ceph/src/c-ares/ares_timeout.c

   1
   2 /* Copyright 1998 by the Massachusetts Institute of Technology.
   3  *
   4  * Permission to use, copy, modify, and distribute this
   5  * software and its documentation for any purpose and without
   6  * fee is hereby granted, provided that the above copyright
   7  * notice appear in all copies and that both that copyright
   8  * notice and this permission notice appear in supporting
   9  * documentation, and that the name of M.I.T. not be used in
  10  * advertising or publicity pertaining to distribution of the
  11  * software without specific, written prior permission.
  12  * M.I.T. makes no representations about the suitability of
  13  * this software for any purpose.  It is provided "as is"
  14  * without express or implied warranty.
  15  */
  16
  17 #include "ares_setup.h"
  18
  19 #ifdef HAVE_LIMITS_H
  20 #include <limits.h>
  21 #endif
  22
  23 #include "ares.h"
  24 #include "ares_private.h"
  25
  26 /* return time offset between now and (future) check, in milliseconds */
  27 static long timeoffset(struct timeval *now, struct timeval *check)
  28 {
  29   return (check->tv_sec - now->tv_sec)*1000 +
  30          (check->tv_usec - now->tv_usec)/1000;
  31 }
  32
  33 /* WARNING: Beware that this is linear in the number of outstanding
  34  * requests! You are probably far better off just calling ares_process()
  35  * once per second, rather than calling ares_timeout() to figure out
  36  * when to next call ares_process().
  37  */
  38 struct timeval *ares_timeout(ares_channel channel, struct timeval *maxtv,
  39                              struct timeval *tvbuf)
  40 {
  41   struct query *query;
  42   struct list_node* list_head;
  43   struct list_node* list_node;
  44   struct timeval now;
  45   struct timeval nextstop;
  46   long offset, min_offset;
  47
  48   /* No queries, no timeout (and no fetch of the current time). */
  49   if (ares__is_list_empty(&(channel->all_queries)))
  50     return maxtv;
  51
  52   /* Find the minimum timeout for the current set of queries. */
  53   now = ares__tvnow();
  54   min_offset = -1;
  55
  56   list_head = &(channel->all_queries);
  57   for (list_node = list_head->next; list_node != list_head;
  58        list_node = list_node->next)
  59     {
  60       query = list_node->data;
  61       if (query->timeout.tv_sec == 0)
  62         continue;
  63       offset = timeoffset(&now, &query->timeout);
  64       if (offset < 0)
  65         offset = 0;
  66       if (min_offset == -1 || offset < min_offset)
  67         min_offset = offset;
  68     }
  69
  70   /* If we found a minimum timeout and it's sooner than the one specified in
  71    * maxtv (if any), return it.  Otherwise go with maxtv.
  72    */
  73   if (min_offset != -1)
  74     {
  75       int ioffset = (min_offset > (long)INT_MAX) ? INT_MAX : (int)min_offset;
  76
  77       nextstop.tv_sec = ioffset/1000;
  78       nextstop.tv_usec = (ioffset%1000)*1000;
  79
  80       if (!maxtv || ares__timedout(maxtv, &nextstop))
  81         {
  82           *tvbuf = nextstop;
  83           return tvbuf;
  84         }
  85     }
  86
  87   return maxtv;
  88 }