mirror of
https://github.com/libevent/libevent.git
synced 2025-01-09 00:56:20 +08:00
performance improvements of select handler by Nick Mathewson; I added
better recovery when memory allocation fails; something that needs to be done for the poll improvements, too. svn:r166
This commit is contained in:
Niels Provos
parent
57fafe6b5f
commit
7a0c530b56
251
select.c
251
select.c
@ -44,6 +44,9 @@
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#include <string.h>
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#include <unistd.h>
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#include <errno.h>
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#ifdef CHECK_INVARIANTS
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#include <assert.h>
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#endif
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#include "event.h"
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#include "event-internal.h"
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@ -59,8 +62,12 @@ extern volatile sig_atomic_t evsignal_caught;
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struct selectop {
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int event_fds; /* Highest fd in fd set */
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int event_fdsz;
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fd_set *event_readset;
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fd_set *event_writeset;
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fd_set *event_readset_in;
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fd_set *event_writeset_in;
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fd_set *event_readset_out;
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fd_set *event_writeset_out;
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struct event **event_r_by_fd;
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struct event **event_w_by_fd;
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sigset_t evsigmask;
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};
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@ -79,6 +86,8 @@ const struct eventop selectops = {
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select_dispatch
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};
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static int select_resize(struct selectop *sop, int fdsz);
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void *
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select_init(void)
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{
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@ -91,11 +100,40 @@ select_init(void)
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if (!(sop = calloc(1, sizeof(struct selectop))))
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return (NULL);
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select_resize(sop, howmany(32 + 1, NFDBITS)*sizeof(fd_mask));
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evsignal_init(&sop->evsigmask);
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return (sop);
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}
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#ifdef CHECK_INVARIANTS
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static void
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check_selectop(struct selectop *sop)
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{
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int i;
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for (i=0;i<=sop->event_fds;++i) {
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if (FD_ISSET(i, sop->event_readset_in)) {
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assert(sop->event_r_by_fd[i]);
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assert(sop->event_r_by_fd[i]->ev_events & EV_READ);
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assert(sop->event_r_by_fd[i]->ev_fd == i);
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} else {
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assert(! sop->event_r_by_fd[i]);
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}
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if (FD_ISSET(i, sop->event_writeset_in)) {
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assert(sop->event_w_by_fd[i]);
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assert(sop->event_w_by_fd[i]->ev_events & EV_WRITE);
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assert(sop->event_w_by_fd[i]->ev_fd == i);
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} else {
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assert(! sop->event_w_by_fd[i]);
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}
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}
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}
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#else
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#define check_selectop(sop)
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#endif
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/*
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* Called with the highest fd that we know about. If it is 0, completely
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* recalculate everything.
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@ -105,41 +143,8 @@ int
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select_recalc(struct event_base *base, void *arg, int max)
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{
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struct selectop *sop = arg;
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fd_set *readset, *writeset;
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struct event *ev;
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int fdsz;
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if (sop->event_fds < max)
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sop->event_fds = max;
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if (!sop->event_fds) {
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TAILQ_FOREACH(ev, &base->eventqueue, ev_next)
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if (ev->ev_fd > sop->event_fds)
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sop->event_fds = ev->ev_fd;
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}
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fdsz = howmany(sop->event_fds + 1, NFDBITS) * sizeof(fd_mask);
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if (fdsz > sop->event_fdsz) {
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if ((readset = realloc(sop->event_readset, fdsz)) == NULL) {
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event_warn("malloc");
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return (-1);
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}
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if ((writeset = realloc(sop->event_writeset, fdsz)) == NULL) {
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event_warn("malloc");
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free(readset);
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return (-1);
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}
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memset((char *)readset + sop->event_fdsz, 0,
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fdsz - sop->event_fdsz);
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memset((char *)writeset + sop->event_fdsz, 0,
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fdsz - sop->event_fdsz);
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sop->event_readset = readset;
