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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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27
libc/calls/clock_nanosleep.c
View file

@ -19,6 +19,7 @@
#include "libc/calls/struct/timespec.h"
#include "libc/dce.h"
#include "libc/errno.h"
#include "libc/sysv/consts/clock.h"
#include "libc/sysv/consts/timer.h"
/**
@ -79,18 +80,32 @@
errno_t clock_nanosleep(int clock, int flags, //
const struct timespec *req, //
struct timespec *rem) {
if (IsMetal()) {
if (IsMetal())
return ENOSYS;
}
if (clock == 127 || //
(flags & ~TIMER_ABSTIME) || //
req->tv_sec < 0 || //
!(0 <= req->tv_nsec && req->tv_nsec <= 999999999)) {
!(0 <= req->tv_nsec && req->tv_nsec <= 999999999))
return EINVAL;
int rc;
errno_t err, old = errno;
TryAgain:
// Ensure fallback for old Linux sticks.
if (IsLinux() && clock == 4 /* CLOCK_MONOTONIC_RAW */)
clock = CLOCK_MONOTONIC_RAW;
rc = sys_clock_nanosleep(clock, flags, req, rem);
// CLOCK_MONOTONIC_RAW is Linux 2.6.28+ so not available on RHEL5
if (IsLinux() && rc && errno == EINVAL &&
clock == 4 /* CLOCK_MONOTONIC_RAW */) {
CLOCK_MONOTONIC_RAW = CLOCK_MONOTONIC;
CLOCK_MONOTONIC_RAW_APPROX = CLOCK_MONOTONIC;
goto TryAgain;
}
errno_t old = errno;
int rc = sys_clock_nanosleep(clock, flags, req, rem);
errno_t err = !rc ? 0 : errno;
err = !rc ? 0 : errno;
errno = old;
return err;
}