ccan/io: rename io_op to io_plan.
[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->fd.finish)
94                 conn->fd.finish(conn, conn->fd.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 static int pollmask(enum io_state state)
116 {
117         switch (state) {
118         case READ:
119         case READPART:
120                 return POLLIN;
121         case WRITE:
122         case WRITEPART:
123                 return POLLOUT;
124         default:
125                 return 0;
126         }
127 }
128
129 void backend_set_state(struct io_conn *conn, struct io_plan *plan)
130 {
131         enum io_state state = from_ioplan(plan);
132         struct pollfd *pfd = &pollfds[conn->fd.backend_info];
133
134         if (pfd->events)
135                 num_waiting--;
136
137         pfd->events = pollmask(state);
138         if (conn->duplex) {
139                 int mask = pollmask(conn->duplex->state);
140                 /* You can't *both* read/write. */
141                 assert(!mask || pfd->events != mask);
142                 pfd->events |= mask;
143         }
144         if (pfd->events)
145                 num_waiting++;
146
147         if (state == NEXT)
148                 num_next++;
149         else if (state == FINISHED)
150                 num_finished++;
151
152         conn->state = state;
153 }
154
155 static void accept_conn(struct io_listener *l)
156 {
157         struct io_conn *c;
158         int fd = accept(l->fd.fd, NULL, NULL);
159
160         /* FIXME: What to do here? */
161         if (fd < 0)
162                 return;
163         c = io_new_conn(fd, l->fd.next, l->fd.finish, l->fd.next_arg);
164         if (!c) {
165                 close(fd);
166                 return;
167         }
168 }
169
170 /* It's OK to miss some, as long as we make progress. */
171 static void finish_and_next(bool finished_only)
172 {
173         unsigned int i;
174
175         for (i = 0; !io_loop_return && i < num_fds; i++) {
176                 struct io_conn *c, *duplex;
177
178                 if (!num_finished) {
179                         if (finished_only || num_next == 0)
180                                 break;
181                 }
182                 if (fds[i]->listener)
183                         continue;
184                 c = (void *)fds[i];
185                 for (duplex = c->duplex; c; c = duplex, duplex = NULL) {
186                         if (c->state == FINISHED) {
187                                 del_conn(c);
188                                 free(c);
189                                 i--;
190                         } else if (!finished_only && c->state == NEXT) {
191                                 backend_set_state(c,
192                                                   c->fd.next(c,
193                                                              c->fd.next_arg));
194                                 num_next--;
195                         }
196                 }
197         }
198 }
199
200 static void ready(struct io_conn *c)
201 {
202         backend_set_state(c, do_ready(c));
203 }
204
205 void backend_add_timeout(struct io_conn *conn, struct timespec duration)
206 {
207         if (!timeouts.base)
208                 timers_init(&timeouts, time_now());
209         timer_add(&timeouts, &conn->timeout->timer,
210                   time_add(time_now(), duration));
211         conn->timeout->conn = conn;
212 }
213
214 void backend_del_timeout(struct io_conn *conn)
215 {
216         assert(conn->timeout->conn == conn);
217         timer_del(&timeouts, &conn->timeout->timer);
218         conn->timeout->conn = NULL;
219 }
220
221 /* This is the main loop. */
222 void *io_loop(void)
223 {
224         void *ret;
225
226         while (!io_loop_return) {
227                 int i, r, timeout = INT_MAX;
228                 struct timespec now;
229
230                 if (timeouts.base) {
231                         struct timespec first;
232                         struct list_head expired;
233                         struct io_timeout *t;
234
235                         now = time_now();
236
237                         /* Call functions for expired timers. */
238                         timers_expire(&timeouts, now, &expired);
239                         while ((t = list_pop(&expired, struct io_timeout, timer.list))) {
240                                 struct io_conn *conn = t->conn;
241                                 /* Clear, in case timer re-adds */
242                                 t->conn = NULL;
243                                 backend_set_state(conn, t->next(conn, t->next_arg));
244                         }
245
246                         /* Now figure out how long to wait for the next one. */
247                         if (timer_earliest(&timeouts, &first)) {
248                                 uint64_t f = time_to_msec(time_sub(first, now));
249                                 if (f < INT_MAX)
250                                         timeout = f;
251                         }
252                 }
253
254                 if (num_finished || num_next) {
255                         finish_and_next(false);
256                         /* Could have started/finished more. */
257                         continue;
258                 }
259
260                 if (num_fds == 0)
261                         break;
262
263                 /* You can't tell them all to go to sleep! */
264                 assert(num_waiting);
265
266                 r = poll(pollfds, num_fds, timeout);
267                 if (r < 0)
268                         break;
269
270                 for (i = 0; i < num_fds && !io_loop_return; i++) {
271                         struct io_conn *c = (void *)fds[i];
272                         int events = pollfds[i].revents;
273
274                         if (r == 0)
275                                 break;
276
277                         if (fds[i]->listener) {
278                                 if (events & POLLIN) {
279                                         accept_conn((void *)c);
280                                         r--;
281                                 }
282                         } else if (events & (POLLIN|POLLOUT)) {
283                                 r--;
284                                 if (c->duplex) {
285                                         int mask = pollmask(c->duplex->state);
286                                         if (events & mask) {
287                                                 ready(c->duplex);
288                                                 events &= ~mask;
289                                                 if (!(events&(POLLIN|POLLOUT)))
290                                                         continue;
291                                         }
292                                 }
293                                 ready(c);
294                         } else if (events & POLLHUP) {
295                                 r--;
296                                 backend_set_state(c, io_close(c, NULL));
297                                 if (c->duplex)
298                                         backend_set_state(c->duplex,
299                                                           io_close(c->duplex,
300                                                                    NULL));
301                         }
302                 }
303         }
304
305         while (num_finished)
306                 finish_and_next(true);
307
308         ret = io_loop_return;
309         io_loop_return = NULL;
310         return ret;
311 }