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LibreOffice 6.2 SDK C/C++ API Reference
singletonref.hxx
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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 >
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 
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 
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 #if defined LIBO_INTERNAL_ONLY
135  SingletonRef & operator =(SingletonRef const &) = default;
136 #endif
137 
140  SingletonClass* operator->() const
141  {
142  // GLOBAL SAFE ->
143  ::osl::MutexGuard aLock(SingletonRef::ownStaticLock());
144  return m_pInstance;
145  // <- GLOBAL SAFE
146  }
147 
148 
151  SingletonClass& operator*() const
152  {
153  // GLOBAL SAFE ->
154  ::osl::MutexGuard aLock(SingletonRef::ownStaticLock());
155  return *m_pInstance;
156  // <- GLOBAL SAFE
157  }
158 
159 
160  // helper
161 
162  private:
164 
171  struct SingletonLockInit
172  {
173  ::osl::Mutex* operator()()
174  {
175  static ::osl::Mutex aInstance;
176  return &aInstance;
177  }
178  };
179 
180  ::osl::Mutex& ownStaticLock() const
181  {
182  return *rtl_Instance< ::osl::Mutex,
183  SingletonLockInit,
185  ::osl::GetGlobalMutex >::create(SingletonLockInit(), ::osl::GetGlobalMutex());
186  }
187 };
188 
189 template< class SingletonClass >
190 SingletonClass* SingletonRef< SingletonClass >::m_pInstance = NULL;
191 
192 template< class SingletonClass >
194 
195 } // namespace salhelper
196 
197 #endif // INCLUDED_SALHELPER_SINGLETONREF_HXX
198 
199 /* vim:set shiftwidth=4 softtabstop=4 expandtab: */
A helper functor for the rtl_Instance template.
Definition: getglobalmutex.hxx:31
A mutual exclusion synchronization object.
Definition: mutex.hxx:30
#define SAL_DELETED_FUNCTION
short-circuit extra-verbose API namespaces
Definition: types.h:396
SingletonRef()
standard ctor.
Definition: singletonref.hxx:95
#define OSL_ENSURE(c, m)
If cond is false, reports an error with message msg.
Definition: diagnose.h:84
template for implementing singleton classes.
Definition: singletonref.hxx:69
Guard< Mutex > MutexGuard
Definition: mutex.hxx:224
Provides simple diagnostic support.
Definition: condition.hxx:30
SingletonClass & operator*() const
Allows (*rSingle).someBodyOp().
Definition: singletonref.hxx:151
~SingletonRef()
standard dtor.
Definition: singletonref.hxx:118
SingletonClass * operator->() const
Allows rSingle->someBodyOp().
Definition: singletonref.hxx:140
A helper class for mutex objects and interfaces.
Definition: mutex.hxx:108