mirror of https://gitee.com/bigwinds/arangodb
116 lines
4.1 KiB
C++
116 lines
4.1 KiB
C++
////////////////////////////////////////////////////////////////////////////////
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/// DISCLAIMER
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///
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/// Copyright 2014-2016 ArangoDB GmbH, Cologne, Germany
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/// Copyright 2004-2014 triAGENS GmbH, Cologne, Germany
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///
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/// Licensed under the Apache License, Version 2.0 (the "License");
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/// you may not use this file except in compliance with the License.
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/// You may obtain a copy of the License at
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///
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/// http://www.apache.org/licenses/LICENSE-2.0
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///
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/// Unless required by applicable law or agreed to in writing, software
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/// distributed under the License is distributed on an "AS IS" BASIS,
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/// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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/// See the License for the specific language governing permissions and
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/// limitations under the License.
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///
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/// Copyright holder is ArangoDB GmbH, Cologne, Germany
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///
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/// @author Frank Celler
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/// @author Achim Brandt
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////////////////////////////////////////////////////////////////////////////////
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#ifndef LIB_BASICS_WRITE_UNLOCKER_H
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#define LIB_BASICS_WRITE_UNLOCKER_H 1
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#include "Basics/Common.h"
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#include "Basics/ReadWriteLock.h"
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////////////////////////////////////////////////////////////////////////////////
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/// @brief construct unlocker with file and line information
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///
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/// Ones needs to use macros twice to get a unique variable based on the line
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/// number.
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////////////////////////////////////////////////////////////////////////////////
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#define WRITE_UNLOCKER_VAR_A(a) _write_unlock_variable##a
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#define WRITE_UNLOCKER_VAR_B(a) WRITE_UNLOCKER_VAR_A(a)
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#define WRITE_UNLOCKER(b) \
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triagens::basics::WriteUnlocker<std::remove_reference<decltype(b)>::type> \
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WRITE_UNLOCKER_VAR_B(__LINE__)(&b, __FILE__, __LINE__)
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namespace triagens {
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namespace basics {
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////////////////////////////////////////////////////////////////////////////////
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/// @brief write unlocker
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///
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/// A WriteUnlocker unlocks a read-write lock during its lifetime and reaquires
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/// the write lock when it is destroyed.
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////////////////////////////////////////////////////////////////////////////////
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template <typename T>
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class WriteUnlocker {
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WriteUnlocker(WriteUnlocker const&);
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WriteUnlocker& operator=(WriteUnlocker const&);
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public:
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//////////////////////////////////////////////////////////////////////////////
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/// @brief unlocks the lock
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///
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/// The constructor unlocks the lock, the destructors aquires a write-lock.
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//////////////////////////////////////////////////////////////////////////////
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explicit WriteUnlocker(T* readWriteLock)
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: WriteUnlocker(readWriteLock, nullptr, 0) {}
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//////////////////////////////////////////////////////////////////////////////
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/// @brief unlocks the lock
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///
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/// The constructor unlocks the lock, the destructors aquires a write-lock.
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//////////////////////////////////////////////////////////////////////////////
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WriteUnlocker(T* readWriteLock, char const* file, int line);
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: _readWriteLock(readWriteLock), _file(file), _line(line) {
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_readWriteLock->unlock();
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}
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////////////////////////////////////////////////////////////////////////////////
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/// @brief aquires the write-lock
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////////////////////////////////////////////////////////////////////////////////
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~WriteUnlocker() { _readWriteLock->writeLock(); }
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private:
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////////////////////////////////////////////////////////////////////////////////
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/// @brief the read-write lock
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////////////////////////////////////////////////////////////////////////////////
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T* _readWriteLock;
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////////////////////////////////////////////////////////////////////////////////
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/// @brief file
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////////////////////////////////////////////////////////////////////////////////
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char const* _file;
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////////////////////////////////////////////////////////////////////////////////
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/// @brief line number
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////////////////////////////////////////////////////////////////////////////////
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int _line;
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};
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}
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}
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#endif
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