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.
20 * @brief BSD sockets select() event engine.
25 /* On BSD, define FD_SETSIZE to what we want before including sys/types.h */
26 #if defined(__FreeBSD__) || defined(__NetBSD__) || defined(__bsdi__)
27 # if !defined(FD_SETSIZE)
28 # define FD_SETSIZE ((MAXCONNECTIONS)+4)
32 #include "ircd_events.h"
38 /* #include <assert.h> -- Now using assert in ircd_log.h */
40 #include <string.h> /* needed for bzero() on OS X */
41 #include <sys/socket.h>
43 #include <sys/types.h>
47 #if FD_SETSIZE < (MAXCONNECTIONS + 4)
51 * All operating systems work when MAXCONNECTIONS <= 252.
52 * Most operating systems work when MAXCONNECTIONS <= 1020 and FD_SETSIZE is
53 * updated correctly in the system headers (on BSD systems sys/types.h might
54 * have abruptly redefined it so the check is still done), you might
55 * already need to recompile your kernel.
56 * For larger FD_SETSIZE your mileage may vary (kernel patches may be needed).
57 * The check is _NOT_ done if we will not use FD_SETS at all (USE_POLL)
59 # error FD_SETSIZE is too small or MAXCONNECTIONS too large.
62 #define SELECT_ERROR_THRESHOLD 20 /**< after 20 select errors, restart */
63 #define ERROR_EXPIRE_TIME 3600 /**< expire errors after an hour */
65 /** Array of active Socket structures, indexed by file descriptor. */
66 static struct Socket* sockList[FD_SETSIZE];
67 /** Maximum file descriptor currently used. */
68 static int highest_fd;
69 /** Global read event interest bitmap. */
70 static fd_set global_read_set;
71 /** Global write event interest bitmap. */
72 static fd_set global_write_set;
74 /** Number of recent errors from select(). */
75 static int errors = 0;
76 /** Periodic timer to forget errors. */
77 static struct Timer clear_error;
79 /** Decrement the error count (once per hour).
80 * @param[in] ev Expired timer event (ignored).
83 error_clear(struct Event* ev)
85 if (!--errors) /* remove timer when error count reaches 0 */
86 timer_del(ev_timer(ev));
89 /** Initialize the select() engine.
90 * @param[in] max_sockets Maximum number of file descriptors to support.
91 * @return Non-zero on success, or zero on failure.
94 engine_init(int max_sockets)
98 if (max_sockets > FD_SETSIZE) { /* too many sockets */
99 log_write(LS_SYSTEM, L_WARNING, 0,
100 "select() engine cannot handle %d sockets (> %d)",
101 max_sockets, FD_SETSIZE);
105 FD_ZERO(&global_read_set); /* zero the global fd sets */
106 FD_ZERO(&global_write_set);
108 for (i = 0; i < FD_SETSIZE; i++) /* zero the sockList */
111 highest_fd = -1; /* No fds in set */
113 return 1; /* initialization successful */
116 /** Figure out what events go with a given state.
117 * @param[in] state %Socket state to consider.
118 * @param[in] events User-specified preferred event set.
119 * @return Actual set of preferred events.
122 state_to_events(enum SocketState state, unsigned int events)
125 case SS_CONNECTING: /* connecting socket */
126 return SOCK_EVENT_WRITABLE;
129 case SS_LISTENING: /* listening socket */
130 case SS_NOTSOCK: /* our signal socket */
131 return SOCK_EVENT_READABLE;
134 case SS_CONNECTED: case SS_DATAGRAM: case SS_CONNECTDG:
135 return events; /* ordinary socket */
143 /** Set interest events in #global_read_set and #global_write_set as appropriate.
144 * @param[in] fd File descriptor to operate on.
145 * @param[in] clear Set of interest events to clear from socket.
146 * @param[in] set Set of interest events to set on socket.
149 set_or_clear(int fd, unsigned int clear, unsigned int set)
151 if ((clear ^ set) & SOCK_EVENT_READABLE) { /* readable has changed */
152 if (set & SOCK_EVENT_READABLE) /* it's set */
153 FD_SET(fd, &global_read_set);
155 FD_CLR(fd, &global_read_set);
158 if ((clear ^ set) & SOCK_EVENT_WRITABLE) { /* writable has changed */
159 if (set & SOCK_EVENT_WRITABLE) /* it's set */
160 FD_SET(fd, &global_write_set);
162 FD_CLR(fd, &global_write_set);
166 /** Add a socket to the event engine.
