97 lines
2.1 KiB
C
97 lines
2.1 KiB
C
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//
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// Copyright 2021 Staysail Systems, Inc. <info@staysail.tech>
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// Copyright 2018 Capitar IT Group BV <info@capitar.com>
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//
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// This software is supplied under the terms of the MIT License, a
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// copy of which should be located in the distribution where this
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// file was obtained (LICENSE.txt). A copy of the license may also be
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// found online at https://opensource.org/licenses/MIT.
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//
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#include "core/nng_impl.h"
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// We pack the wfd and rfd into a uint64_t so that we can update the pair
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// atomically and use nni_atomic_cas64, to be lock free.
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#define WFD(fds) ((int) ((fds) &0xffffffffu))
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#define RFD(fds) ((int) (((fds) >> 32u) & 0xffffffffu))
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#define FD_JOIN(wfd, rfd) ((uint64_t)(wfd) + ((uint64_t)(rfd) << 32u))
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void
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nni_pollable_init(nni_pollable *p)
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{
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nni_atomic_init_bool(&p->p_raised);
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nni_atomic_set64(&p->p_fds, (uint64_t) -1);
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}
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void
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nni_pollable_fini(nni_pollable *p)
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{
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uint64_t fds;
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fds = nni_atomic_get64(&p->p_fds);
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if (fds != (uint64_t) -1) {
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int rfd, wfd;
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// Read in the high order, write in the low order.
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rfd = RFD(fds);
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wfd = WFD(fds);
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nni_plat_pipe_close(rfd, wfd);
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}
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}
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void
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nni_pollable_raise(nni_pollable *p)
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{
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if (!nni_atomic_swap_bool(&p->p_raised, true)) {
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uint64_t fds;
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if ((fds = nni_atomic_get64(&p->p_fds)) != (uint64_t) -1) {
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nni_plat_pipe_raise(WFD(fds));
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}
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}
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}
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void
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nni_pollable_clear(nni_pollable *p)
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{
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if (nni_atomic_swap_bool(&p->p_raised, false)) {
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uint64_t fds;
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if ((fds = nni_atomic_get64(&p->p_fds)) != (uint64_t) -1) {
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nni_plat_pipe_clear(RFD(fds));
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}
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}
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}
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int
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nni_pollable_getfd(nni_pollable *p, int *fdp)
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{
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if (p == NULL) {
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return (NNG_EINVAL);
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}
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for (;;) {
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int rfd;
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int wfd;
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int rv;
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uint64_t fds;
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if ((fds = nni_atomic_get64(&p->p_fds)) != (uint64_t) -1) {
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*fdp = RFD(fds);
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return (0);
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}
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if ((rv = nni_plat_pipe_open(&wfd, &rfd)) != 0) {
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return (rv);
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}
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fds = FD_JOIN(wfd, rfd);
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if (nni_atomic_cas64(&p->p_fds, (uint64_t) -1, fds)) {
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if (nni_atomic_get_bool(&p->p_raised)) {
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nni_plat_pipe_raise(wfd);
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}
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*fdp = rfd;
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return (0);
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}
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// Someone beat us. Close ours, and try again.
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nni_plat_pipe_close(wfd, rfd);
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}
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}
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