diff options
Diffstat (limited to 'include/unotools/readwritemutexguard.hxx')
-rw-r--r-- | include/unotools/readwritemutexguard.hxx | 106 |
1 files changed, 106 insertions, 0 deletions
diff --git a/include/unotools/readwritemutexguard.hxx b/include/unotools/readwritemutexguard.hxx new file mode 100644 index 000000000000..dd182d1e9a67 --- /dev/null +++ b/include/unotools/readwritemutexguard.hxx @@ -0,0 +1,106 @@ +/* -*- 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: */ |