167 * @param[in] sock Socket to add to engine.
168 * @return Non-zero on success, or zero on error.
171 engine_add(struct Socket* sock)
174 assert(0 == sockList[s_fd(sock)]);
176 /* bounds-check... */
177 if (s_fd(sock) >= FD_SETSIZE) {
178 log_write(LS_SYSTEM, L_ERROR, 0,
179 "Attempt to add socket %d (> %d) to event engine", s_fd(sock),
184 sockList[s_fd(sock)] = sock; /* add to list */
186 if (s_fd(sock) >= highest_fd) /* update highest_fd */
187 highest_fd = s_fd(sock);
189 Debug((DEBUG_ENGINE, "select: Adding socket %d to engine [%p], state %s",
190 s_fd(sock), sock, state_to_name(s_state(sock))));
192 /* set the fd set bits */
193 set_or_clear(s_fd(sock), 0, state_to_events(s_state(sock), s_events(sock)));
195 return 1; /* success */
198 /** Handle state transition for a socket.
199 * @param[in] sock Socket changing state.
200 * @param[in] new_state New state for socket.
203 engine_state(struct Socket* sock, enum SocketState new_state)
206 assert(sock == sockList[s_fd(sock)]);
208 Debug((DEBUG_ENGINE, "select: Changing state for socket %p to %s", sock,
209 state_to_name(new_state)));
211 /* set the correct events */
212 set_or_clear(s_fd(sock),
213 state_to_events(s_state(sock), s_events(sock)), /* old state */
214 state_to_events(new_state, s_events(sock))); /* new state */
217 /** Handle change to preferred socket events.
218 * @param[in] sock Socket getting new interest list.
219 * @param[in] new_events New set of interesting events for socket.
222 engine_events(struct Socket* sock, unsigned int new_events)
225 assert(sock == sockList[s_fd(sock)]);
227 Debug((DEBUG_ENGINE, "select: Changing event mask for socket %p to [%s]",
228 sock, sock_flags(new_events)));
230 /* set the correct events */
231 set_or_clear(s_fd(sock),
232 state_to_events(s_state(sock), s_events(sock)), /* old events */
233 state_to_events(s_state(sock), new_events)); /* new events */
236 /** Remove a socket from the event engine.
237 * @param[in] sock Socket being destroyed.
240 engine_delete(struct Socket* sock)
243 assert(sock == sockList[s_fd(sock)]);
245 Debug((DEBUG_ENGINE, "select: Deleting socket %d [%p], state %s", s_fd(sock),
246 sock, state_to_name(s_state(sock))));
248 FD_CLR(s_fd(sock), &global_read_set); /* clear event set bits */
249 FD_CLR(s_fd(sock), &global_write_set);
251 sockList[s_fd(sock)] = 0; /* zero the socket list entry */
253 while (highest_fd > -1 && sockList[highest_fd] == 0) /* update highest_fd */
257 /** Run engine event loop.
258 * @param[in] gen Lists of generators of various types.
