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49 lines
2.6 KiB
C
49 lines
2.6 KiB
C
/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
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│ vi: set et ft=c ts=2 sts=2 sw=2 fenc=utf-8 :vi │
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╞══════════════════════════════════════════════════════════════════════════════╡
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│ Copyright 2022 Justine Alexandra Roberts Tunney │
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│ │
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│ Permission to use, copy, modify, and/or distribute this software for │
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│ any purpose with or without fee is hereby granted, provided that the │
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│ above copyright notice and this permission notice appear in all copies. │
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│ │
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│ THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL │
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│ WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED │
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│ WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE │
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│ AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL │
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│ DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR │
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│ PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER │
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│ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR │
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│ PERFORMANCE OF THIS SOFTWARE. │
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╚─────────────────────────────────────────────────────────────────────────────*/
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#include "libc/intrin/atomic.h"
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#include "libc/thread/thread.h"
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/**
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* Acquires spin lock, e.g.
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*
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* pthread_spinlock_t lock;
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* pthread_spin_init(&lock, PTHREAD_PROCESS_PRIVATE);
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* pthread_spin_lock(&lock);
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* // do work...
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* pthread_spin_unlock(&lock);
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* pthread_spin_destroy(&lock);
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*
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* This function has undefined behavior when `spin` wasn't intialized,
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* was destroyed, or if the lock's already held by the calling thread.
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*
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* @return 0 on success, or errno on error
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* @see pthread_spin_trylock
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* @see pthread_spin_unlock
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* @see pthread_spin_init
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*/
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errno_t pthread_spin_lock(pthread_spinlock_t *spin) {
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for (;;) {
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if (!atomic_exchange_explicit(&spin->_lock, 1, memory_order_acquire))
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break;
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for (;;)
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if (!atomic_load_explicit(&spin->_lock, memory_order_relaxed))
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break;
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}
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return 0;
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}
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