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 <string.h> /* needed for bzero() on OS X */
39 #include <sys/socket.h>
41 #include <sys/types.h>
45 #define SELECT_ERROR_THRESHOLD 20 /* after 20 select errors, restart */
46 #define ERROR_EXPIRE_TIME 3600 /* expire errors after an hour */
48 static struct Socket* sockList[FD_SETSIZE];
49 static int highest_fd;
50 static fd_set global_read_set;
51 static fd_set global_write_set;
53 static int errors = 0;
54 static struct Timer clear_error;
56 /* decrements the error count once per hour */
58 error_clear(struct Event* ev)
60 if (!--errors) /* remove timer when error count reaches 0 */
61 timer_del(ev_timer(ev));
64 /* initialize the select engine */
66 engine_init(int max_sockets)
70 if (max_sockets > FD_SETSIZE) { /* too many sockets */
71 log_write(LS_SYSTEM, L_WARNING, 0,
72 "select() engine cannot handle %d sockets (> %d)",
73 max_sockets, FD_SETSIZE);
77 FD_ZERO(&global_read_set); /* zero the global fd sets */
78 FD_ZERO(&global_write_set);
80 for (i = 0; i < FD_SETSIZE; i++) /* zero the sockList */
83 highest_fd = -1; /* No fds in set */
85 return 1; /* initialization successful */
88 /* Figure out what events go with a given state */
90 state_to_events(enum SocketState state, unsigned int events)
93 case SS_CONNECTING: /* connecting socket */
94 return SOCK_EVENT_WRITABLE;
97 case SS_LISTENING: /* listening socket */
98 case SS_NOTSOCK: /* our signal socket */
99 return SOCK_EVENT_READABLE;
102 case SS_CONNECTED: case SS_DATAGRAM: case SS_CONNECTDG:
103 return events; /* ordinary socket */
111 /* Toggle bits in the global fd sets appropriately */
113 set_or_clear(int fd, unsigned int clear, unsigned int set)
115 if ((clear ^ set) & SOCK_EVENT_READABLE) { /* readable has changed */
116 if (set & SOCK_EVENT_READABLE) /* it's set */
117 FD_SET(fd, &global_read_set);
119 FD_CLR(fd, &global_read_set);
122 if ((clear ^ set) & SOCK_EVENT_WRITABLE) { /* writable has changed */
123 if (set & SOCK_EVENT_WRITABLE) /* it's set */
124 FD_SET(fd, &global_write_set);
126 FD_CLR(fd, &global_write_set);
130 /* add a socket to be listened on */
132 engine_add(struct Socket* sock)
135 assert(0 == sockList[s_fd(sock)]);
137 /* bounds-check... */
138 if (s_fd(sock) >= FD_SETSIZE) {
139 log_write(LS_SYSTEM, L_ERROR, 0,
140 "Attempt to add socket %d (> %d) to event engine", s_fd(sock),
145 sockList[s_fd(sock)] = sock; /* add to list */
147 if (s_fd(sock) >= highest_fd) /* update highest_fd */
148 highest_fd = s_fd(sock);
150 Debug((DEBUG_ENGINE, "select: Adding socket %d to engine [%p], state %s",
151 s_fd(sock), sock, state_to_name(s_state(sock))));
153 /* set the fd set bits */
154 set_or_clear(s_fd(sock), 0, state_to_events(s_state(sock), s_events(sock)));
156 return 1; /* success */
159 /* socket switching to new state */
161 engine_state(struct Socket* sock, enum SocketState new_state)
164 assert(sock == sockList[s_fd(sock)]);
166 Debug((DEBUG_ENGINE, "select: Changing state for socket %p to %s", sock,
167 state_to_name(new_state)));
169 /* set the correct events */
170 set_or_clear(s_fd(sock),
171 state_to_events(s_state(sock), s_events(sock)), /* old state */
172 state_to_events(new_state, s_events(sock))); /* new state */
175 /* socket events changing */
177 engine_events(struct Socket* sock, unsigned int new_events)
180 assert(sock == sockList[s_fd(sock)]);
182 Debug((DEBUG_ENGINE, "select: Changing event mask for socket %p to [%s]",
183 sock, sock_flags(new_events)));
185 /* set the correct events */
186 set_or_clear(s_fd(sock),
187 state_to_events(s_state(sock), s_events(sock)), /* old events */
188 state_to_events(s_state(sock), new_events)); /* new events */
191 /* socket going away */
193 engine_delete(struct Socket* sock)
196 assert(sock == sockList[s_fd(sock)]);
198 Debug((DEBUG_ENGINE, "select: Deleting socket %d [%p], state %s", s_fd(sock),
199 sock, state_to_name(s_state(sock))));
201 FD_CLR(s_fd(sock), &global_read_set); /* clear event set bits */
202 FD_CLR(s_fd(sock), &global_write_set);
204 sockList[s_fd(sock)] = 0; /* zero the socket list entry */
206 while (highest_fd > -1 && sockList[highest_fd] == 0) /* update highest_fd */
210 /* engine event loop */
