From 28d336020ca1f6dbb88d64cac3ffdd1a67ee3de7 Mon Sep 17 00:00:00 2001 From: Lennart Poettering Date: Tue, 17 May 2005 00:03:50 +0000 Subject: * split packet scheduler into three seperate parts * test against Aplle test suit, most tests pass now * suppress auxiliary records by known answers * handle very large records git-svn-id: file:///home/lennart/svn/public/avahi/trunk@74 941a03a8-eaeb-0310-b9a0-b1bbd8fe43fe --- avahi-core/query-sched.c | 379 +++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 379 insertions(+) create mode 100644 avahi-core/query-sched.c (limited to 'avahi-core/query-sched.c') diff --git a/avahi-core/query-sched.c b/avahi-core/query-sched.c new file mode 100644 index 0000000..32d0e91 --- /dev/null +++ b/avahi-core/query-sched.c @@ -0,0 +1,379 @@ +/* $Id$ */ + +/*** + 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 + USA. +***/ + +#ifdef HAVE_CONFIG_H +#include +#endif + +#include "query-sched.h" +#include "util.h" + +#define AVAHI_QUERY_HISTORY_MSEC 100 +#define AVAHI_QUERY_DEFER_MSEC 100 + +typedef struct AvahiQueryJob AvahiQueryJob; +typedef struct AvahiKnownAnswer AvahiKnownAnswer; + +struct AvahiQueryJob { + AvahiQueryScheduler *scheduler; + AvahiTimeEvent *time_event; + + gboolean done; + GTimeVal delivery; + + AvahiKey *key; + + AVAHI_LLIST_FIELDS(AvahiQueryJob, jobs); +}; + +struct AvahiKnownAnswer { + AvahiQueryScheduler *scheduler; + AvahiRecord *record; + + AVAHI_LLIST_FIELDS(AvahiKnownAnswer, known_answer); +}; + +struct AvahiQueryScheduler { + AvahiInterface *interface; + AvahiTimeEventQueue *time_event_queue; + + AVAHI_LLIST_HEAD(AvahiQueryJob, jobs); + AVAHI_LLIST_HEAD(AvahiQueryJob, history); + AVAHI_LLIST_HEAD(AvahiKnownAnswer, known_answers); +}; + +static AvahiQueryJob* job_new(AvahiQueryScheduler *s, AvahiKey *key, gboolean done) { + AvahiQueryJob *qj; + + g_assert(s); + g_assert(key); + + qj = g_new(AvahiQueryJob, 1); + qj->scheduler = s; + qj->key = avahi_key_ref(key); + qj->time_event = NULL; + + if ((qj->done = done)) + AVAHI_LLIST_PREPEND(AvahiQueryJob, jobs, s->history, qj); + else + AVAHI_LLIST_PREPEND(AvahiQueryJob, jobs, s->jobs, qj); + + return qj; +} + +static void job_free(AvahiQueryScheduler *s, AvahiQueryJob *qj) { + g_assert(s); + g_assert(qj); + + if (qj->time_event) + avahi_time_event_queue_remove(s->time_event_queue, qj->time_event); + + if (qj->done) + AVAHI_LLIST_REMOVE(AvahiQueryJob, jobs, s->history, qj); + else + AVAHI_LLIST_REMOVE(AvahiQueryJob, jobs, s->jobs, qj); + + avahi_key_unref(qj->key); + g_free(qj); +} + +static void elapse_callback(AvahiTimeEvent *e, gpointer data); + +static void job_set_elapse_time(AvahiQueryScheduler *s, AvahiQueryJob *qj, guint msec, guint jitter) { + GTimeVal tv; + + g_assert(s); + g_assert(qj); + + avahi_elapse_time(&tv, msec, jitter); + + if (qj->time_event) + avahi_time_event_queue_update(s->time_event_queue, qj->time_event, &tv); + else + qj->time_event = avahi_time_event_queue_add(s->time_event_queue, &tv, elapse_callback, qj); +} + +static void job_mark_done(AvahiQueryScheduler *s, AvahiQueryJob *qj) { + g_assert(s); + g_assert(qj); + + g_assert(!qj->done); + + AVAHI_LLIST_REMOVE(AvahiQueryJob, jobs, s->jobs, qj); + AVAHI_LLIST_PREPEND(AvahiQueryJob, jobs, s->history, qj); + + qj->done = TRUE; + + job_set_elapse_time(s, qj, AVAHI_QUERY_HISTORY_MSEC, 0); + g_get_current_time(&qj->delivery); +} + +AvahiQueryScheduler *avahi_query_scheduler_new(AvahiInterface *i) { + AvahiQueryScheduler *s; + g_assert(i); + + s = g_new(AvahiQueryScheduler, 1); + s->interface = i; + s->time_event_queue = i->monitor->server->time_event_queue; + + AVAHI_LLIST_HEAD_INIT(AvahiQueryJob, s->jobs); + AVAHI_LLIST_HEAD_INIT(AvahiQueryJob, s->history); + AVAHI_LLIST_HEAD_INIT(AvahiKnownAnswer, s->known_answers); + + return s; +} + +void avahi_query_scheduler_free(AvahiQueryScheduler *s) { + g_assert(s); + + g_assert(!s->known_answers); + avahi_query_scheduler_clear(s); + g_free(s); +} + +void avahi_query_scheduler_clear(AvahiQueryScheduler *s) { + g_assert(s); + + while (s->jobs) + job_free(s, s->jobs); + while (s->history) + job_free(s, s->history); +} + +static gpointer known_answer_walk_callback(AvahiCache *c, AvahiKey *pattern, AvahiCacheEntry *e, gpointer userdata) { + AvahiQueryScheduler *s = userdata; + AvahiKnownAnswer *ka; + + g_assert(c); + g_assert(pattern); + g_assert(e); + g_assert(s); + + if (avahi_cache_entry_half_ttl(c, e)) + return NULL; + + ka = g_new0(AvahiKnownAnswer, 1); + ka->scheduler = s; + ka->record = avahi_record_ref(e->record); + + AVAHI_LLIST_PREPEND(AvahiKnownAnswer, known_answer, s->known_answers, ka); + return NULL; +} + +static gboolean packet_add_query_job(AvahiQueryScheduler *s, AvahiDnsPacket *p, AvahiQueryJob *qj) { + g_assert(s); + g_assert(p); + g_assert(qj); + + if (!avahi_dns_packet_append_key(p, qj->key, FALSE)) + return FALSE; + + /* 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 TRUE; +} + +static void append_known_answers_and_send(AvahiQueryScheduler *s, AvahiDnsPacket *p) { + AvahiKnownAnswer *ka; + guint n; + g_assert(s); + g_assert(p); + + n = 0; + + while ((ka = s->known_answers)) { + gboolean too_large = FALSE; + + while (!avahi_dns_packet_append_record(p, ka->record, FALSE, 0)) { + + if (avahi_dns_packet_is_empty(p)) { + /* The record is too large to fit into one packet, so + there's no point in sending it. Better is letting + the owner of the record send it as a response. This + has the advantage of a cache refresh. */ + + too_large = TRUE; + break; + } + + avahi_dns_packet_set_field(p, AVAHI_DNS_FIELD_FLAGS, avahi_dns_packet_get_field(p, AVAHI_DNS_FIELD_FLAGS) | AVAHI_DNS_FLAG_TC); + avahi_dns_packet_set_field(p, AVAHI_DNS_FIELD_ANCOUNT, n); + avahi_interface_send_packet(s->interface, p); + avahi_dns_packet_free(p); + + p = avahi_dns_packet_new_query(s->interface->hardware->mtu); + n = 0; + } + + AVAHI_LLIST_REMOVE(AvahiKnownAnswer, known_answer, s->known_answers, ka); + avahi_record_unref(ka->record); + g_free(ka); + + 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); +} + +static void