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