mirror of
https://github.com/jart/cosmopolitan.git
synced 2025-02-07 06:53:33 +00:00
Give up on making clock_nanosleep() precise
Multiple projects I care about make the assumption that this isn't a system call that sleeps for a particular number of nanonseconds, but rather a function that parks processes on kernel scheduler quantums. Anyone who wants the old behavior should use cosmo_clock_nanosleep()
This commit is contained in:
Justine Tunney
parent
99f0491f04
commit
38bceaeb8f
4 changed files with 150 additions and 109 deletions
84
libc/calls/clock_nanosleep-cosmo.c
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84
libc/calls/clock_nanosleep-cosmo.c
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@ -0,0 +1,84 @@
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/*-*- 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=2 sts=2 sw=2 fenc=utf-8 :vi │
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╞══════════════════════════════════════════════════════════════════════════════╡
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│ Copyright 2024 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/calls.h"
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#include "libc/calls/internal.h"
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#include "libc/calls/struct/timespec.h"
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#include "libc/errno.h"
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#include "libc/runtime/clktck.h"
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#include "libc/runtime/runtime.h"
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#include "libc/sysv/consts/clock.h"
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#include "libc/sysv/consts/timer.h"
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/**
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* Sleeps with higher accuracy at the cost of cpu.
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*/
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int cosmo_clock_nanosleep(int clock, int flags, const struct timespec *req,
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struct timespec *rem) {
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// pick clocks
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int time_clock;
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int sleep_clock;
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if (clock == CLOCK_REALTIME || //
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clock == CLOCK_REALTIME_PRECISE) {
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time_clock = clock;
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sleep_clock = CLOCK_REALTIME;
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} else if (clock == CLOCK_MONOTONIC || //
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clock == CLOCK_MONOTONIC_PRECISE) {
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time_clock = clock;
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sleep_clock = CLOCK_MONOTONIC;
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} else if (clock == CLOCK_REALTIME_COARSE || //
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clock == CLOCK_REALTIME_FAST) {
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return sys_clock_nanosleep(CLOCK_REALTIME, flags, req, rem);
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} else if (clock == CLOCK_MONOTONIC_COARSE || //
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clock == CLOCK_MONOTONIC_FAST) {
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return sys_clock_nanosleep(CLOCK_MONOTONIC, flags, req, rem);
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} else {
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return sys_clock_nanosleep(clock, flags, req, rem);
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}
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// sleep bulk of time in kernel
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struct timespec start, deadline, remain, waitfor, now;
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struct timespec quantum = timespec_fromnanos(1000000000 / CLK_TCK);
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clock_gettime(time_clock, &start);
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deadline = flags & TIMER_ABSTIME ? *req : timespec_add(start, *req);
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if (timespec_cmp(start, deadline) >= 0) return 0;
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remain = timespec_sub(deadline, start);
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if (timespec_cmp(remain, quantum) > 0) {
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waitfor = timespec_sub(remain, quantum);
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if (sys_clock_nanosleep(sleep_clock, 0, &waitfor, rem) == -1) {
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if (!flags && rem && errno == EINTR) {
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*rem = timespec_add(*rem, quantum);
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}
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return -1;
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}
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}
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// spin through final scheduling quantum
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int rc = 0;
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ftrace_enabled(-1);
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do {
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if (_check_cancel()) {
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rc = -1;
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break;
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}
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clock_gettime(time_clock, &now);
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} while (timespec_cmp(now, deadline) < 0);
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ftrace_enabled(+1);
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return rc;
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}
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61
libc/calls/clock_nanosleep-sys.c
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61
libc/calls/clock_nanosleep-sys.c
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@ -0,0 +1,61 @@
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/*-*- 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=2 sts=2 sw=2 fenc=utf-8 :vi │
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╞══════════════════════════════════════════════════════════════════════════════╡
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│ Copyright 2024 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/calls.h"
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#include "libc/calls/cp.internal.h"
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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/dce.h"
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#include "libc/errno.h"
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#include "libc/intrin/describeflags.internal.h"
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#include "libc/intrin/strace.internal.h"
