LibreOffice: salhelper/singletonref.hxx Source File

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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 <osl/mutex.hxx>
24 #include <rtl/instance.hxx>
25 #include <osl/diagnose.h>
26 #include <osl/getglobalmutex.hxx>
27
28
29 namespace salhelper{
30
31
64 template< class SingletonClass >
65 class SingletonRef
66 {
67
68 // member
69
70 private :
71
73 static SingletonClass* m_pInstance;
74
76 static sal_Int32 m_nRef;
77
78
79 // interface
80
81 public :
82
83
84
92 SingletonRef()
93 {
94 // GLOBAL SAFE ->
95 ::osl::MutexGuard aLock(SingletonRef::ownStaticLock());
96
97 // must be increased before(!) the check is done.
98 // Otherwise this check can fail inside the same thread ...
99 ++m_nRef;
100 if (m_nRef == 1)
101 m_pInstance = new SingletonClass();
102
103 OSL_ENSURE(m_nRef>0 && m_pInstance, "Race? Ref count of singleton >0, but instance is NULL!");
104 // <- GLOBAL SAFE
105 }
106
107
108
116 ~SingletonRef()
117 {
118 // GLOBAL SAFE ->
119 ::osl::MutexGuard aLock(SingletonRef::ownStaticLock());
120
121 // must be decreased before(!) the check is done.
122 // Otherwise this check can fail inside the same thread ...
123 --m_nRef;
124 if (m_nRef == 0)
125 {
126 delete m_pInstance;
127 m_pInstance = 0;
128 }
129 // <- GLOBAL SAFE
130 }
131
132
133
136 SingletonClass* operator->() const
137 {
138 // GLOBAL SAFE ->
139 ::osl::MutexGuard aLock(SingletonRef::ownStaticLock());
140 return m_pInstance;
141 // <- GLOBAL SAFE
142 }
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
162
169 struct SingletonLockInit
170 {
171 ::osl::Mutex* operator()()
172 {
173 static ::osl::Mutex aInstance;
174 return &aInstance;
175 }
176 };
177
178 ::osl::Mutex& ownStaticLock() const
179 {
180 return *rtl_Instance< ::osl::Mutex,
181 SingletonLockInit,
182 ::osl::MutexGuard,
183 ::osl::GetGlobalMutex >::create(SingletonLockInit(), ::osl::GetGlobalMutex());
184 }
185 };
186
187 template< class SingletonClass >
188 SingletonClass* SingletonRef< SingletonClass >::m_pInstance = 0;
189
190 template< class SingletonClass >
191 sal_Int32 SingletonRef< SingletonClass >::m_nRef = 0;
192
193 } // namespace salhelper
194
195 #endif // INCLUDED_SALHELPER_SINGLETONREF_HXX
196
197 /* vim:set shiftwidth=4 softtabstop=4 expandtab: */
osl::Guard
A helper class for mutex objects and interfaces.
Definition: mutex.hxx:121
osl::Mutex
A mutual exclusion synchronization object.
Definition: mutex.hxx:30
salhelper
Definition: condition.hxx:29
salhelper::SingletonRef::SingletonRef
SingletonRef()
standard ctor.
Definition: singletonref.hxx:92
salhelper::SingletonRef
template for implementing singleton classes.
Definition: singletonref.hxx:65
getglobalmutex.hxx
diagnose.h
osl::MutexGuard
Guard< Mutex > MutexGuard
Definition: mutex.hxx:236
salhelper::SingletonRef::operator*
SingletonClass & operator*() const
Allows (*rSingle).someBodyOp().
Definition: singletonref.hxx:148
salhelper::SingletonRef::~SingletonRef
~SingletonRef()
standard dtor.
Definition: singletonref.hxx:116
OSL_ENSURE
#define OSL_ENSURE(c, m)
Definition: diagnose.h:106
instance.hxx
salhelper::SingletonRef::operator->
SingletonClass * operator->() const
Allows rSingle->someBodyOp().
Definition: singletonref.hxx:136
osl::GetGlobalMutex
A helper functor for the rtl_Instance template.
Definition: getglobalmutex.hxx:31
mutex.hxx