libustcomm/multipoll.c

   1 /*
   2  * multipoll.c
   3  *
   4  * Copyright (C) 2010 - Pierre-Marc Fournier (pierre-marc dot fournier at polymtl dot ca)
   5  *
   6  * This library is free software; you can redistribute it and/or
   7  * modify it under the terms of the GNU Lesser General Public
   8  * License as published by the Free Software Foundation; either
   9  * version 2.1 of the License, or (at your option) any later version.
  10  *
  11  * This library is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14  * Lesser General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU Lesser General Public
  17  * License along with this library; if not, write to the Free Software
  18  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301 USA
  19  */
  20
  21 /* Multipoll is a framework to poll on several file descriptors and to call
  22  * a specific callback depending on the fd that had activity.
  23  */
  24
  25 #include <poll.h>
  26 #include <stdlib.h>
  27 #include "multipoll.h"
  28 #include "usterr.h"
  29
  30 #define INITIAL_N_AVAIL 16
  31
  32 /* multipoll_init
  33  *
  34  * Initialize an mpentries struct, which is initially empty of any fd.
  35  */
  36
  37 int multipoll_init(struct mpentries *ent)
  38 {
  39         ent->n_used = 0;
  40         ent->n_avail = INITIAL_N_AVAIL;
  41
  42         ent->pollfds = (struct pollfd *) zmalloc(sizeof(struct pollfd) * INITIAL_N_AVAIL);
  43         ent->extras = (struct pollfd_extra *) zmalloc(sizeof(struct pollfd_extra) * INITIAL_N_AVAIL);
  44
  45         return 0;
  46 }
  47
  48 /* multipoll_destroy: free a struct mpentries
  49  */
  50
  51 int multipoll_destroy(struct mpentries *ent)
  52 {
  53         int i;
  54
  55         for(i=0; i<ent->n_used; i++) {
  56                 if(ent->extras[i].destroy_priv) {
  57                         ent->extras[i].destroy_priv(ent->extras[i].priv);
  58                 }
  59         }
  60
  61         free(ent->pollfds);
  62         free(ent->extras);
  63
  64         return 0;
  65 }
  66
  67 /* multipoll_add
  68  *
  69  * Add a file descriptor to be waited on in a struct mpentries.
  70  *
  71  * @ent: the struct mpentries to add an fd to
  72  * @fd: the fd to wait on
  73  * @events: a mask of the types of events to wait on, see the poll(2) man page
  74  * @func: the callback function to be called if there is activity on the fd
  75  * @priv: the private pointer to pass to func
  76  * @destroy_priv: a callback to destroy the priv pointer when the mpentries
  77                   is destroyed; may be NULL
  78  */
  79
  80 int multipoll_add(struct mpentries *ent, int fd, short events, int (*func)(void *priv, int fd, short events), void *priv, int (*destroy_priv)(void *))
  81 {
  82         int cur;
  83
  84         if(ent->n_used == ent->n_avail) {
  85                 ent->n_avail *= 2;
  86                 ent->pollfds = (struct pollfd *) realloc(ent->pollfds, sizeof(struct pollfd) * ent->n_avail);
  87                 ent->extras = (struct pollfd_extra *) realloc(ent->extras, sizeof(struct pollfd_extra) * ent->n_avail);
  88         }
  89
  90         cur = ent->n_used;
  91         ent->n_used++;
  92
  93         ent->pollfds[cur].fd = fd;
  94         ent->pollfds[cur].events = events;
  95         ent->extras[cur].func = func;
  96         ent->extras[cur].priv = priv;
  97         ent->extras[cur].destroy_priv = destroy_priv;
  98
  99         return 0;
 100 }
 101
 102 /* multipoll_poll: do the actual poll on a struct mpentries
 103  *
 104  * File descriptors should have been already added with multipoll_add().
 105  *
 106  * A struct mpentries may be reused for multiple multipoll_poll calls.
 107  *
 108  * @ent: the struct mpentries to poll on.
 109  * @timeout: the timeout after which to return if there was no activity.
 110  */
 111
 112 int multipoll_poll(struct mpentries *ent, int timeout)
 113 {
 114         int result;
 115         int i;
 116
 117         result = poll(ent->pollfds, ent->n_used, timeout);
 118         if(result == -1) {
 119                 PERROR("poll");
 120                 return -1;
 121         }
 122
 123         for(i=0; i<ent->n_used; i++) {
 124                 if(ent->pollfds[i].revents) {
 125                         ent->extras[i].func(ent->extras[i].priv, ent->pollfds[i].fd, ent->pollfds[i].revents);
 126                 }
 127         }
 128
 129         return 0;
 130 }