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#include "libc/intrin/weaken.h"
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#include "libc/sysv/errfuns.h"
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#include "libc/thread/thread.h"
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int sys_clock_nanosleep(int clock, int flags, //
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const struct timespec *req, struct timespec *rem) {
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int rc;
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BEGIN_CANCELATION_POINT;
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if (IsLinux() || IsFreebsd() || IsNetbsd()) {
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rc = __sys_clock_nanosleep(clock, flags, req, rem);
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} else if (IsXnu()) {
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rc = sys_clock_nanosleep_xnu(clock, flags, req, rem);
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} else if (IsOpenbsd()) {
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rc = sys_clock_nanosleep_openbsd(clock, flags, req, rem);
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} else if (IsWindows()) {
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rc = sys_clock_nanosleep_nt(clock, flags, req, rem);
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} else {
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rc = enosys();
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}
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if (rc > 0) {
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errno = rc;
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rc = -1;
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}
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// system call support might not detect cancelation on bsds
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if (rc == -1 && errno == EINTR && //
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_weaken(pthread_testcancel_np) && //
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_weaken(pthread_testcancel_np)()) {
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rc = ecanceled();
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}
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END_CANCELATION_POINT;
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STRACE("sys_clock_nanosleep(%s, %s, %s, [%s]) → %d% m",
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DescribeClockName(clock), DescribeSleepFlags(flags),
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DescribeTimespec(0, req), DescribeTimespec(rc, rem), rc);
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return rc;
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}
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@ -16,112 +16,10 @@
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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/assert.h"
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#include "libc/calls/cp.internal.h"
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#include "libc/calls/internal.h"
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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/dce.h"
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#include "libc/errno.h"
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#include "libc/intrin/describeflags.internal.h"
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#include "libc/intrin/kprintf.h"
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#include "libc/intrin/strace.internal.h"
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#include "libc/intrin/weaken.h"
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#include "libc/runtime/clktck.h"
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#include "libc/runtime/runtime.h"
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#include "libc/sysv/consts/clock.h"
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#include "libc/sysv/consts/timer.h"
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#include "libc/sysv/errfuns.h"
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#include "libc/thread/thread.h"
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static int sys_clock_nanosleep(int clock, int flags, //
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const struct timespec *req,
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struct timespec *rem) {
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int rc;
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BEGIN_CANCELATION_POINT;
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if (IsLinux() || IsFreebsd() || IsNetbsd()) {
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rc = __sys_clock_nanosleep(clock, flags, req, rem);
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} else if (IsXnu()) {
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rc = sys_clock_nanosleep_xnu(clock, flags, req, rem);
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} else if (IsOpenbsd()) {
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rc = sys_clock_nanosleep_openbsd(clock, flags, req, rem);
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} else if (IsWindows()) {
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rc = sys_clock_nanosleep_nt(clock, flags, req, rem);
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} else {
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rc = enosys();
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}
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if (rc > 0) {
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errno = rc;
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rc = -1;
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}
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// system call support might not detect cancelation on bsds
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if (rc == -1 && errno == EINTR && //
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_weaken(pthread_testcancel_np) && //
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_weaken(pthread_testcancel_np)()) {
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rc = ecanceled();
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}
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END_CANCELATION_POINT;
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STRACE("sys_clock_nanosleep(%s, %s, %s, [%s]) → %d% m",
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DescribeClockName(clock), DescribeSleepFlags(flags),
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DescribeTimespec(0, req), DescribeTimespec(rc, rem), rc);
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return rc;
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}
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static int cosmo_clock_nanosleep(int clock, int flags,
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const struct timespec *req,
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struct timespec *rem) {
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// pick clocks
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int time_clock;
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int sleep_clock;