elapse_callback(AvahiTimeEvent *e, gpointer data) { + AvahiQueryJob *qj = data; + AvahiQueryScheduler *s; + AvahiDnsPacket *p; + guint n; + gboolean b; + + g_assert(qj); + s = qj->scheduler; + + if (qj->done) { + /* Lets remove it from the history */ + job_free(s, qj); + return; + } + + g_assert(!s->known_answers); + + p = avahi_dns_packet_new_query(s->interface->hardware->mtu); + b = packet_add_query_job(s, p, qj); + g_assert(b); /* An query must always fit in */ + n = 1; + + /* Try to fill up packet with more queries, if available */ + while (s->jobs) { + + if (!packet_add_query_job(s, p, s->jobs)) + break; + + n++; + } + + avahi_dns_packet_set_field(p, AVAHI_DNS_FIELD_QDCOUNT, n); + + /* Now add known answers */ + append_known_answers_and_send(s, p); +} + +static AvahiQueryJob* find_scheduled_job(AvahiQueryScheduler *s, AvahiKey *key) { + AvahiQueryJob *qj; + + g_assert(s); + g_assert(key); + + for (qj = s->jobs; qj; qj = qj->jobs_next) { + g_assert(!qj->done); + + if (avahi_key_equal(qj->key, key)) + return qj; + } + + return NULL; +} + +static AvahiQueryJob* find_history_job(AvahiQueryScheduler *s, AvahiKey *key) { + AvahiQueryJob *qj; + + g_assert(s); + g_assert(key); + + for (qj = s->history; qj; qj = qj->jobs_next) { + g_assert(qj->done); + + if (avahi_key_equal(qj->key, key)) { + /* Check whether this entry is outdated */ + + if (avahi_age(&qj->delivery) > AVAHI_QUERY_HISTORY_MSEC*1000) { + /* it is outdated, so let's remove it */ + job_free(s, qj); + return NULL; + } + + return qj; + } + } + + return NULL; +} + +gboolean avahi_query_scheduler_post(AvahiQueryScheduler *s, AvahiKey *key, gboolean immediately) { + GTimeVal tv; + AvahiQueryJob *qj; + + g_assert(s); + g_assert(key); + + if ((qj = find_history_job(s, key))) { + g_message("Query suppressed by local duplicate suppression (history)"); + return FALSE; + } + + avahi_elapse_time(&tv, immediately ? 0 : AVAHI_QUERY_DEFER_MSEC, 0); + + if ((qj = find_scheduled_job(s, key))) { + /* Duplicate questions suppression */ + + g_message("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 */ + qj->delivery = tv; + avahi_time_event_queue_update(s->time_event_queue, qj->time_event, &qj->delivery); + } + + return TRUE; + } else { + g_message("Accepted new query job.\n"); + + qj = job_new(s, key, FALSE); + qj->delivery = tv; + qj->time_event = avahi_time_event_queue_add(s->time_event_queue, &qj->delivery, elapse_callback, qj); + + return TRUE; + } +} + +void avahi_query_scheduler_incoming(AvahiQueryScheduler *s, AvahiKey *key) { + AvahiQueryJob *qj; + + g_assert(s); + g_assert(key); + + /* This function is called whenever an incoming query was + * receieved. We drop scheduled queries that match. The keyword is + * "DUPLICATE QUESTION SUPPRESION". */ + + if ((qj = find_scheduled_job(s, key))) { + g_message("Query suppressed by distributed duplicate suppression"); + job_mark_done(s, qj); + return; + } + + qj = job_new(s, key, TRUE); + g_get_current_time(&qj->delivery); + job_set_elapse_time(s, qj, AVAHI_QUERY_HISTORY_MSEC, 0); +} + -- cgit