2 * IRC - Internet Relay Chat, ircd/engine_select.c
3 * Copyright (C) 2001 Kevin L. Mitchell <klmitch@mit.edu>
5 * This program is free software; you can redistribute it and/or modify
6 * it under the terms of the GNU General Public License as published by
7 * the Free Software Foundation; either version 1, or (at your option)
10 * This program is distributed in the hope that it will be useful,
11 * but WITHOUT ANY WARRANTY; without even the implied warranty of
12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
13 * GNU General Public License for more details.
15 * You should have received a copy of the GNU General Public License
16 * along with this program; if not, write to the Free Software
17 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
23 #include "ircd_events.h"
29 /* On BSD, define FD_SETSIZE to what we want before including sys/types.h */
30 #if defined(__FreeBSD__) || defined(__NetBSD__) || defined(__bsdi__)
31 # if !defined(FD_SETSIZE)
32 # define FD_SETSIZE MAXCONNECTIONS
38 #include <sys/socket.h>
40 #include <sys/types.h>
44 #define SELECT_ERROR_THRESHOLD 20 /* after 20 select errors, restart */
45 #define ERROR_EXPIRE_TIME 3600 /* expire errors after an hour */
47 static struct Socket* sockList[FD_SETSIZE];
48 static int highest_fd;
49 static fd_set global_read_set;
50 static fd_set global_write_set;
52 static int errors = 0;
53 static struct Timer clear_error;
55 /* decrements the error count once per hour */
57 error_clear(struct Event* ev)
59 if (!--errors) /* remove timer when error count reaches 0 */
60 timer_del(ev_timer(ev));
63 /* initialize the select engine */
65 engine_init(int max_sockets)
69 if (max_sockets > FD_SETSIZE) { /* too many sockets */
70 log_write(LS_SYSTEM, L_WARNING, 0,
71 "select() engine cannot handle %d sockets (> %d)",
72 max_sockets, FD_SETSIZE);
76 FD_ZERO(&global_read_set); /* zero the global fd sets */
77 FD_ZERO(&global_write_set);
79 for (i = 0; i < FD_SETSIZE; i++) /* zero the sockList */
82 highest_fd = -1; /* No fds in set */
84 return 1; /* initialization successful */
87 /* Figure out what events go with a given state */
89 state_to_events(enum SocketState state, unsigned int events)
92 case SS_CONNECTING: /* connecting socket */
93 return SOCK_EVENT_WRITABLE;
96 case SS_LISTENING: /* listening socket */
97 case SS_NOTSOCK: /* our signal socket */
98 return SOCK_EVENT_READABLE;
101 case SS_CONNECTED: case SS_DATAGRAM: case SS_CONNECTDG:
102 return events; /* ordinary socket */
110 /* Toggle bits in the global fd sets appropriately */
112 set_or_clear(int fd, unsigned int clear, unsigned int set)
114 if ((clear ^ set) & SOCK_EVENT_READABLE) { /* readable has changed */
115 if (set & SOCK_EVENT_READABLE) /* it's set */
116 FD_SET(fd, &global_read_set);
118 FD_CLR(fd, &global_read_set);
121 if ((clear ^ set) & SOCK_EVENT_WRITABLE) { /* writable has changed */
122 if (set & SOCK_EVENT_WRITABLE) /* it's set */
123 FD_SET(fd, &global_write_set);
125 FD_CLR(fd, &global_write_set);
129 /* add a socket to be listened on */
131 engine_add(struct Socket* sock)
134 assert(0 == sockList[s_fd(sock)]);
136 /* bounds-check... */
137 if (s_fd(sock) >= FD_SETSIZE) {
138 log_write(LS_SYSTEM, L_ERROR, 0,
139 "Attempt to add socket %d (> %d) to event engine", s_fd(sock),
144 sockList[s_fd(sock)] = sock; /* add to list */
146 if (s_fd(sock) >= highest_fd) /* update highest_fd */
147 highest_fd = s_fd(sock);
149 Debug((DEBUG_ENGINE, "select: Adding socket %d to engine [%p], state %s",
150 s_fd(sock), sock, state_to_name(s_state(sock))));
152 /* set the fd set bits */
153 set_or_clear(s_fd(sock), 0, state_to_events(s_state(sock), s_events(sock)));
155 return 1; /* success */
158 /* socket switching to new state */
160 engine_state(struct Socket* sock, enum SocketState new_state)
163 assert(sock == sockList[s_fd(sock)]);
165 Debug((DEBUG_ENGINE, "select: Changing state for socket %p to %s", sock,
166 state_to_name(new_state)));
168 /* set the correct events */
169 set_or_clear(s_fd(sock),
170 state_to_events(s_state(sock), s_events(sock)), /* old state */
171 state_to_events(new_state, s_events(sock))); /* new state */
174 /* socket events changing */
176 engine_events(struct Socket* sock, unsigned int new_events)
179 assert(sock == sockList[s_fd(sock)]);
181 Debug((DEBUG_ENGINE, "select: Changing event mask for socket %p to [%s]",
182 sock, sock_flags(new_events)));
184 /* set the correct events */
185 set_or_clear(s_fd(sock),
186 state_to_events(s_state(sock), s_events(sock)), /* old events */
187 state_to_events(s_state(sock), new_events)); /* new events */
190 /* socket going away */
192 engine_delete(struct Socket* sock)
