construct/include/ircd/ctx/shared_state.h

// Matrix Construct
//
// Copyright (C) Matrix Construct Developers, Authors & Contributors
// Copyright (C) 2016-2018 Jason Volk <jason@zemos.net>
//
// Permission to use, copy, modify, and/or distribute this software for any
// purpose with or without fee is hereby granted, provided that the above
// copyright notice and this permission notice is present in all copies. The
// full license for this software is available in the LICENSE file.

#pragma once
#define HAVE_IRCD_CTX_SHARED_STATE_H

namespace ircd::ctx
{
	struct shared_state_base;
	template<class T = void> struct shared_state;
	template<> struct shared_state<void>;
}

struct ircd::ctx::shared_state_base
{
	dock cond;
	std::exception_ptr eptr;
	uint promise_refcnt {0};
	bool finished {false};

	void reset();
};

template<class T>
struct ircd::ctx::shared_state
:shared_state_base
,std::enable_shared_from_this<shared_state<T>>
{
	using value_type      = T;
	using pointer_type    = T *;
	using reference_type  = T &;

	T val;

	std::shared_ptr<const shared_state<T>> share() const;
	std::shared_ptr<shared_state<T>> share();
};

template<>
struct ircd::ctx::shared_state<void>
:shared_state_base
,std::enable_shared_from_this<shared_state<void>>
{
	using value_type      = void;

	std::shared_ptr<const shared_state<void>> share() const;
	std::shared_ptr<shared_state<void>> share();
};

inline std::shared_ptr<ircd::ctx::shared_state<void>>
ircd::ctx::shared_state<void>::share()
{
	return this->shared_from_this();
}

template<class T>
std::shared_ptr<ircd::ctx::shared_state<T>>
ircd::ctx::shared_state<T>::share()
{
	return this->shared_from_this();
}

inline std::shared_ptr<const ircd::ctx::shared_state<void>>
ircd::ctx::shared_state<void>::share()
const
{
	return this->shared_from_this();
}

template<class T>
std::shared_ptr<const ircd::ctx::shared_state<T>>
ircd::ctx::shared_state<T>::share()
const
{
	return this->shared_from_this();
}

inline void
ircd::ctx::shared_state_base::reset()
{
	eptr = nullptr;
	finished = false;
}