summaryrefslogtreecommitdiffstats
path: root/ipc/chromium/src/base/message_pump_glib.h
blob: 0cb48ca36adc7cc3cb8f75050e9859584f72a9f7 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
// Copyright (c) 2008 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_PUMP_GLIB_H_
#define BASE_MESSAGE_PUMP_GLIB_H_

#include "base/message_pump.h"
#include "base/observer_list.h"
#include "base/time.h"
#include "mozilla/UniquePtr.h"
#include "mozilla/Atomics.h"

typedef union _GdkEvent GdkEvent;
typedef struct _GMainContext GMainContext;
typedef struct _GPollFD GPollFD;
typedef struct _GSource GSource;

namespace base {

// This class implements a MessagePump needed for TYPE_UI MessageLoops on
// OS_LINUX platforms using GLib.
class MessagePumpForUI : public MessagePump {
 public:
  // Observer is notified prior to a GdkEvent event being dispatched. As
  // Observers are notified of every change, they have to be FAST!
  class Observer {
   public:
    virtual ~Observer() {}

    // This method is called before processing a message.
    virtual void WillProcessEvent(GdkEvent* event) = 0;

    // This method is called after processing a message.
    virtual void DidProcessEvent(GdkEvent* event) = 0;
  };

  // Dispatcher is used during a nested invocation of Run to dispatch events.
  // If Run is invoked with a non-NULL Dispatcher, MessageLoop does not
  // dispatch events (or invoke gtk_main_do_event), rather every event is
  // passed to Dispatcher's Dispatch method for dispatch. It is up to the
  // Dispatcher to dispatch, or not, the event.
  //
  // The nested loop is exited by either posting a quit, or returning false
  // from Dispatch.
  class Dispatcher {
   public:
    virtual ~Dispatcher() {}
    // Dispatches the event. If true is returned processing continues as
    // normal. If false is returned, the nested loop exits immediately.
    virtual bool Dispatch(GdkEvent* event) = 0;
  };

  MessagePumpForUI();
  virtual ~MessagePumpForUI();

  // Like MessagePump::Run, but GdkEvent objects are routed through dispatcher.
  virtual void RunWithDispatcher(Delegate* delegate, Dispatcher* dispatcher);

  virtual void Run(Delegate* delegate) { RunWithDispatcher(delegate, NULL); }
  virtual void Quit();
  virtual void ScheduleWork();
  virtual void ScheduleDelayedWork(const TimeTicks& delayed_work_time);

  // Internal methods used for processing the pump callbacks.  They are
  // public for simplicity but should not be used directly.  HandlePrepare
  // is called during the prepare step of glib, and returns a timeout that
  // will be passed to the poll. HandleCheck is called after the poll
  // has completed, and returns whether or not HandleDispatch should be called.
  // HandleDispatch is called if HandleCheck returned true.
  int HandlePrepare();
  bool HandleCheck();
  void HandleDispatch();

  // Adds an Observer, which will start receiving notifications immediately.
  void AddObserver(Observer* observer);

  // Removes an Observer.  It is safe to call this method while an Observer is
  // receiving a notification callback.
  void RemoveObserver(Observer* observer);

 private:
  // We may make recursive calls to Run, so we save state that needs to be
  // separate between them in this structure type.
  struct RunState {
    Delegate* delegate;
    Dispatcher* dispatcher;

    // 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;

    // This keeps the state of whether the pump got signaled that there was new
    // work to be done. Since we eat the message on the wake up pipe as soon as
    // we get it, we keep that state here to stay consistent.
    bool has_work;
  };

  // Invoked from EventDispatcher. Notifies all observers we're about to
  // process an event.
  void WillProcessEvent(GdkEvent* event);

  // Invoked from EventDispatcher. Notifies all observers we processed an
  // event.
  void DidProcessEvent(GdkEvent* event);

  // Callback prior to gdk dispatching an event.
  static void EventDispatcher(GdkEvent* event, void* data);

  RunState* state_;

  // This is a GLib structure that we can add event sources to.  We use the
  // default GLib context, which is the one to which all GTK events are
  // dispatched.
  GMainContext* context_;

  // This is the time when we need to do delayed work.
  TimeTicks delayed_work_time_;

  // The work source.  It is shared by all calls to Run and destroyed when
  // the message pump is destroyed.
  GSource* work_source_;

  // We use a wakeup pipe to make sure we'll get out of the glib polling phase
  // when another thread has scheduled us to do some work.  There is a glib
  // mechanism g_main_context_wakeup, but this won't guarantee that our event's
  // Dispatch() will be called.
  int wakeup_pipe_read_;
  int wakeup_pipe_write_;
  // Use an autoptr to avoid needing the definition of GPollFD in the header.
  mozilla::UniquePtr<GPollFD> wakeup_gpollfd_;

  mozilla::Atomic<bool> pipe_full_;

  // List of observers.
  ObserverList<Observer> observers_;

  DISALLOW_COPY_AND_ASSIGN(MessagePumpForUI);
};

}  // namespace base

#endif  // BASE_MESSAGE_PUMP_GLIB_H_