly.  HandlePrepare
     46   // is called during the prepare step of glib, and returns a timeout that
     47   // will be passed to the poll. HandleCheck is called after the poll
     48   // has completed, and returns whether or not HandleDispatch should be called.
     49   // HandleDispatch is called if HandleCheck returned true.
     50   int HandlePrepare();
     51   bool HandleCheck();
     52   void HandleDispatch();
     53 
     54   // Adds an Observer, which will start receiving notifications immediately.
     55   void AddObserver(MessagePumpObserver* observer);
     56 
     57   // Removes an Observer.  It is safe to call this method while an Observer is
     58   // receiving a notification callback.
     59   void RemoveObserver(MessagePumpObserver* observer);
     60 
     61   // Overridden from MessagePump:
     62   virtual void Run(Delegate* delegate) OVERRIDE;
     63   virtual void Quit() OVERRIDE;
     64   virtual void ScheduleWork() OVERRIDE;
     65   virtual void ScheduleDelayedWork(const TimeTicks& delayed_work_time) OVERRIDE;
     66 
     67  protected:
     68   // Returns the dispatcher for the current run state (|state_->dispatcher|).
     69   MessagePumpDispatcher* GetDispatcher();
     70 
     71   ObserverList<MessagePumpObserver>& observers() { return observers_; }
     72 
     73  private:
     74   // We may make recursive calls to Run, so we save state that needs to be
     75   // separate between them in this structure type.
     76   struct RunState;
     77 
     78   RunState* state_;
     79 
     80   // This is a GLib structure that we can add event sources to.  We use the
     81   // default GLib context, which is the one to which all GTK events are
     82   // dispatched.
     83   GMainContext* context_;
     84 
     85   // This is the time when we need to do delayed work.
     86   TimeTicks delayed_work_time_;
     87 
     88   // The work source.  It is shared by all calls to Run and destroyed when
     89   // the message pump is destroyed.
     90   GSource* work_source_;
     91 
     92   // We use a wakeup pipe to make sure we'll get out of the glib polling phase
     93   // when another thread has scheduled us to do some work.  There is a glib
     94   // mechanism g_main_context_wakeup, but this won't guarantee that our event's
     95   // Dispatch() will be called.
     96   int wakeup_pipe_read_;
     97   int wakeup_pipe_write_;
     98   // Use a scoped_ptr to avoid needing the definition of GPollFD in the header.
     99   scoped_ptr<GPollFD> wakeup_gpollfd_;
    100 
    101   // List of observers.
    102   ObserverList<MessagePumpObserver> observers_;
    103 
    104   DISALLOW_COPY_AND_ASSIGN(MessagePumpGlib);
    105 };
    106 
    107 }  // namespace base
    108 
    109 #endif  // BASE_MESSAGE_LOOP_MESSAGE_PUMP_GLIB_H_
    110