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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.
129 lines
5.3 KiB
C
129 lines
5.3 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=2 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/sysv/consts/itimer.h"
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#include "libc/calls/sig.internal.h"
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#include "libc/calls/state.internal.h"
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#include "libc/calls/struct/itimerval.h"
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#include "libc/calls/struct/itimerval.internal.h"
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#include "libc/calls/struct/sigset.internal.h"
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#include "libc/calls/struct/timeval.h"
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#include "libc/cosmo.h"
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#include "libc/intrin/maps.h"
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#include "libc/intrin/strace.h"
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#include "libc/nt/enum/processcreationflags.h"
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#include "libc/nt/thread.h"
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#include "libc/str/str.h"
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#include "libc/sysv/consts/clock.h"
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#include "libc/sysv/consts/sicode.h"
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#include "libc/sysv/consts/sig.h"
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#include "libc/sysv/errfuns.h"
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#include "libc/thread/itimer.internal.h"
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#include "libc/thread/tls.h"
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#include "third_party/nsync/mu.h"
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#ifdef __x86_64__
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#define STACK_SIZE 65536
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struct IntervalTimer __itimer;
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static textwindows dontinstrument uint32_t __itimer_worker(void *arg) {
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struct CosmoTib tls;
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char *sp = __builtin_frame_address(0);
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__bootstrap_tls(&tls, sp);
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__maps_track(
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(char *)(((uintptr_t)sp + __pagesize - 1) & -__pagesize) - STACK_SIZE,
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STACK_SIZE);
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for (;;) {
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bool dosignal = false;
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struct timeval now, waituntil;
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nsync_mu_lock(&__itimer.lock);
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now = timeval_real();
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if (timeval_iszero(__itimer.it.it_value)) {
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waituntil = timeval_max;
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} else {
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if (timeval_cmp(now, __itimer.it.it_value) < 0) {
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waituntil = __itimer.it.it_value;
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} else {
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if (timeval_iszero(__itimer.it.it_interval)) {
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__itimer.it.it_value = timeval_zero;
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waituntil = timeval_max;
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} else {
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do {
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__itimer.it.it_value =
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timeval_add(__itimer.it.it_value, __itimer.it.it_interval);
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} while (timeval_cmp(now, __itimer.it.it_value) > 0);
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waituntil = __itimer.it.it_value;
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}
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dosignal = true;
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}
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}
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nsync_mu_unlock(&__itimer.lock);
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if (dosignal)
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__sig_generate(SIGALRM, SI_TIMER);
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nsync_mu_lock(&__itimer.lock);
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nsync_cv_wait_with_deadline(&__itimer.cond, &__itimer.lock, CLOCK_REALTIME,
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timeval_totimespec(waituntil), 0);
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nsync_mu_unlock(&__itimer.lock);
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}
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return 0;
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}
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static textwindows void __itimer_setup(void) {
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__itimer.thread = CreateThread(0, STACK_SIZE, __itimer_worker, 0,
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kNtStackSizeParamIsAReservation, 0);
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}
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textwindows void __itimer_wipe(void) {
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// this function is called by fork(), because
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// timers aren't inherited by forked subprocesses
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bzero(&__itimer, sizeof(__itimer));
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}
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textwindows int sys_setitimer_nt(int which, const struct itimerval *neu,
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struct itimerval *old) {
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struct itimerval config;
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cosmo_once(&__itimer.once, __itimer_setup);
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if (which != ITIMER_REAL || (neu && (!timeval_isvalid(neu->it_value) ||
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!timeval_isvalid(neu->it_interval)))) {
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return einval();
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}
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if (neu) {
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// POSIX defines setitimer() with the restrict keyword but let's
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// accommodate the usage setitimer(ITIMER_REAL, &it, &it) anyway
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config = *neu;
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}
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BLOCK_SIGNALS;
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nsync_mu_lock(&__itimer.lock);
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if (old) {
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old->it_interval = __itimer.it.it_interval;
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old->it_value = timeval_subz(__itimer.it.it_value, timeval_real());
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}
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if (neu) {
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if (!timeval_iszero(config.it_value)) {
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config.it_value = timeval_add(config.it_value, timeval_real());
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}
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__itimer.it = config;
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nsync_cv_signal(&__itimer.cond);
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}
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nsync_mu_unlock(&__itimer.lock);
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ALLOW_SIGNALS;
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return 0;
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}
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#endif /* __x86_64__ */
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