mirror of https://gitee.com/bigwinds/arangodb
227 lines
7.3 KiB
C++
227 lines
7.3 KiB
C++
////////////////////////////////////////////////////////////////////////////////
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/// @brief read locker
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///
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/// @file
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///
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/// DISCLAIMER
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///
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/// Copyright 2014 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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/// @author Copyright 2014, ArangoDB GmbH, Cologne, Germany
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/// @author Copyright 2010-2013, triAGENS GmbH, Cologne, Germany
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////////////////////////////////////////////////////////////////////////////////
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#ifndef ARANGODB_BASICS_READ_LOCKER_H
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#define ARANGODB_BASICS_READ_LOCKER_H 1
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#include "Basics/Common.h"
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#include "Basics/ReadWriteLock.h"
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#ifdef TRI_SHOW_LOCK_TIME
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#include "Basics/logging.h"
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#endif
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// -----------------------------------------------------------------------------
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// --SECTION-- public macros
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// -----------------------------------------------------------------------------
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////////////////////////////////////////////////////////////////////////////////
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/// @brief construct locker 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 READ_LOCKER_VAR_A(a) _read_lock_variable ## a
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#define READ_LOCKER_VAR_B(a) READ_LOCKER_VAR_A(a)
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#ifdef TRI_SHOW_LOCK_TIME
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#define READ_LOCKER(b) \
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triagens::basics::ReadLocker<std::remove_reference<decltype(b)>::type> READ_LOCKER_VAR_B(__LINE__)(&b, __FILE__, __LINE__)
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#define READ_LOCKER_EVENTUAL(b, t) \
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triagens::basics::ReadLocker<std::remove_reference<decltype(b)>::type> READ_LOCKER_VAR_B(__LINE__)(&b, t, __FILE__, __LINE__)
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#else
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#define READ_LOCKER(b) \
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triagens::basics::ReadLocker<std::remove_reference<decltype(b)>::type> READ_LOCKER_VAR_B(__LINE__)(&b)
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#define READ_LOCKER_EVENTUAL(b, t) \
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triagens::basics::ReadLocker<std::remove_reference<decltype(b)>::type> READ_LOCKER_VAR_B(__LINE__)(&b, t)
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#endif
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// -----------------------------------------------------------------------------
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// --SECTION-- class ReadLocker
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// -----------------------------------------------------------------------------
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namespace triagens {
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namespace basics {
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////////////////////////////////////////////////////////////////////////////////
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/// @brief read locker
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///
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/// A ReadLocker read-locks a read-write lock during its lifetime and unlocks
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/// the lock when it is destroyed.
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////////////////////////////////////////////////////////////////////////////////
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template<typename T>
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class ReadLocker {
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ReadLocker (ReadLocker const&);
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ReadLocker& operator= (ReadLocker const&);
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// -----------------------------------------------------------------------------
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// --SECTION-- constructors and destructors
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// -----------------------------------------------------------------------------
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public:
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////////////////////////////////////////////////////////////////////////////////
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/// @brief aquires a read-lock
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///
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/// The constructors read-locks the lock, the destructors unlocks the lock.
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////////////////////////////////////////////////////////////////////////////////
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#ifdef TRI_SHOW_LOCK_TIME
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ReadLocker (T* readWriteLock, char const* file, int line)
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: _readWriteLock(readWriteLock), _file(file), _line(line) {
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double t = TRI_microtime();
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_readWriteLock->readLock();
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_time = TRI_microtime() - t;
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}
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#else
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explicit ReadLocker (T* readWriteLock)
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: _readWriteLock(readWriteLock) {
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_readWriteLock->readLock();
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}
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#endif
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////////////////////////////////////////////////////////////////////////////////
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/// @brief aquires a read-lock, with periodic sleeps while not acquired
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/// sleep time is specified in nanoseconds
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////////////////////////////////////////////////////////////////////////////////
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#ifdef TRI_SHOW_LOCK_TIME
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ReadLocker (T* readWriteLock,
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uint64_t sleepTime,
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char const* file,
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int line)
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: _readWriteLock(readWriteLock), _file(file), _line(line) {
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double t = TRI_microtime();
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while (! _readWriteLock->tryReadLock()) {
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#ifdef _WIN32
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usleep((unsigned long) sleepTime);
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#else
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usleep((useconds_t) sleepTime);
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#endif
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}
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_time = TRI_microtime() - t;
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}
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#else
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ReadLocker (T* readWriteLock,
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uint64_t sleepTime)
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: _readWriteLock(readWriteLock) {
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while (! _readWriteLock->tryReadLock()) {
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#ifdef _WIN32
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usleep((unsigned long) sleepTime);
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#else
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usleep((useconds_t) sleepTime);
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#endif
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}
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}
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#endif
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////////////////////////////////////////////////////////////////////////////////
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/// @brief releases the read-lock
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////////////////////////////////////////////////////////////////////////////////
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~ReadLocker () {
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_readWriteLock->unlock();
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#ifdef TRI_SHOW_LOCK_TIME
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if (_time > TRI_SHOW_LOCK_THRESHOLD) {
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LOG_WARNING("ReadLocker %s:%d took %f s", _file, _line, _time);
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}
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#endif
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}
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// -----------------------------------------------------------------------------
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// --SECTION-- private variables
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// -----------------------------------------------------------------------------
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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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#ifdef TRI_SHOW_LOCK_TIME
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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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/// @brief lock time
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////////////////////////////////////////////////////////////////////////////////
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double _time;
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#endif
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};
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}
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}
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#endif
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// -----------------------------------------------------------------------------
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// --SECTION-- END-OF-FILE
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// -----------------------------------------------------------------------------
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// Local Variables:
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// mode: outline-minor
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// outline-regexp: "/// @brief\\|/// {@inheritDoc}\\|/// @page\\|// --SECTION--\\|/// @\\}"
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// End:
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