Annotation of embedaddon/libevent/select.c, revision 1.1.1.1
1.1 misho 1: /* $OpenBSD: select.c,v 1.2 2002/06/25 15:50:15 mickey Exp $ */
2:
3: /*
4: * Copyright 2000-2002 Niels Provos <provos@citi.umich.edu>
5: * All rights reserved.
6: *
7: * Redistribution and use in source and binary forms, with or without
8: * modification, are permitted provided that the following conditions
9: * are met:
10: * 1. Redistributions of source code must retain the above copyright
11: * notice, this list of conditions and the following disclaimer.
12: * 2. Redistributions in binary form must reproduce the above copyright
13: * notice, this list of conditions and the following disclaimer in the
14: * documentation and/or other materials provided with the distribution.
15: * 3. The name of the author may not be used to endorse or promote products
16: * derived from this software without specific prior written permission.
17: *
18: * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
19: * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
20: * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
21: * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
22: * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
23: * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
24: * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
25: * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
26: * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
27: * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
28: */
29: #ifdef HAVE_CONFIG_H
30: #include "config.h"
31: #endif
32:
33: #include <sys/types.h>
34: #ifdef HAVE_SYS_TIME_H
35: #include <sys/time.h>
36: #else
37: #include <sys/_libevent_time.h>
38: #endif
39: #ifdef HAVE_SYS_SELECT_H
40: #include <sys/select.h>
41: #endif
42: #include <sys/queue.h>
43: #include <signal.h>
44: #include <stdio.h>
45: #include <stdlib.h>
46: #include <string.h>
47: #include <unistd.h>
48: #include <errno.h>
49: #ifdef CHECK_INVARIANTS
50: #include <assert.h>
51: #endif
52:
53: #include "event.h"
54: #include "evutil.h"
55: #include "event-internal.h"
56: #include "evsignal.h"
57: #include "log.h"
58:
59: #ifndef howmany
60: #define howmany(x, y) (((x)+((y)-1))/(y))
61: #endif
62:
63: #ifndef _EVENT_HAVE_FD_MASK
64: /* This type is mandatory, but Android doesn't define it. */
65: #undef NFDBITS
66: #define NFDBITS (sizeof(long)*8)
67: typedef unsigned long fd_mask;
68: #endif
69:
70: struct selectop {
71: int event_fds; /* Highest fd in fd set */
72: int event_fdsz;
73: fd_set *event_readset_in;
74: fd_set *event_writeset_in;
75: fd_set *event_readset_out;
76: fd_set *event_writeset_out;
77: struct event **event_r_by_fd;
78: struct event **event_w_by_fd;
79: };
80:
81: static void *select_init (struct event_base *);
82: static int select_add (void *, struct event *);
83: static int select_del (void *, struct event *);
84: static int select_dispatch (struct event_base *, void *, struct timeval *);
85: static void select_dealloc (struct event_base *, void *);
86:
87: const struct eventop selectops = {
88: "select",
89: select_init,
90: select_add,
91: select_del,
92: select_dispatch,
93: select_dealloc,
94: 0
95: };
96:
97: static int select_resize(struct selectop *sop, int fdsz);
98:
99: static void *
100: select_init(struct event_base *base)
101: {
102: struct selectop *sop;
103:
104: /* Disable select when this environment variable is set */