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if (clock == CLOCK_REALTIME || //
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clock == CLOCK_REALTIME_PRECISE) {
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time_clock = clock;
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sleep_clock = CLOCK_REALTIME;
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} else if (clock == CLOCK_MONOTONIC || //
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clock == CLOCK_MONOTONIC_PRECISE) {
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time_clock = clock;
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sleep_clock = CLOCK_MONOTONIC;
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} else if (clock == CLOCK_REALTIME_COARSE || //
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clock == CLOCK_REALTIME_FAST) {
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return sys_clock_nanosleep(CLOCK_REALTIME, flags, req, rem);
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} else if (clock == CLOCK_MONOTONIC_COARSE || //
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clock == CLOCK_MONOTONIC_FAST) {
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return sys_clock_nanosleep(CLOCK_MONOTONIC, flags, req, rem);
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} else {
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return sys_clock_nanosleep(clock, flags, req, rem);
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}
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// sleep bulk of time in kernel
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struct timespec start, deadline, remain, waitfor, now;
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struct timespec quantum = timespec_fromnanos(1000000000 / CLK_TCK);
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unassert(!clock_gettime(time_clock, &start));
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deadline = flags & TIMER_ABSTIME ? *req : timespec_add(start, *req);
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if (timespec_cmp(start, deadline) >= 0) return 0;
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remain = timespec_sub(deadline, start);
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if (timespec_cmp(remain, quantum) > 0) {
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waitfor = timespec_sub(remain, quantum);
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if (sys_clock_nanosleep(sleep_clock, 0, &waitfor, rem) == -1) {
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if (!flags && rem && errno == EINTR) {
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*rem = timespec_add(*rem, quantum);
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}
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return -1;
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}
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}
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// spin through final scheduling quantum
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int rc = 0;
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ftrace_enabled(-1);
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do {
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if (_check_cancel()) {
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rc = -1;
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break;
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}
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unassert(!clock_gettime(time_clock, &now));
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} while (timespec_cmp(now, deadline) < 0);
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ftrace_enabled(+1);
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return rc;
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}
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/**
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* Sleeps for particular amount of time.
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@ -157,10 +55,8 @@ static int cosmo_clock_nanosleep(int clock, int flags,
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* on OpenBSD it's good; on XNU it's bad; and on Windows it's ugly.
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*
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* @param clock may be
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* - `CLOCK_REALTIME` to have nanosecond-accurate wall time sleeps
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* - `CLOCK_REALTIME_COARSE` to not spin through scheduler quantum
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* - `CLOCK_MONOTONIC` to base the sleep off the monotinic clock
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* - `CLOCK_MONOTONIC_COARSE` to once again not do userspace spin
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* - `CLOCK_REALTIME`
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* - `CLOCK_MONOTONIC`
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* @param flags can be 0 for relative and `TIMER_ABSTIME` for absolute
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* @param req can be a relative or absolute time, depending on `flags`
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* @param rem shall be updated with the remainder of unslept time when
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@ -193,7 +89,7 @@ errno_t clock_nanosleep(int clock, int flags, //
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return EINVAL;
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}
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errno_t old = errno;
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int rc = cosmo_clock_nanosleep(clock, flags, req, rem);
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int rc = sys_clock_nanosleep(clock, flags, req, rem);
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errno_t err = !rc ? 0 : errno;
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errno = old;
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return err;
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@ -19,8 +19,8 @@ int timespec_getres(struct timespec *, int) libcesque;
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int timespec_get(struct timespec *, int) libcesque;
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#ifdef _COSMO_SOURCE
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/* cosmopolitan libc's non-posix timespec library
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removed by default due to emacs codebase clash */
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int sys_clock_nanosleep(int, int, const struct timespec *, struct timespec *);
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int cosmo_clock_nanosleep(int, int, const struct timespec *, struct timespec *);
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#define timespec_zero ((struct timespec){0})
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#define timespec_max ((struct timespec){0x7fffffffffffffff, 999999999})
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libcesque int timespec_cmp(struct timespec, struct timespec) pureconst;
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