ui/base/gtk/g_object_destructor_filo.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 UI_BASE_GTK_G_OBJECT_DESTRUCTOR_FILO_H_
   6 #define UI_BASE_GTK_G_OBJECT_DESTRUCTOR_FILO_H_
   7
   8 #include <glib.h>
   9 #include <list>
  10 #include <map>
  11
  12 #include "base/basictypes.h"
  13 #include "ui/base/ui_base_export.h"
  14
  15 template <typename T> struct DefaultSingletonTraits;
  16
  17 typedef struct _GObject GObject;
  18
  19 namespace ui {
  20
  21 // This class hooks calls to g_object_weak_ref()/unref() and executes them in
  22 // FILO order. This is important if there are several hooks to the single object
  23 // (set up at different levels of class hierarchy) and the lowest hook (set up
  24 // first) is deleting self - it must be called last (among hooks for the given
  25 // object). Unfortunately Glib does not provide this guarantee.
  26 //
  27 // Use it as follows:
  28 //
  29 // static void OnDestroyedThunk(gpointer data, GObject *where_the_object_was) {
  30 //   reinterpret_cast<MyClass*>(data)->OnDestroyed(where_the_object_was);
  31 // }
  32 // void MyClass::OnDestroyed(GObject *where_the_object_was) {
  33 //   destroyed_ = true;
  34 //   delete this;
  35 // }
  36 // MyClass::Init() {
  37 //   ...
  38 //   ui::GObjectDestructorFILO::GetInstance()->Connect(
  39 //       G_OBJECT(my_widget), &OnDestroyedThunk, this);
  40 // }
  41 // MyClass::~MyClass() {
  42 //   if (!destroyed_) {
  43 //     ui::GObjectDestructorFILO::GetInstance()->Disconnect(
  44 //         G_OBJECT(my_widget), &OnDestroyedThunk, this);
  45 //   }
  46 // }
  47 //
  48 // TODO(glotov): Probably worth adding ScopedGObjectDtor<T>.
  49 //
  50 // This class is a singleton. Not thread safe. Must be called within UI thread.
  51 class UI_BASE_EXPORT GObjectDestructorFILO {
  52  public:
  53   typedef void (*DestructorHook)(void* context, GObject* where_the_object_was);
  54
  55   static GObjectDestructorFILO* GetInstance();
  56   void Connect(GObject* object, DestructorHook callback, void* context);
  57   void Disconnect(GObject* object, DestructorHook callback, void* context);
  58
  59  private:
  60   struct Hook {
  61     Hook(GObject* o, DestructorHook cb, void* ctx)
  62         : object(o), callback(cb), context(ctx) {
  63     }
  64     bool equal(GObject* o, DestructorHook cb, void* ctx) const {
  65       return object == o && callback == cb && context == ctx;
  66     }
  67     GObject* object;
  68     DestructorHook callback;
  69     void* context;
  70   };
  71   typedef std::list<Hook> HandlerList;
  72   typedef std::map<GObject*, HandlerList> HandlerMap;
  73
  74   GObjectDestructorFILO();
  75   ~GObjectDestructorFILO();
  76   friend struct DefaultSingletonTraits<GObjectDestructorFILO>;
  77
  78   void WeakNotify(GObject* where_the_object_was);
  79   static void WeakNotifyThunk(gpointer data, GObject* where_the_object_was) {
  80     reinterpret_cast<GObjectDestructorFILO*>(data)->WeakNotify(
  81         where_the_object_was);
  82   }
  83
  84   HandlerMap handler_map_;
  85
  86   DISALLOW_COPY_AND_ASSIGN(GObjectDestructorFILO);
  87 };
  88
  89 }  // namespace ui
  90
  91 #endif  // UI_BASE_GTK_G_OBJECT_DESTRUCTOR_FILO_H_