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/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
/*************************************************************************
*
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* Copyright 2000, 2010 Oracle and/or its affiliates.
*
* OpenOffice.org - a multi-platform office productivity suite
*
* This file is part of OpenOffice.org.
*
* OpenOffice.org is free software: you can redistribute it and/or modify
* it under the terms of the GNU Lesser General Public License version 3
* only, as published by the Free Software Foundation.
*
* OpenOffice.org is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Lesser General Public License version 3 for more details
* (a copy is included in the LICENSE file that accompanied this code).
*
* You should have received a copy of the GNU Lesser General Public License
* version 3 along with OpenOffice.org. If not, see
* <http://www.openoffice.org/license.html>
* for a copy of the LGPLv3 License.
*
************************************************************************/
#include "unotools/readwritemutexguard.hxx"
#include <tools/debug.hxx>
namespace utl {
ReadWriteGuard::ReadWriteGuard( ReadWriteMutex& rMutexP,
sal_Int32 nRequestMode )
: rMutex( rMutexP )
{
// don't do anything until a pending write completed (or another
// ReadWriteGuard leaves the ctor phase)
::osl::MutexGuard aGuard( rMutex.pWriteMutex );
nMode = nRequestMode;
if ( nMode & ReadWriteGuardMode::nWrite )
{
rMutex.pWriteMutex->acquire();
// wait for any read to complete
// TODO: set up a waiting thread instead of a loop
sal_Bool bWait = sal_True;
do
{
rMutex.pMutex->acquire();
bWait = (rMutex.nReadCount != 0);
if ( nMode & ReadWriteGuardMode::nCriticalChange )
bWait |= (rMutex.nBlockCriticalCount != 0);
rMutex.pMutex->release();
} while ( bWait );
}
else if ( nMode & ReadWriteGuardMode::nBlockCritical )
{
rMutex.pMutex->acquire();
++rMutex.nBlockCriticalCount;
rMutex.pMutex->release();
}
else
{
rMutex.pMutex->acquire();
++rMutex.nReadCount;
rMutex.pMutex->release();
}
}
ReadWriteGuard::~ReadWriteGuard()
{
if ( nMode & ReadWriteGuardMode::nWrite )
rMutex.pWriteMutex->release();
else if ( nMode & ReadWriteGuardMode::nBlockCritical )
{
rMutex.pMutex->acquire();
--rMutex.nBlockCriticalCount;
rMutex.pMutex->release();
}
else
{
rMutex.pMutex->acquire();
--rMutex.nReadCount;
rMutex.pMutex->release();
}
}
void ReadWriteGuard::changeReadToWrite()
{
sal_Bool bOk = !(nMode & (ReadWriteGuardMode::nWrite | ReadWriteGuardMode::nBlockCritical));
DBG_ASSERT( bOk, "ReadWriteGuard::changeReadToWrite: can't" );
if ( bOk )
{
// MUST release read before acquiring write mutex or dead lock would
// occur if there was a write in another thread waiting for this read
// to complete.
rMutex.pMutex->acquire();
--rMutex.nReadCount;
rMutex.pMutex->release();
rMutex.pWriteMutex->acquire();
nMode |= ReadWriteGuardMode::nWrite;
// wait for any other read to complete
// TODO: set up a waiting thread instead of a loop
sal_Bool bWait = sal_True;
do
{
rMutex.pMutex->acquire();
bWait = (rMutex.nReadCount != 0);
rMutex.pMutex->release();
} while ( bWait );
}
}
} // namespace utl
/* vim:set shiftwidth=4 softtabstop=4 expandtab: */
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