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 #include "ircd_events.h"
31 /* On BSD, define FD_SETSIZE to what we want before including sys/types.h */
32 #if defined(__FreeBSD__) || defined(__NetBSD__) || defined(__bsdi__)
33 # if !defined(FD_SETSIZE)
34 # define FD_SETSIZE MAXCONNECTIONS
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 #define SELECT_ERROR_THRESHOLD 20 /**< after 20 select errors, restart */
48 #define ERROR_EXPIRE_TIME 3600 /**< expire errors after an hour */
50 /** Array of active Socket structures, indexed by file descriptor. */
51 static struct Socket* sockList[FD_SETSIZE];
52 /** Maximum file descriptor currently used. */
53 static int highest_fd;
54 /** Global read event interest bitmap. */
55 static fd_set global_read_set;
56 /** Global write event interest bitmap. */
57 static fd_set global_write_set;
59 /** Number of recent errors from select(). */
60 static int errors = 0;
61 /** Periodic timer to forget errors. */
62 static struct Timer clear_error;
64 /** Decrement the error count (once per hour).
65 * @param[in] ev Expired timer event (ignored).
68 error_clear(struct Event* ev)
70 if (!--errors) /* remove timer when error count reaches 0 */
71 timer_del(ev_timer(ev));
74 /** Initialize the select() engine.
75 * @param[in] max_sockets Maximum number of file descriptors to support.
76 * @return Non-zero on success, or zero on failure.
79 engine_init(int max_sockets)
83 if (max_sockets > FD_SETSIZE) { /* too many sockets */
84 log_write(LS_SYSTEM, L_WARNING, 0,
85 "select() engine cannot handle %d sockets (> %d)",
86 max_sockets, FD_SETSIZE);
90 FD_ZERO(&global_read_set); /* zero the global fd sets */
91 FD_ZERO(&global_write_set);
93 for (i = 0; i < FD_SETSIZE; i++) /* zero the sockList */
96 highest_fd = -1; /* No fds in set */
98 return 1; /* initialization successful */
101 /** Figure out what events go with a given state.
102 * @param[in] state %Socket state to consider.
103 * @param[in] events User-specified preferred event set.
104 * @return Actual set of preferred events.
107 state_to_events(enum SocketState state, unsigned int events)
110 case SS_CONNECTING: /* connecting socket */
111 return SOCK_EVENT_WRITABLE;
114 case SS_LISTENING: /* listening socket */
115 case SS_NOTSOCK: /* our signal socket */
116 return SOCK_EVENT_READABLE;
119 case SS_CONNECTED: case SS_DATAGRAM: case SS_CONNECTDG:
120 return events; /* ordinary socket */
128 /** Set interest events in #global_read_set and #global_write_set as appropriate.
129 * @param[in] fd File descriptor to operate on.
130 * @param[in] clear Set of interest events to clear from socket.
131 * @param[in] set Set of interest events to set on socket.
134 set_or_clear(int fd, unsigned int clear, unsigned int set)
136 if ((clear ^ set) & SOCK_EVENT_READABLE) { /* readable has changed */
137 if (set & SOCK_EVENT_READABLE) /* it's set */
138 FD_SET(fd, &global_read_set);
140 FD_CLR(fd, &global_read_set);
143 if ((clear ^ set) & SOCK_EVENT_WRITABLE) { /* writable has changed */
144 if (set & SOCK_EVENT_WRITABLE) /* it's set */
145 FD_SET(fd, &global_write_set);
147 FD_CLR(fd, &global_write_set);
151 /** Add a socket to the event engine.
152 * @param[in] sock Socket to add to engine.
153 * @return Non-zero on success, or zero on error.
