140 lines
4.1 KiB
C++
140 lines
4.1 KiB
C++
////////////////////////////////////////////////////////////
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//
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// SFML - Simple and Fast Multimedia Library
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// Copyright (C) 2007-2018 Laurent Gomila (laurent@sfml-dev.org)
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//
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// This software is provided 'as-is', without any express or implied warranty.
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// In no event will the authors be held liable for any damages arising from the use of this software.
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//
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// Permission is granted to anyone to use this software for any purpose,
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// including commercial applications, and to alter it and redistribute it freely,
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// subject to the following restrictions:
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//
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// 1. The origin of this software must not be misrepresented;
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// you must not claim that you wrote the original software.
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// If you use this software in a product, an acknowledgment
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// in the product documentation would be appreciated but is not required.
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//
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// 2. Altered source versions must be plainly marked as such,
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// and must not be misrepresented as being the original software.
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//
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// 3. This notice may not be removed or altered from any source distribution.
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//
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////////////////////////////////////////////////////////////
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#ifndef SFML_LOCK_HPP
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#define SFML_LOCK_HPP
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////////////////////////////////////////////////////////////
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// Headers
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////////////////////////////////////////////////////////////
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#include <SFML/System/Export.hpp>
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#include <SFML/System/NonCopyable.hpp>
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namespace sf
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{
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class Mutex;
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////////////////////////////////////////////////////////////
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/// \brief Automatic wrapper for locking and unlocking mutexes
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///
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////////////////////////////////////////////////////////////
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class SFML_SYSTEM_API Lock : NonCopyable
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{
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public:
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////////////////////////////////////////////////////////////
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/// \brief Construct the lock with a target mutex
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///
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/// The mutex passed to sf::Lock is automatically locked.
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///
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/// \param mutex Mutex to lock
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///
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////////////////////////////////////////////////////////////
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explicit Lock(Mutex& mutex);
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////////////////////////////////////////////////////////////
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/// \brief Destructor
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///
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/// The destructor of sf::Lock automatically unlocks its mutex.
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///
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////////////////////////////////////////////////////////////
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~Lock();
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private:
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////////////////////////////////////////////////////////////
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// Member data
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////////////////////////////////////////////////////////////
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Mutex& m_mutex; ///< Mutex to lock / unlock
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};
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} // namespace sf
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#endif // SFML_LOCK_HPP
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////////////////////////////////////////////////////////////
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/// \class sf::Lock
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/// \ingroup system
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///
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/// sf::Lock is a RAII wrapper for sf::Mutex. By unlocking
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/// it in its destructor, it ensures that the mutex will
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/// always be released when the current scope (most likely
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/// a function) ends.
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/// This is even more important when an exception or an early
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/// return statement can interrupt the execution flow of the
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/// function.
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///
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/// For maximum robustness, sf::Lock should always be used
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/// to lock/unlock a mutex.
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///
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/// Usage example:
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/// \code
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/// sf::Mutex mutex;
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///
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/// void function()
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/// {
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/// sf::Lock lock(mutex); // mutex is now locked
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///
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/// functionThatMayThrowAnException(); // mutex is unlocked if this function throws
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///
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/// if (someCondition)
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/// return; // mutex is unlocked
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///
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/// } // mutex is unlocked
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/// \endcode
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///
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/// Because the mutex is not explicitly unlocked in the code,
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/// it may remain locked longer than needed. If the region
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/// of the code that needs to be protected by the mutex is
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/// not the entire function, a good practice is to create a
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/// smaller, inner scope so that the lock is limited to this
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/// part of the code.
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///
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/// \code
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/// sf::Mutex mutex;
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///
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/// void function()
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/// {
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/// {
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/// sf::Lock lock(mutex);
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/// codeThatRequiresProtection();
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///
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/// } // mutex is unlocked here
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///
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/// codeThatDoesntCareAboutTheMutex();
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/// }
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/// \endcode
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///
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/// Having a mutex locked longer than required is a bad practice
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/// which can lead to bad performances. Don't forget that when
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/// a mutex is locked, other threads may be waiting doing nothing
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/// until it is released.
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///
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/// \see sf::Mutex
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///
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////////////////////////////////////////////////////////////
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