mirror of
https://github.com/jart/cosmopolitan.git
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100 lines
4.1 KiB
C
100 lines
4.1 KiB
C
/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
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│vi: set net 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/dce.h"
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#include "libc/intrin/atomic.h"
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#include "libc/intrin/futex.internal.h"
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#include "libc/intrin/pthread.h"
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#include "libc/limits.h"
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static dontinline int pthread_cond_signal_impl(pthread_cond_t *cond, int n) {
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if (atomic_load_explicit(&cond->waits, memory_order_relaxed)) {
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atomic_fetch_add(&cond->seq, 1);
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if (IsLinux() || IsOpenbsd()) {
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if (cond->attr == PTHREAD_PROCESS_SHARED) {
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_futex_wake_public(&cond->seq, n);
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} else {
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_futex_wake_private(&cond->seq, n);
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}
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}
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}
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return 0;
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}
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/**
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* Wakes at least one thread waiting on condition, e.g.
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*
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* pthread_cond_t cond = PTHREAD_COND_INITIALIZER;
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* pthread_mutex_t lock = PTHREAD_MUTEX_INITIALIZER;
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*
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* // thread pool waiters
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* pthread_mutex_lock(&lock);
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* pthread_cond_wait(&cond, &lock);
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* pthread_mutex_unlock(&lock);
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*
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* // waker upper
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* pthread_mutex_lock(&lock);
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* pthread_cond_signal(&cond);
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* pthread_mutex_unlock(&lock);
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*
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* This function has no effect if there aren't any threads currently
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* waiting on the condition.
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*
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* @return 0 on success, or errno on error
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* @see pthread_cond_broadcast
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* @see pthread_cond_wait
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*/
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int pthread_cond_signal(pthread_cond_t *cond) {
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return pthread_cond_signal_impl(cond, 1);
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}
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/**
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* Wakes all threads waiting on condition, e.g.
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*
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* pthread_mutex_t lock;
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* pthread_mutexattr_t mattr;
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* pthread_mutexattr_init(&mattr);
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* pthread_mutexattr_settype(&mattr, PTHREAD_MUTEX_ERRORCHECK);
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* pthread_mutex_init(&lock, &mattr);
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*
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* pthread_cond_t cond;
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* pthread_condattr_t cattr;
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* pthread_condattr_init(&cattr);
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* pthread_condattr_setpshared(&cattr, PTHREAD_PROCESS_SHARED);
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* pthread_cond_init(&cond, &cattr);
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*
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* // waiting threads
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* CHECK_EQ(0, pthread_mutex_lock(&lock));
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* CHECK_EQ(0, pthread_cond_wait(&cond, &lock));
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* pthread_mutex_unlock(&lock);
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*
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* // notifying thread
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* CHECK_EQ(0, pthread_mutex_lock(&lock));
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* pthread_cond_broadcast(&cond);
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* pthread_mutex_unlock(&lock);
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*
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* This function has no effect if there aren't any threads currently
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* waiting on the condition.
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*
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* @return 0 on success, or errno on error
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* @see pthread_cond_signal
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* @see pthread_cond_wait
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*/
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int pthread_cond_broadcast(pthread_cond_t *cond) {
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return pthread_cond_signal_impl(cond, INT_MAX);
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}
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