2 * libev select fd activity backend
4 * Copyright (c) 2007,2008,2009,2010,2011 Marc Alexander Lehmann <libev@schmorp.de>
7 * Redistribution and use in source and binary forms, with or without modifica-
8 * tion, are permitted provided that the following conditions are met:
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41 /* for unix systems */
42 # include <inttypes.h>
44 /* for REAL unix systems */
45 # include <sys/select.h>
49 #ifndef EV_SELECT_USE_FD_SET
51 # define EV_SELECT_USE_FD_SET 0
53 # define EV_SELECT_USE_FD_SET 1
57 #if EV_SELECT_IS_WINSOCKET
58 # undef EV_SELECT_USE_FD_SET
59 # define EV_SELECT_USE_FD_SET 1
64 #if !EV_SELECT_USE_FD_SET
65 # define NFDBYTES (NFDBITS / 8)
71 select_modify (EV_P_ int fd, int oev, int nev)
77 #if EV_SELECT_USE_FD_SET
79 #if EV_SELECT_IS_WINSOCKET
80 SOCKET handle = anfds [fd].handle;
85 assert (("libev: fd >= FD_SETSIZE passed to fd_set-based select backend", fd < FD_SETSIZE));
87 /* FD_SET is broken on windows (it adds the fd to a set twice or more,
88 * which eventually leads to overflows). Need to call it only on changes.
90 #if EV_SELECT_IS_WINSOCKET
91 if ((oev ^ nev) & EV_READ)
94 FD_SET (handle, (fd_set *)vec_ri);
96 FD_CLR (handle, (fd_set *)vec_ri);
98 #if EV_SELECT_IS_WINSOCKET
99 if ((oev ^ nev) & EV_WRITE)
102 FD_SET (handle, (fd_set *)vec_wi);
104 FD_CLR (handle, (fd_set *)vec_wi);
108 int word = fd / NFDBITS;
109 fd_mask mask = 1UL << (fd % NFDBITS);
111 if (expect_false (vec_max <= word))
113 int new_max = word + 1;
115 vec_ri = ev_realloc (vec_ri, new_max * NFDBYTES);
116 vec_ro = ev_realloc (vec_ro, new_max * NFDBYTES); /* could free/malloc */
117 vec_wi = ev_realloc (vec_wi, new_max * NFDBYTES);
118 vec_wo = ev_realloc (vec_wo, new_max * NFDBYTES); /* could free/malloc */
120 vec_eo = ev_realloc (vec_eo, new_max * NFDBYTES); /* could free/malloc */
123 for (; vec_max < new_max; ++vec_max)
124 ((fd_mask *)vec_ri) [vec_max] =
125 ((fd_mask *)vec_wi) [vec_max] = 0;
128 ((fd_mask *)vec_ri) [word] |= mask;
129 if (!(nev & EV_READ))
130 ((fd_mask *)vec_ri) [word] &= ~mask;
132 ((fd_mask *)vec_wi) [word] |= mask;
133 if (!(nev & EV_WRITE))
134 ((fd_mask *)vec_wi) [word] &= ~mask;
140 select_poll (EV_P_ ev_tstamp timeout)
147 EV_TV_SET (tv, timeout);
149 #if EV_SELECT_USE_FD_SET
150 fd_setsize = sizeof (fd_set);
152 fd_setsize = vec_max * NFDBYTES;
155 memcpy (vec_ro, vec_ri, fd_setsize);
156 memcpy (vec_wo, vec_wi, fd_setsize);
159 /* pass in the write set as except set.
160 * the idea behind this is to work around a windows bug that causes
161 * errors to be reported as an exception and not by setting
162 * the writable bit. this is so uncontrollably lame.
164 memcpy (vec_eo, vec_wi, fd_setsize);
165 res = select (vec_max * NFDBITS, (fd_set *)vec_ro, (fd_set *)vec_wo, (fd_set *)vec_eo, &tv);
166 #elif EV_SELECT_USE_FD_SET
167 fd_setsize = anfdmax < FD_SETSIZE ? anfdmax : FD_SETSIZE;
168 res = select (fd_setsize, (fd_set *)vec_ro, (fd_set *)vec_wo, 0, &tv);
170 res = select (vec_max * NFDBITS, (fd_set *)vec_ro, (fd_set *)vec_wo, 0, &tv);
174 if (expect_false (res < 0))
176 #if EV_SELECT_IS_WINSOCKET
177 errno = WSAGetLastError ();
180 /* on windows, select returns incompatible error codes, fix this */
181 if (errno >= WSABASEERR && errno < WSABASEERR + 1000)
182 if (errno == WSAENOTSOCK)
189 /* select on windows erroneously returns EINVAL when no fd sets have been
190 * provided (this is documented). what microsoft doesn't tell you that this bug
191 * exists even when the fd sets _are_ provided, so we have to check for this bug
192 * here and emulate by sleeping manually.
193 * we also get EINVAL when the timeout is invalid, but we ignore this case here
194 * and assume that EINVAL always means: you have to wait manually.
200 unsigned long ms = timeout * 1e3;
210 else if (errno == ENOMEM && !syserr_cb)
212 else if (errno != EINTR)
213 ev_syserr ("(libev) select");
218 #if EV_SELECT_USE_FD_SET
223 for (fd = 0; fd < anfdmax; ++fd)
224 if (anfds [fd].events)
227 #if EV_SELECT_IS_WINSOCKET
228 SOCKET handle = anfds [fd].handle;
233 if (FD_ISSET (handle, (fd_set *)vec_ro)) events |= EV_READ;
234 if (FD_ISSET (handle, (fd_set *)vec_wo)) events |= EV_WRITE;
236 if (FD_ISSET (handle, (fd_set *)vec_eo)) events |= EV_WRITE;
239 if (expect_true (events))
240 fd_event (EV_A_ fd, events);
248 for (word = vec_max; word--; )
250 fd_mask word_r = ((fd_mask *)vec_ro) [word];
251 fd_mask word_w = ((fd_mask *)vec_wo) [word];
253 word_w |= ((fd_mask *)vec_eo) [word];
256 if (word_r || word_w)
257 for (bit = NFDBITS; bit--; )
259 fd_mask mask = 1UL << bit;
262 events |= word_r & mask ? EV_READ : 0;
263 events |= word_w & mask ? EV_WRITE : 0;
265 if (expect_true (events))
266 fd_event (EV_A_ word * NFDBITS + bit, events);
275 select_init (EV_P_ int flags)
277 backend_mintime = 1e-6;
278 backend_modify = select_modify;
279 backend_poll = select_poll;
281 #if EV_SELECT_USE_FD_SET
282 vec_ri = ev_malloc (sizeof (fd_set)); FD_ZERO ((fd_set *)vec_ri);
283 vec_ro = ev_malloc (sizeof (fd_set));
284 vec_wi = ev_malloc (sizeof (fd_set)); FD_ZERO ((fd_set *)vec_wi);
285 vec_wo = ev_malloc (sizeof (fd_set));
287 vec_eo = ev_malloc (sizeof (fd_set));
300 return EVBACKEND_SELECT;
304 select_destroy (EV_P)