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Allow user to override pthread mutex and cond

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Justine Tunney 2024-12-23 21:57:52 -08:00
parent 4705705548
commit 55b7aa1632
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54 changed files with 216 additions and 102 deletions
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libc/thread/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 et 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/atomic.h"
#include "libc/intrin/strace.h"
#include "libc/thread/thread.h"
/**
* Acquires spin lock, e.g.
*
* 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);
*
* This function has undefined behavior when `spin` wasn't intialized or
* was destroyed, and if the lock is already held by the calling thread.
*
* You can debug locks the acquisition of locks by building your program
* with `cosmocc -mdbg` and passing the `--strace` flag to your program.
* This will cause a line to be logged each time a mutex or spin lock is
* locked or unlocked. When locking, this is printed after the lock gets
* acquired. The entry to the lock operation will be logged too but only
* if the lock couldn't be immediately acquired. Lock logging works best
* when `mutex` refers to a static variable, in which case its name will
* be printed in the log.
*
* @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) {
if (atomic_exchange_explicit(&spin->_lock, 1, memory_order_acquire)) {
LOCKTRACE("acquiring pthread_spin_lock(%t)...", spin);
for (;;) {
for (;;)
if (!atomic_load_explicit(&spin->_lock, memory_order_relaxed))
break;
if (!atomic_exchange_explicit(&spin->_lock, 1, memory_order_acquire))
break;
}
}
LOCKTRACE("pthread_spin_lock(%t)", spin);
return 0;
}