mirror of
https://github.com/matrix-construct/construct
synced 2024-08-29 21:05:16 +02:00
160 lines
2.5 KiB
C++
160 lines
2.5 KiB
C++
// Matrix Construct
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//
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// Copyright (C) Matrix Construct Developers, Authors & Contributors
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// Copyright (C) 2016-2018 Jason Volk <jason@zemos.net>
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//
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// Permission to use, copy, modify, and/or distribute this software for any
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// purpose with or without fee is hereby granted, provided that the above
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// copyright notice and this permission notice is present in all copies. The
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// full license for this software is available in the LICENSE file.
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#pragma once
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#define HAVE_IRCD_CTX_MUTEX_H
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namespace ircd::ctx
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{
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class mutex;
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template<class queue> void release_sequence(queue &);
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}
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//
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// The mutex only allows one context to lock it and continue,
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// additional contexts are queued. This can be used with std::
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// locking concepts.
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//
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class ircd::ctx::mutex
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{
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bool m;
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list q;
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public:
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size_t waiting() const;
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bool try_lock();
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template<class time_point> bool try_lock_until(const time_point &);
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template<class duration> bool try_lock_for(const duration &);
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void lock();
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void unlock();
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mutex();
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mutex(mutex &&) noexcept;
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mutex(const mutex &) = delete;
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mutex &operator=(mutex &&) noexcept;
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mutex &operator=(const mutex &) = delete;
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~mutex() noexcept;
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};
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inline
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ircd::ctx::mutex::mutex()
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:m{false}
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{
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}
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inline
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ircd::ctx::mutex::mutex(mutex &&o)
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noexcept
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:m{std::move(o.m)}
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{
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o.m = false;
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}
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inline
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ircd::ctx::mutex &
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ircd::ctx::mutex::operator=(mutex &&o)
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noexcept
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{
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this->~mutex();
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std::swap(m, o.m);
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return *this;
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}
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inline
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ircd::ctx::mutex::~mutex()
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noexcept
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{
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assert(!m);
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}
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inline void
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ircd::ctx::mutex::unlock()
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{
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assert(m);
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m = false;
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release_sequence(q);
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}
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inline void
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ircd::ctx::mutex::lock()
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{
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if(likely(try_lock()))
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return;
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q.push_back(current);
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while(!try_lock())
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wait();
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}
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template<class duration>
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bool
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ircd::ctx::mutex::try_lock_for(const duration &d)
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{
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return try_lock_until(steady_clock::now() + d);
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}
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template<class time_point>
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bool
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ircd::ctx::mutex::try_lock_until(const time_point &tp)
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{
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if(likely(try_lock()))
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return true;
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q.push_back(current);
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while(!try_lock())
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{
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if(unlikely(wait_until<std::nothrow_t>(tp)))
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{
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q.remove(current);
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return false;
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}
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}
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return true;
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}
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inline bool
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ircd::ctx::mutex::try_lock()
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{
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if(m)
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return false;
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m = true;
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return true;
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}
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inline size_t
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ircd::ctx::mutex::waiting()
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const
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{
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return q.size();
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}
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template<class queue>
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void
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ircd::ctx::release_sequence(queue &q)
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{
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ctx *next; do
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{
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if(!q.empty())
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{
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next = q.front();
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q.pop_front();
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}
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else next = nullptr;
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}
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while(next == current);
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if(next)
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yield(*next);
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}
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