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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                 :            : #include "unotools/readwritemutexguard.hxx"
      21                 :            : #include <tools/debug.hxx>
      22                 :            : 
      23                 :            : 
      24                 :            : namespace utl {
      25                 :            : 
      26                 :    2816176 : ReadWriteGuard::ReadWriteGuard( ReadWriteMutex& rMutexP,
      27                 :            :             sal_Int32 nRequestMode )
      28                 :    2816176 :         : rMutex( rMutexP )
      29                 :            : {
      30                 :            :     // don't do anything until a pending write completed (or another
      31                 :            :     // ReadWriteGuard leaves the ctor phase)
      32         [ +  - ]:    2816176 :     ::osl::MutexGuard aGuard( rMutex.pWriteMutex );
      33                 :    2816176 :     nMode = nRequestMode;
      34         [ +  + ]:    2816176 :     if ( nMode & ReadWriteGuardMode::nWrite )
      35                 :            :     {
      36         [ +  - ]:      32434 :         rMutex.pWriteMutex->acquire();
      37                 :            :         // wait for any read to complete
      38                 :            : // TODO: set up a waiting thread instead of a loop
      39                 :      32434 :         sal_Bool bWait = sal_True;
      40         [ -  + ]:      32434 :         do
      41                 :            :         {
      42         [ +  - ]:      32434 :             rMutex.pMutex->acquire();
      43                 :      32434 :             bWait = (rMutex.nReadCount != 0);
      44         [ +  - ]:      32434 :             if ( nMode & ReadWriteGuardMode::nCriticalChange )
      45                 :      32434 :                 bWait |= (rMutex.nBlockCriticalCount != 0);
      46         [ +  - ]:      32434 :             rMutex.pMutex->release();
      47                 :            :         } while ( bWait );
      48                 :            :     }
      49         [ +  + ]:    2783742 :     else if ( nMode & ReadWriteGuardMode::nBlockCritical )
      50                 :            :     {
      51         [ +  - ]:      39033 :         rMutex.pMutex->acquire();
      52                 :      39033 :         ++rMutex.nBlockCriticalCount;
      53         [ +  - ]:      39033 :         rMutex.pMutex->release();
      54                 :            :     }
      55                 :            :     else
      56                 :            :     {
      57         [ +  - ]:    2744709 :         rMutex.pMutex->acquire();
      58                 :    2744709 :         ++rMutex.nReadCount;
      59         [ +  - ]:    2744709 :         rMutex.pMutex->release();
      60         [ +  - ]:    2816176 :     }
      61                 :    2816176 : }
      62                 :            : 
      63                 :            : 
      64                 :    2816176 : ReadWriteGuard::~ReadWriteGuard()
      65                 :            : {
      66         [ +  + ]:    2816176 :     if ( nMode & ReadWriteGuardMode::nWrite )
      67                 :      60792 :         rMutex.pWriteMutex->release();
      68         [ +  + ]:    2755384 :     else if ( nMode & ReadWriteGuardMode::nBlockCritical )
      69                 :            :     {
      70                 :      39033 :         rMutex.pMutex->acquire();
      71                 :      39033 :         --rMutex.nBlockCriticalCount;
      72                 :      39033 :         rMutex.pMutex->release();
      73                 :            :     }
      74                 :            :     else
      75                 :            :     {
      76                 :    2716351 :         rMutex.pMutex->acquire();
      77                 :    2716351 :         --rMutex.nReadCount;
      78                 :    2716351 :         rMutex.pMutex->release();
      79                 :            :     }
      80                 :    2816176 : }
      81                 :            : 
      82                 :            : 
      83                 :      28358 : void ReadWriteGuard::changeReadToWrite()
      84                 :            : {
      85                 :      28358 :     sal_Bool bOk = !(nMode & (ReadWriteGuardMode::nWrite | ReadWriteGuardMode::nBlockCritical));
      86                 :            :     DBG_ASSERT( bOk, "ReadWriteGuard::changeReadToWrite: can't" );
      87         [ +  - ]:      28358 :     if ( bOk )
      88                 :            :     {
      89                 :            :         // MUST release read before acquiring write mutex or dead lock would
      90                 :            :         // occur if there was a write in another thread waiting for this read
      91                 :            :         // to complete.
      92                 :      28358 :         rMutex.pMutex->acquire();
      93                 :      28358 :         --rMutex.nReadCount;
      94                 :      28358 :         rMutex.pMutex->release();
      95                 :            : 
      96                 :      28358 :         rMutex.pWriteMutex->acquire();
      97                 :      28358 :         nMode |= ReadWriteGuardMode::nWrite;
      98                 :            :         // wait for any other read to complete
      99                 :            : // TODO: set up a waiting thread instead of a loop
     100                 :      28358 :         sal_Bool bWait = sal_True;
     101         [ -  + ]:      28358 :         do
     102                 :            :         {
     103                 :      28358 :             rMutex.pMutex->acquire();
     104                 :      28358 :             bWait = (rMutex.nReadCount != 0);
     105                 :      28358 :             rMutex.pMutex->release();
     106                 :            :         } while ( bWait );
     107                 :            :     }
     108                 :      28358 : }
     109                 :            : 
     110                 :            : }   // namespace utl
     111                 :            : 
     112                 :            : /* vim:set shiftwidth=4 softtabstop=4 expandtab: */