156 engine_add(struct Socket* sock)
159 assert(0 == sockList[s_fd(sock)]);
161 /* bounds-check... */
162 if (s_fd(sock) >= FD_SETSIZE) {
163 log_write(LS_SYSTEM, L_ERROR, 0,
164 "Attempt to add socket %d (> %d) to event engine", s_fd(sock),
169 sockList[s_fd(sock)] = sock; /* add to list */
171 if (s_fd(sock) >= highest_fd) /* update highest_fd */
172 highest_fd = s_fd(sock);
174 Debug((DEBUG_ENGINE, "select: Adding socket %d to engine [%p], state %s",
175 s_fd(sock), sock, state_to_name(s_state(sock))));
177 /* set the fd set bits */
178 set_or_clear(s_fd(sock), 0, state_to_events(s_state(sock), s_events(sock)));
180 return 1; /* success */
183 /** Handle state transition for a socket.
184 * @param[in] sock Socket changing state.
185 * @param[in] new_state New state for socket.
188 engine_state(struct Socket* sock, enum SocketState new_state)
191 assert(sock == sockList[s_fd(sock)]);
193 Debug((DEBUG_ENGINE, "select: Changing state for socket %p to %s", sock,
194 state_to_name(new_state)));
196 /* set the correct events */
197 set_or_clear(s_fd(sock),
198 state_to_events(s_state(sock), s_events(sock)), /* old state */
199 state_to_events(new_state, s_events(sock))); /* new state */
202 /** Handle change to preferred socket events.
203 * @param[in] sock Socket getting new interest list.
204 * @param[in] new_events New set of interesting events for socket.
207 engine_events(struct Socket* sock, unsigned int new_events)
210 assert(sock == sockList[s_fd(sock)]);
212 Debug((DEBUG_ENGINE, "select: Changing event mask for socket %p to [%s]",
213 sock, sock_flags(new_events)));
215 /* set the correct events */
216 set_or_clear(s_fd(sock),
217 state_to_events(s_state(sock), s_events(sock)), /* old events */
218 state_to_events(s_state(sock), new_events)); /* new events */
221 /** Remove a socket from the event engine.
222 * @param[in] sock Socket being destroyed.
225 engine_delete(struct Socket* sock)
228 assert(sock == sockList[s_fd(sock)]);
230 Debug((DEBUG_ENGINE, "select: Deleting socket %d [%p], state %s", s_fd(sock),
231 sock, state_to_name(s_state(sock))));
233 FD_CLR(s_fd(sock), &global_read_set); /* clear event set bits */
234 FD_CLR(s_fd(sock), &global_write_set);
236 sockList[s_fd(sock)] = 0; /* zero the socket list entry */
238 while (highest_fd > -1 && sockList[highest_fd] == 0) /* update highest_fd */
242 /** Run engine event loop.
243 * @param[in] gen Lists of generators of various types.
246 engine_loop(struct Generators* gen)
258 read_set = global_read_set; /* all hail structure copy!! */
259 write_set = global_write_set;
261 /* set up the sleep time */
262 wait.tv_sec = timer_next(gen) ? (timer_next(gen) - CurrentTime) : -1;
265 Debug((DEBUG_INFO, "select: delay: %Tu (%Tu) %Tu", timer_next(gen),
266 CurrentTime, wait.tv_sec));
268 /* check for active files */
269 nfds = select(highest_fd + 1, &read_set, &write_set, 0,
270 wait.tv_sec < 0 ? 0 : &wait);
272 CurrentTime = time(0); /* set current time... */
275 if (errno != EINTR) { /* ignore select interrupts */
276 /* Log the select error */
277 log_write(LS_SOCKET, L_ERROR, 0, "select() error: %m");
279 timer_add(timer_init(&clear_error), error_clear, 0, TT_PERIODIC,
281 else if (errors > SELECT_ERROR_THRESHOLD) /* too many errors... */
282 server_restart("too many select errors");
284 /* old code did a sleep(1) here; with usage these days,
