chrome/browser/ui/libgtk2ui/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 CHROME_BROWSER_UI_LIBGTK2UI_G_OBJECT_DESTRUCTOR_FILO_H_
   6 #define CHROME_BROWSER_UI_LIBGTK2UI_G_OBJECT_DESTRUCTOR_FILO_H_
   7
   8 #include <glib.h>
   9 #include <list>
  10 #include <map>
  11
  12 #include "base/basictypes.h"
  13
  14 template <typename T> struct DefaultSingletonTraits;
  15
  16 typedef struct _GObject GObject;
  17
  18 namespace libgtk2ui {
  19
  20 // This class hooks calls to g_object_weak_ref()/unref() and executes them in
  21 // FILO order. This is important if there are several hooks to the single object
  22 // (set up at different levels of class hierarchy) and the lowest hook (set up
  23 // first) is deleting self - it must be called last (among hooks for the given
  24 // object). Unfortunately Glib does not provide this guarantee.
  25 //
  26 // Use it as follows:
  27 //
  28 // static void OnDestroyedThunk(gpointer data, GObject *where_the_object_was) {
  29 //   reinterpret_cast<MyClass*>(data)->OnDestroyed(where_the_object_was);
  30 // }
  31 // void MyClass::OnDestroyed(GObject *where_the_object_was) {
  32 //   destroyed_ = true;
  33 //   delete this;
  34 // }
  35 // MyClass::Init() {
  36 //   ...
  37 //   ui::GObjectDestructorFILO::GetInstance()->Connect(
  38 //       G_OBJECT(my_widget), &OnDestroyedThunk, this);
  39 // }
  40 // MyClass::~MyClass() {
  41 //   if (!destroyed_) {
  42 //     ui::GObjectDestructorFILO::GetInstance()->Disconnect(
  43 //         G_OBJECT(my_widget), &OnDestroyedThunk, this);
  44 //   }
  45 // }
  46 //
  47 // TODO(glotov): Probably worth adding ScopedGObjectDtor<T>.
  48 //
  49 // This class is a singleton. Not thread safe. Must be called within UI thread.
  50 class GObjectDestructorFILO {
  51  public:
  52   typedef void (*DestructorHook)(void* context, GObject* where_the_object_was);
  53
  54   static GObjectDestructorFILO* GetInstance();
  55   void Connect(GObject* object, DestructorHook callback, void* context);
  56   void Disconnect(GObject* object, DestructorHook callback, void* context);
  57
  58  private:
  59   struct Hook {
  60     Hook(GObject* o, DestructorHook cb, void* ctx)
  61         : object(o), callback(cb), context(ctx) {
  62     }
  63     bool equal(GObject* o, DestructorHook cb, void* ctx) const {
  64       return object == o && callback == cb && context == ctx;
  65     }
  66     GObject* object;
  67     DestructorHook callback;
  68     void* context;
  69   };
  70   typedef std::list<Hook> HandlerList;
  71   typedef std::map<GObject*, HandlerList> HandlerMap;
  72
  73   GObjectDestructorFILO();
  74   ~GObjectDestructorFILO();
  75   friend struct DefaultSingletonTraits<GObjectDestructorFILO>;
  76
  77   void WeakNotify(GObject* where_the_object_was);
  78   static void WeakNotifyThunk(gpointer data, GObject* where_the_object_was) {
  79     reinterpret_cast<GObjectDestructorFILO*>(data)->WeakNotify(
  80         where_the_object_was);
  81   }
  82
  83   HandlerMap handler_map_;
  84
  85   DISALLOW_COPY_AND_ASSIGN(GObjectDestructorFILO);
  86 };
  87
  88 }  // namespace libgtk2ui
  89
  90 #endif  // CHROME_BROWSER_UI_LIBGTK2UI_G_OBJECT_DESTRUCTOR_FILO_H_