47 lines
1.3 KiB
C++
47 lines
1.3 KiB
C++
/*
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* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/.
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*
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* Copyright 2018-2019 Danny Robson <danny@nerdcruft.net>
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*/
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#pragma once
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#include <atomic>
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namespace cruft::thread {
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/// A CPU intensive, but lower latency, lock.
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///
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/// std::atomic_flag seems like it might have been a good option on which
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/// to base our implementation, but it appears potentially expensive to
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/// spin over without a cheap read operation.
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///
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/// Satisfies BasicLockable.
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///
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/// NOTE: All move operations assume that either the lock is held by the
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/// client performing the move, or that is not held by any client.
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class spinlock {
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public:
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spinlock ();
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~spinlock ();
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spinlock (spinlock &&) noexcept;
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spinlock& operator= (spinlock &&) noexcept;
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spinlock (const spinlock&) = delete;
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spinlock& operator= (const spinlock&) = delete;
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void lock ();
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void unlock ();
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private:
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static_assert (
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::std::atomic<bool>::is_always_lock_free,
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"we require a lock free primitive or the entire point is moot"
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);
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::std::atomic<bool> held;
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};
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};
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