mirror of
https://github.com/matrix-construct/construct
synced 2024-12-11 08:02:59 +01:00
174 lines
2.7 KiB
C++
174 lines
2.7 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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}
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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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struct ircd::ctx::mutex
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{
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dock q;
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bool m;
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void deadlock_assertion() const noexcept;
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public:
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bool locked() const noexcept;
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size_t waiting() const noexcept;
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bool waiting(const ctx &) const noexcept;
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bool try_lock() noexcept;
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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() noexcept;
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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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noexcept
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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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:q{std::move(o.q)}
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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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q = std::move(o.q);
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m = std::move(o.m);
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o.m = false;
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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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q.notify_one();
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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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deadlock_assertion();
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q.wait([this]
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{
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return !locked();
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});
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m = true;
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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(system_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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deadlock_assertion();
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const bool success
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{
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q.wait_until(tp, [this]
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{
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return !locked();
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})
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};
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if(likely(success))
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m = true;
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return success;
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}
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inline bool
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ircd::ctx::mutex::try_lock()
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noexcept
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{
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deadlock_assertion();
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if(locked())
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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 bool
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ircd::ctx::mutex::waiting(const ctx &c)
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const noexcept
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{
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return q.waiting(c);
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}
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inline size_t
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ircd::ctx::mutex::waiting()
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const noexcept
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{
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return q.size();
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}
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inline bool
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ircd::ctx::mutex::locked()
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const noexcept
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{
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return m;
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}
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inline void
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__attribute__((always_inline, artificial))
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ircd::ctx::mutex::deadlock_assertion()
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const noexcept
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{
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assert(!locked() || !waiting(cur()));
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}
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