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52 lines
1.6 KiB
C++
52 lines
1.6 KiB
C++
/* Copyright (C) 2019 MariaDB Corporation
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This program is free software; you can redistribute it and/or
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modify it under the terms of the GNU General Public License
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as published by the Free Software Foundation; version 2 of
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the License.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program; if not, write to the Free Software
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Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
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MA 02110-1301, USA. */
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#include <boost/thread/mutex.hpp>
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#include <boost/thread/condition.hpp>
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/* Quicky impl of a read-write lock that prioritizes writers. */
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namespace storagemanager
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{
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class RWLock
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{
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public:
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RWLock();
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~RWLock();
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void readLock();
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// this version will release the lock in the parameter after locking this instance
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void readLock(boost::unique_lock<boost::mutex>&);
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void readUnlock();
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void writeLock();
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// this version will release the lock in the parameter after locking this instance
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void writeLock(boost::unique_lock<boost::mutex>&);
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void writeUnlock();
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// returns true if anything is blocked on or owns this lock instance.
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bool inUse();
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private:
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uint readersWaiting;
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uint readersRunning;
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uint writersWaiting;
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uint writersRunning;
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boost::mutex m;
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boost::condition okToWrite;
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boost::condition okToRead;
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};
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} // namespace storagemanager
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