src/ioset-select.c

   1 /* ioset select() backend for srvx
   2  * Copyright 2002-2006 srvx Development Team
   3  *
   4  * This file is part of srvx.
   5  *
   6  * srvx is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License as published by
   8  * the Free Software Foundation; either version 3 of the License, or
   9  * (at your option) any later version.
  10  *
  11  * This program 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
  14  * GNU General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU General Public License
  17  * along with srvx; if not, write to the Free Software Foundation,
  18  * Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA.
  19  */
  20
  21 #include "ioset-impl.h"
  22 #include "common.h"
  23 #include "log.h"
  24
  25 #include <stdlib.h>
  26 #include <string.h>
  27
  28 #ifdef HAVE_SYS_SELECT_H
  29 # include <sys/select.h>
  30 #endif
  31
  32 #ifdef HAVE_SYS_SOCKET_H
  33 # include <sys/socket.h>
  34 #endif
  35
  36 extern int clock_skew;
  37 static struct io_fd **fds;
  38 static unsigned int fds_size;
  39 static fd_set read_fds;
  40 static fd_set write_fds;
  41 static fd_set except_fds;
  42
  43 static int
  44 ioset_select_init(void)
  45 {
  46     return 1;
  47 }
  48
  49 static void
  50 ioset_select_add(struct io_fd *fd)
  51 {
  52     if ((unsigned)fd->fd >= fds_size) {
  53         unsigned int old_size = fds_size;
  54         fds_size = fd->fd + 8;
  55         fds = realloc(fds, fds_size*sizeof(*fds));
  56         memset(fds+old_size, 0, (fds_size-old_size)*sizeof(*fds));
  57     }
  58     fds[fd->fd] = fd;
  59 }
  60
  61 static void
  62 ioset_select_remove(struct io_fd *fd, int closed)
  63 {
  64     FD_CLR(fd->fd, &read_fds);
  65     FD_CLR(fd->fd, &write_fds);
  66     FD_CLR(fd->fd, &except_fds);
  67     fds[fd->fd] = NULL;
  68     (void)closed;
  69 }
  70
  71 static void
  72 ioset_select_update(struct io_fd *fd)
  73 {
  74     (void)fd;
  75 }
  76
  77 static void
  78 ioset_select_cleanup(void)
  79 {
  80     free(fds);
  81 }
  82
  83 #if DEBUG_FDSETS
  84 static void
  85 debug_fdsets(const char *msg, int nfds, fd_set *read_fds, fd_set *write_fds, fd_set *except_fds, struct timeval *select_timeout) {
  86     static const char *flag_text[8] = { "---", "r", "w", "rw", "e", "er", "ew", "erw" };
  87     char buf[MAXLEN];
  88     int pos, ii, flags;
  89     struct timeval now;
  90
  91     for (pos=ii=0; ii<nfds; ++ii) {
  92         flags  = FD_ISSET(ii, read_fds) ? 1 : 0;
  93         flags |= FD_ISSET(ii, write_fds) ? 2 : 0;
  94         flags |= FD_ISSET(ii, except_fds) ? 4 : 0;
  95         if (flags)
  96             pos += sprintf(buf+pos, " %d%s", ii, flag_text[flags]);
  97     }
  98     gettimeofday(&now, NULL);
  99     if (select_timeout) {
 100         log_module(MAIN_LOG, LOG_DEBUG, "%s, at %lu.%06lu:%s (timeout %lu.%06lu)", msg, (unsigned long)now.tv_sec, (unsigned long)now.tv_usec, buf, (unsigned long)select_timeout->tv_sec, (unsigned long)select_timeout->tv_usec);
 101     } else {
 102         log_module(MAIN_LOG, LOG_DEBUG, "%s, at %lu.%06lu:%s (no timeout)", msg, (unsigned long)now.tv_sec, (unsigned long)now.tv_usec, buf);
 103     }
 104 }
 105 #else
 106 # define debug_fdsets(MSG, NFDS, READ_FDS, WRITE_FDS, EXCEPT_FDS, SELECT_TIMEOUT) (void)0
 107 #endif
 108
 109 static int
 110 ioset_select_loop(struct timeval *timeout)
 111 {
 112     struct io_fd *fd;
 113     unsigned int nn;
 114     int select_result;
 115     int max_fd;
 116
 117     /* Set up read_fds and write_fds fdsets. */
 118     FD_ZERO(&read_fds);
 119     FD_ZERO(&write_fds);
 120     FD_ZERO(&except_fds);
 121     max_fd = -1;
 122     for (nn=0; nn<fds_size; nn++) {
 123         if (!(fd = fds[nn]))
 124             continue;
 125         max_fd = nn;
 126         FD_SET(nn, &read_fds);
 127         FD_SET(nn, &except_fds);
 128         if (fd_wants_writes(fd))
 129             FD_SET(nn, &write_fds);
 130     }
 131
 132     /* Check for activity, update time. */
 133     debug_fdsets("Entering select", max_fd+1, &read_fds, &write_fds, &except_fds, timeout);
 134     select_result = select(max_fd + 1, &read_fds, &write_fds, NULL, timeout);
 135     debug_fdsets("After select", max_fd+1, &read_fds, &write_fds, &except_fds, timeout);
 136     now = time(NULL) + clock_skew;
 137     if (select_result < 0) {
 138         if (errno != EINTR) {
 139             log_module(MAIN_LOG, LOG_ERROR, "select() error %d: %s", errno, strerror(errno));
 140             close_socket();
 141         }
 142         return 1;
 143     }
 144
 145     /* Call back anybody that has connect or read activity and wants to know. */
 146     for (nn=0; nn<fds_size; nn++) {
 147         ioset_events(fds[nn], FD_ISSET(nn, &read_fds) | FD_ISSET(nn, &except_fds), FD_ISSET(nn, &write_fds));
 148     }
 149     return 0;
 150 }
 151
 152 struct io_engine io_engine_select = {
 153     .name = "select",
 154     .init = ioset_select_init,
 155     .add = ioset_select_add,
 156     .remove = ioset_select_remove,
 157     .update = ioset_select_update,
 158     .loop = ioset_select_loop,
 159     .cleanup = ioset_select_cleanup,
 160 };