150 lines
2.9 KiB
C++
150 lines
2.9 KiB
C++
//
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// detail/conditionally_enabled_mutex.hpp
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// ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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//
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// Copyright (c) 2003-2021 Christopher M. Kohlhoff (chris at kohlhoff dot com)
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//
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// Distributed under the Boost Software License, Version 1.0. (See accompanying
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// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
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//
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#ifndef ASIO_DETAIL_CONDITIONALLY_ENABLED_MUTEX_HPP
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#define ASIO_DETAIL_CONDITIONALLY_ENABLED_MUTEX_HPP
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#if defined(_MSC_VER) && (_MSC_VER >= 1200)
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# pragma once
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#endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
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#include "asio/detail/config.hpp"
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#include "asio/detail/mutex.hpp"
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#include "asio/detail/noncopyable.hpp"
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#include "asio/detail/scoped_lock.hpp"
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#include "asio/detail/push_options.hpp"
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namespace asio {
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namespace detail {
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// Mutex adapter used to conditionally enable or disable locking.
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class conditionally_enabled_mutex
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: private noncopyable
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{
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public:
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// Helper class to lock and unlock a mutex automatically.
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class scoped_lock
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: private noncopyable
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{
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public:
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// Tag type used to distinguish constructors.
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enum adopt_lock_t { adopt_lock };
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// Constructor adopts a lock that is already held.
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scoped_lock(conditionally_enabled_mutex& m, adopt_lock_t)
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: mutex_(m),
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locked_(m.enabled_)
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{
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}
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// Constructor acquires the lock.
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explicit scoped_lock(conditionally_enabled_mutex& m)
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: mutex_(m)
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{
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if (m.enabled_)
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{
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mutex_.mutex_.lock();
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locked_ = true;
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}
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else
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locked_ = false;
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}
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// Destructor releases the lock.
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~scoped_lock()
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{
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if (locked_)
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mutex_.mutex_.unlock();
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}
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// Explicitly acquire the lock.
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void lock()
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{
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if (mutex_.enabled_ && !locked_)
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{
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mutex_.mutex_.lock();
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locked_ = true;
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}
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}
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// Explicitly release the lock.
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void unlock()
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{
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if (locked_)
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{
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mutex_.unlock();
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locked_ = false;
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}
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}
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// Test whether the lock is held.
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bool locked() const
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{
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return locked_;
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}
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// Get the underlying mutex.
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asio::detail::mutex& mutex()
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{
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return mutex_.mutex_;
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}
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private:
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friend class conditionally_enabled_event;
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conditionally_enabled_mutex& mutex_;
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bool locked_;
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};
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// Constructor.
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explicit conditionally_enabled_mutex(bool enabled)
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: enabled_(enabled)
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{
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}
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// Destructor.
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~conditionally_enabled_mutex()
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{
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}
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// Determine whether locking is enabled.
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bool enabled() const
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{
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return enabled_;
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}
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// Lock the mutex.
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void lock()
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{
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if (enabled_)
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mutex_.lock();
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}
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// Unlock the mutex.
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void unlock()
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{
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if (enabled_)
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mutex_.unlock();
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}
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private:
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friend class scoped_lock;
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friend class conditionally_enabled_event;
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asio::detail::mutex mutex_;
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const bool enabled_;
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};
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} // namespace detail
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} // namespace asio
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#include "asio/detail/pop_options.hpp"
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#endif // ASIO_DETAIL_CONDITIONALLY_ENABLED_MUTEX_HPP
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