ccan/io: remove next & finish from union.
[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_next = 0, num_finished = 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         return true;
41 }
42
43 static void del_fd(struct fd *fd)
44 {
45         size_t n = fd->backend_info;
46
47         assert(n != -1);
48         assert(n < num_fds);
49         if (n != num_fds - 1) {
50                 /* Move last one over us. */
51                 pollfds[n] = pollfds[num_fds-1];
52                 fds[n] = fds[num_fds-1];
53                 assert(fds[n]->backend_info == num_fds-1);
54                 fds[n]->backend_info = n;
55         } else if (num_fds == 1) {
56                 /* Free everything when no more fds. */
57                 free(pollfds);
58                 free(fds);
59                 pollfds = NULL;
60                 fds = NULL;
61                 max_fds = 0;
62         }
63         num_fds--;
64         fd->backend_info = -1;
65         close(fd->fd);
66 }
67
68 bool add_listener(struct io_listener *l)
69 {
70         if (!add_fd(&l->fd, POLLIN))
71                 return false;
72         num_waiting++;
73         return true;
74 }
75
76 bool add_conn(struct io_conn *c)
77 {
78         if (!add_fd(&c->fd, 0))
79                 return false;
80         num_next++;
81         return true;
82 }
83
84 bool add_duplex(struct io_conn *c)
85 {
86         c->fd.backend_info = c->duplex->fd.backend_info;
87         num_next++;
88         return true;
89 }
90
91 static void del_conn(struct io_conn *conn)
92 {
93         if (conn->finish)
94                 conn->finish(conn, conn->finish_arg);
95         if (timeout_active(conn))
96                 backend_del_timeout(conn);
97         free(conn->timeout);
98         if (conn->duplex) {
99                 /* In case fds[] pointed to the other one. */
100                 fds[conn->fd.backend_info] = &conn->duplex->fd;
101                 conn->duplex->duplex = NULL;
102         } else
103                 del_fd(&conn->fd);
104         if (conn->state == FINISHED)
105                 num_finished--;
106         else if (conn->state == NEXT)
107                 num_next--;
108 }
109
110 void del_listener(struct io_listener *l)
111 {
112         del_fd(&l->fd);
113 }
114
115 void backend_set_state(struct io_conn *conn, struct io_plan *plan)
116 {
117         enum io_state state = from_ioplan(plan);
118         struct pollfd *pfd = &pollfds[conn->fd.backend_info];
119
120         if (pfd->events)
121                 num_waiting--;
122
123         pfd->events = conn->pollflag;
124         if (conn->duplex) {
125                 int mask = conn->duplex->pollflag;
126                 /* You can't *both* read/write. */
127                 assert(!mask || pfd->events != mask);
128                 pfd->events |= mask;
129         }
130         if (pfd->events)
131                 num_waiting++;
132
133         if (state == NEXT)
134                 num_next++;
135         else if (state == FINISHED)
136                 num_finished++;
137
138         conn->state = state;
139 }
140
141 static void accept_conn(struct io_listener *l)
142 {
143         struct io_conn *c;
144         int fd = accept(l->fd.fd, NULL, NULL);
145
146         /* FIXME: What to do here? */
147         if (fd < 0)
148                 return;
149         c = io_new_conn(fd, l->next, l->finish, l->conn_arg);
150         if (!c) {
151                 close(fd);
152                 return;
153         }
154 }
155
156 /* It's OK to miss some, as long as we make progress. */
157 static void finish_and_next(bool finished_only)
158 {
159         unsigned int i;
160
161         for (i = 0; !io_loop_return && i < num_fds; i++) {
162                 struct io_conn *c, *duplex;
163
164                 if (!num_finished) {
165                         if (finished_only || num_next == 0)
166                                 break;
167                 }
168                 if (fds[i]->listener)
169                         continue;
170                 c = (void *)fds[i];
171                 for (duplex = c->duplex; c; c = duplex, duplex = NULL) {
172                         if (c->state == FINISHED) {
173                                 del_conn(c);
174                                 free(c);
175                                 i--;
176                         } else if (!finished_only && c->state == NEXT) {
177                                 backend_set_state(c, c->next(c, c->next_arg));
178                                 num_next--;
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_finished || num_next) {
239                         finish_and_next(false);
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->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_finished)
290                 finish_and_next(true);
291
292         ret = io_loop_return;
293         io_loop_return = NULL;
294         return ret;
295 }