X-Git-Url: https://git.llucax.com/software/libev.git/blobdiff_plain/b7186278d06b224100f3bbaed1976d014246bbd9..7a5cc2e0a749c9e9f9b2aaa2018f75eaaf46958c:/ev_epoll.c?ds=sidebyside diff --git a/ev_epoll.c b/ev_epoll.c index c6d3af5..76645ec 100644 --- a/ev_epoll.c +++ b/ev_epoll.c @@ -1,104 +1,182 @@ /* + * libev epoll fd activity backend + * * Copyright (c) 2007 Marc Alexander Lehmann * All rights reserved. * - * Redistribution and use in source and binary forms, with or without - * modification, are permitted provided that the following conditions are - * met: + * Redistribution and use in source and binary forms, with or without modifica- + * tion, are permitted provided that the following conditions are met: + * + * 1. Redistributions of source code must retain the above copyright notice, + * this list of conditions and the following disclaimer. + * + * 2. Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in the + * documentation and/or other materials provided with the distribution. + * + * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED + * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MER- + * CHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO + * EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPE- + * CIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, + * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; + * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, + * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTH- + * ERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED + * OF THE POSSIBILITY OF SUCH DAMAGE. * - * * Redistributions of source code must retain the above copyright - * notice, this list of conditions and the following disclaimer. + * Alternatively, the contents of this file may be used under the terms of + * the GNU General Public License ("GPL") version 2 or any later version, + * in which case the provisions of the GPL are applicable instead of + * the above. If you wish to allow the use of your version of this file + * only under the terms of the GPL and not to allow others to use your + * version of this file under the BSD license, indicate your decision + * by deleting the provisions above and replace them with the notice + * and other provisions required by the GPL. If you do not delete the + * provisions above, a recipient may use your version of this file under + * either the BSD or the GPL. + */ + +/* + * general notes about epoll: * - * * Redistributions in binary form must reproduce the above - * copyright notice, this list of conditions and the following - * disclaimer in the documentation and/or other materials provided - * with the distribution. + * a) epoll silently removes fds from the fd set. as nothing tells us + * that an fd has been removed otherwise, we have to continually + * "rearm" fds that we suspect *might* have changed (same + * problem with kqueue, but much less costly there). + * b) the fact that ADD != MOD creates a lot of extra syscalls due to a) + * and seems not to have any advantage. + * c) the inability to handle fork or file descriptors (think dup) + * limits the applicability over poll, so this is not a generic + * poll replacement. * - * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS - * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT - * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR - * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT - * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, - * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT - * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, - * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY - * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT - * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE - * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. + * lots of "weird code" and complication handling in this file is due + * to these design problems with epoll, as we try very hard to avoid + * epoll_ctl syscalls for common usage patterns. */ #include -static int epoll_fd = -1; - static void -epoll_modify (int fd, int oev, int nev) +epoll_modify (EV_P_ int fd, int oev, int nev) { - int mode = nev ? oev ? EPOLL_CTL_MOD : EPOLL_CTL_ADD : EPOLL_CTL_DEL; - struct