46b2334e7e03ef481cd8ff74d047ce443d5cddc8
[ccan] / ccan / io / poll.c
1 /* Licensed under LGPLv2.1+ - see LICENSE file for details */
2 #include "io.h"
3 #include "backend.h"
4 #include <assert.h>
5 #include <poll.h>
6 #include <stdlib.h>
7 #include <sys/types.h>
8 #include <sys/socket.h>
9 #include <limits.h>
10
11 static size_t num_fds = 0, max_fds = 0, num_closing = 0, num_waiting = 0;
12 static struct pollfd *pollfds = NULL;
13 static struct fd **fds = NULL;
14 static struct timers timeouts;
15
16 static bool add_fd(struct fd *fd, short events)
17 {
18         if (num_fds + 1 > max_fds) {
19                 struct pollfd *newpollfds;
20                 struct fd **newfds;
21                 size_t num = max_fds ? max_fds * 2 : 8;
22
23                 newpollfds = realloc(pollfds, sizeof(*newpollfds) * num);
24                 if (!newpollfds)
25                         return false;
26                 pollfds = newpollfds;
27                 newfds = realloc(fds, sizeof(*newfds) * num);
28                 if (!newfds)
29                         return false;
30                 fds = newfds;
31                 max_fds = num;
32         }
33
34         pollfds[num_fds].fd = fd->fd;
35         pollfds[num_fds].events = events;
36         pollfds[num_fds].revents = 0; /* In case we're iterating now */
37         fds[num_fds] = fd;
38         fd->backend_info = num_fds;
39         num_fds++;
40         if (events)
41                 num_waiting++;
42
43         return true;
44 }
45
46 static void del_fd(struct fd *fd)
47 {
48         size_t n = fd->backend_info;
49
50         assert(n != -1);
51         assert(n < num_fds);
52         if (pollfds[n].events)
53                 num_waiting--;
54         if (n != num_fds - 1) {
55                 /* Move last one over us. */
56                 pollfds[n] = pollfds[num_fds-1];
57                 fds[n] = fds[num_fds-1];
58                 assert(fds[n]->backend_info == num_fds-1);
59                 fds[n]->backend_info = n;
60         } else if (num_fds == 1) {
61                 /* Free everything when no more fds. */
62                 free(pollfds);
63                 free(fds);
64                 pollfds = NULL;
65                 fds = NULL;
66                 max_fds = 0;
67         }
68         num_fds--;
69         fd->backend_info = -1;
70         close(fd->fd);
71 }
72
73 bool add_listener(struct io_listener *l)
74 {
75         if (!add_fd(&l->fd, POLLIN))
76                 return false;
77         return true;
78 }
79
80 static void update_pollevents(struct io_conn *conn)
81 {
82         struct pollfd *pfd = &pollfds[conn->fd.backend_info];
83
84         if (pfd->events)
85                 num_waiting--;
86
87         pfd->events = conn->plan.pollflag;
88         if (conn->duplex) {
89                 int mask = conn->duplex->plan.pollflag;
90                 /* You can't *both* read/write. */
91                 assert(!mask || pfd->events != mask);
92                 pfd->events |= mask;
93         }
94         if (pfd->events)
95                 num_waiting++;
96
97         if (!conn->plan.next)
98                 num_closing++;
99 }
100
101 bool add_conn(struct io_conn *c)
102 {
103         if (!add_fd(&c->fd, c->plan.pollflag))
104                 return false;
105         /* Immediate close is allowed. */
106         if (!c->plan.next)
107                 num_closing++;
108         return true;
109 }
110
111 bool add_duplex(struct io_conn *c)
112 {
113         c->fd.backend_info = c->duplex->fd.backend_info;
114         update_pollevents(c);
115         return true;
116 }
117
118 static void del_conn(struct io_conn *conn)
119 {
120         if (conn->finish)
121                 conn->finish(conn, conn->finish_arg);
122         if (timeout_active(conn))
123                 backend_del_timeout(conn);
124         free(conn->timeout);
125         if (conn->duplex) {
126                 /* In case fds[] pointed to the other one. */
127                 fds[conn->fd.backend_info] = &conn->duplex->fd;
128                 conn->duplex->duplex = NULL;
129         } else
130                 del_fd(&conn->fd);
131         num_closing--;
132 }
133
134 void del_listener(struct io_listener *l)
135 {
136         del_fd(&l->fd);
137 }
138
139 static void backend_set_state(struct io_conn *conn, struct io_plan plan)
140 {
141         conn->plan = plan;
142         update_pollevents(conn);
143 }
144
145 void backend_wakeup(struct io_conn *conn)
146 {
147         update_pollevents(conn);
148 }
149
150 static void accept_conn(struct io_listener *l)
151 {
152         int fd = accept(l->fd.fd, NULL, NULL);
153
154         /* FIXME: What to do here? */
155         if (fd < 0)
156                 return;
157         l->init(fd, l->arg);
158 }
159
160 /* It's OK to miss some, as long as we make progress. */
161 static void finish_conns(void)
162 {
163         unsigned int i;
164
165         for (i = 0; !io_loop_return && i < num_fds; i++) {
166                 struct io_conn *c, *duplex;
167
168                 if (!num_closing)
