mirror of
https://github.com/matrix-construct/construct
synced 2024-08-28 20:35:16 +02:00
213 lines
5 KiB
C++
213 lines
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_FUTURE_H
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namespace ircd::ctx
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{
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IRCD_OVERLOAD(use_future)
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template<class T = void> class future;
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template<> class future<void>;
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template<class... T> struct scoped_future;
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enum class future_status;
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template<class T,
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class time_point>
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future_status wait_until(const future<T> &, const time_point &);
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}
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enum class ircd::ctx::future_status
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{
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ready,
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timeout,
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deferred,
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};
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template<class T>
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class ircd::ctx::future
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{
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std::shared_ptr<shared_state<T>> st;
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public:
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using value_type = typename shared_state<T>::value_type;
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using pointer_type = typename shared_state<T>::pointer_type;
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using reference_type = typename shared_state<T>::reference_type;
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bool valid() const { return bool(st); }
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bool operator!() const { return !valid(); }
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operator bool() const { return valid(); }
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template<class U, class time_point> friend future_status wait_until(const future<U> &, const time_point &);
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template<class time_point> future_status wait_until(const time_point &) const;
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template<class duration> future_status wait(const duration &d) const;
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void wait() const;
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T get();
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operator T() { return get(); }
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future();
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future(promise<T> &promise);
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};
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template<>
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class ircd::ctx::future<void>
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{
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std::shared_ptr<shared_state<void>> st;
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public:
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using value_type = typename shared_state<void>::value_type;
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bool valid() const { return bool(st); }
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bool operator!() const { return !valid(); }
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operator bool() const { return valid(); }
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template<class U, class time_point> friend future_status wait_until(const future<U> &, const time_point &);
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template<class time_point> future_status wait_until(const time_point &) const;
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template<class duration> future_status wait(const duration &d) const;
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void wait() const;
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future();
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future(promise<void> &promise);
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};
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template<class... T>
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struct ircd::ctx::scoped_future
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:future<T...>
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{
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template<class... Args> scoped_future(Args&&... args);
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~scoped_future() noexcept;
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};
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template<class... T>
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template<class... Args>
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ircd::ctx::scoped_future<T...>::scoped_future(Args&&... args)
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:future<T...>{std::forward<Args>(args)...}
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{
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}
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template<class... T>
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ircd::ctx::scoped_future<T...>::~scoped_future()
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noexcept
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{
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if(std::uncaught_exception())
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return;
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if(this->valid())
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this->wait();
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}
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inline
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ircd::ctx::future<void>::future()
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:st{nullptr}
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{
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}
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template<class T>
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ircd::ctx::future<T>::future()
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:st{nullptr}
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{
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}
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inline
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ircd::ctx::future<void>::future(promise<void> &promise)
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:st{promise.get_state().share()}
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{
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}
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template<class T>
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ircd::ctx::future<T>::future(promise<T> &promise)
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:st{promise.get_state().share()}
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{
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}
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template<class T>
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T
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ircd::ctx::future<T>::get()
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{
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wait();
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if(unlikely(bool(st->eptr)))
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std::rethrow_exception(st->eptr);
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return st->val;
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}
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inline void
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ircd::ctx::future<void>::wait()
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const
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{
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this->wait_until(steady_clock::time_point::max());
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}
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template<class T>
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void
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ircd::ctx::future<T>::wait()
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const
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{
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this->wait_until(steady_clock::time_point::max());
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}
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template<class duration>
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ircd::ctx::future_status
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ircd::ctx::future<void>::wait(const duration &d)
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const
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{
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return this->wait_until(steady_clock::now() + d);
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}
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template<class T>
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template<class duration>
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ircd::ctx::future_status
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ircd::ctx::future<T>::wait(const duration &d)
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const
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{
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return this->wait_until(steady_clock::now() + d);
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}
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template<class T>
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template<class time_point>
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ircd::ctx::future_status
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ircd::ctx::future<T>::wait_until(const time_point &tp)
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const
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{
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return ircd::ctx::wait_until(*this, tp);
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}
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template<class time_point>
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ircd::ctx::future_status
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ircd::ctx::future<void>::wait_until(const time_point &tp)
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const
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{
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return ircd::ctx::wait_until(*this, tp);
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}
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template<class T,
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class time_point>
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ircd::ctx::future_status
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ircd::ctx::wait_until(const future<T> &f,
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const time_point &tp)
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{
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const auto wfun([&f]() -> bool
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{
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return f.st->finished;
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});
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if(unlikely(!f.valid()))
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throw no_state();
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if(unlikely(!f.st->cond.wait_until(tp, wfun)))
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return future_status::timeout;
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return likely(wfun())? future_status::ready:
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future_status::deferred;
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}
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