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/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
/*
* This file is part of the LibreOffice project.
*
* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/.
*
* This file incorporates work covered by the following license notice:
*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed
* with this work for additional information regarding copyright
* ownership. The ASF licenses this file to you under the Apache
* License, Version 2.0 (the "License"); you may not use this file
* except in compliance with the License. You may obtain a copy of
* the License at http://www.apache.org/licenses/LICENSE-2.0 .
*/
#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
/* vim:set shiftwidth=4 softtabstop=4 expandtab: */
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