89 lines
2.7 KiB
C
89 lines
2.7 KiB
C
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/* Copyright 1998 by the Massachusetts Institute of Technology.
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*
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* Permission to use, copy, modify, and distribute this
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* software and its documentation for any purpose and without
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* fee is hereby granted, provided that the above copyright
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* notice appear in all copies and that both that copyright
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* notice and this permission notice appear in supporting
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* documentation, and that the name of M.I.T. not be used in
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* advertising or publicity pertaining to distribution of the
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* software without specific, written prior permission.
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* M.I.T. makes no representations about the suitability of
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* this software for any purpose. It is provided "as is"
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* without express or implied warranty.
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*/
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#include "ares_setup.h"
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#ifdef HAVE_LIMITS_H
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#include <limits.h>
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#endif
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#include "ares.h"
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#include "ares_private.h"
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/* return time offset between now and (future) check, in milliseconds */
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static long timeoffset(struct timeval *now, struct timeval *check)
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{
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return (check->tv_sec - now->tv_sec)*1000 +
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(check->tv_usec - now->tv_usec)/1000;
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}
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/* WARNING: Beware that this is linear in the number of outstanding
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* requests! You are probably far better off just calling ares_process()
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* once per second, rather than calling ares_timeout() to figure out
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* when to next call ares_process().
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*/
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struct timeval *ares_timeout(ares_channel channel, struct timeval *maxtv,
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struct timeval *tvbuf)
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{
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struct query *query;
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struct list_node* list_head;
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struct list_node* list_node;
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struct timeval now;
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struct timeval nextstop;
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long offset, min_offset;
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/* No queries, no timeout (and no fetch of the current time). */
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if (ares__is_list_empty(&(channel->all_queries)))
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return maxtv;
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/* Find the minimum timeout for the current set of queries. */
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now = ares__tvnow();
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min_offset = -1;
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list_head = &(channel->all_queries);
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for (list_node = list_head->next; list_node != list_head;
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list_node = list_node->next)
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{
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query = list_node->data;
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if (query->timeout.tv_sec == 0)
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continue;
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offset = timeoffset(&now, &query->timeout);
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if (offset < 0)
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offset = 0;
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if (min_offset == -1 || offset < min_offset)
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min_offset = offset;
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}
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/* If we found a minimum timeout and it's sooner than the one specified in
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* maxtv (if any), return it. Otherwise go with maxtv.
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*/
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if (min_offset != -1)
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{
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int ioffset = (min_offset > (long)INT_MAX) ? INT_MAX : (int)min_offset;
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nextstop.tv_sec = ioffset/1000;
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nextstop.tv_usec = (ioffset%1000)*1000;
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if (!maxtv || ares__timedout(maxtv, &nextstop))
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{
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*tvbuf = nextstop;
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return tvbuf;
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}
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}
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return maxtv;
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}
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