Line data    Source code

       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     1744984 : ReadWriteGuard::ReadWriteGuard( ReadWriteMutex& rMutexP,
      27             :             sal_Int32 nRequestMode )
      28     1744984 :         : rMutex( rMutexP )
      29             : {
      30             :     // don't do anything until a pending write completed (or another
      31             :     // ReadWriteGuard leaves the ctor phase)
      32     1744984 :     ::osl::MutexGuard aGuard( rMutex.pWriteMutex );
      33     1744984 :     nMode = nRequestMode;
      34     1744984 :     if ( nMode & ReadWriteGuardMode::nWrite )
      35             :     {
      36        6284 :         rMutex.pWriteMutex->acquire();
      37             :         // wait for any read to complete
      38             : // TODO: set up a waiting thread instead of a loop
      39        6284 :         sal_Bool bWait = sal_True;
      40        6284 :         do
      41             :         {
      42        6284 :             rMutex.pMutex->acquire();
      43        6284 :             bWait = (rMutex.nReadCount != 0);
      44        6284 :             if ( nMode & ReadWriteGuardMode::nCriticalChange )
      45        6284 :                 bWait |= (rMutex.nBlockCriticalCount != 0);
      46        6284 :             rMutex.pMutex->release();
      47             :         } while ( bWait );
      48             :     }
      49     1738700 :     else if ( nMode & ReadWriteGuardMode::nBlockCritical )
      50             :     {
      51       21446 :         rMutex.pMutex->acquire();
      52       21446 :         ++rMutex.nBlockCriticalCount;
      53       21446 :         rMutex.pMutex->release();
      54             :     }
      55             :     else
      56             :     {
      57     1717254 :         rMutex.pMutex->acquire();
      58     1717254 :         ++rMutex.nReadCount;
      59     1717254 :         rMutex.pMutex->release();
      60     1744984 :     }
      61     1744984 : }
      62             : 
      63             : 
      64     1744984 : ReadWriteGuard::~ReadWriteGuard()
      65             : {
      66     1744984 :     if ( nMode & ReadWriteGuardMode::nWrite )
      67       25015 :         rMutex.pWriteMutex->release();
      68     1719969 :     else if ( nMode & ReadWriteGuardMode::nBlockCritical )
      69             :     {
      70       21446 :         rMutex.pMutex->acquire();
      71       21446 :         --rMutex.nBlockCriticalCount;
      72       21446 :         rMutex.pMutex->release();
      73             :     }
      74             :     else
      75             :     {
      76     1698523 :         rMutex.pMutex->acquire();
      77     1698523 :         --rMutex.nReadCount;
      78     1698523 :         rMutex.pMutex->release();
      79             :     }
      80     1744984 : }
      81             : 
      82             : 
      83       18731 : void ReadWriteGuard::changeReadToWrite()
      84             : {
      85       18731 :     sal_Bool bOk = !(nMode & (ReadWriteGuardMode::nWrite | ReadWriteGuardMode::nBlockCritical));
      86             :     DBG_ASSERT( bOk, "ReadWriteGuard::changeReadToWrite: can't" );
      87       18731 :     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       18731 :         rMutex.pMutex->acquire();
      93       18731 :         --rMutex.nReadCount;
      94       18731 :         rMutex.pMutex->release();
      95             : 
      96       18731 :         rMutex.pWriteMutex->acquire();
      97       18731 :         nMode |= ReadWriteGuardMode::nWrite;
      98             :         // wait for any other read to complete
      99             : // TODO: set up a waiting thread instead of a loop
     100       18731 :         sal_Bool bWait = sal_True;
     101       18731 :         do
     102             :         {
     103       18731 :             rMutex.pMutex->acquire();
     104       18731 :             bWait = (rMutex.nReadCount != 0);
     105       18731 :             rMutex.pMutex->release();
     106             :         } while ( bWait );
     107             :     }
     108       18731 : }
     109             : 
     110             : }   // namespace utl
     111             : 
     112             : /* vim:set shiftwidth=4 softtabstop=4 expandtab: */