mirror of
https://github.com/jart/cosmopolitan.git
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77 lines
4.1 KiB
C
77 lines
4.1 KiB
C
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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 net ft=c ts=2 sts=2 sw=2 fenc=utf-8 :vi│
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╞══════════════════════════════════════════════════════════════════════════════╡
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│ Copyright 2023 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/sigset.internal.h"
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#include "libc/errno.h"
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#include "libc/intrin/atomic.h"
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#include "libc/nt/synchronization.h"
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#include "libc/sysv/errfuns.h"
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#include "libc/thread/posixthread.internal.h"
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#include "libc/thread/tls.h"
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#ifdef __x86_64__
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// each thread has its own pt_futex which is used by both posix signals
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// and posix thread cancelation to "park" blocking operations that dont
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// need win32 overlapped i/o. the delay is advisory and may be -1 which
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// means wait forever. these functions don't guarantee to wait the full
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// duration. other threads wanting to deliver a signal, can wake parked
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// futexes without releasing them, just to stir up activity. if a futex
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// is both woken and released then the cancelation point shall generate
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// an eintr. we also abstract checking for signals & thread cancelation
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static textwindows int _park_wait(uint32_t msdelay, bool restartable,
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struct PosixThread *pt) {
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int got, expect = 0;
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if (_check_cancel() == -1) return -1;
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if (_check_signal(restartable) == -1) return -1;
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WaitOnAddress(&pt->pt_futex, &expect, sizeof(expect), msdelay);
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got = atomic_load_explicit(&pt->pt_futex, memory_order_acquire);
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return got != expect ? eintr() : 0;
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}
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static textwindows int _park_thread(uint32_t msdelay, sigset_t waitmask,
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bool restartable) {
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int rc;
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sigset_t om;
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struct PosixThread *pt;
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pt = _pthread_self();
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pt->pt_flags &= ~PT_RESTARTABLE;
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if (restartable) pt->pt_flags |= PT_RESTARTABLE;
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atomic_store_explicit(&pt->pt_futex, 0, memory_order_release);
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atomic_store_explicit(&pt->pt_blocker, &pt->pt_futex, memory_order_release);
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om = __sig_beginwait(waitmask);
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rc = _park_wait(msdelay, restartable, pt);
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if (rc == -1 && errno == EINTR) _check_cancel();
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__sig_finishwait(om);
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atomic_store_explicit(&pt->pt_blocker, PT_BLOCKER_CPU, memory_order_release);
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pt->pt_flags &= ~PT_RESTARTABLE;
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return rc;
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}
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textwindows int _park_norestart(uint32_t msdelay, sigset_t waitmask) {
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return _park_thread(msdelay, waitmask, false);
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}
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textwindows int _park_restartable(uint32_t msdelay, sigset_t waitmask) {
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return _park_thread(msdelay, waitmask, true);
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}
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#endif /* __x86_64__ */
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