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simplify the ast_channel walking routines. 

(the previous version was mine, but this way it is definitely
more readable).



git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@20543 65c4cc65-6c06-0410-ace0-fbb531ad65f3
This commit is contained in:
Luigi Rizzo 2006-04-16 16:58:56 +00:00
parent ebc152c0da
commit 8f80cbea14
1 changed files with 25 additions and 37 deletions
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62
channel.c
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@ -793,60 +793,48 @@ static struct ast_channel *channel_find_locked(const struct ast_channel *prev,
const char *context, const char *exten)
{
const char *msg = prev ? "deadlock" : "initial deadlock";
int retries, done;
int retries;
struct ast_channel *c;
for (retries = 0; retries < 10; retries++) {
int done;
AST_LIST_LOCK(&channels);
AST_LIST_TRAVERSE(&channels, c, chan_list) {
if (!prev) {
/* want head of list */
if (!name && !exten)
break;
if (name) {
/* want match by full name */
if (!namelen) {
if (!strcasecmp(c->name, name))
break;
else
continue;
}
/* want match by name prefix */
if (!strncasecmp(c->name, name, namelen))
break;
} else if (exten) {
/* want match by context and exten */
if (context && (strcasecmp(c->context, context) &&
strcasecmp(c->macrocontext, context)))
continue;
/* match by exten */
if (strcasecmp(c->exten, exten) &&
strcasecmp(c->macroexten, exten))
continue;
else
break;
}
} else if (c == prev) { /* found, return c->next */
if (prev) { /* look for next item */
if (c != prev) /* not this one */
continue;
/* found, prepare to return c->next */
c = AST_LIST_NEXT(c, chan_list);
break;
} else if (name) { /* want match by name */
if ( (!namelen && strcasecmp(c->name, name)) ||
(namelen && strncasecmp(c->name, name, namelen)) )
continue; /* name match failed */
} else if (exten) {
if (context && strcasecmp(c->context, context) &&
strcasecmp(c->macrocontext, context))
continue; /* context match failed */
if (strcasecmp(c->exten, exten) &&
strcasecmp(c->macroexten, exten))
continue; /* exten match failed */
}
/* if we get here, c points to the desired record */
break;
}
/* exit if chan not found or mutex acquired successfully */
done = (c == NULL) || (ast_mutex_trylock(&c->lock) == 0);
/* this is slightly unsafe, as we _should_ hold the lock to access c->name */
if (!done && c)
ast_log(LOG_DEBUG, "Avoiding %s for '%s'\n", msg, c->name);
done = c == NULL || ast_mutex_trylock(&c->lock) == 0;
if (!done)
ast_log(LOG_DEBUG, "Avoiding %s for channel '%p'\n", msg, c);
AST_LIST_UNLOCK(&channels);
if (done)
return c;
usleep(1);
usleep(1); /* give other threads a chance before retrying */
}
/*
* c is surely not null, but we don't have the lock so cannot
* access c->name
*/
ast_log(LOG_WARNING, "Avoided %s for '%p', %d retries!\n",
msg, c, retries);
ast_log(LOG_WARNING, "Failure, could not lock '%p' after %d retries!\n",
c, retries);
return NULL;
}