-/* $Id$ */
-
/***
This file is part of avahi.
-
+
avahi is free software; you can redistribute it and/or modify it
under the terms of the GNU Lesser General Public License as
published by the Free Software Foundation; either version 2.1 of the
License, or (at your option) any later version.
-
+
avahi is distributed in the hope that it will be useful, but WITHOUT
ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General
Public License for more details.
-
+
You should have received a copy of the GNU Lesser General Public
License along with avahi; if not, write to the Free Software
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
#include <config.h>
#endif
+#include <stdlib.h>
+
#include <avahi-common/timeval.h>
#include <avahi-common/malloc.h>
#include <avahi-common/error.h>
AvahiTimeEvent *time_event;
struct timeval creation_time;
-
+
+ unsigned post_id;
+ int post_id_valid;
+
AVAHI_LLIST_FIELDS(AvahiQuerier, queriers);
};
avahi_key_unref(q->key);
avahi_time_event_free(q->time_event);
-
+
avahi_free(q);
}
-static void querier_elapse_callback(AvahiTimeEvent *e, void *userdata) {
+static void querier_elapse_callback(AVAHI_GCC_UNUSED AvahiTimeEvent *e, void *userdata) {
AvahiQuerier *q = userdata;
struct timeval tv;
-
+
assert(q);
- avahi_interface_post_query(q->interface, q->key, 0);
+ if (q->n_used <= 0) {
+
+ /* We are not referenced by anyone anymore, so let's free
+ * ourselves. We should not send out any further queries from
+ * this querier object anymore. */
+
+ avahi_querier_free(q);
+ return;
+ }
+
+ if (avahi_interface_post_query(q->interface, q->key, 0, &q->post_id)) {
+
+ /* The queue accepted our query. We store the query id here,
+ * that allows us to drop the query at a later point if the
+ * query is very short-lived. */
+
+ q->post_id_valid = 1;
+ }
q->sec_delay *= 2;
-
+
if (q->sec_delay >= 60*60) /* 1h */
q->sec_delay = 60*60;
-
+
avahi_elapse_time(&tv, q->sec_delay*1000, 0);
avahi_time_event_update(q->time_event, &tv);
}
void avahi_querier_add(AvahiInterface *i, AvahiKey *key, struct timeval *ret_ctime) {
AvahiQuerier *q;
struct timeval tv;
-
+
assert(i);
assert(key);
if ((q = avahi_hashmap_lookup(i->queriers_by_key, key))) {
+
/* Someone is already browsing for records of this RR key */
q->n_used++;
- /* Return the creation time */
+ /* Return the creation time. This is used for generating the
+ * ALL_FOR_NOW event one second after the querier was
+ * initially created. */
if (ret_ctime)
*ret_ctime = q->creation_time;
return;
/* No one is browsing for this RR key, so we add a new querier */
if (!(q = avahi_new(AvahiQuerier, 1)))
return; /* OOM */
-
+
q->key = avahi_key_ref(key);
q->interface = i;
q->n_used = 1;
q->sec_delay = 1;
+ q->post_id_valid = 0;
gettimeofday(&q->creation_time, NULL);
/* Do the initial query */
- avahi_interface_post_query(i, key, 0);
+ if (avahi_interface_post_query(i, key, 0, &q->post_id))
+ q->post_id_valid = 1;
/* Schedule next queries */
q->time_event = avahi_time_event_new(i->monitor->server->time_event_queue, avahi_elapse_time(&tv, q->sec_delay*1000, 0), querier_elapse_callback, q);
AVAHI_LLIST_PREPEND(AvahiQuerier, queriers, i->queriers, q);
avahi_hashmap_insert(i->queriers_by_key, q->key, q);
- /* Return the creation time */
+ /* Return the creation time. This is used for generating the
+ * ALL_FOR_NOW event one second after the querier was initially
+ * created. */
if (ret_ctime)
*ret_ctime = q->creation_time;
}
void avahi_querier_remove(AvahiInterface *i, AvahiKey *key) {
AvahiQuerier *q;
- if (!(q = avahi_hashmap_lookup(i->queriers_by_key, key))) {
- /* The was no querier for this RR key */
- avahi_log_warn(__FILE__": querier_remove() called but no querier to remove");
+ /* There was no querier for this RR key, or it wasn't referenced
+ * by anyone. */
+ if (!(q = avahi_hashmap_lookup(i->queriers_by_key, key)) || q->n_used <= 0)
return;
- }
- assert(q->n_used >= 1);
- if ((--q->n_used) <= 0)
- avahi_querier_free(q);
+ if ((--q->n_used) <= 0) {
+
+ /* Nobody references us anymore. */
+
+ if (q->post_id_valid && avahi_interface_withraw_query(i, q->post_id)) {
+
+ /* We succeeded in withdrawing our query from the queue,
+ * so let's drop dead. */
+
+ avahi_querier_free(q);
+ }
+
+ /* If we failed to withdraw our query from the queue, we stay
+ * alive, in case someone else might recycle our querier at a
+ * later point. We are freed at our next expiry, in case
+ * nobody recycled us. */
+ }
}
static void remove_querier_callback(AvahiInterfaceMonitor *m, AvahiInterface *i, void* userdata) {
void avahi_querier_remove_for_all(AvahiServer *s, AvahiIfIndex idx, AvahiProtocol protocol, AvahiKey *key) {
assert(s);
assert(key);
-
+
avahi_interface_monitor_walk(s->monitor, idx, protocol, remove_querier_callback, key);
}
static void add_querier_callback(AvahiInterfaceMonitor *m, AvahiInterface *i, void* userdata) {
struct cbdata *cbdata = userdata;
-
+
assert(m);
assert(i);
assert(cbdata);
void avahi_querier_add_for_all(AvahiServer *s, AvahiIfIndex idx, AvahiProtocol protocol, AvahiKey *key, struct timeval *ret_ctime) {
struct cbdata cbdata;
-
+
assert(s);
assert(key);
if (ret_ctime)
ret_ctime->tv_sec = ret_ctime->tv_usec = 0;
-
+
avahi_interface_monitor_walk(s->monitor, idx, protocol, add_querier_callback, &cbdata);
}
-int avahi_querier_exists(AvahiInterface *i, AvahiKey *key) {
+int avahi_querier_shall_refresh_cache(AvahiInterface *i, AvahiKey *key) {
+ AvahiQuerier *q;
+
assert(i);
assert(key);
- if (avahi_hashmap_lookup(i->queriers_by_key, key))
- return 1;
+ /* Called by the cache maintainer */
+
+ if (!(q = avahi_hashmap_lookup(i->queriers_by_key, key)))
+ /* This key is currently not subscribed at all, so no cache
+ * refresh is needed */
+ return 0;
+
+ if (q->n_used <= 0) {
+
+ /* If this is an entry nobody references right now, don't
+ * consider it "existing". */
+
+ /* Remove this querier since it is referenced by nobody
+ * and the cached data will soon be out of date */
+ avahi_querier_free(q);
- return 0;
+ /* Tell the cache that no refresh is needed */
+ return 0;
+
+ } else {
+ struct timeval tv;
+
+ /* We can defer our query a little, since the cache will now
+ * issue a refresh query anyway. */
+ avahi_elapse_time(&tv, q->sec_delay*1000, 0);
+ avahi_time_event_update(q->time_event, &tv);
+
+ /* Tell the cache that a refresh should be issued */
+ return 1;
+ }
}
void avahi_querier_free_all(AvahiInterface *i) {
assert(i);
- while (i->queriers)
+ while (i->queriers)
avahi_querier_free(i->queriers);
}
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