git.ozlabs.org Git - ccan/blob - 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->plan.state == IO_FINISHED)
 105                 num_finished--;
 106         else if (conn->plan.state == IO_NEXT)
 107                 num_next--;
 108 }
 109
 110 void del_listener(struct io_listener *l)
 111 {
 112         del_fd(&l->fd);
 113 }
 114
 115 static void backend_set_state(struct io_conn *conn, struct io_plan plan)
 116 {
 117         struct pollfd *pfd = &pollfds[conn->fd.backend_info];
 118
 119         if (pfd->events)
 120                 num_waiting--;
 121
 122         pfd->events = plan.pollflag;
 123         if (conn->duplex) {
 124                 int mask = conn->duplex->plan.pollflag;
 125                 /* You can't *both* read/write. */
 126                 assert(!mask || pfd->events != mask);
 127                 pfd->events |= mask;
 128         }
 129         if (pfd->events)
 130                 num_waiting++;
 131
 132         if (plan.state == IO_NEXT)
 133                 num_next++;
 134         else if (plan.state == IO_FINISHED)
 135                 num_finished++;
 136
 137         conn->plan = plan;
 138 }
 139
 140 void backend_wakeup(struct io_conn *conn)
 141 {
 142         num_next++;
 143 }
 144
 145 static void accept_conn(struct io_listener *l)
 146 {
 147         int fd = accept(l->fd.fd, NULL, NULL);
 148
 149         /* FIXME: What to do here? */
 150         if (fd < 0)
 151                 return;
 152         l->init(fd, l->arg);
 153 }
 154
 155 /* It's OK to miss some, as long as we make progress. */
 156 static void finish_and_next(bool finished_only)
 157 {
 158         unsigned int i;
 159
 160         for (i = 0; !io_loop_return && i < num_fds; i++) {
 161                 struct io_conn *c, *duplex;
 162
 163                 if (!num_finished) {
 164                         if (finished_only || num_next == 0)
 165                                 break;
 166                 }
 167                 if (fds[i]->listener)
 168                         continue;
 169                 c = (void *)fds[i];
 170                 for (duplex = c->duplex; c; c = duplex, duplex = NULL) {
 171                         if (c->plan.state == IO_FINISHED) {
 172                                 del_conn(c);
 173                                 free(c);
 174                                 i--;
 175                         } else if (!finished_only && c->plan.state == IO_NEXT) {
 176                                 backend_set_state(c, c->plan.next(c, c->plan.next_arg));
 177                                 num_next--;
 178                         }
 179                 }
 180         }
 181 }
 182
 183 static void ready(struct io_conn *c)
 184 {
 185         backend_set_state(c, do_ready(c));
 186 }
 187
 188 void backend_add_timeout(struct io_conn *conn, struct timespec duration)
 189 {
 190         if (!timeouts.base)
 191                 timers_init(&timeouts, time_now());
 192         timer_add(&timeouts, &conn->timeout->timer,
 193                   time_add(time_now(), duration));
 194         conn->timeout->conn = conn;
 195 }
 196
 197 void backend_del_timeout(struct io_conn *conn)
 198 {
 199         assert(conn->timeout->conn == conn);
 200         timer_del(&timeouts, &conn->timeout->timer);
 201         conn->timeout->conn = NULL;
 202 }
 203
 204 /* This is the main loop. */
 205 void *io_loop(void)
 206 {
 207         void *ret;
 208
 209         while (!io_loop_return) {
 210                 int i, r, timeout = INT_MAX;
 211                 struct timespec now;
 212
 213                 if (timeouts.base) {
 214                         struct timespec first;
 215                         struct list_head expired;
 216                         struct io_timeout *t;
 217
 218                         now = time_now();
 219
 220                         /* Call functions for expired timers. */
 221                         timers_expire(&timeouts, now, &expired);
 222                         while ((t = list_pop(&expired, struct io_timeout, timer.list))) {
 223                                 struct io_conn *conn = t->conn;
 224                                 /* Clear, in case timer re-adds */
 225                                 t->conn = NULL;
 226                                 backend_set_state(conn, t->next(conn, t->next_arg));
 227                         }
 228
 229                         /* Now figure out how long to wait for the next one. */
 230                         if (timer_earliest(&timeouts, &first)) {
 231                                 uint64_t f = time_to_msec(time_sub(first, now));
 232                                 if (f < INT_MAX)
 233                                         timeout = f;
 234                         }
 235                 }
 236
 237                 if (num_finished || num_next) {
 238                         finish_and_next(false);
 239                         /* Could have started/finished more. */
 240                         continue;
 241                 }
 242
 243                 if (num_fds == 0)
 244                         break;
 245
 246                 /* You can't tell them all to go to sleep! */
 247                 assert(num_waiting);
 248
 249                 r = poll(pollfds, num_fds, timeout);
 250                 if (r < 0)
 251                         break;
 252
 253                 for (i = 0; i < num_fds && !io_loop_return; i++) {
 254                         struct io_conn *c = (void *)fds[i];
 255                         int events = pollfds[i].revents;
 256
 257                         if (r == 0)
 258                                 break;
 259
 260                         if (fds[i]->listener) {
 261                                 if (events & POLLIN) {
 262                                         accept_conn((void *)c);
 263                                         r--;
 264                                 }
 265                         } else if (events & (POLLIN|POLLOUT)) {
 266                                 r--;
 267                                 if (c->duplex) {
 268                                         int mask = c->duplex->plan.pollflag;
 269                                         if (events & mask) {
 270                                                 ready(c->duplex);
 271                                                 events &= ~mask;
 272                                                 if (!(events&(POLLIN|POLLOUT)))
 273                                                         continue;
 274                                         }
 275                                 }
 276                                 ready(c);
 277                         } else if (events & POLLHUP) {
 278                                 r--;
 279                                 backend_set_state(c, io_close(c, NULL));
 280                                 if (c->duplex)
 281                                         backend_set_state(c->duplex,
 282                                                           io_close(c->duplex,
 283                                                                    NULL));
 284                         }
 285                 }
 286         }
 287
 288         while (num_finished)
 289                 finish_and_next(true);
 290
 291         ret = io_loop_return;
 292         io_loop_return = NULL;
 293         return ret;
 294 }