261 engine_loop(struct Generators* gen)
273 read_set = global_read_set; /* all hail structure copy!! */
274 write_set = global_write_set;
276 /* set up the sleep time */
277 wait.tv_sec = timer_next(gen) ? (timer_next(gen) - CurrentTime) : -1;
280 Debug((DEBUG_INFO, "select: delay: %Tu (%Tu) %Tu", timer_next(gen),
281 CurrentTime, wait.tv_sec));
283 /* check for active files */
284 nfds = select(highest_fd + 1, &read_set, &write_set, 0,
285 wait.tv_sec < 0 ? 0 : &wait);
287 CurrentTime = time(0); /* set current time... */
290 if (errno != EINTR) { /* ignore select interrupts */
291 /* Log the select error */
292 log_write(LS_SOCKET, L_ERROR, 0, "select() error: %m");
294 timer_add(timer_init(&clear_error), error_clear, 0, TT_PERIODIC,
296 else if (errors > SELECT_ERROR_THRESHOLD) /* too many errors... */
297 server_restart("too many select errors");
299 /* old code did a sleep(1) here; with usage these days,
300 * that may be too expensive
305 for (i = 0; nfds && i <= highest_fd; i++) {
306 if (!(sock = sockList[i])) /* skip empty socket elements */
309 assert(s_fd(sock) == i);
311 gen_ref_inc(sock); /* can't have it going away on us */
313 Debug((DEBUG_ENGINE, "select: Checking socket %p (fd %d) state %s, "
314 "events %s", sock, i, state_to_name(s_state(sock)),
315 sock_flags(s_events(sock))));
317 if (s_state(sock) != SS_NOTSOCK) {
318 errcode = 0; /* check for errors on socket */
319 codesize = sizeof(errcode);
320 if (getsockopt(i, SOL_SOCKET, SO_ERROR, &errcode, &codesize) < 0)
321 errcode = errno; /* work around Solaris implementation */
323 if (errcode) { /* an error occurred; generate an event */
324 Debug((DEBUG_ENGINE, "select: Error %d on fd %d, socket %p", errcode,
326 event_generate(ET_ERROR, sock, errcode);
327 gen_ref_dec(sock); /* careful not to leak reference counts */
332 switch (s_state(sock)) {
334 if (FD_ISSET(i, &write_set)) { /* connection completed */
335 Debug((DEBUG_ENGINE, "select: Connection completed"));
336 event_generate(ET_CONNECT, sock, 0);
343 if (FD_ISSET(i, &read_set)) { /* connection to be accepted */
344 Debug((DEBUG_ENGINE, "select: Ready for accept"));
345 event_generate(ET_ACCEPT, sock, 0);
351 if (FD_ISSET(i, &read_set)) { /* data on socket */
352 /* can't peek; it's not a socket */
353 Debug((DEBUG_ENGINE, "select: non-socket readable"));
354 event_generate(ET_READ, sock, 0);
360 if (FD_ISSET(i, &read_set)) { /* data to be read from socket */
363 switch (recv(i, &c, 1, MSG_PEEK)) { /* check for EOF */
364 case -1: /* error occurred?!? */
365 if (errno == EAGAIN) {
366 Debug((DEBUG_ENGINE, "select: Resource temporarily "
370 Debug((DEBUG_ENGINE, "select: Uncaught error!"));
371 event_generate(ET_ERROR, sock, errno);
374 case 0: /* EOF from client */
375 Debug((DEBUG_ENGINE, "select: EOF from client"));
376 event_generate(ET_EOF, sock, 0);
379 default: /* some data can be read */
380 Debug((DEBUG_ENGINE, "select: Data to be read"));
381 event_generate(ET_READ, sock, 0);
385 if (FD_ISSET(i, &write_set)) { /* data can be written to socket */
386 Debug((DEBUG_ENGINE, "select: Data can be written"));
387 event_generate(ET_WRITE, sock, 0);
389 if (FD_ISSET(i, &read_set) || FD_ISSET(i, &write_set))
393 case SS_DATAGRAM: case SS_CONNECTDG:
394 if (FD_ISSET(i, &read_set)) { /* data to be read from socket */
395 Debug((DEBUG_ENGINE, "select: Datagram to be read"));
396 event_generate(ET_READ, sock, 0);
398 if (FD_ISSET(i, &write_set)) { /* data can be written to socket */
399 Debug((DEBUG_ENGINE, "select: Datagram can be written"));
400 event_generate(ET_WRITE, sock, 0);
402 if (FD_ISSET(i, &read_set) || FD_ISSET(i, &write_set))
407 assert(s_fd(sock) == i);
409 gen_ref_dec(sock); /* we're done with it */
412 timer_run(); /* execute any pending timers */
416 /** Descriptor for select() event engine. */
417 struct Engine engine_select = {
418 "select()", /* Engine name */
419 engine_init, /* Engine initialization function */
420 0, /* Engine signal registration function (none) */
421 engine_add, /* Engine socket registration function */
422 engine_state, /* Engine socket state change function */
423 engine_events, /* Engine socket events mask function */
424 engine_delete, /* Engine socket deletion function */
425 engine_loop /* Core engine event loop */