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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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16
third_party/nsync/mu_semaphore_futex.c vendored
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@ -63,7 +63,7 @@ errno_t nsync_mu_semaphore_p_futex (nsync_semaphore *s) {
int futex_result;
futex_result = -nsync_futex_wait_ (
(atomic_int *)&f->i, i,
PTHREAD_PROCESS_PRIVATE, 0);
PTHREAD_PROCESS_PRIVATE, 0, 0);
ASSERT (futex_result == 0 ||
futex_result == EINTR ||
futex_result == EAGAIN ||
@ -81,7 +81,7 @@ errno_t nsync_mu_semaphore_p_futex (nsync_semaphore *s) {
while additionally supporting a time parameter specifying at what point
in the future ETIMEDOUT should be returned, if neither cancellation, or
semaphore release happens. */
errno_t nsync_mu_semaphore_p_with_deadline_futex (nsync_semaphore *s, nsync_time abs_deadline) {
errno_t nsync_mu_semaphore_p_with_deadline_futex (nsync_semaphore *s, int clock, nsync_time abs_deadline) {
struct futex *f = (struct futex *)s;
int i;
int result = 0;
@ -98,7 +98,8 @@ errno_t nsync_mu_semaphore_p_with_deadline_futex (nsync_semaphore *s, nsync_time
ts = &ts_buf;
}
futex_result = nsync_futex_wait_ ((atomic_int *)&f->i, i,
PTHREAD_PROCESS_PRIVATE, ts);
PTHREAD_PROCESS_PRIVATE,
clock, ts);
ASSERT (futex_result == 0 ||
futex_result == -EINTR ||
futex_result == -EAGAIN ||
@ -106,9 +107,12 @@ errno_t nsync_mu_semaphore_p_with_deadline_futex (nsync_semaphore *s, nsync_time
futex_result == -ETIMEDOUT ||
futex_result == -EWOULDBLOCK);
/* Some systems don't wait as long as they are told. */
if (futex_result == -ETIMEDOUT &&
nsync_time_cmp (abs_deadline, nsync_time_now ()) <= 0) {
result = ETIMEDOUT;
if (futex_result == -ETIMEDOUT) {
nsync_time now;
if (clock_gettime (clock, &now))
result = EINVAL;
if (nsync_time_cmp (now, abs_deadline) >= 0)
result = ETIMEDOUT;
}
if (futex_result == -ECANCELED) {
result = ECANCELED;