105: if (evutil_getenv("EVENT_NOSELECT"))
106: return (NULL);
107:
108: if (!(sop = calloc(1, sizeof(struct selectop))))
109: return (NULL);
110:
111: select_resize(sop, howmany(32 + 1, NFDBITS)*sizeof(fd_mask));
112:
113: evsignal_init(base);
114:
115: return (sop);
116: }
117:
118: #ifdef CHECK_INVARIANTS
119: static void
120: check_selectop(struct selectop *sop)
121: {
122: int i;
123: for (i = 0; i <= sop->event_fds; ++i) {
124: if (FD_ISSET(i, sop->event_readset_in)) {
125: assert(sop->event_r_by_fd[i]);
126: assert(sop->event_r_by_fd[i]->ev_events & EV_READ);
127: assert(sop->event_r_by_fd[i]->ev_fd == i);
128: } else {
129: assert(! sop->event_r_by_fd[i]);
130: }
131: if (FD_ISSET(i, sop->event_writeset_in)) {
132: assert(sop->event_w_by_fd[i]);
133: assert(sop->event_w_by_fd[i]->ev_events & EV_WRITE);
134: assert(sop->event_w_by_fd[i]->ev_fd == i);
135: } else {
136: assert(! sop->event_w_by_fd[i]);
137: }
138: }
139:
140: }
141: #else
142: #define check_selectop(sop) do { (void) sop; } while (0)
143: #endif
144:
145: static int
146: select_dispatch(struct event_base *base, void *arg, struct timeval *tv)
147: {
148: int res, i, j;
149: struct selectop *sop = arg;
150:
151: check_selectop(sop);
152:
153: memcpy(sop->event_readset_out, sop->event_readset_in,
154: sop->event_fdsz);
155: memcpy(sop->event_writeset_out, sop->event_writeset_in,
156: sop->event_fdsz);
157:
158: res = select(sop->event_fds + 1, sop->event_readset_out,
159: sop->event_writeset_out, NULL, tv);
160:
161: check_selectop(sop);
162:
163: if (res == -1) {
164: if (errno != EINTR) {
165: event_warn("select");
166: return (-1);
167: }
168:
169: evsignal_process(base);
170: return (0);
171: } else if (base->sig.evsignal_caught) {
172: evsignal_process(base);
173: }
174:
175: event_debug(("%s: select reports %d", __func__, res));
176:
177: check_selectop(sop);
178: i = random() % (sop->event_fds+1);
179: for (j = 0; j <= sop->event_fds; ++j) {
180: struct event *r_ev = NULL, *w_ev = NULL;
181: if (++i >= sop->event_fds+1)
182: i = 0;
183:
184: res = 0;
185: if (FD_ISSET(i, sop->event_readset_out)) {
186: r_ev = sop->event_r_by_fd[i];
187: res |= EV_READ;
188: }
189: if (FD_ISSET(i, sop->event_writeset_out)) {
190: w_ev = sop->event_w_by_fd[i];
191: res |= EV_WRITE;
192: }
193: if (r_ev && (res & r_ev->ev_events)) {
194: event_active(r_ev, res & r_ev->ev_events, 1);
195: }
196: if (w_ev && w_ev != r_ev && (res & w_ev->ev_events)) {
197: event_active(w_ev, res & w_ev->ev_events, 1);
198: }
199: }
200: check_selectop(sop);
201:
202: return (0);
203: }
204:
205:
206: static int
207: select_resize(struct selectop *sop, int fdsz)
208: {
209: int n_events, n_events_old;
210:
211: fd_set *readset_in = NULL;
212: fd_set *writeset_in = NULL;
213: fd_set *readset_out = NULL;
214: fd_set *writeset_out = NULL;
215: struct event **r_by_fd = NULL;
216: struct event **w_by_fd = NULL;
217:
218: n_events = (fdsz/sizeof(fd_mask)) * NFDBITS;
219: n_events_old = (sop->event_fdsz/sizeof(fd_mask)) * NFDBITS;
220:
221: if (sop->event_readset_in)
222: check_selectop(sop);
223:
224: if ((readset_in = realloc(sop->event_readset_in, fdsz)) == NULL)
225: goto error;
226: sop->event_readset_in = readset_in;
227: if ((readset_out = realloc(sop->event_readset_out, fdsz)) == NULL)
228: goto error;
229: sop->event_readset_out = readset_out;
230: if ((writeset_in = realloc(sop->event_writeset_in, fdsz)) == NULL)
231: goto error;
232: sop->event_writeset_in = writeset_in;
