mirrors/cosmopolitan
1
0
Fork 0
mirror of https://github.com/jart/cosmopolitan.git synced 2025-06-30 08:18:30 +00:00
Code Issues Projects Releases Packages Wiki Activity Actions 1

Introduce cosmo_futex_wait and cosmo_futex_wake

Browse source 
Cosmopolitan Futexes are now exposed as a public API.
This commit is contained in:
Justine Tunney 2024-11-22 11:08:29 -08:00
parent 729f7045e3
commit 9ddbfd921e
No known key found for this signature in database
GPG key ID: BE714B4575D6E328
66 changed files with 886 additions and 917 deletions
Download patch file Download diff file Expand all files Collapse all files

14
libc/intrin/pthread_mutex_unlock.c
View file

@ -18,6 +18,7 @@
╚─────────────────────────────────────────────────────────────────────────────*/
#include "libc/calls/calls.h"
#include "libc/calls/state.internal.h"
#include "libc/cosmo.h"
#include "libc/dce.h"
#include "libc/errno.h"
#include "libc/intrin/atomic.h"
@ -26,19 +27,14 @@
#include "libc/runtime/internal.h"
#include "libc/thread/lock.h"
#include "libc/thread/thread.h"
#include "third_party/nsync/futex.internal.h"
#include "third_party/nsync/mu.h"
static void pthread_mutex_unlock_spin(atomic_int *word) {
atomic_store_explicit(word, 0, memory_order_release);
}
// see "take 3" algorithm in "futexes are tricky" by ulrich drepper
static void pthread_mutex_unlock_drepper(atomic_int *futex, char pshare) {
int word = atomic_fetch_sub_explicit(futex, 1, memory_order_release);
if (word == 2) {
atomic_store_explicit(futex, 0, memory_order_release);
_weaken(nsync_futex_wake_)(futex, 1, pshare);
cosmo_futex_wake(futex, 1, pshare);
}
}
@ -137,11 +133,7 @@ errno_t pthread_mutex_unlock(pthread_mutex_t *mutex) {
// implement barebones normal mutexes
if (MUTEX_TYPE(word) == PTHREAD_MUTEX_NORMAL) {
if (_weaken(nsync_futex_wake_)) {
pthread_mutex_unlock_drepper(&mutex->_futex, MUTEX_PSHARED(word));
} else {
pthread_mutex_unlock_spin(&mutex->_futex);
}
pthread_mutex_unlock_drepper(&mutex->_futex, MUTEX_PSHARED(word));
return 0;
}