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https://github.com/jart/cosmopolitan.git
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3c61a541bd
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.
121 lines
4.8 KiB
C
121 lines
4.8 KiB
C
/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
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│ vi: set et ft=c ts=8 sts=2 sw=2 fenc=utf-8 :vi │
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╞══════════════════════════════════════════════════════════════════════════════╡
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│ Copyright 2020 Justine Alexandra Roberts Tunney │
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│ │
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│ Permission to use, copy, modify, and/or distribute this software for │
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│ any purpose with or without fee is hereby granted, provided that the │
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│ above copyright notice and this permission notice appear in all copies. │
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│ │
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│ THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL │
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│ WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED │
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│ WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE │
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│ AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL │
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│ DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR │
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│ PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER │
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│ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR │
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│ PERFORMANCE OF THIS SOFTWARE. │
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╚─────────────────────────────────────────────────────────────────────────────*/
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#include "libc/calls/struct/timespec.h"
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#include "libc/calls/struct/timespec.internal.h"
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#include "libc/calls/syscall_support-sysv.internal.h"
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#include "libc/dce.h"
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#include "libc/errno.h"
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#include "libc/intrin/describeflags.h"
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#include "libc/intrin/strace.h"
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#include "libc/runtime/syslib.internal.h"
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#include "libc/sysv/consts/clock.h"
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#ifdef __aarch64__
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#define CGT_VDSO __vdsosym("LINUX_2.6.39", "__kernel_clock_gettime")
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#else
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#define CGT_VDSO __vdsosym("LINUX_2.6", "__vdso_clock_gettime")
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#endif
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typedef int clock_gettime_f(int, struct timespec *);
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static clock_gettime_f *__clock_gettime_get(void) {
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clock_gettime_f *cgt;
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if (IsLinux() && (cgt = CGT_VDSO)) {
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return cgt;
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} else if (__syslib) {
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return (void *)__syslib->__clock_gettime;
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} else if (IsWindows()) {
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return sys_clock_gettime_nt;
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#ifdef __x86_64__
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} else if (IsXnu()) {
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return sys_clock_gettime_xnu;
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#endif
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} else {
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return sys_clock_gettime;
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}
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}
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static int __clock_gettime_init(int, struct timespec *);
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static clock_gettime_f *__clock_gettime = __clock_gettime_init;
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static int __clock_gettime_init(int clockid, struct timespec *ts) {
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clock_gettime_f *cgt;
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__clock_gettime = cgt = __clock_gettime_get();
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return cgt(clockid, ts);
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}
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static int clock_gettime_impl(int clock, struct timespec *ts) {
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int rc;
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if (!IsLinux())
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return __clock_gettime(clock, ts);
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TryAgain:
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// Ensure fallback for old Linux sticks.
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if (clock == 4 /* CLOCK_MONOTONIC_RAW */)
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clock = CLOCK_MONOTONIC_RAW;
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// Call appropriate implementation.
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rc = __clock_gettime(clock, ts);
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// CLOCK_MONOTONIC_RAW is Linux 2.6.28+ so not available on RHEL5
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if (rc == -EINVAL && clock == 4 /* CLOCK_MONOTONIC_RAW */) {
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CLOCK_MONOTONIC_RAW = CLOCK_MONOTONIC;
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CLOCK_MONOTONIC_RAW_APPROX = CLOCK_MONOTONIC;
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goto TryAgain;
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}
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return rc;
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}
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/**
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* Returns nanosecond time.
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*
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* @param clock supports the following values across OSes:
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* - `CLOCK_REALTIME`
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* - `CLOCK_MONOTONIC`
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* - `CLOCK_MONOTONIC_RAW`
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* - `CLOCK_MONOTONIC_RAW_APPROX`
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* - `CLOCK_REALTIME_FAST`
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* - `CLOCK_REALTIME_COARSE`
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* - `CLOCK_REALTIME_PRECISE`
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* - `CLOCK_MONOTONIC_FAST`
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* - `CLOCK_MONOTONIC_COARSE`
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* - `CLOCK_MONOTONIC_PRECISE`
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* - `CLOCK_THREAD_CPUTIME_ID`
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* - `CLOCK_PROCESS_CPUTIME_ID`
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* @param ts is where the result is stored (or null to do clock check)
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* @return 0 on success, or -1 w/ errno
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* @raise EFAULT if `ts` points to invalid memory
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* @error EINVAL if `clock` isn't supported on this system
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* @error EPERM if pledge() is in play without stdio promise
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* @error ESRCH on NetBSD if PID/TID OR'd into `clock` wasn't found
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* @see strftime(), gettimeofday()
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* @asyncsignalsafe
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* @vforksafe
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*/
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int clock_gettime(int clock, struct timespec *ts) {
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// threads on win32 stacks call this so we can't asan check *ts
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int rc = clock_gettime_impl(clock, ts);
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if (rc) {
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errno = -rc;
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rc = -1;
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}
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TIMETRACE("clock_gettime(%s, [%s]) → %d% m", DescribeClockName(clock),
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DescribeTimespec(rc, ts), rc);
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return rc;
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}
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