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sop->event_writeset = writeset;
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sop->event_fdsz = fdsz;
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}
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check_selectop(sop);
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return (evsignal_recalc(&sop->evsigmask));
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}
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@ -147,26 +152,23 @@ select_recalc(struct event_base *base, void *arg, int max)
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int
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select_dispatch(struct event_base *base, void *arg, struct timeval *tv)
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{
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int maxfd, res;
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struct event *ev, *next;
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int res, i;
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struct selectop *sop = arg;
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memset(sop->event_readset, 0, sop->event_fdsz);
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memset(sop->event_writeset, 0, sop->event_fdsz);
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check_selectop(sop);
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TAILQ_FOREACH(ev, &base->eventqueue, ev_next) {
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if (ev->ev_events & EV_WRITE)
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FD_SET(ev->ev_fd, sop->event_writeset);
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if (ev->ev_events & EV_READ)
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FD_SET(ev->ev_fd, sop->event_readset);
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}
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memcpy(sop->event_readset_out, sop->event_readset_in,
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sop->event_fdsz);
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memcpy(sop->event_writeset_out, sop->event_writeset_in,
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sop->event_fdsz);
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if (evsignal_deliver(&sop->evsigmask) == -1)
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return (-1);
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res = select(sop->event_fds + 1, sop->event_readset,
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sop->event_writeset, NULL, tv);
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res = select(sop->event_fds + 1, sop->event_readset_out,
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sop->event_writeset_out, NULL, tv);
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check_selectop(sop);
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if (evsignal_recalc(&sop->evsigmask) == -1)
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return (-1);
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@ -183,32 +185,94 @@ select_dispatch(struct event_base *base, void *arg, struct timeval *tv)
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event_debug(("%s: select reports %d", __func__, res));
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maxfd = 0;
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for (ev = TAILQ_FIRST(&base->eventqueue); ev != NULL; ev = next) {
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next = TAILQ_NEXT(ev, ev_next);
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check_selectop(sop);
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for (i = 0; i <= sop->event_fds; ++i) {
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struct event *r_ev = NULL, *w_ev = NULL;
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res = 0;
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if (FD_ISSET(ev->ev_fd, sop->event_readset))
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if (FD_ISSET(i, sop->event_readset_out)) {
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r_ev = sop->event_r_by_fd[i];
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res |= EV_READ;
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if (FD_ISSET(ev->ev_fd, sop->event_writeset))
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}
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if (FD_ISSET(i, sop->event_writeset_out)) {
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w_ev = sop->event_w_by_fd[i];
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res |= EV_WRITE;
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res &= ev->ev_events;
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if (res) {
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if (!(ev->ev_events & EV_PERSIST))
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event_del(ev);
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else if (ev->ev_fd > maxfd)
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maxfd = ev->ev_fd;
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event_active(ev, res, 1);
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} else if (ev->ev_fd > maxfd)
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maxfd = ev->ev_fd;
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}
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if (r_ev && (res & r_ev->ev_events)) {
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if (!(r_ev->ev_events & EV_PERSIST))
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event_del(r_ev);
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event_active(r_ev, res & r_ev->ev_events, 1);
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}
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if (w_ev && w_ev != r_ev && (res & w_ev->ev_events)) {
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if (!(w_ev->ev_events & EV_PERSIST))
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event_del(w_ev);
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event_active(w_ev, res & w_ev->ev_events, 1);
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}
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}
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sop->event_fds = maxfd;
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check_selectop(sop);
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return (0);
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}
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static int
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select_resize(struct selectop *sop, int fdsz)
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{
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int n_events, n_events_old;
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fd_set *readset_in = NULL;
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fd_set *writeset_in = NULL;
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fd_set *readset_out = NULL;
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fd_set *writeset_out = NULL;
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struct event **r_by_fd = NULL;
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struct event **w_by_fd = NULL;
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n_events = (fdsz/sizeof(fd_mask)) * NFDBITS;
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n_events_old = (sop->event_fdsz/sizeof(fd_mask)) * NFDBITS;
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if (sop->event_readset_in)
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check_selectop(sop);
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if ((readset_in = realloc(sop->event_readset_in, fdsz)) == NULL)
