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Implement POSIX threads API

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Justine Tunney 2022-09-05 08:26:03 -07:00
parent af24f21556
commit 9be364d40a
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95 changed files with 6029 additions and 317 deletions
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libc/intrin/pthread_spin_lock.c Normal file
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/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
│vi: set net ft=c ts=2 sts=2 sw=2 fenc=utf-8 :vi│
╞══════════════════════════════════════════════════════════════════════════════╡
│ Copyright 2022 Justine Alexandra Roberts Tunney │
│ │
│ 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 appear in all copies. │
│ │
│ THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL │
│ WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED │
│ WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE │
│ AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL │
│ DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR │
│ PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER │
│ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR │
│ PERFORMANCE OF THIS SOFTWARE. │
╚─────────────────────────────────────────────────────────────────────────────*/
#include "libc/intrin/pthread.h"
/**
* Acquires spin lock.
*
* spin l: 181,570c 58,646ns
* mutex normal l: 297,965c 96,241ns
* mutex recursive l: 1,112,166c 359,223ns
* mutex errorcheck l: 1,449,723c 468,252ns
*
* If the lock is already held, this function will wait for it to become
* available. No genuine error conditions are currently defined. This is
* similar to pthread_mutex_lock() except spin locks are much simpler so
* this API is able to offer a performance advantage in situations where
* scalable contention handling isn't necessary. Spinlocks are also very
* small especially in MODE=tiny where a lock needs 16 bytes of code and
* unlocking needs just 5 bytes. The lock object also only takes 1 byte.
*
* The posixly correct way to use this API is as follows:
*
* pthread_spinlock_t lock;
* pthread_spin_init(&lock, PTHREAD_PROCESS_PRIVATE);
* pthread_spin_lock(&lock);
* // do work...
* pthread_spin_unlock(&lock);
* pthread_spin_destroy(&lock);
*
* Cosmopolitan permits succinct notation for spin locks:
*
* pthread_spinlock_t lock = 0;
* pthread_spin_lock(&lock);
* // do work...
* pthread_spin_unlock(&lock);
*
* @return 0 on success, or errno on error
* @see pthread_spin_trylock
* @see pthread_spin_unlock
* @see pthread_spin_init
*/
int(pthread_spin_lock)(pthread_spinlock_t *spin) {
return pthread_spin_lock(spin);
}