73ef4ff3
 Hu Chunming
提交三方库
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/* Copyright 1998 by the Massachusetts Institute of Technology.
*
* Permission to use, copy, modify, and distribute this
* software and its documentation for any purpose and without
* fee is hereby granted, provided that the above copyright
* notice appear in all copies and that both that copyright
* notice and this permission notice appear in supporting
* documentation, and that the name of M.I.T. not be used in
* advertising or publicity pertaining to distribution of the
* software without specific, written prior permission.
* M.I.T. makes no representations about the suitability of
* this software for any purpose. It is provided "as is"
* without express or implied warranty.
*/
#include "ares_setup.h"
#ifdef HAVE_LIMITS_H
#include <limits.h>
#endif
#include "ares.h"
#include "ares_private.h"
/* return time offset between now and (future) check, in milliseconds */
static long timeoffset(struct timeval *now, struct timeval *check)
{
return (check->tv_sec - now->tv_sec)*1000 +
(check->tv_usec - now->tv_usec)/1000;
}
/* WARNING: Beware that this is linear in the number of outstanding
* requests! You are probably far better off just calling ares_process()
* once per second, rather than calling ares_timeout() to figure out
* when to next call ares_process().
*/
struct timeval *ares_timeout(ares_channel channel, struct timeval *maxtv,
struct timeval *tvbuf)
{
struct query *query;
struct list_node* list_head;
struct list_node* list_node;
struct timeval now;
struct timeval nextstop;
long offset, min_offset;
/* No queries, no timeout (and no fetch of the current time). */
if (ares__is_list_empty(&(channel->all_queries)))
return maxtv;
/* Find the minimum timeout for the current set of queries. */
now = ares__tvnow();
min_offset = -1;
list_head = &(channel->all_queries);
for (list_node = list_head->next; list_node != list_head;
list_node = list_node->next)
{
query = list_node->data;
if (query->timeout.tv_sec == 0)
continue;
offset = timeoffset(&now, &query->timeout);
if (offset < 0)
offset = 0;
if (min_offset == -1 || offset < min_offset)
min_offset = offset;
}
/* If we found a minimum timeout and it's sooner than the one specified in
* maxtv (if any), return it. Otherwise go with maxtv.
*/
if (min_offset != -1)
{
int ioffset = (min_offset > (long)INT_MAX) ? INT_MAX : (int)min_offset;
nextstop.tv_sec = ioffset/1000;
nextstop.tv_usec = (ioffset%1000)*1000;
if (!maxtv || ares__timedout(maxtv, &nextstop))
{
*tvbuf = nextstop;
return tvbuf;
}
}
return maxtv;
}
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