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goto error;
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sop->event_readset_in = readset_in;
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if ((readset_out = realloc(sop->event_readset_out, fdsz)) == NULL)
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goto error;
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sop->event_readset_out = readset_out;
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if ((writeset_in = realloc(sop->event_writeset_in, fdsz)) == NULL)
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goto error;
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sop->event_writeset_in = writeset_in;
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if ((writeset_out = realloc(sop->event_writeset_out, fdsz)) == NULL)
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goto error;
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sop->event_writeset_out = writeset_out;
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if ((r_by_fd = realloc(sop->event_r_by_fd,
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n_events*sizeof(struct event*))) == NULL)
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goto error;
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sop->event_r_by_fd = r_by_fd;
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if ((w_by_fd = realloc(sop->event_w_by_fd,
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n_events * sizeof(struct event*))) == NULL)
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goto error;
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sop->event_w_by_fd = w_by_fd;
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memset((char *)sop->event_readset_in + sop->event_fdsz, 0,
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fdsz - sop->event_fdsz);
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memset((char *)sop->event_writeset_in + sop->event_fdsz, 0,
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fdsz - sop->event_fdsz);
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memset(sop->event_r_by_fd + n_events_old, 0,
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(n_events-n_events_old) * sizeof(struct event*));
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memset(sop->event_w_by_fd + n_events_old, 0,
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(n_events-n_events_old) * sizeof(struct event*));
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sop->event_fdsz = fdsz;
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check_selectop(sop);
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return (0);
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error:
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event_warn("malloc");
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return (-1);
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}
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int
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select_add(void *arg, struct event *ev)
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{
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@ -217,12 +281,40 @@ select_add(void *arg, struct event *ev)
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if (ev->ev_events & EV_SIGNAL)
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return (evsignal_add(&sop->evsigmask, ev));
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/*
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check_selectop(sop);
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/*
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* Keep track of the highest fd, so that we can calculate the size
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* of the fd_sets for select(2)
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*/
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if (sop->event_fds < ev->ev_fd)
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if (sop->event_fds < ev->ev_fd) {
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int fdsz = sop->event_fdsz;
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if (fdsz < sizeof(fd_mask))
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fdsz = sizeof(fd_mask);
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while (fdsz <
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(howmany(ev->ev_fd + 1, NFDBITS) * sizeof(fd_mask)))
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fdsz *= 2;
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if (fdsz != sop->event_fdsz) {
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if (select_resize(sop, fdsz)) {
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check_selectop(sop);
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return (-1);
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}
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}
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sop->event_fds = ev->ev_fd;
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}
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if (ev->ev_events & EV_READ) {
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FD_SET(ev->ev_fd, sop->event_readset_in);
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sop->event_r_by_fd[ev->ev_fd] = ev;
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}
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if (ev->ev_events & EV_WRITE) {
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FD_SET(ev->ev_fd, sop->event_writeset_in);
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sop->event_w_by_fd[ev->ev_fd] = ev;
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}
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check_selectop(sop);
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return (0);
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}
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@ -236,8 +328,25 @@ select_del(void *arg, struct event *ev)
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{
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struct selectop *sop = arg;
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if (!(ev->ev_events & EV_SIGNAL))
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return (0);
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check_selectop(sop);
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if (ev->ev_events & EV_SIGNAL)
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return (evsignal_del(&sop->evsigmask, ev));
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return (evsignal_del(&sop->evsigmask, ev));
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if (sop->event_fds < ev->ev_fd) {
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check_selectop(sop);
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return (0);
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}
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if (ev->ev_events & EV_READ) {
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FD_CLR(ev->ev_fd, sop->event_readset_in);
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sop->event_r_by_fd[ev->ev_fd] = NULL;
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}
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if (ev->ev_events & EV_WRITE) {
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FD_CLR(ev->ev_fd, sop->event_writeset_in);
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sop->event_w_by_fd[ev->ev_fd] = NULL;
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}
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check_selectop(sop);
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return (0);
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}
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