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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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12
third_party/nsync/mem/nsync_cv.c vendored
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@ -175,6 +175,7 @@ struct nsync_cv_wait_with_deadline_s {
void *pmu;
void (*lock) (void *);
nsync_mu *cv_mu;
int clock;
nsync_time abs_deadline;
nsync_note cancel_note;
waiter *w;
@ -187,7 +188,7 @@ static int nsync_cv_wait_with_deadline_impl_ (struct nsync_cv_wait_with_deadline
IGNORE_RACES_START ();
while (ATM_LOAD_ACQ (&c->w->nw.waiting) != 0) { /* acquire load */
if (c->sem_outcome == 0) {
c->sem_outcome = nsync_sem_wait_with_cancel_ (c->w, c->abs_deadline, c->cancel_note);
c->sem_outcome = nsync_sem_wait_with_cancel_ (c->w, c->clock, c->abs_deadline, c->cancel_note);
}
if (c->sem_outcome != 0 && ATM_LOAD (&c->w->nw.waiting) != 0) {
/* A timeout or cancellation occurred, and no wakeup.
@ -278,13 +279,14 @@ static void nsync_cv_wait_with_deadline_unwind_ (void *arg) {
programmes. */
int nsync_cv_wait_with_deadline_generic (nsync_cv *pcv, void *pmu,
void (*lock) (void *), void (*unlock) (void *),
nsync_time abs_deadline,
int clock, nsync_time abs_deadline,
nsync_note cancel_note) {
int outcome;
struct nsync_cv_wait_with_deadline_s c;
IGNORE_RACES_START ();
c.w = nsync_waiter_new_ ();
c.clock = clock;
c.abs_deadline = abs_deadline;
c.cancel_note = cancel_note;
c.cv_mu = NULL;
@ -470,10 +472,10 @@ void nsync_cv_broadcast (nsync_cv *pcv) {
/* Wait with deadline, using an nsync_mu. */
errno_t nsync_cv_wait_with_deadline (nsync_cv *pcv, nsync_mu *pmu,
nsync_time abs_deadline,
int clock, nsync_time abs_deadline,
nsync_note cancel_note) {
return (nsync_cv_wait_with_deadline_generic (pcv, pmu, &void_mu_lock,
&void_mu_unlock,
&void_mu_unlock, clock,
abs_deadline, cancel_note));
}
@ -486,7 +488,7 @@ errno_t nsync_cv_wait_with_deadline (nsync_cv *pcv, nsync_mu *pmu,
ECANCELED may be returned if calling POSIX thread is cancelled only when
the PTHREAD_CANCEL_MASKED mode is in play. */
errno_t nsync_cv_wait (nsync_cv *pcv, nsync_mu *pmu) {
return nsync_cv_wait_with_deadline (pcv, pmu, nsync_time_no_deadline, NULL);
return nsync_cv_wait_with_deadline (pcv, pmu, 0, nsync_time_no_deadline, NULL);
}
static nsync_time cv_ready_time (void *v, struct nsync_waiter_s *nw) {