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_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 }