//
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// Copyright (c) 2016-2019 Vinnie Falco (vinnie dot falco at gmail 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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// Official repository: https://github.com/boostorg/beast
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//
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#ifndef BOOST_BEAST_WEBSOCKET_DETAIL_SOFT_MUTEX_HPP
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#define BOOST_BEAST_WEBSOCKET_DETAIL_SOFT_MUTEX_HPP
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#include <boost/assert.hpp>
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namespace boost {
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namespace beast {
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namespace websocket {
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namespace detail {
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// used to order reads, writes in websocket streams
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class soft_mutex
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{
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int id_ = 0;
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public:
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soft_mutex() = default;
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soft_mutex(soft_mutex const&) = delete;
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soft_mutex& operator=(soft_mutex const&) = delete;
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soft_mutex(soft_mutex&& other) noexcept
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: id_(boost::exchange(other.id_, 0))
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{
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}
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soft_mutex& operator=(soft_mutex&& other) noexcept
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{
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id_ = other.id_;
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other.id_ = 0;
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return *this;
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}
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// VFALCO I'm not too happy that this function is needed
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void
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reset()
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{
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id_ = 0;
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}
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bool
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is_locked() const noexcept
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{
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return id_ != 0;
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}
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template<class T>
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bool
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is_locked(T const*) const noexcept
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{
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return id_ == T::id;
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}
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template<class T>
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void
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lock(T const*)
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{
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BOOST_ASSERT(id_ == 0);
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id_ = T::id;
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}
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template<class T>
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void
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unlock(T const*)
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{
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BOOST_ASSERT(id_ == T::id);
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id_ = 0;
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}
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template<class T>
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bool
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try_lock(T const*)
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{
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// If this assert goes off it means you are attempting to
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// simultaneously initiate more than one of same asynchronous
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// operation, which is not allowed. For example, you must wait
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// for an async_read to complete before performing another
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// async_read.
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//
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BOOST_ASSERT(id_ != T::id);
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if(id_ != 0)
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return false;
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id_ = T::id;
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return true;
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}
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template<class T>
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bool
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try_unlock(T const*) noexcept
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{
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if(id_ != T::id)
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return false;
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id_ = 0;
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return true;
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}
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};
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} // detail
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} // websocket
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} // beast
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} // boost
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#endif
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