195 assert(sock == sockList[s_fd(sock)]);
197 Debug((DEBUG_ENGINE, "select: Deleting socket %d [%p], state %s", s_fd(sock),
198 sock, state_to_name(s_state(sock))));
200 FD_CLR(s_fd(sock), &global_read_set); /* clear event set bits */
201 FD_CLR(s_fd(sock), &global_write_set);
203 sockList[s_fd(sock)] = 0; /* zero the socket list entry */
205 while (highest_fd > -1 && sockList[highest_fd] == 0) /* update highest_fd */
209 /* engine event loop */
211 engine_loop(struct Generators* gen)
223 read_set = global_read_set; /* all hail structure copy!! */
224 write_set = global_write_set;
226 /* set up the sleep time */
227 wait.tv_sec = timer_next(gen) ? (timer_next(gen) - CurrentTime) : -1;
230 Debug((DEBUG_INFO, "select: delay: %Tu (%Tu) %Tu", timer_next(gen),
231 CurrentTime, wait.tv_sec));
233 /* check for active files */
234 nfds = select(highest_fd + 1, &read_set, &write_set, 0,
235 wait.tv_sec < 0 ? 0 : &wait);
237 CurrentTime = time(0); /* set current time... */
240 if (errno != EINTR) { /* ignore select interrupts */
241 /* Log the select error */
242 log_write(LS_SOCKET, L_ERROR, 0, "select() error: %m");
244 timer_add(timer_init(&clear_error), error_clear, 0, TT_PERIODIC,
246 else if (errors > SELECT_ERROR_THRESHOLD) /* too many errors... */
247 server_restart("too many select errors");
249 /* old code did a sleep(1) here; with usage these days,
250 * that may be too expensive
255 for (i = 0; nfds && i <= highest_fd; i++) {
256 if (!(sock = sockList[i])) /* skip empty socket elements */
259 assert(s_fd(sock) == i);
261 gen_ref_inc(sock); /* can't have it going away on us */
263 Debug((DEBUG_ENGINE, "select: Checking socket %p (fd %d) state %s, "
264 "events %s", sock, i, state_to_name(s_state(sock)),
265 sock_flags(s_events(sock))));
267 if (s_state(sock) != SS_NOTSOCK) {
268 errcode = 0; /* check for errors on socket */
269 codesize = sizeof(errcode);
270 if (getsockopt(i, SOL_SOCKET, SO_ERROR, &errcode, &codesize) < 0)
271 errcode = errno; /* work around Solaris implementation */
273 if (errcode) { /* an error occurred; generate an event */
274 Debug((DEBUG_ENGINE, "select: Error %d on fd %d, socket %p", errcode,
276 event_generate(ET_ERROR, sock, errcode);
277 gen_ref_dec(sock); /* careful not to leak reference counts */
282 switch (s_state(sock)) {
284 if (FD_ISSET(i, &write_set)) { /* connection completed */
285 Debug((DEBUG_ENGINE, "select: Connection completed"));
286 event_generate(ET_CONNECT, sock, 0);
293 if (FD_ISSET(i, &read_set)) { /* connection to be accepted */
294 Debug((DEBUG_ENGINE, "select: Ready for accept"));
295 event_generate(ET_ACCEPT, sock, 0);
301 if (FD_ISSET(i, &read_set)) { /* data on socket */
302 /* can't peek; it's not a socket */
303 Debug((DEBUG_ENGINE, "select: non-socket readable"));
304 event_generate(ET_READ, sock, 0);
310 if (FD_ISSET(i, &read_set)) { /* data to be read from socket */
313 switch (recv(i, &c, 1, MSG_PEEK)) { /* check for EOF */
314 case -1: /* error occurred?!? */
315 if (errno == EAGAIN) {
316 Debug((DEBUG_ENGINE, "select: Resource temporarily "
320 Debug((DEBUG_ENGINE, "select: Uncaught error!"));
321 event_generate(ET_ERROR, sock, errno);
324 case 0: /* EOF from client */
325 Debug((DEBUG_ENGINE, "select: EOF from client"));
326 event_generate(ET_EOF, sock, 0);
329 default: /* some data can be read */
330 Debug((DEBUG_ENGINE, "select: Data to be read"));
331 event_generate(ET_READ, sock, 0);
335 if (FD_ISSET(i, &write_set)) { /* data can be written to socket */
336 Debug((DEBUG_ENGINE, "select: Data can be written"));
337 event_generate(ET_WRITE, sock, 0);
339 if (FD_ISSET(i, &read_set) || FD_ISSET(i, &write_set))
343 case SS_DATAGRAM: case SS_CONNECTDG:
344 if (FD_ISSET(i, &read_set)) { /* data to be read from socket */
345 Debug((DEBUG_ENGINE, "select: Datagram to be read"));
346 event_generate(ET_READ, sock, 0);
348 if (FD_ISSET(i, &write_set)) { /* data can be written to socket */
349 Debug((DEBUG_ENGINE, "select: Datagram can be written"));
350 event_generate(ET_WRITE, sock, 0);
352 if (FD_ISSET(i, &read_set) || FD_ISSET(i, &write_set))
357 assert(s_fd(sock) == i);
359 gen_ref_dec(sock); /* we're done with it */
362 timer_run(); /* execute any pending timers */
366 struct Engine engine_select = {
367 "select()", /* Engine name */
368 engine_init, /* Engine initialization function */
369 0, /* Engine signal registration function (none) */
370 engine_add, /* Engine socket registration function */
371 engine_state, /* Engine socket state change function */
372 engine_events, /* Engine socket events mask function */
373 engine_delete, /* Engine socket deletion function */
374 engine_loop /* Core engine event loop */