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Make futexes cancellable by pthreads

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Justine Tunney 2022-11-04 18:19:05 -07:00
parent 2278327eba
commit 022536cab6
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GPG key ID: BE714B4575D6E328
101 changed files with 627 additions and 391 deletions
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21
third_party/nsync/mu_semaphore.c vendored
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@ -17,6 +17,8 @@
╚─────────────────────────────────────────────────────────────────────────────*/
#include "libc/assert.h"
#include "libc/errno.h"
#include "libc/intrin/kprintf.h"
#include "libc/intrin/weaken.h"
#include "libc/str/str.h"
#include "libc/thread/thread.h"
#include "third_party/nsync/atomic.h"
@ -51,25 +53,32 @@ void nsync_mu_semaphore_init (nsync_semaphore *s) {
}
/* Wait until the count of *s exceeds 0, and decrement it. */
void nsync_mu_semaphore_p (nsync_semaphore *s) {
errno_t nsync_mu_semaphore_p (nsync_semaphore *s) {
struct futex *f = (struct futex *) s;
int i;
int result = 0;
do {
i = ATM_LOAD ((nsync_atomic_uint32_ *) &f->i);
if (i == 0) {
int futex_result = nsync_futex_wait_ ((atomic_int *)&f->i, i, PTHREAD_PROCESS_PRIVATE, NULL);
int futex_result = nsync_futex_wait_ (
(atomic_int *)&f->i, i, PTHREAD_PROCESS_PRIVATE, NULL);
ASSERT (futex_result == 0 ||
futex_result == -EINTR ||
futex_result == -EAGAIN ||
futex_result == -ECANCELED ||
futex_result == -EWOULDBLOCK);
if (futex_result == -ECANCELED) {
result = ECANCELED;
}
}
} while (i == 0 || !ATM_CAS_ACQ ((nsync_atomic_uint32_ *) &f->i, i, i-1));
} while (result == 0 && (i == 0 || !ATM_CAS_ACQ ((nsync_atomic_uint32_ *) &f->i, i, i-1)));
return result;
}
/* Wait until one of:
the count of *s is non-zero, in which case decrement *s and return 0;
or abs_deadline expires, in which case return ETIMEDOUT. */
int nsync_mu_semaphore_p_with_deadline (nsync_semaphore *s, nsync_time abs_deadline) {
errno_t nsync_mu_semaphore_p_with_deadline (nsync_semaphore *s, nsync_time abs_deadline) {
struct futex *f = (struct futex *)s;
int i;
int result = 0;
@ -103,6 +112,7 @@ int nsync_mu_semaphore_p_with_deadline (nsync_semaphore *s, nsync_time abs_deadl
ASSERT (futex_result == 0 ||
futex_result == -EINTR ||
futex_result == -EAGAIN ||
futex_result == -ECANCELED ||
futex_result == -ETIMEDOUT ||
futex_result == -EWOULDBLOCK);
/* Some systems don't wait as long as they are told. */
@ -110,6 +120,9 @@ int nsync_mu_semaphore_p_with_deadline (nsync_semaphore *s, nsync_time abs_deadl
nsync_time_cmp (abs_deadline, nsync_time_now ()) <= 0) {
result = ETIMEDOUT;
}
if (futex_result == -ECANCELED) {
result = ECANCELED;
}
}
} while (result == 0 && (i == 0 || !ATM_CAS_ACQ ((nsync_atomic_uint32_ *) &f->i, i, i - 1)));
return (result);