140 lines
4.1 KiB
C++
140 lines
4.1 KiB
C++
////////////////////////////////////////////////////////////
|
|
//
|
|
// SFML - Simple and Fast Multimedia Library
|
|
// Copyright (C) 2007-2017 Laurent Gomila (laurent@sfml-dev.org)
|
|
//
|
|
// This software is provided 'as-is', without any express or implied warranty.
|
|
// In no event will the authors be held liable for any damages arising from the use of this software.
|
|
//
|
|
// Permission is granted to anyone to use this software for any purpose,
|
|
// including commercial applications, and to alter it and redistribute it freely,
|
|
// subject to the following restrictions:
|
|
//
|
|
// 1. The origin of this software must not be misrepresented;
|
|
// you must not claim that you wrote the original software.
|
|
// If you use this software in a product, an acknowledgment
|
|
// in the product documentation would be appreciated but is not required.
|
|
//
|
|
// 2. Altered source versions must be plainly marked as such,
|
|
// and must not be misrepresented as being the original software.
|
|
//
|
|
// 3. This notice may not be removed or altered from any source distribution.
|
|
//
|
|
////////////////////////////////////////////////////////////
|
|
|
|
#ifndef SFML_LOCK_HPP
|
|
#define SFML_LOCK_HPP
|
|
|
|
////////////////////////////////////////////////////////////
|
|
// Headers
|
|
////////////////////////////////////////////////////////////
|
|
#include <SFML/System/Export.hpp>
|
|
#include <SFML/System/NonCopyable.hpp>
|
|
|
|
|
|
namespace sf
|
|
{
|
|
class Mutex;
|
|
|
|
////////////////////////////////////////////////////////////
|
|
/// \brief Automatic wrapper for locking and unlocking mutexes
|
|
///
|
|
////////////////////////////////////////////////////////////
|
|
class SFML_SYSTEM_API Lock : NonCopyable
|
|
{
|
|
public:
|
|
|
|
////////////////////////////////////////////////////////////
|
|
/// \brief Construct the lock with a target mutex
|
|
///
|
|
/// The mutex passed to sf::Lock is automatically locked.
|
|
///
|
|
/// \param mutex Mutex to lock
|
|
///
|
|
////////////////////////////////////////////////////////////
|
|
explicit Lock(Mutex& mutex);
|
|
|
|
////////////////////////////////////////////////////////////
|
|
/// \brief Destructor
|
|
///
|
|
/// The destructor of sf::Lock automatically unlocks its mutex.
|
|
///
|
|
////////////////////////////////////////////////////////////
|
|
~Lock();
|
|
|
|
private:
|
|
|
|
////////////////////////////////////////////////////////////
|
|
// Member data
|
|
////////////////////////////////////////////////////////////
|
|
Mutex& m_mutex; ///< Mutex to lock / unlock
|
|
};
|
|
|
|
} // namespace sf
|
|
|
|
|
|
#endif // SFML_LOCK_HPP
|
|
|
|
|
|
////////////////////////////////////////////////////////////
|
|
/// \class sf::Lock
|
|
/// \ingroup system
|
|
///
|
|
/// sf::Lock is a RAII wrapper for sf::Mutex. By unlocking
|
|
/// it in its destructor, it ensures that the mutex will
|
|
/// always be released when the current scope (most likely
|
|
/// a function) ends.
|
|
/// This is even more important when an exception or an early
|
|
/// return statement can interrupt the execution flow of the
|
|
/// function.
|
|
///
|
|
/// For maximum robustness, sf::Lock should always be used
|
|
/// to lock/unlock a mutex.
|
|
///
|
|
/// Usage example:
|
|
/// \code
|
|
/// sf::Mutex mutex;
|
|
///
|
|
/// void function()
|
|
/// {
|
|
/// sf::Lock lock(mutex); // mutex is now locked
|
|
///
|
|
/// functionThatMayThrowAnException(); // mutex is unlocked if this function throws
|
|
///
|
|
/// if (someCondition)
|
|
/// return; // mutex is unlocked
|
|
///
|
|
/// } // mutex is unlocked
|
|
/// \endcode
|
|
///
|
|
/// Because the mutex is not explicitly unlocked in the code,
|
|
/// it may remain locked longer than needed. If the region
|
|
/// of the code that needs to be protected by the mutex is
|
|
/// not the entire function, a good practice is to create a
|
|
/// smaller, inner scope so that the lock is limited to this
|
|
/// part of the code.
|
|
///
|
|
/// \code
|
|
/// sf::Mutex mutex;
|
|
///
|
|
/// void function()
|
|
/// {
|
|
/// {
|
|
/// sf::Lock lock(mutex);
|
|
/// codeThatRequiresProtection();
|
|
///
|
|
/// } // mutex is unlocked here
|
|
///
|
|
/// codeThatDoesntCareAboutTheMutex();
|
|
/// }
|
|
/// \endcode
|
|
///
|
|
/// Having a mutex locked longer than required is a bad practice
|
|
/// which can lead to bad performances. Don't forget that when
|
|
/// a mutex is locked, other threads may be waiting doing nothing
|
|
/// until it is released.
|
|
///
|
|
/// \see sf::Mutex
|
|
///
|
|
////////////////////////////////////////////////////////////
|