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 void backend_plan_changed(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         backend_plan_changed(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 set_plan(struct io_conn *conn, struct io_plan plan)
 140 {
 141         conn->plan = plan;
 142         backend_plan_changed(conn);
 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_conns(void)
 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_closing)
 164                         break;
 165
 166                 if (fds[i]->listener)
 167                         continue;
 168                 c = (void *)fds[i];
 169                 for (duplex = c->duplex; c; c = duplex, duplex = NULL) {
 170                         if (!c->plan.next) {
 171                                 del_conn(c);
 172                                 free(c);
 173                                 i--;
 174                         }
 175                 }
 176         }
 177 }
 178
 179 void backend_add_timeout(struct io_conn *conn, struct timespec duration)
 180 {
 181         if (!timeouts.base)
 182                 timers_init(&timeouts, time_now());
 183         timer_add(&timeouts, &conn->timeout->timer,
 184                   time_add(time_now(), duration));
 185         conn->timeout->conn = conn;
 186 }
 187
 188 void backend_del_timeout(struct io_conn *conn)
 189 {
 190         assert(conn->timeout->conn == conn);
 191         timer_del(&timeouts, &conn->timeout->timer);
 192         conn->timeout->conn = NULL;
 193 }
 194
 195 /* This is the main loop. */
 196 void *io_loop(void)
 197 {
 198         void *ret;
 199
 200         while (!io_loop_return) {
 201                 int i, r, timeout = INT_MAX;
 202                 struct timespec now;
 203
 204                 if (timeouts.base) {
 205                         struct timespec first;
 206                         struct list_head expired;
 207                         struct io_timeout *t;
 208
 209                         now = time_now();
 210
 211                         /* Call functions for expired timers. */
 212                         timers_expire(&timeouts, now, &expired);
 213                         while ((t = list_pop(&expired, struct io_timeout, timer.list))) {
 214                                 struct io_conn *conn = t->conn;
 215                                 /* Clear, in case timer re-adds */
 216                                 t->conn = NULL;
 217                                 set_plan(conn, t->next(conn, t->next_arg));
 218                         }
 219
 220                         /* Now figure out how long to wait for the next one. */
 221                         if (timer_earliest(&timeouts, &first)) {
 222                                 uint64_t f = time_to_msec(time_sub(first, now));
 223                                 if (f < INT_MAX)
 224                                         timeout = f;
 225                         }
 226                 }
 227
 228                 if (num_closing) {
 229                         finish_conns();
 230                         /* Could have started/finished more. */
 231                         continue;
 232                 }
 233
 234                 if (num_fds == 0)
 235                         break;
 236
 237                 /* You can't tell them all to go to sleep! */
 238                 assert(num_waiting);
 239
 240                 r = poll(pollfds, num_fds, timeout);
 241                 if (r < 0)
 242                         break;
 243
 244                 for (i = 0; i < num_fds && !io_loop_return; i++) {
 245                         struct io_conn *c = (void *)fds[i];
 246                         int events = pollfds[i].revents;
 247
 248                         if (r == 0)
 249                                 break;
 250
 251                         if (fds[i]->listener) {
 252                                 if (events & POLLIN) {
 253                                         accept_conn((void *)c);
 254                                         r--;
 255                                 }
 256                         } else if (events & (POLLIN|POLLOUT)) {
 257                                 r--;
 258                                 if (c->duplex) {
 259                                         int mask = c->duplex->plan.pollflag;
 260                                         if (events & mask) {
 261                                                 io_ready(c->duplex);
 262                                                 events &= ~mask;
 263                                                 if (!(events&(POLLIN|POLLOUT)))
 264                                                         continue;
 265                                         }
 266                                 }
 267                                 io_ready(c);
 268                         } else if (events & POLLHUP) {
 269                                 r--;
 270                                 set_plan(c, io_close(c, NULL));
 271                                 if (c->duplex)
 272                                         set_plan(c->duplex,
 273                                                  io_close(c->duplex, NULL));
 274                         }
 275                 }
 276         }
 277
 278         while (num_closing)
 279                 finish_conns();
 280
 281         ret = io_loop_return;
 282         io_loop_return = NULL;
 283         return ret;
 284 }