mirror of
https://github.com/jart/cosmopolitan.git
synced 2025-02-01 03:53:33 +00:00
c7a8cd21e9
This change improves copy_file_range(), sendfile(), splice(), openpty(), closefrom(), close_range(), fadvise() and posix_fadvise() in addition to writing tests that confirm things like errno and seeking behavior across platforms. We now less aggressively polyfill behavior with some of these functions when the platform support isn't available. Please see: https://justine.lol/cosmopolitan/functions.html
55 lines
3 KiB
C
55 lines
3 KiB
C
/*-*- 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/thread/thread.h"
|
|
|
|
/**
|
|
* Acquires spin lock.
|
|
*
|
|
* 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
|
|
*/
|
|
errno_t(pthread_spin_lock)(pthread_spinlock_t *spin) {
|
|
return pthread_spin_lock(spin);
|
|
}
|