include/comphelper/accessiblecontexthelper.hxx

   1 /* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
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  19
  20 #ifndef INCLUDED_COMPHELPER_ACCESSIBLECONTEXTHELPER_HXX
  21 #define INCLUDED_COMPHELPER_ACCESSIBLECONTEXTHELPER_HXX
  22
  23 #include <comphelper/accessiblecomponenthelper.hxx>
  24 #include <comphelper/solarmutex.hxx>
  25
  26
  27 namespace comphelper
  28 {
  29
  30
  31     //= OContextEntryGuard
  32
  33     /** helper class for guarding the entry into OCommonAccessibleComponent methods.
  34
  35         <p>The class has two responsibilities:
  36         <ul><li>it locks the mutex of an OCommonAccessibleComponent instance, as long as the guard lives</li>
  37             <li>it checks if a given OCommonAccessibleComponent instance is alive, else an exception is thrown
  38                 our of the constructor of the guard</li>
  39         </ul>
  40         <br/>
  41         This makes it your first choice (hopefully :) for guarding any interface method implementations of
  42         you derived class.
  43         </p>
  44     */
  45     class OContextEntryGuard : public ::osl::ClearableMutexGuard
  46     {
  47     public:
  48         /** constructs the guard
  49
  50             <p>The given context (it's mutex, respectively) is locked, and an exception is thrown if the context
  51             is not alive anymore. In the latter case, of course, the mutex is freed, again.</p>
  52
  53         @param _pContext
  54             the context which shall be guarded
  55         @precond <arg>_pContext</arg> != NULL
  56         */
  57         inline OContextEntryGuard( OCommonAccessibleComponent* _pContext );
  58     };
  59
  60
  61     inline OContextEntryGuard::OContextEntryGuard( OCommonAccessibleComponent* _pContext  )
  62         : ::osl::ClearableMutexGuard( _pContext->GetMutex() )
  63     {
  64         _pContext->ensureAlive();
  65     }
  66
  67
  68     //= OExternalLockGuard
  69
  70     class OExternalLockGuard
  71             :public osl::Guard<SolarMutex>
  72             ,public OContextEntryGuard
  73     {
  74     public:
  75         inline OExternalLockGuard( OCommonAccessibleComponent* _pContext );
  76     };
  77
  78
  79     inline OExternalLockGuard::OExternalLockGuard( OCommonAccessibleComponent* _pContext )
  80         :osl::Guard<SolarMutex>( SolarMutex::get() )
  81         ,OContextEntryGuard( _pContext )
  82     {
  83         // Only lock the external mutex,
  84         // release the ::osl::Mutex of the OCommonAccessibleComponent instance.
  85         // If you call into another UNO object with locked ::osl::Mutex,
  86         // this may lead to dead locks.
  87         clear();
  88     }
  89
  90
  91 }   // namespace comphelper
  92
  93
  94 #endif // INCLUDED_COMPHELPER_ACCESSIBLECONTEXTHELPER_HXX
  95
  96
  97 /* vim:set shiftwidth=4 softtabstop=4 expandtab: */