mirror of
https://github.com/matrix-construct/construct
synced 2024-10-31 10:58:54 +01:00
143 lines
3.3 KiB
C++
143 lines
3.3 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_UNINTERRUPTIBLE_H
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namespace ircd::ctx
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{
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bool interruptible(const ctx &) noexcept;
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void interruptible(ctx &, const bool &) noexcept;
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}
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namespace ircd::ctx {
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inline namespace this_ctx
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{
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struct uninterruptible;
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bool interruptible() noexcept;
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void interruptible(const bool &);
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void interruptible(const bool &, std::nothrow_t) noexcept;
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}}
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/// An instance of uninterruptible will suppress interrupts sent to the
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/// context for the scope. Suppression does not discard any interrupt,
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/// it merely ignores it at all interruption points until the suppression
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/// ends, after which it will be thrown.
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///
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struct ircd::ctx::this_ctx::uninterruptible
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{
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struct nothrow;
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bool theirs;
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uninterruptible(const bool & = true);
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uninterruptible(uninterruptible &&) = delete;
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uninterruptible(const uninterruptible &) = delete;
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~uninterruptible() noexcept(false);
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};
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/// A variant of uinterruptible for users that must guarantee the ending of
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/// the suppression scope will not be an interruption point. The default
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/// behavior for uninterruptible is to throw, even from its destructor, to
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/// fulfill the interruption request without any more delay.
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///
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struct ircd::ctx::this_ctx::uninterruptible::nothrow
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{
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bool theirs;
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nothrow(const bool & = true) noexcept;
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nothrow(nothrow &&) = delete;
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nothrow(const nothrow &) = delete;
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~nothrow() noexcept;
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};
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//
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// uninterruptible
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//
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inline
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ircd::ctx::this_ctx::uninterruptible::uninterruptible(const bool &ours)
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:theirs
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{
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interruptible(cur())
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}
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{
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interruptible(!ours);
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}
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inline
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ircd::ctx::this_ctx::uninterruptible::~uninterruptible()
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noexcept(false)
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{
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interruptible(theirs);
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}
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//
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// uninterruptible::nothrow
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//
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inline
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ircd::ctx::this_ctx::uninterruptible::nothrow::nothrow(const bool &ours)
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noexcept
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:theirs
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{
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interruptible(cur())
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}
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{
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interruptible(!ours, std::nothrow);
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}
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inline
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ircd::ctx::this_ctx::uninterruptible::nothrow::~nothrow()
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noexcept
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{
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interruptible(theirs, std::nothrow);
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}
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//
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// interruptible
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//
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inline void
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ircd::ctx::this_ctx::interruptible(const bool &b,
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std::nothrow_t)
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noexcept
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{
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interruptible(cur(), b);
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}
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inline bool
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ircd::ctx::this_ctx::interruptible()
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noexcept
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{
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return interruptible(cur());
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}
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/// Marks `ctx` for whether to allow or suppress interruption. Suppression
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/// does not ignore an interrupt itself, it only ignores the interruption
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/// points. Thus when a suppression ends if the interrupt flag was ever set
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/// the next interruption point will throw as expected.
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inline void
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ircd::ctx::interruptible(ctx &ctx,
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const bool &b)
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noexcept
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{
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flags(ctx) ^= (flags(ctx) ^ (ulong(b) - 1)) & context::NOINTERRUPT;
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assert(bool(flags(ctx) & context::NOINTERRUPT) == !b);
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assert(interruptible(ctx) == b);
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}
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inline bool
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ircd::ctx::interruptible(const ctx &ctx)
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noexcept
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{
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return ~flags(ctx) & context::NOINTERRUPT;
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}
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