-/* $Id$ */
-
/***
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>
typedef struct AvahiKnownAnswer AvahiKnownAnswer;
struct AvahiQueryJob {
+ unsigned id;
+ int n_posted;
+
AvahiQueryScheduler *scheduler;
AvahiTimeEvent *time_event;
-
+
int done;
struct timeval delivery;
AvahiKey *key;
+ /* Jobs are stored in a simple linked list. It might turn out in
+ * the future that this list grows too long and we must switch to
+ * some other kind of data structure. This needs further
+ * investigation. I expect the list to be very short (< 20
+ * entries) most of the time, but this might be a wrong
+ * assumption, especially on setups where traffic reflection is
+ * involved. */
+
AVAHI_LLIST_FIELDS(AvahiQueryJob, jobs);
};
AvahiInterface *interface;
AvahiTimeEventQueue *time_event_queue;
+ unsigned next_id;
+
AVAHI_LLIST_HEAD(AvahiQueryJob, jobs);
AVAHI_LLIST_HEAD(AvahiQueryJob, history);
AVAHI_LLIST_HEAD(AvahiKnownAnswer, known_answers);
static AvahiQueryJob* job_new(AvahiQueryScheduler *s, AvahiKey *key, int done) {
AvahiQueryJob *qj;
-
+
assert(s);
assert(key);
avahi_log_error(__FILE__": Out of memory");
return NULL;
}
-
+
qj->scheduler = s;
qj->key = avahi_key_ref(key);
qj->time_event = NULL;
-
- if ((qj->done = done))
+ qj->n_posted = 1;
+ qj->id = s->next_id++;
+
+ if ((qj->done = done))
AVAHI_LLIST_PREPEND(AvahiQueryJob, jobs, s->history, qj);
else
AVAHI_LLIST_PREPEND(AvahiQueryJob, jobs, s->jobs, qj);
avahi_log_error(__FILE__": Out of memory");
return NULL; /* OOM */
}
-
+
s->interface = i;
s->time_event_queue = i->monitor->server->time_event_queue;
-
+ s->next_id = 0;
+
AVAHI_LLIST_HEAD_INIT(AvahiQueryJob, s->jobs);
AVAHI_LLIST_HEAD_INIT(AvahiQueryJob, s->history);
AVAHI_LLIST_HEAD_INIT(AvahiKnownAnswer, s->known_answers);
void avahi_query_scheduler_clear(AvahiQueryScheduler *s) {
assert(s);
-
+
while (s->jobs)
job_free(s, s->jobs);
while (s->history)
static void* known_answer_walk_callback(AvahiCache *c, AvahiKey *pattern, AvahiCacheEntry *e, void* userdata) {
AvahiQueryScheduler *s = userdata;
AvahiKnownAnswer *ka;
-
+
assert(c);
assert(pattern);
assert(e);
if (avahi_cache_entry_half_ttl(c, e))
return NULL;
-
+
if (!(ka = avahi_new0(AvahiKnownAnswer, 1))) {
avahi_log_error(__FILE__": Out of memory");
return NULL;
}
-
+
ka->scheduler = s;
ka->record = avahi_record_ref(e->record);
/* Add all matching known answers to the list */
avahi_cache_walk(s->interface->cache, qj->key, known_answer_walk_callback, s);
-
+
job_mark_done(s, qj);
return 1;
assert(p);
n = 0;
-
+
while ((ka = s->known_answers)) {
int too_large = 0;
if (!too_large)
n++;
}
-
+
avahi_dns_packet_set_field(p, AVAHI_DNS_FIELD_ANCOUNT, n);
avahi_interface_send_packet(s->interface, p);
avahi_dns_packet_free(p);
}
assert(!s->known_answers);
-
+
if (!(p = avahi_dns_packet_new_query(s->interface->hardware->mtu)))
return; /* OOM */
-
+
b = packet_add_query_job(s, p, qj);
assert(b); /* An query must always fit in */
n = 1;
for (qj = s->jobs; qj; qj = qj->jobs_next) {
assert(!qj->done);
-
+
if (avahi_key_equal(qj->key, key))
return qj;
}
