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singletonref.hxx
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1 /* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
2 /*
3 * This file is part of the LibreOffice project.
4 *
5 * This Source Code Form is subject to the terms of the Mozilla Public
6 * License, v. 2.0. If a copy of the MPL was not distributed with this
7 * file, You can obtain one at http://mozilla.org/MPL/2.0/.
8 *
9 * This file incorporates work covered by the following license notice:
10 *
11 * Licensed to the Apache Software Foundation (ASF) under one or more
12 * contributor license agreements. See the NOTICE file distributed
13 * with this work for additional information regarding copyright
14 * ownership. The ASF licenses this file to you under the Apache
15 * License, Version 2.0 (the "License"); you may not use this file
16 * except in compliance with the License. You may obtain a copy of
17 * the License at http://www.apache.org/licenses/LICENSE-2.0 .
18 */
19
20 #ifndef INCLUDED_SALHELPER_SINGLETONREF_HXX
21 #define INCLUDED_SALHELPER_SINGLETONREF_HXX
22
23 #include <sal/config.h>
24
25 #include <cstddef>
26
27 #include <osl/mutex.hxx>
28 #include <rtl/instance.hxx>
29 #include <osl/diagnose.h>
30 #include <osl/getglobalmutex.hxx>
31
32
33 namespace salhelper{
34
35
68 template< class SingletonClass >
69 class SingletonRef
70 {
71
72 // member
73
74 private:
75
77 static SingletonClass* m_pInstance;
78
80 static sal_Int32 m_nRef;
81
82
83 // interface
84
85 public:
86
87
95 SingletonRef()
96 {
97 // GLOBAL SAFE ->
98 ::osl::MutexGuard aLock(SingletonRef::ownStaticLock());
99
100 // must be increased before(!) the check is done.
101 // Otherwise this check can fail inside the same thread ...
102 ++m_nRef;
103 if (m_nRef == 1)
104 m_pInstance = new SingletonClass();
105
106 OSL_ENSURE(m_nRef>0 && m_pInstance, "Race? Ref count of singleton >0, but instance is NULL!");
107 // <- GLOBAL SAFE
108 }
109
110
118 ~SingletonRef()
119 {
120 // GLOBAL SAFE ->
121 ::osl::MutexGuard aLock(SingletonRef::ownStaticLock());
122
123 // must be decreased before(!) the check is done.
124 // Otherwise this check can fail inside the same thread ...
125 --m_nRef;
126 if (m_nRef == 0)
127 {
128 delete m_pInstance;
129 m_pInstance = NULL;
130 }
131 // <- GLOBAL SAFE
132 }
133
134
137 SingletonClass* operator->() const
138 {
139 // GLOBAL SAFE ->
140 ::osl::MutexGuard aLock(SingletonRef::ownStaticLock());
141 return m_pInstance;
142 // <- GLOBAL SAFE
143 }
144
145
148 SingletonClass& operator*() const
149 {
150 // GLOBAL SAFE ->
151 ::osl::MutexGuard aLock(SingletonRef::ownStaticLock());
152 return *m_pInstance;
153 // <- GLOBAL SAFE
154 }
155
156
157 // helper
158
159 private:
160
161
168 struct SingletonLockInit
169 {
170 ::osl::Mutex* operator()()
171 {
172 static ::osl::Mutex aInstance;
173 return &aInstance;
174 }
175 };
176
177 ::osl::Mutex& ownStaticLock() const
178 {
179 return *rtl_Instance< ::osl::Mutex,
180 SingletonLockInit,
181 ::osl::MutexGuard,
182 ::osl::GetGlobalMutex >::create(SingletonLockInit(), ::osl::GetGlobalMutex());
183 }
184 };
185
186 template< class SingletonClass >
187 SingletonClass* SingletonRef< SingletonClass >::m_pInstance = NULL;
188
189 template< class SingletonClass >
190 sal_Int32 SingletonRef< SingletonClass >::m_nRef = 0;
191
192 } // namespace salhelper
193
194 #endif // INCLUDED_SALHELPER_SINGLETONREF_HXX
195
196 /* vim:set shiftwidth=4 softtabstop=4 expandtab: */
osl::GetGlobalMutex
A helper functor for the rtl_Instance template.
Definition: getglobalmutex.hxx:31
salhelper
Definition: condition.hxx:29
config.h
osl::Mutex
A mutual exclusion synchronization object.
Definition: mutex.hxx:30
salhelper::SingletonRef::SingletonRef
SingletonRef()
standard ctor.
Definition: singletonref.hxx:95
salhelper::SingletonRef
template for implementing singleton classes.
Definition: singletonref.hxx:69
getglobalmutex.hxx
diagnose.h
osl::MutexGuard
Guard< Mutex > MutexGuard
Definition: mutex.hxx:224
salhelper::SingletonRef::operator*
SingletonClass & operator*() const
Allows (*rSingle).someBodyOp().
Definition: singletonref.hxx:148
salhelper::SingletonRef::~SingletonRef
~SingletonRef()
standard dtor.
Definition: singletonref.hxx:118
OSL_ENSURE
#define OSL_ENSURE(c, m)
Definition: diagnose.h:101
instance.hxx
salhelper::SingletonRef::operator->
SingletonClass * operator->() const
Allows rSingle->someBodyOp().
Definition: singletonref.hxx:137
osl::Guard
A helper class for mutex objects and interfaces.
Definition: mutex.hxx:108
mutex.hxx