1 : /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
2 : /* vim: set sw=2 ts=8 et ft=cpp : */
3 : /* ***** BEGIN LICENSE BLOCK *****
4 : * Version: MPL 1.1/GPL 2.0/LGPL 2.1
5 : *
6 : * The contents of this file are subject to the Mozilla Public License Version
7 : * 1.1 (the "License"); you may not use this file except in compliance with
8 : * the License. You may obtain a copy of the License at:
9 : * http://www.mozilla.org/MPL/
10 : *
11 : * Software distributed under the License is distributed on an "AS IS" basis,
12 : * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
13 : * for the specific language governing rights and limitations under the
14 : * License.
15 : *
16 : * The Original Code is Mozilla Code.
17 : *
18 : * The Initial Developer of the Original Code is
19 : * The Mozilla Foundation
20 : * Portions created by the Initial Developer are Copyright (C) 2011
21 : * the Initial Developer. All Rights Reserved.
22 : *
23 : * Contributor(s):
24 : * Justin Lebar <justin.lebar@gmail.com>
25 : *
26 : * Alternatively, the contents of this file may be used under the terms of
27 : * either the GNU General Public License Version 2 or later (the "GPL"), or
28 : * the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
29 : * in which case the provisions of the GPL or the LGPL are applicable instead
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31 : * under the terms of either the GPL or the LGPL, and not to allow others to
32 : * use your version of this file under the terms of the MPL, indicate your
33 : * decision by deleting the provisions above and replace them with the notice
34 : * and other provisions required by the GPL or the LGPL. If you do not delete
35 : * the provisions above, a recipient may use your version of this file under
36 : * the terms of any one of the MPL, the GPL or the LGPL.
37 : *
38 : * ***** END LICENSE BLOCK ***** */
39 :
40 : #ifndef mozilla_ClearOnShutdown_h
41 : #define mozilla_ClearOnShutdown_h
42 :
43 : #include "mozilla/LinkedList.h"
44 :
45 : /*
46 : * This header exports one public method in the mozilla namespace:
47 : *
48 : * template<class SmartPtr>
49 : * void ClearOnShutdown(SmartPtr *aPtr)
50 : *
51 : * This function takes a pointer to a smart pointer (i.e., nsCOMPtr<T>*,
52 : * nsRefPtr<T>*, or nsAutoPtr<T>*) and nulls the smart pointer on shutdown.
53 : *
54 : * This is useful if you have a global smart pointer object which you don't
55 : * want to "leak" on shutdown.
56 : *
57 : * There is no way to undo a call to ClearOnShutdown, so you can call it only
58 : * on smart pointers which you know will live until the program shuts down.
59 : */
60 :
61 : namespace mozilla {
62 : namespace ClearOnShutdown_Internal {
63 :
64 : class ShutdownObserver : public LinkedListElement<ShutdownObserver>
65 4 : {
66 : public:
67 : virtual void Shutdown() = 0;
68 : };
69 :
70 : template<class SmartPtr>
71 : class PointerClearer : public ShutdownObserver
72 : {
73 : public:
74 4 : PointerClearer(SmartPtr *aPtr)
75 4 : : mPtr(aPtr)
76 4 : {}
77 :
78 4 : virtual void Shutdown()
79 : {
80 4 : if (mPtr) {
81 4 : *mPtr = NULL;
82 : }
83 4 : }
84 :
85 : private:
86 : SmartPtr *mPtr;
87 : };
88 :
89 : extern bool sHasShutDown;
90 : extern LinkedList<ShutdownObserver> sShutdownObservers;
91 :
92 : } // namespace ClearOnShutdown_Internal
93 :
94 : template<class SmartPtr>
95 4 : inline void ClearOnShutdown(SmartPtr *aPtr)
96 : {
97 : using namespace ClearOnShutdown_Internal;
98 :
99 4 : MOZ_ASSERT(!sHasShutDown);
100 4 : ShutdownObserver *observer = new PointerClearer<SmartPtr>(aPtr);
101 4 : sShutdownObservers.insertBack(observer);
102 4 : }
103 :
104 : // Called when XPCOM is shutting down, after all shutdown notifications have
105 : // been sent and after all threads' event loops have been purged.
106 1419 : inline void KillClearOnShutdown()
107 : {
108 : using namespace ClearOnShutdown_Internal;
109 :
110 : ShutdownObserver *observer;
111 2842 : while ((observer = sShutdownObservers.popFirst())) {
112 4 : observer->Shutdown();
113 : delete observer;
114 : }
115 :
116 1419 : sHasShutDown = true;
117 1419 : }
118 :
119 : } // namespace mozilla
120 :
121 : #endif
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