233: if ((writeset_out = realloc(sop->event_writeset_out, fdsz)) == NULL)
234: goto error;
235: sop->event_writeset_out = writeset_out;
236: if ((r_by_fd = realloc(sop->event_r_by_fd,
237: n_events*sizeof(struct event*))) == NULL)
238: goto error;
239: sop->event_r_by_fd = r_by_fd;
240: if ((w_by_fd = realloc(sop->event_w_by_fd,
241: n_events * sizeof(struct event*))) == NULL)
242: goto error;
243: sop->event_w_by_fd = w_by_fd;
244:
245: memset((char *)sop->event_readset_in + sop->event_fdsz, 0,
246: fdsz - sop->event_fdsz);
247: memset((char *)sop->event_writeset_in + sop->event_fdsz, 0,
248: fdsz - sop->event_fdsz);
249: memset(sop->event_r_by_fd + n_events_old, 0,
250: (n_events-n_events_old) * sizeof(struct event*));
251: memset(sop->event_w_by_fd + n_events_old, 0,
252: (n_events-n_events_old) * sizeof(struct event*));
253:
254: sop->event_fdsz = fdsz;
255: check_selectop(sop);
256:
257: return (0);
258:
259: error:
260: event_warn("malloc");
261: return (-1);
262: }
263:
264:
265: static int
266: select_add(void *arg, struct event *ev)
267: {
268: struct selectop *sop = arg;
269:
270: if (ev->ev_events & EV_SIGNAL)
271: return (evsignal_add(ev));
272:
273: check_selectop(sop);
274: /*
275: * Keep track of the highest fd, so that we can calculate the size
276: * of the fd_sets for select(2)
277: */
278: if (sop->event_fds < ev->ev_fd) {
279: int fdsz = sop->event_fdsz;
280:
281: if (fdsz < sizeof(fd_mask))
282: fdsz = sizeof(fd_mask);
283:
284: while (fdsz <
285: (howmany(ev->ev_fd + 1, NFDBITS) * sizeof(fd_mask)))
286: fdsz *= 2;
287:
288: if (fdsz != sop->event_fdsz) {
289: if (select_resize(sop, fdsz)) {
290: check_selectop(sop);
291: return (-1);
292: }
293: }
294:
295: sop->event_fds = ev->ev_fd;
296: }
297:
298: if (ev->ev_events & EV_READ) {
299: FD_SET(ev->ev_fd, sop->event_readset_in);
300: sop->event_r_by_fd[ev->ev_fd] = ev;
301: }
302: if (ev->ev_events & EV_WRITE) {
303: FD_SET(ev->ev_fd, sop->event_writeset_in);
304: sop->event_w_by_fd[ev->ev_fd] = ev;
305: }
306: check_selectop(sop);
307:
308: return (0);
309: }
310:
311: /*
312: * Nothing to be done here.
313: */
314:
315: static int
316: select_del(void *arg, struct event *ev)
317: {
318: struct selectop *sop = arg;
319:
320: check_selectop(sop);
321: if (ev->ev_events & EV_SIGNAL)
322: return (evsignal_del(ev));
323:
324: if (sop->event_fds < ev->ev_fd) {
325: check_selectop(sop);
326: return (0);
327: }
328:
329: if (ev->ev_events & EV_READ) {
330: FD_CLR(ev->ev_fd, sop->event_readset_in);
331: sop->event_r_by_fd[ev->ev_fd] = NULL;
332: }
333:
334: if (ev->ev_events & EV_WRITE) {
335: FD_CLR(ev->ev_fd, sop->event_writeset_in);
336: sop->event_w_by_fd[ev->ev_fd] = NULL;
337: }
338:
339: check_selectop(sop);
340: return (0);
341: }
342:
343: static void
344: select_dealloc(struct event_base *base, void *arg)
345: {
346: struct selectop *sop = arg;
347:
348: evsignal_dealloc(base);
349: if (sop->event_readset_in)
350: free(sop->event_readset_in);
351: if (sop->event_writeset_in)
352: free(sop->event_writeset_in);
353: if (sop->event_readset_out)
354: free(sop->event_readset_out);
355: if (sop->event_writeset_out)
356: free(sop->event_writeset_out);
357: if (sop->event_r_by_fd)
358: free(sop->event_r_by_fd);
359: if (sop->event_w_by_fd)
360: free(sop->event_w_by_fd);
361:
362: memset(sop, 0, sizeof(struct selectop));
363: free(sop);
364: }
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