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Introduce pthread_condattr_setclock()

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This is one of the few POSIX APIs that was missing. It lets you choose a
monotonic clock for your condition variables. This might improve perf on
some platforms. It might also grant more flexibility with NTP configs. I
know Qt is one project that believes it needs this. To introduce this, I
needed to change some the *NSYNC APIs, to support passing a clock param.
There's also new benchmarks, demonstrating Cosmopolitan's supremacy over
many libc implementations when it comes to mutex performance. Cygwin has
an alarmingly bad pthread_mutex_t implementation. It is so bad that they
would have been significantly better off if they'd used naive spinlocks.
This commit is contained in:
Justine Tunney 2024-09-02 23:37:50 -07:00
parent 79516bf08e
commit 3c61a541bd
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GPG key ID: BE714B4575D6E328
55 changed files with 449 additions and 155 deletions
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3
libc/thread/sem_timedwait.c
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@ -28,6 +28,7 @@
#include "libc/intrin/weaken.h"
#include "libc/limits.h"
#include "libc/runtime/syslib.internal.h"
#include "libc/sysv/consts/clock.h"
#include "libc/sysv/errfuns.h"
#include "libc/thread/semaphore.h"
#include "libc/thread/thread.h"
@ -121,7 +122,7 @@ int sem_timedwait(sem_t *sem, const struct timespec *abstime) {
do {
if (!(v = atomic_load_explicit(&sem->sem_value, memory_order_relaxed))) {
rc = nsync_futex_wait_(&sem->sem_value, v, true, abstime);
rc = nsync_futex_wait_(&sem->sem_value, v, true, CLOCK_REALTIME, abstime);
if (rc == -EINTR || rc == -ECANCELED) {
errno = -rc;
rc = -1;