--- libev/ev_epoll.c 2007/10/31 11:56:34 1.4 +++ libev/ev_epoll.c 2008/10/23 04:56:49 1.35 @@ -1,75 +1,200 @@ +/* + * libev epoll fd activity backend + * + * Copyright (c) 2007,2008 Marc Alexander Lehmann + * All rights reserved. + * + * 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. + * + * 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: + * + * 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. + * + * 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; +void inline_size +unsigned_char_init (unsigned char *base, int count) +{ + /* memset might be overkill */ + while (count--) + *base++ = 0; +} 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); + unsigned char oldmask; - 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. + * the fd is later added, we try to ADD it, and, if that + * fails, we assume it still has the same eventmask. + */ + if (!nev) + return; -void epoll_postfork_child (void) -{ - int fd; + oldmask = anfds [fd].emask; + anfds [fd].emask = nev; - epoll_fd = epoll_create (256); - fcntl (epoll_fd, F_SETFD, FD_CLOEXEC); + 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); - /* re-register interest in fds */ - for (fd = 0; fd < anfdmax; ++fd) - if (anfds [fd].wev) - epoll_modify (fd, EV_NONE, anfds [fd].wev); -} + if (expect_true (!epoll_ctl (backend_fd, oev ? EPOLL_CTL_MOD : EPOLL_CTL_ADD, fd, &ev))) + return; -static struct epoll_event *events; -static int eventmax; + if (expect_true (errno == ENOENT)) + { + /* if ENOENT then the fd went away, so try to do the right thing */ + if (!nev) + return; -static void epoll_poll (ev_tstamp timeout) + if (!epoll_ctl (backend_fd, EPOLL_CTL_ADD, fd, &ev)) + return; + } + else if (expect_true (errno == EEXIST)) + { + /* EEXIST means we ignored a previous DEL, but the fd is still active */ + /* if the kernel mask is the same as the new mask, we assume it hasn't changed */ + if (oldmask == nev || !epoll_ctl (backend_fd, EPOLL_CTL_MOD, fd, &ev)) + return; + } + + fd_kill (EV_A_ fd); +} + +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)) + { + anfds [fd].emask = want; + + /* we received an event but are not interested in it, try mod or del */ + /* I don't think we ever need MOD, but let's handle it anyways */ + 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 (epoll_fd, F_SETFD, FD_CLOEXEC); + fcntl (backend_fd, F_SETFD, FD_CLOEXEC); - ev_method = EVMETHOD_EPOLL; - method_fudge = 1e-3; /* needed to compensate for epoll returning early */ - method_modify = epoll_modify; - method_poll = epoll_poll; + backend_fudge = 0.; /* kernel sources seem to indicate this to be zero */ + backend_modify = epoll_modify; + backend_poll = epoll_poll; - eventmax = 64; /* intiial number of events receivable per poll */ - events = malloc (sizeof (struct epoll_event) * eventmax); + epoll_eventmax = 64; /* intiial number of events receivable per poll */ + epoll_events = (struct epoll_event *)ev_malloc (sizeof (struct epoll_event) * epoll_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); +} +