X-Git-Url: https://git.llucax.com/software/libev.git/blobdiff_plain/f776d56f36abeed4a6091c2ec9b96363213ce2b2..da64db6d2bfa6add6c6ad65d51468dba440d03e3:/ev_epoll.c diff --git a/ev_epoll.c b/ev_epoll.c index 8bc8658..52f8337 100644 --- a/ev_epoll.c +++ b/ev_epoll.c @@ -29,81 +29,145 @@ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. */ +/* + * 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 void 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; + + /* + * 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; + 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); + 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; + + if (expect_true (errno == ENOENT)) + { + /* on ENOENT the fd went away, so try to do the right thing */ + if (!nev) + return; + + 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; + } - epoll_ctl (epoll_fd, mode, fd, &ev); + fd_kill (EV_A_ fd); } static void epoll_poll (EV_P_ ev_tstamp timeout) { - int eventcnt = epoll_wait (epoll_fd, epoll_events, epoll_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 ( - EV_A_ - epoll_events [i].data.u64, - (epoll_events [i].events & (EPOLLOUT | EPOLLERR | EPOLLHUP) ? EV_WRITE : 0) - | (epoll_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 (expect_false (eventcnt == epoll_eventmax)) { - free (epoll_events); - epoll_eventmax = array_roundsize (epoll_events, epoll_eventmax << 1); - epoll_events = malloc (sizeof (struct epoll_event) * epoll_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); } } -static int +int inline_size epoll_init (EV_P_ int flags) { - epoll_fd = epoll_create (256); + backend_fd = epoll_create (256); - if (epoll_fd < 0) + if (backend_fd < 0) return 0; - fcntl (epoll_fd, F_SETFD, FD_CLOEXEC); + fcntl (backend_fd, F_SETFD, FD_CLOEXEC); - 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; epoll_eventmax = 64; /* intiial number of events receivable per poll */ - epoll_events = malloc (sizeof (struct epoll_event) * epoll_eventmax); + epoll_events = (struct epoll_event *)ev_malloc (sizeof (struct epoll_event) * epoll_eventmax); - return EVMETHOD_EPOLL; + return EVBACKEND_EPOLL; } -static void +void inline_size epoll_destroy (EV_P) { - close (epoll_fd); - - free (epoll_events); + ev_free (epoll_events); } -static void +void inline_size epoll_fork (EV_P) { - epoll_fd = epoll_create (256); - fcntl (epoll_fd, F_SETFD, FD_CLOEXEC); + 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); }