mirror of
https://github.com/matrix-construct/construct
synced 2024-11-02 20:09:16 +01:00
95 lines
2.9 KiB
C++
95 lines
2.9 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_SHARED_STATE_H
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namespace ircd::ctx
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{
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enum class future_state :uintptr_t;
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struct shared_state_base;
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struct promise_base;
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template<class T> struct shared_state;
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template<> struct shared_state<void>;
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IRCD_EXCEPTION(ircd::ctx::error, future_error)
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future_state state(const shared_state_base &);
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bool is(const shared_state_base &, const future_state &);
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void set(shared_state_base &, const future_state &);
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size_t refcount(const shared_state_base &);
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void invalidate(shared_state_base &);
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void update(shared_state_base &);
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void notify(shared_state_base &);
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}
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/// Internal state enumeration for the promise / future / related. These can
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/// all be observed through state() or is(); only some can be set(). This is
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/// not for public manipulation.
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enum class ircd::ctx::future_state
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:uintptr_t
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{
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INVALID = 0, ///< Null.
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PENDING = 1, ///< Promise is attached and busy.
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READY = 2, ///< Result ready; promise is gone.
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OBSERVED = 3, ///< Special case for when_*(); not a state; promise is gone.
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RETRIEVED = 4, ///< User retrieved future value; promise is gone.
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};
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/// Internal Non-template base of the state object shared by promise and
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/// future. It is extended by the appropriate template, and usually resides
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/// in the future's instance, where the promise finds it.
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struct ircd::ctx::shared_state_base
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{
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mutable dock cond;
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std::exception_ptr eptr;
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std::function<void (shared_state_base &)> then;
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union
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{
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promise_base *p {nullptr};
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future_state st;
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};
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shared_state_base(promise_base &p);
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shared_state_base() = default;
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shared_state_base(shared_state_base &&) = default;
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shared_state_base(const shared_state_base &) = delete;
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shared_state_base &operator=(shared_state_base &&) = default;
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shared_state_base &operator=(const shared_state_base &) = delete;
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~shared_state_base() noexcept;
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};
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/// Internal shared state between future and promise appropos a future value.
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template<class T>
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struct ircd::ctx::shared_state
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:shared_state_base
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{
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using value_type = T;
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using pointer_type = T *;
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using reference_type = T &;
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T val;
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using shared_state_base::shared_state_base;
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using shared_state_base::operator=;
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};
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/// Internal shared state between future and promise when there is no future
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/// value, only a notification of completion or exception.
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template<>
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struct ircd::ctx::shared_state<void>
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:shared_state_base
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{
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using value_type = void;
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using shared_state_base::shared_state_base;
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using shared_state_base::operator=;
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};
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