212 engine_loop(struct Generators* gen)
224 read_set = global_read_set; /* all hail structure copy!! */
225 write_set = global_write_set;
227 /* set up the sleep time */
228 wait.tv_sec = timer_next(gen) ? (timer_next(gen) - CurrentTime) : -1;
231 Debug((DEBUG_INFO, "select: delay: %Tu (%Tu) %Tu", timer_next(gen),
232 CurrentTime, wait.tv_sec));
234 /* check for active files */
235 nfds = select(highest_fd + 1, &read_set, &write_set, 0,
236 wait.tv_sec < 0 ? 0 : &wait);
238 CurrentTime = time(0); /* set current time... */
241 if (errno != EINTR) { /* ignore select interrupts */
242 /* Log the select error */
243 log_write(LS_SOCKET, L_ERROR, 0, "select() error: %m");
245 timer_add(timer_init(&clear_error), error_clear, 0, TT_PERIODIC,
247 else if (errors > SELECT_ERROR_THRESHOLD) /* too many errors... */
248 server_restart("too many select errors");
250 /* old code did a sleep(1) here; with usage these days,
251 * that may be too expensive
256 for (i = 0; nfds && i <= highest_fd; i++) {
257 if (!(sock = sockList[i])) /* skip empty socket elements */
260 assert(s_fd(sock) == i);
262 gen_ref_inc(sock); /* can't have it going away on us */
264 Debug((DEBUG_ENGINE, "select: Checking socket %p (fd %d) state %s, "
265 "events %s", sock, i, state_to_name(s_state(sock)),
266 sock_flags(s_events(sock))));
268 if (s_state(sock) != SS_NOTSOCK) {
269 errcode = 0; /* check for errors on socket */
270 codesize = sizeof(errcode);
271 if (getsockopt(i, SOL_SOCKET, SO_ERROR, &errcode, &codesize) < 0)
272 errcode = errno; /* work around Solaris implementation */
274 if (errcode) { /* an error occurred; generate an event */
275 Debug((DEBUG_ENGINE, "select: Error %d on fd %d, socket %p", errcode,
277 event_generate(ET_ERROR, sock, errcode);
278 gen_ref_dec(sock); /* careful not to leak reference counts */
283 switch (s_state(sock)) {
285 if (FD_ISSET(i, &write_set)) { /* connection completed */
286 Debug((DEBUG_ENGINE, "select: Connection completed"));
287 event_generate(ET_CONNECT, sock, 0);
294 if (FD_ISSET(i, &read_set)) { /* connection to be accepted */
295 Debug((DEBUG_ENGINE, "select: Ready for accept"));
296 event_generate(ET_ACCEPT, sock, 0);
302 if (FD_ISSET(i, &read_set)) { /* data on socket */
303 /* can't peek; it's not a socket */
304 Debug((DEBUG_ENGINE, "select: non-socket readable"));
305 event_generate(ET_READ, sock, 0);
311 if (FD_ISSET(i, &read_set)) { /* data to be read from socket */
314 switch (recv(i, &c, 1, MSG_PEEK)) { /* check for EOF */
315 case -1: /* error occurred?!? */
316 if (errno == EAGAIN) {
317 Debug((DEBUG_ENGINE, "select: Resource temporarily "
321 Debug((DEBUG_ENGINE, "select: Uncaught error!"));
322 event_generate(ET_ERROR, sock, errno);
325 case 0: /* EOF from client */
326 Debug((DEBUG_ENGINE, "select: EOF from client"));
327 event_generate(ET_EOF, sock, 0);
330 default: /* some data can be read */
331 Debug((DEBUG_ENGINE, "select: Data to be read"));
332 event_generate(ET_READ, sock, 0);
336 if (FD_ISSET(i, &write_set)) { /* data can be written to socket */
337 Debug((DEBUG_ENGINE, "select: Data can be written"));
338 event_generate(ET_WRITE, sock, 0);
340 if (FD_ISSET(i, &read_set) || FD_ISSET(i, &write_set))
344 case SS_DATAGRAM: case SS_CONNECTDG:
345 if (FD_ISSET(i, &read_set)) { /* data to be read from socket */
346 Debug((DEBUG_ENGINE, "select: Datagram to be read"));
347 event_generate(ET_READ, sock, 0);
349 if (FD_ISSET(i, &write_set)) { /* data can be written to socket */
350 Debug((DEBUG_ENGINE, "select: Datagram can be written"));
351 event_generate(ET_WRITE, sock, 0);
353 if (FD_ISSET(i, &read_set) || FD_ISSET(i, &write_set))
358 assert(s_fd(sock) == i);
360 gen_ref_dec(sock); /* we're done with it */
363 timer_run(); /* execute any pending timers */
367 struct Engine engine_select = {
368 "select()", /* Engine name */
369 engine_init, /* Engine initialization function */
370 0, /* Engine signal registration function (none) */
371 engine_add, /* Engine socket registration function */
372 engine_state, /* Engine socket state change function */
373 engine_events, /* Engine socket events mask function */
374 engine_delete, /* Engine socket deletion function */
375 engine_loop /* Core engine event loop */