static AvahiQueryJob* find_history_job(AvahiQueryScheduler *s, AvahiKey *key) {
AvahiQueryJob *qj;
-
+
assert(s);
assert(key);
job_free(s, qj);
return NULL;
}
-
+
return qj;
}
}
return NULL;
}
-int avahi_query_scheduler_post(AvahiQueryScheduler *s, AvahiKey *key, int immediately) {
+int avahi_query_scheduler_post(AvahiQueryScheduler *s, AvahiKey *key, int immediately, unsigned *ret_id) {
struct timeval tv;
AvahiQueryJob *qj;
-
+
assert(s);
assert(key);
- if ((qj = find_history_job(s, key))) {
-/* avahi_log_debug("Query suppressed by local duplicate suppression (history)"); */
+ if ((qj = find_history_job(s, key)))
return 0;
- }
-
+
avahi_elapse_time(&tv, immediately ? 0 : AVAHI_QUERY_DEFER_MSEC, 0);
if ((qj = find_scheduled_job(s, key))) {
/* Duplicate questions suppression */
-/* avahi_log_debug("Query suppressed by local duplicate suppression (scheduled)"); */
-
if (avahi_timeval_compare(&tv, &qj->delivery) < 0) {
/* If the new entry should be scheduled earlier,
* update the old entry */
avahi_time_event_update(qj->time_event, &qj->delivery);
}
- return 1;
+ qj->n_posted++;
+
} else {
-/* avahi_log_debug("Accepted new query job."); */
if (!(qj = job_new(s, key, 0)))
return 0; /* OOM */
-
+
qj->delivery = tv;
qj->time_event = avahi_time_event_new(s->time_event_queue, &qj->delivery, elapse_callback, qj);
-
- return 1;
}
+
+ if (ret_id)
+ *ret_id = qj->id;
+
+ return 1;
}
void avahi_query_scheduler_incoming(AvahiQueryScheduler *s, AvahiKey *key) {
AvahiQueryJob *qj;
-
+
assert(s);
assert(key);
/* This function is called whenever an incoming query was
- * receieved. We drop scheduled queries that match. The keyword is
+ * received. We drop scheduled queries that match. The keyword is
* "DUPLICATE QUESTION SUPPRESION". */
if ((qj = find_scheduled_job(s, key))) {
-/* avahi_log_debug("Query suppressed by distributed duplicate suppression"); */
job_mark_done(s, qj);
return;
}
-
- if (!(qj = job_new(s, key, 1)))
- return; /* OOM */
-
+
+ /* Look if there's a history job for this key. If there is, just
+ * update the elapse time */
+ if (!(qj = find_history_job(s, key)))
+ if (!(qj = job_new(s, key, 1)))
+ return; /* OOM */
+
gettimeofday(&qj->delivery, NULL);
job_set_elapse_time(s, qj, AVAHI_QUERY_HISTORY_MSEC, 0);
}
+int avahi_query_scheduler_withdraw_by_id(AvahiQueryScheduler *s, unsigned id) {
+ AvahiQueryJob *qj;
+
+ assert(s);
+
+ /* Very short lived queries can withdraw an already scheduled item
+ * from the queue using this function, simply by passing the id
+ * returned by avahi_query_scheduler_post(). */
+
+ for (qj = s->jobs; qj; qj = qj->jobs_next) {
+ assert(!qj->done);
+
+ if (qj->id == id) {
+ /* Entry found */
+
+ assert(qj->n_posted >= 1);
+
+ if (--qj->n_posted <= 0) {
+
+ /* We withdraw this job only if the calling object was
+ * the only remaining poster. (Usually this is the
+ * case since there should exist only one querier per
+ * key, but there are exceptions, notably reflected
+ * traffic.) */
+
+ job_free(s, qj);
+ return 1;
+ }
+ }
+ }
+
+ return 0;
+}
projects / catta / blobdiff