X-Git-Url: http://git.meshlink.io/?a=blobdiff_plain;f=avahi-core%2Fquery-sched.c;h=ff833f97b95c2fe3243c5961fecbd79f148a8e8b;hb=9c0f9c65093cfa53d45f9b68782321eb8063a032;hp=00968385b37dda144b93dc07ff14437345076243;hpb=854f901f491ccda79aee11edc3d59109cb229d28;p=catta diff --git a/avahi-core/query-sched.c b/avahi-core/query-sched.c index 0096838..ff833f9 100644 --- a/avahi-core/query-sched.c +++ b/avahi-core/query-sched.c @@ -1,18 +1,16 @@ -/* $Id$ */ - /*** 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 @@ -23,6 +21,8 @@ #include #endif +#include + #include #include @@ -36,14 +36,25 @@ typedef struct AvahiQueryJob AvahiQueryJob; 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); }; @@ -58,6 +69,8 @@ struct AvahiQueryScheduler { 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); @@ -65,7 +78,7 @@ struct AvahiQueryScheduler { static AvahiQueryJob* job_new(AvahiQueryScheduler *s, AvahiKey *key, int done) { AvahiQueryJob *qj; - + assert(s); assert(key); @@ -73,12 +86,14 @@ static AvahiQueryJob* job_new(AvahiQueryScheduler *s, AvahiKey *key, int done) { 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); @@ -141,10 +156,11 @@ AvahiQueryScheduler *avahi_query_scheduler_new(AvahiInterface *i) { 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); @@ -162,7 +178,7 @@ void avahi_query_scheduler_free(AvahiQueryScheduler *s) { void avahi_query_scheduler_clear(AvahiQueryScheduler *s) { assert(s); - + while (s->jobs) job_free(s, s->jobs); while (s->history) @@ -172,7 +188,7 @@ void avahi_query_scheduler_clear(AvahiQueryScheduler *s) { 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); @@ -180,12 +196,12 @@ static void* known_answer_walk_callback(AvahiCache *c, AvahiKey *pattern, AvahiC 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); @@ -203,7 +219,7 @@ static int packet_add_query_job(AvahiQueryScheduler *s, AvahiDnsPacket *p, Avahi /* 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; @@ -216,7 +232,7 @@ static void append_known_answers_and_send(AvahiQueryScheduler *s, AvahiDnsPacket assert(p); n = 0; - + while ((ka = s->known_answers)) { int too_large = 0; @@ -248,7 +264,7 @@ static void append_known_answers_and_send(AvahiQueryScheduler *s, AvahiDnsPacket 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); @@ -271,10 +287,10 @@ static void elapse_callback(AVAHI_GCC_UNUSED AvahiTimeEvent *e, void* data) { } 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; @@ -302,7 +318,7 @@ static AvahiQueryJob* find_scheduled_job(AvahiQueryScheduler *s, AvahiKey *key) for (qj = s->jobs; qj; qj = qj->jobs_next) { assert(!qj->done); - + if (avahi_key_equal(qj->key, key)) return qj; } @@ -312,7 +328,7 @@ static AvahiQueryJob* find_scheduled_job(AvahiQueryScheduler *s, AvahiKey *key) static AvahiQueryJob* find_history_job(AvahiQueryScheduler *s, AvahiKey *key) { AvahiQueryJob *qj; - + assert(s); assert(key); @@ -327,7 +343,7 @@ static AvahiQueryJob* find_history_job(AvahiQueryScheduler *s, AvahiKey *key) { job_free(s, qj); return NULL; } - + return qj; } } @@ -335,25 +351,21 @@ static AvahiQueryJob* find_history_job(AvahiQueryScheduler *s, AvahiKey *key) { 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 */ @@ -361,40 +373,78 @@ int avahi_query_scheduler_post(AvahiQueryScheduler *s, AvahiKey *key, int immedi 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; +}