169                         break;
170
171                 if (fds[i]->listener)
172                         continue;
173                 c = (void *)fds[i];
174                 for (duplex = c->duplex; c; c = duplex, duplex = NULL) {
175                         if (!c->plan.next) {
176                                 del_conn(c);
177                                 free(c);
178                                 i--;
179                         }
180                 }
181         }
182 }
183
184 static void ready(struct io_conn *c)
185 {
186         backend_set_state(c, do_ready(c));
187 }
188
189 void backend_add_timeout(struct io_conn *conn, struct timespec duration)
190 {
191         if (!timeouts.base)
192                 timers_init(&timeouts, time_now());
193         timer_add(&timeouts, &conn->timeout->timer,
194                   time_add(time_now(), duration));
195         conn->timeout->conn = conn;
196 }
197
198 void backend_del_timeout(struct io_conn *conn)
199 {
200         assert(conn->timeout->conn == conn);
201         timer_del(&timeouts, &conn->timeout->timer);
202         conn->timeout->conn = NULL;
203 }
204
205 /* This is the main loop. */
206 void *io_loop(void)
207 {
208         void *ret;
209
210         while (!io_loop_return) {
211                 int i, r, timeout = INT_MAX;
212                 struct timespec now;
213
214                 if (timeouts.base) {
215                         struct timespec first;
216                         struct list_head expired;
217                         struct io_timeout *t;
218
219                         now = time_now();
220
221                         /* Call functions for expired timers. */
222                         timers_expire(&timeouts, now, &expired);
223                         while ((t = list_pop(&expired, struct io_timeout, timer.list))) {
224                                 struct io_conn *conn = t->conn;
225                                 /* Clear, in case timer re-adds */
226                                 t->conn = NULL;
227                                 backend_set_state(conn, t->next(conn, t->next_arg));
228                         }
229
230                         /* Now figure out how long to wait for the next one. */
231                         if (timer_earliest(&timeouts, &first)) {
232                                 uint64_t f = time_to_msec(time_sub(first, now));
233                                 if (f < INT_MAX)
234                                         timeout = f;
235                         }
236                 }
237
238                 if (num_closing) {
239                         finish_conns();
240                         /* Could have started/finished more. */
241                         continue;
242                 }
243
244                 if (num_fds == 0)
245                         break;
246
247                 /* You can't tell them all to go to sleep! */
248                 assert(num_waiting);
249
250                 r = poll(pollfds, num_fds, timeout);
251                 if (r < 0)
252                         break;
253
254                 for (i = 0; i < num_fds && !io_loop_return; i++) {
255                         struct io_conn *c = (void *)fds[i];
256                         int events = pollfds[i].revents;
257
258                         if (r == 0)
259                                 break;
260
261                         if (fds[i]->listener) {
262                                 if (events & POLLIN) {
263                                         accept_conn((void *)c);
264                                         r--;
265                                 }
266                         } else if (events & (POLLIN|POLLOUT)) {
267                                 r--;
268                                 if (c->duplex) {
269                                         int mask = c->duplex->plan.pollflag;
270                                         if (events & mask) {
271                                                 ready(c->duplex);
272                                                 events &= ~mask;
273                                                 if (!(events&(POLLIN|POLLOUT)))
274                                                         continue;
275                                         }
276                                 }
277                                 ready(c);
278                         } else if (events & POLLHUP) {
279                                 r--;
280                                 backend_set_state(c, io_close(c, NULL));
281                                 if (c->duplex)
282                                         backend_set_state(c->duplex,
283                                                           io_close(c->duplex,
284                                                                    NULL));
285                         }
286                 }
287         }
288
289         while (num_closing)
290                 finish_conns();
291
292         ret = io_loop_return;
293         io_loop_return = NULL;
294         return ret;
295 }