unotools/source/i18n/readwritemutexguard.cxx

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  30
  31 // MARKER(update_precomp.py): autogen include statement, do not remove
  32 #include "precompiled_unotools.hxx"
  33 #include "unotools/readwritemutexguard.hxx"
  34 #include <tools/debug.hxx>
  35
  36
  37 namespace utl {
  38
  39 ReadWriteGuard::ReadWriteGuard( ReadWriteMutex& rMutexP,
  40             sal_Int32 nRequestMode )
  41         : rMutex( rMutexP )
  42 {
  43     // don't do anything until a pending write completed (or another
  44     // ReadWriteGuard leaves the ctor phase)
  45     ::osl::MutexGuard aGuard( rMutex.pWriteMutex );
  46     nMode = nRequestMode;
  47     if ( nMode & ReadWriteGuardMode::nWrite )
  48     {
  49         rMutex.pWriteMutex->acquire();
  50         // wait for any read to complete
  51 // TODO: set up a waiting thread instead of a loop
  52         sal_Bool bWait = sal_True;
  53         do
  54         {
  55             rMutex.pMutex->acquire();
  56             bWait = (rMutex.nReadCount != 0);
  57             if ( nMode & ReadWriteGuardMode::nCriticalChange )
  58                 bWait |= (rMutex.nBlockCriticalCount != 0);
  59             rMutex.pMutex->release();
  60         } while ( bWait );
  61     }
  62     else if ( nMode & ReadWriteGuardMode::nBlockCritical )
  63     {
  64         rMutex.pMutex->acquire();
  65         ++rMutex.nBlockCriticalCount;
  66         rMutex.pMutex->release();
  67     }
  68     else
  69     {
  70         rMutex.pMutex->acquire();
  71         ++rMutex.nReadCount;
  72         rMutex.pMutex->release();
  73     }
  74 }
  75
  76
  77 ReadWriteGuard::~ReadWriteGuard()
  78 {
  79     if ( nMode & ReadWriteGuardMode::nWrite )
  80         rMutex.pWriteMutex->release();
  81     else if ( nMode & ReadWriteGuardMode::nBlockCritical )
  82     {
  83         rMutex.pMutex->acquire();
  84         --rMutex.nBlockCriticalCount;
  85         rMutex.pMutex->release();
  86     }
  87     else
  88     {
  89         rMutex.pMutex->acquire();
  90         --rMutex.nReadCount;
  91         rMutex.pMutex->release();
  92     }
  93 }
  94
  95
  96 void ReadWriteGuard::changeReadToWrite()
  97 {
  98     sal_Bool bOk = !(nMode & (ReadWriteGuardMode::nWrite | ReadWriteGuardMode::nBlockCritical));
  99     DBG_ASSERT( bOk, "ReadWriteGuard::changeReadToWrite: can't" );
 100     if ( bOk )
 101     {
 102         // MUST release read before acquiring write mutex or dead lock would
 103         // occur if there was a write in another thread waiting for this read
 104         // to complete.
 105         rMutex.pMutex->acquire();
 106         --rMutex.nReadCount;
 107         rMutex.pMutex->release();
 108
 109         rMutex.pWriteMutex->acquire();
 110         nMode |= ReadWriteGuardMode::nWrite;
 111         // wait for any other read to complete
 112 // TODO: set up a waiting thread instead of a loop
 113         sal_Bool bWait = sal_True;
 114         do
 115         {
 116             rMutex.pMutex->acquire();
 117             bWait = (rMutex.nReadCount != 0);
 118             rMutex.pMutex->release();
 119         } while ( bWait );
 120     }
 121 }
 122
 123 }   // namespace utl