epoll_event ev; - ev.data.fd = fd; - ev.events = - (nev & EV_READ ? EPOLLIN : 0) - | (nev & EV_WRITE ? EPOLLOUT : 0); - epoll_ctl (epoll_fd, mode, fd, &ev); -} + /* + * we handle EPOLL_CTL_DEL by ignoring it here + * on the assumption that the fd is gone anyways + * if that is wrong, we have to handle the spurious + * event in epoll_poll. + */ + if (!nev) + return; -void epoll_postfork_child (void) -{ - int fd; + ev.data.u64 = fd; /* use u64 to fully initialise the struct, for nicer strace etc. */ + ev.events = (nev & EV_READ ? EPOLLIN : 0) + | (nev & EV_WRITE ? EPOLLOUT : 0); + + if (expect_true (!epoll_ctl (backend_fd, oev ? EPOLL_CTL_MOD : EPOLL_CTL_ADD, fd, &ev))) + return; - epoll_fd = epoll_create (256); - fcntl (epoll_fd, F_SETFD, FD_CLOEXEC); + if (expect_true (errno == ENOENT)) + { + /* on ENOENT the fd went away, so try to do the right thing */ + if (!nev) + return; - /* re-register interest in fds */ - for (fd = 0; fd < anfdmax; ++fd) - if (anfds [fd].wev) - epoll_modify (fd, EV_NONE, anfds [fd].wev); -} + if (!epoll_ctl (backend_fd, EPOLL_CTL_ADD, fd, &ev)) + return; + } + else if (expect_true (errno == EEXIST)) + { + /* on EEXIST we ignored a previous DEL */ + if (!epoll_ctl (backend_fd, EPOLL_CTL_MOD, fd, &ev)) + return; + } -static struct epoll_event *events; -static int eventmax; + fd_kill (EV_A_ fd); +} -static void epoll_poll (ev_tstamp timeout) +static void +epoll_poll (EV_P_ ev_tstamp timeout) { - int eventcnt = epoll_wait (epoll_fd, events, eventmax, ceil (timeout * 1000.)); int i; + int eventcnt = epoll_wait (backend_fd, epoll_events, epoll_eventmax, (int)ceil (timeout * 1000.)); - if (eventcnt < 0) - return; + if (expect_false (eventcnt < 0)) + { + if (errno != EINTR) + syserr ("(libev) epoll_wait"); + + return; + } for (i = 0; i < eventcnt; ++i) - fd_event ( - events [i].data.fd, - (events [i].events & (EPOLLOUT | EPOLLERR | EPOLLHUP) ? EV_WRITE : 0) - | (events [i].events & (EPOLLIN | EPOLLERR | EPOLLHUP) ? EV_READ : 0) - ); + { + struct epoll_event *ev = epoll_events + i; + + int fd = ev->data.u64; + int got = (ev->events & (EPOLLOUT | EPOLLERR | EPOLLHUP) ? EV_WRITE : 0) + | (ev->events & (EPOLLIN | EPOLLERR | EPOLLHUP) ? EV_READ : 0); + int want = anfds [fd].events; + + if (expect_false (got & ~want)) + { + /* we received an event but are not interested in it, try mod or del */ + ev->events = (want & EV_READ ? EPOLLIN : 0) + | (want & EV_WRITE ? EPOLLOUT : 0); + + epoll_ctl (backend_fd, want ? EPOLL_CTL_MOD : EPOLL_CTL_DEL, fd, ev); + } + + fd_event (EV_A_ fd, got); + } /* if the receive array was full, increase its size */ - if (eventcnt == eventmax) + if (expect_false (eventcnt == epoll_eventmax)) { - free (events); - eventmax += eventmax >> 1; - events = malloc (sizeof (struct epoll_event) * eventmax); + ev_free (epoll_events); + epoll_eventmax = array_nextsize (sizeof (struct epoll_event), epoll_eventmax, epoll_eventmax + 1); + epoll_events = (struct epoll_event *)ev_malloc (sizeof (struct epoll_event) * epoll_eventmax); } } -void epoll_init (int flags) +int inline_size +epoll_init (EV_P_ int flags) { - epoll_fd = epoll_create (256); + backend_fd = epoll_create (256); - if (epoll_fd < 0) - return; + if (backend_fd < 0) + return 0; + + fcntl (backend_fd, F_SETFD, FD_CLOEXEC); - fcntl (epoll_fd, F_SETFD, FD_CLOEXEC); + backend_fudge = 0.; /* kernel sources seem to indicate this to be zero */ + backend_modify = epoll_modify; + backend_poll = epoll_poll; - ev_method = EVMETHOD_EPOLL; - method_fudge = 1e-3; /* needed to compensate for epoll returning early */ - method_modify = epoll_modify; - method_poll = epoll_poll; + epoll_eventmax = 64; /* intiial number of events receivable per poll */ + epoll_events = (struct epoll_event *)ev_malloc (sizeof (struct epoll_event) * epoll_eventmax); - eventmax = 64; /* intiial number of events receivable per poll */ - events = malloc (sizeof (struct epoll_event) * eventmax); + return EVBACKEND_EPOLL; } + +void inline_size +epoll_destroy (EV_P) +{ + ev_free (epoll_events); +} + +void inline_size +epoll_fork (EV_P) +{ + close (backend_fd); + + while ((backend_fd = epoll_create (256)) < 0) + syserr ("(libev) epoll_create"); + + fcntl (backend_fd, F_SETFD, FD_CLOEXEC); + + fd_rearm_all (EV_A); +} +