285 * that may be too expensive
290 for (i = 0; nfds && i <= highest_fd; i++) {
291 if (!(sock = sockList[i])) /* skip empty socket elements */
294 assert(s_fd(sock) == i);
296 gen_ref_inc(sock); /* can't have it going away on us */
298 Debug((DEBUG_ENGINE, "select: Checking socket %p (fd %d) state %s, "
299 "events %s", sock, i, state_to_name(s_state(sock)),
300 sock_flags(s_events(sock))));
302 if (s_state(sock) != SS_NOTSOCK) {
303 errcode = 0; /* check for errors on socket */
304 codesize = sizeof(errcode);
305 if (getsockopt(i, SOL_SOCKET, SO_ERROR, &errcode, &codesize) < 0)
306 errcode = errno; /* work around Solaris implementation */
308 if (errcode) { /* an error occurred; generate an event */
309 Debug((DEBUG_ENGINE, "select: Error %d on fd %d, socket %p", errcode,
311 event_generate(ET_ERROR, sock, errcode);
312 gen_ref_dec(sock); /* careful not to leak reference counts */
317 switch (s_state(sock)) {
319 if (FD_ISSET(i, &write_set)) { /* connection completed */
320 Debug((DEBUG_ENGINE, "select: Connection completed"));
321 event_generate(ET_CONNECT, sock, 0);
328 if (FD_ISSET(i, &read_set)) { /* connection to be accepted */
329 Debug((DEBUG_ENGINE, "select: Ready for accept"));
330 event_generate(ET_ACCEPT, sock, 0);
336 if (FD_ISSET(i, &read_set)) { /* data on socket */
337 /* can't peek; it's not a socket */
338 Debug((DEBUG_ENGINE, "select: non-socket readable"));
339 event_generate(ET_READ, sock, 0);
345 if (FD_ISSET(i, &read_set)) { /* data to be read from socket */
348 switch (recv(i, &c, 1, MSG_PEEK)) { /* check for EOF */
349 case -1: /* error occurred?!? */
350 if (errno == EAGAIN) {
351 Debug((DEBUG_ENGINE, "select: Resource temporarily "
355 Debug((DEBUG_ENGINE, "select: Uncaught error!"));
356 event_generate(ET_ERROR, sock, errno);
359 case 0: /* EOF from client */
360 Debug((DEBUG_ENGINE, "select: EOF from client"));
361 event_generate(ET_EOF, sock, 0);
364 default: /* some data can be read */
365 Debug((DEBUG_ENGINE, "select: Data to be read"));
366 event_generate(ET_READ, sock, 0);
370 if (FD_ISSET(i, &write_set)) { /* data can be written to socket */
371 Debug((DEBUG_ENGINE, "select: Data can be written"));
372 event_generate(ET_WRITE, sock, 0);
374 if (FD_ISSET(i, &read_set) || FD_ISSET(i, &write_set))
378 case SS_DATAGRAM: case SS_CONNECTDG:
379 if (FD_ISSET(i, &read_set)) { /* data to be read from socket */
380 Debug((DEBUG_ENGINE, "select: Datagram to be read"));
381 event_generate(ET_READ, sock, 0);
383 if (FD_ISSET(i, &write_set)) { /* data can be written to socket */
384 Debug((DEBUG_ENGINE, "select: Datagram can be written"));
385 event_generate(ET_WRITE, sock, 0);
387 if (FD_ISSET(i, &read_set) || FD_ISSET(i, &write_set))
392 assert(s_fd(sock) == i);
394 gen_ref_dec(sock); /* we're done with it */
397 timer_run(); /* execute any pending timers */
401 /** Descriptor for select() event engine. */
402 struct Engine engine_select = {
403 "select()", /* Engine name */
404 engine_init, /* Engine initialization function */
405 0, /* Engine signal registration function (none) */
406 engine_add, /* Engine socket registration function */
407 engine_state, /* Engine socket state change function */
408 engine_events, /* Engine socket events mask function */
409 engine_delete, /* Engine socket deletion function */
410 engine_loop /* Core engine event loop */