devpoll.c revision 3c0e74b55846b1bc1b4047506ed07e86ec32ed1e
1/*
2 * Copyright 2000-2009 Niels Provos <provos@citi.umich.edu>
3 * Copyright 2009-2012 Niels Provos and Nick Mathewson
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 *    notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 *    notice, this list of conditions and the following disclaimer in the
12 *    documentation and/or other materials provided with the distribution.
13 * 3. The name of the author may not be used to endorse or promote products
14 *    derived from this software without specific prior written permission.
15 *
16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
17 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
18 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
19 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
20 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
21 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
22 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
23 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
24 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
25 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
26 */
27#include "event2/event-config.h"
28#include "evconfig-private.h"
29
30#ifdef EVENT__HAVE_DEVPOLL
31
32#include <sys/types.h>
33#include <sys/resource.h>
34#ifdef EVENT__HAVE_SYS_TIME_H
35#include <sys/time.h>
36#endif
37#include <sys/queue.h>
38#include <sys/devpoll.h>
39#include <signal.h>
40#include <stdio.h>
41#include <stdlib.h>
42#include <string.h>
43#include <unistd.h>
44#include <fcntl.h>
45#include <errno.h>
46
47#include "event2/event.h"
48#include "event2/event_struct.h"
49#include "event2/thread.h"
50#include "event-internal.h"
51#include "evsignal-internal.h"
52#include "log-internal.h"
53#include "evmap-internal.h"
54#include "evthread-internal.h"
55
56struct devpollop {
57	struct pollfd *events;
58	int nevents;
59	int dpfd;
60	struct pollfd *changes;
61	int nchanges;
62};
63
64static void *devpoll_init(struct event_base *);
65static int devpoll_add(struct event_base *, int fd, short old, short events, void *);
66static int devpoll_del(struct event_base *, int fd, short old, short events, void *);
67static int devpoll_dispatch(struct event_base *, struct timeval *);
68static void devpoll_dealloc(struct event_base *);
69
70const struct eventop devpollops = {
71	"devpoll",
72	devpoll_init,
73	devpoll_add,
74	devpoll_del,
75	devpoll_dispatch,
76	devpoll_dealloc,
77	1, /* need reinit */
78	EV_FEATURE_FDS|EV_FEATURE_O1,
79	0
80};
81
82#define NEVENT	32000
83
84static int
85devpoll_commit(struct devpollop *devpollop)
86{
87	/*
88	 * Due to a bug in Solaris, we have to use pwrite with an offset of 0.
89	 * Write is limited to 2GB of data, until it will fail.
90	 */
91	if (pwrite(devpollop->dpfd, devpollop->changes,
92		sizeof(struct pollfd) * devpollop->nchanges, 0) == -1)
93		return (-1);
94
95	devpollop->nchanges = 0;
96	return (0);
97}
98
99static int
100devpoll_queue(struct devpollop *devpollop, int fd, int events) {
101	struct pollfd *pfd;
102
103	if (devpollop->nchanges >= devpollop->nevents) {
104		/*
105		 * Change buffer is full, must commit it to /dev/poll before
106		 * adding more
107		 */
108		if (devpoll_commit(devpollop) != 0)
109			return (-1);
110	}
111
112	pfd = &devpollop->changes[devpollop->nchanges++];
113	pfd->fd = fd;
114	pfd->events = events;
115	pfd->revents = 0;
116
117	return (0);
118}
119
120static void *
121devpoll_init(struct event_base *base)
122{
123	int dpfd, nfiles = NEVENT;
124	struct rlimit rl;
125	struct devpollop *devpollop;
126
127	if (!(devpollop = mm_calloc(1, sizeof(struct devpollop))))
128		return (NULL);
129
130	if (getrlimit(RLIMIT_NOFILE, &rl) == 0 &&
131	    rl.rlim_cur != RLIM_INFINITY)
132		nfiles = rl.rlim_cur;
133
134	/* Initialize the kernel queue */
135	if ((dpfd = evutil_open_closeonexec_("/dev/poll", O_RDWR, 0)) == -1) {
136		event_warn("open: /dev/poll");
137		mm_free(devpollop);
138		return (NULL);
139	}
140
141	devpollop->dpfd = dpfd;
142
143	/* Initialize fields */
144	/* FIXME: allocating 'nfiles' worth of space here can be
145	 * expensive and unnecessary.  See how epoll.c does it instead. */
