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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 <memory>
      9 
     10 #include "base/base_export.h"
     11 #include "base/macros.h"
     12 #include "base/message_loop/message_pump.h"
     13 #include "base/observer_list.h"
     14 #include "base/time/time.h"
     15 
     16 typedef struct _GMainContext GMainContext;
     17 typedef struct _GPollFD GPollFD;
     18 typedef struct _GSource GSource;
     19 
     20 namespace base {
     21 
     22 // This class implements a base MessagePump needed for TYPE_UI MessageLoops on
     23 // platforms using GLib.
     24 class BASE_EXPORT MessagePumpGlib : public MessagePump {
     25  public:
     26   MessagePumpGlib();
     27   ~MessagePumpGlib() override;
     28 
     29   // Internal methods used for processing the pump callbacks.  They are
     30   // public for simplicity but should not be used directly.  HandlePrepare
     31   // is called during the prepare step of glib, and returns a timeout that
     32   // will be passed to the poll. HandleCheck is called after the poll
     33   // has completed, and returns whether or not HandleDispatch should be called.
     34   // HandleDispatch is called if HandleCheck returned true.
     35   int HandlePrepare();
     36   bool HandleCheck();
     37   void HandleDispatch();
     38 
     39   // Overridden from MessagePump:
     40   void Run(Delegate* delegate) override;
     41   void Quit() override;
     42   void ScheduleWork() override;
     43   void ScheduleDelayedWork(const TimeTicks& delayed_work_time) override;
     44 
     45  private:
     46   bool ShouldQuit() const;
     47 
     48   // We may make recursive calls to Run, so we save state that needs to be
     49   // separate between them in this structure type.
     50   struct RunState;
     51 
     52   RunState* state_;
     53 
     54   // This is a GLib structure that we can add event sources to.  We use the
     55   // default GLib context, which is the one to which all GTK events are
     56   // dispatched.
     57   GMainContext* context_;
     58 
     59   // This is the time when we need to do delayed work.
     60   TimeTicks delayed_work_time_;
     61 
     62   // The work source.  It is shared by all calls to Run and destroyed when
     63   // the message pump is destroyed.
     64   GSource* work_source_;
     65 
     66   // We use a wakeup pipe to make sure we'll get out of the glib polling phase
     67   // when another thread has scheduled us to do some work.  There is a glib
     68   // mechanism g_main_context_wakeup, but this won't guarantee that our event's
     69   // Dispatch() will be called.
     70   int wakeup_pipe_read_;
     71   int wakeup_pipe_write_;
     72   // Use a scoped_ptr to avoid needing the definition of GPollFD in the header.
     73   std::unique_ptr<GPollFD> wakeup_gpollfd_;
     74 
     75   DISALLOW_COPY_AND_ASSIGN(MessagePumpGlib);
     76 };
     77 
     78 }  // namespace base
     79 
     80 #endif  // BASE_MESSAGE_LOOP_MESSAGE_PUMP_GLIB_H_
     81