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 namespace base {
  15 template <typename T> struct DefaultSingletonTraits;
  16 }
  17
  18 typedef struct _GObject GObject;
  19
  20 namespace libgtk2ui {
  21
  22 // This class hooks calls to g_object_weak_ref()/unref() and executes them in
  23 // FILO order. This is important if there are several hooks to the single object
  24 // (set up at different levels of class hierarchy) and the lowest hook (set up
  25 // first) is deleting self - it must be called last (among hooks for the given
  26 // object). Unfortunately Glib does not provide this guarantee.
  27 //
  28 // Use it as follows:
  29 //
  30 // static void OnDestroyedThunk(gpointer data, GObject *where_the_object_was) {
  31 //   reinterpret_cast<MyClass*>(data)->OnDestroyed(where_the_object_was);
  32 // }
  33 // void MyClass::OnDestroyed(GObject *where_the_object_was) {
  34 //   destroyed_ = true;
  35 //   delete this;
  36 // }
  37 // MyClass::Init() {
  38 //   ...
  39 //   ui::GObjectDestructorFILO::GetInstance()->Connect(
  40 //       G_OBJECT(my_widget), &OnDestroyedThunk, this);
  41 // }
  42 // MyClass::~MyClass() {
  43 //   if (!destroyed_) {
  44 //     ui::GObjectDestructorFILO::GetInstance()->Disconnect(
  45 //         G_OBJECT(my_widget), &OnDestroyedThunk, this);
  46 //   }
  47 // }
  48 //
  49 // TODO(glotov): Probably worth adding ScopedGObjectDtor<T>.
  50 //
  51 // This class is a singleton. Not thread safe. Must be called within UI thread.
  52 class GObjectDestructorFILO {
  53  public:
  54   typedef void (*DestructorHook)(void* context, GObject* where_the_object_was);
  55
  56   static GObjectDestructorFILO* GetInstance();
  57   void Connect(GObject* object, DestructorHook callback, void* context);
  58   void Disconnect(GObject* object, DestructorHook callback, void* context);
  59
  60  private:
  61   struct Hook {
  62     Hook(GObject* o, DestructorHook cb, void* ctx)
  63         : object(o), callback(cb), context(ctx) {
  64     }
  65     bool equal(GObject* o, DestructorHook cb, void* ctx) const {
  66       return object == o && callback == cb && context == ctx;
  67     }
  68     GObject* object;
  69     DestructorHook callback;
  70     void* context;
  71   };
  72   typedef std::list<Hook> HandlerList;
  73   typedef std::map<GObject*, HandlerList> HandlerMap;
  74
  75   GObjectDestructorFILO();
  76   ~GObjectDestructorFILO();
  77   friend struct base::DefaultSingletonTraits<GObjectDestructorFILO>;
  78
  79   void WeakNotify(GObject* where_the_object_was);
  80   static void WeakNotifyThunk(gpointer data, GObject* where_the_object_was) {
  81     reinterpret_cast<GObjectDestructorFILO*>(data)->WeakNotify(
  82         where_the_object_was);
  83   }
  84
  85   HandlerMap handler_map_;
  86
  87   DISALLOW_COPY_AND_ASSIGN(GObjectDestructorFILO);
  88 };
  89
  90 }  // namespace libgtk2ui
  91
  92 #endif  // CHROME_BROWSER_UI_LIBGTK2UI_G_OBJECT_DESTRUCTOR_FILO_H_