146	devpollop->events = mm_calloc(nfiles, sizeof(struct pollfd));
147	if (devpollop->events == NULL) {
148		mm_free(devpollop);
149		close(dpfd);
150		return (NULL);
151	}
152	devpollop->nevents = nfiles;
153
154	devpollop->changes = mm_calloc(nfiles, sizeof(struct pollfd));
155	if (devpollop->changes == NULL) {
156		mm_free(devpollop->events);
157		mm_free(devpollop);
158		close(dpfd);
159		return (NULL);
160	}
161
162	evsig_init_(base);
163
164	return (devpollop);
165}
166
167static int
168devpoll_dispatch(struct event_base *base, struct timeval *tv)
169{
170	struct devpollop *devpollop = base->evbase;
171	struct pollfd *events = devpollop->events;
172	struct dvpoll dvp;
173	int i, res, timeout = -1;
174
175	if (devpollop->nchanges)
176		devpoll_commit(devpollop);
177
178	if (tv != NULL)
179		timeout = tv->tv_sec * 1000 + (tv->tv_usec + 999) / 1000;
180
181	dvp.dp_fds = devpollop->events;
182	dvp.dp_nfds = devpollop->nevents;
183	dvp.dp_timeout = timeout;
184
185	EVBASE_RELEASE_LOCK(base, th_base_lock);
186
187	res = ioctl(devpollop->dpfd, DP_POLL, &dvp);
188
189	EVBASE_ACQUIRE_LOCK(base, th_base_lock);
190
191	if (res == -1) {
192		if (errno != EINTR) {
193			event_warn("ioctl: DP_POLL");
194			return (-1);
195		}
196
197		return (0);
198	}
199
200	event_debug(("%s: devpoll_wait reports %d", __func__, res));
201
202	for (i = 0; i < res; i++) {
203		int which = 0;
204		int what = events[i].revents;
205
206		if (what & POLLHUP)
207			what |= POLLIN | POLLOUT;
208		else if (what & POLLERR)
209			what |= POLLIN | POLLOUT;
210
211		if (what & POLLIN)
212			which |= EV_READ;
213		if (what & POLLOUT)
214			which |= EV_WRITE;
215
216		if (!which)
217			continue;
218
219		/* XXX(niels): not sure if this works for devpoll */
220		evmap_io_active_(base, events[i].fd, which);
221	}
222
223	return (0);
224}
225
226
227static int
228devpoll_add(struct event_base *base, int fd, short old, short events, void *p)
229{
230	struct devpollop *devpollop = base->evbase;
231	int res;
232	(void)p;
233
234	/*
235	 * It's not necessary to OR the existing read/write events that we
236	 * are currently interested in with the new event we are adding.
237	 * The /dev/poll driver ORs any new events with the existing events
238	 * that it has cached for the fd.
239	 */
240
241	res = 0;
242	if (events & EV_READ)
243		res |= POLLIN;
244	if (events & EV_WRITE)
245		res |= POLLOUT;
246
247	if (devpoll_queue(devpollop, fd, res) != 0)
248		return (-1);
249
250	return (0);
251}
252
253static int
254devpoll_del(struct event_base *base, int fd, short old, short events, void *p)
255{
256	struct devpollop *devpollop = base->evbase;
257	int res;
258	(void)p;
259
260	res = 0;
261	if (events & EV_READ)
262		res |= POLLIN;
263	if (events & EV_WRITE)
264		res |= POLLOUT;
265
266	/*
267	 * The only way to remove an fd from the /dev/poll monitored set is
268	 * to use POLLREMOVE by itself.  This removes ALL events for the fd
269	 * provided so if we care about two events and are only removing one
270	 * we must re-add the other event after POLLREMOVE.
271	 */
272
273	if (devpoll_queue(devpollop, fd, POLLREMOVE) != 0)
274		return (-1);
275
276	if ((res & (POLLIN|POLLOUT)) != (POLLIN|POLLOUT)) {
277		/*
278		 * We're not deleting all events, so we must resubmit the
279		 * event that we are still interested in if one exists.
280		 */
281
282		if ((res & POLLIN) && (old & EV_WRITE)) {
283			/* Deleting read, still care about write */
284			devpoll_queue(devpollop, fd, POLLOUT);
285		} else if ((res & POLLOUT) && (old & EV_READ)) {
286			/* Deleting write, still care about read */
287			devpoll_queue(devpollop, fd, POLLIN);
288		}
289	}
290
291	return (0);
292}
293
294static void
295devpoll_dealloc(struct event_base *base)
296{
297	struct devpollop *devpollop = base->evbase;
298
299	evsig_dealloc_(base);
300	if (devpollop->events)
301		mm_free(devpollop->events);
302	if (devpollop->changes)
303		mm_free(devpollop->changes);
304	if (devpollop->dpfd >= 0)
305		close(devpollop->dpfd);
306
307	memset(devpollop, 0, sizeof(struct devpollop));
308	mm_free(devpollop);
309}
310
311#endif /* EVENT__HAVE_DEVPOLL */
312