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/*************************************************************************
*
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* Copyright 2008 by Sun Microsystems, Inc.
*
* OpenOffice.org - a multi-platform office productivity suite
*
* $RCSfile: readwritemutexguard.hxx,v $
* $Revision: 1.3 $
*
* 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.
*
************************************************************************/
#ifndef INCLUDED_UNOTOOLS_READWRITEMUTEXGUARD_HXX
#define INCLUDED_UNOTOOLS_READWRITEMUTEXGUARD_HXX
#include <osl/mutex.hxx>
namespace utl {
class ReadWriteGuard;
class ReadWriteMutex
{
friend class ReadWriteGuard;
sal_uInt32 nReadCount;
sal_uInt32 nBlockCriticalCount;
::osl::Mutex* pMutex;
::osl::Mutex* pWriteMutex;
public:
ReadWriteMutex()
: nReadCount(0)
, nBlockCriticalCount(0)
, pMutex( new ::osl::Mutex )
, pWriteMutex( new ::osl::Mutex )
{}
~ReadWriteMutex()
{
delete pMutex;
delete pWriteMutex;
}
};
namespace ReadWriteGuardMode {
const sal_Int32 nWrite = 0x01;
const sal_Int32 nCriticalChange = 0x02 | nWrite;
const sal_Int32 nBlockCritical = 0x04; // only a block, not a read, exclusive flag!
}
/** Enable multiple threads to read simultaneously, but a write blocks all
other reads and writes, and a read blocks any write.
Used in I18N wrappers to be able to maintain a single instance of a wrapper
for the standard Office locale.
NEVER construct a writing guard if there is already a reading guard in the
same context, the following will dead lock EVEN IN THE SAME THREAD!
void foo()
{
ReadWriteGuard aGuard1( aMutex );
bar();
}
void bar()
{
// waits forever for aGuard1
ReadWriteGuard aGuard2( aMutex, ReadWriteGuardMode::nWrite );
}
*/
class ReadWriteGuard
{
ReadWriteMutex& rMutex;
sal_Int32 nMode;
public:
ReadWriteGuard(
ReadWriteMutex& rMutex,
sal_Int32 nRequestMode = 0 // read only
);
~ReadWriteGuard();
/** Be careful with this, it does wait for ANY read to complete.
The following will dead lock EVEN IN THE SAME THREAD!
void foo()
{
ReadWriteGuard aGuard1( aMutex );
bar();
}
void bar()
{
ReadWriteGuard aGuard2( aMutex );
aGuard2.changeReadToWrite(); // waits forever for aGuard1
}
*/
void changeReadToWrite();
};
} // namespace utl
#endif // INCLUDED_UNOTOOLS_READWRITEMUTEXGUARD_HXX
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