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resolved: use a temporary Set to speed up dns question parsing

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This doesn't necessarily make things faster, because we still spend more time
in dns_answer_add(), but it improves the compuational complexity of this part.
If we even make dns_resource_key_equal_faster, this will become worthwhile.
This commit is contained in:
Zbigniew Jędrzejewski-Szmek 2019-02-27 07:01:50 +01:00
parent 46d4d67d79
commit 2d34cf0c16
3 changed files with 36 additions and 8 deletions
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21
src/resolve/resolved-dns-packet.c
View File

@ -7,6 +7,7 @@
#include "alloc-util.h"
#include "dns-domain.h"
#include "resolved-dns-packet.h"
#include "set.h"
#include "string-table.h"
#include "strv.h"
#include "unaligned.h"
@ -2133,6 +2134,17 @@ static int dns_packet_extract_question(DnsPacket *p, DnsQuestion **ret_question)
if (!question)
return -ENOMEM;
_cleanup_set_free_ Set *keys = NULL; /* references to keys are kept by Question */
keys = set_new(&dns_resource_key_hash_ops);
if (!keys)
return log_oom();
r = set_reserve(keys, n * 2); /* Higher multipliers give slightly higher efficiency through
* hash collisions, but the gains quickly drop of after 2. */
if (r < 0)
return r;
for (i = 0; i < n; i++) {
_cleanup_(dns_resource_key_unrefp) DnsResourceKey *key = NULL;
bool cache_flush;
@ -2147,7 +2159,14 @@ static int dns_packet_extract_question(DnsPacket *p, DnsQuestion **ret_question)
if (!dns_type_is_valid_query(key->type))
return -EBADMSG;
r = dns_question_add(question, key);
r = set_put(keys, key);
if (r < 0)
return r;
if (r == 0)
/* Already in the Question, let's skip */
continue;
r = dns_question_add_raw(question, key);
if (r < 0)
return r;
}

22
src/resolve/resolved-dns-question.c
View File

@ -32,8 +32,20 @@ static DnsQuestion *dns_question_free(DnsQuestion *q) {
DEFINE_TRIVIAL_REF_UNREF_FUNC(DnsQuestion, dns_question, dns_question_free);
int dns_question_add_raw(DnsQuestion *q, DnsResourceKey *key) {
/* Insert without checking for duplicates. */
assert(key);
assert(q);
if (q->n_keys >= q->n_allocated)
return -ENOSPC;
q->keys[q->n_keys++] = dns_resource_key_ref(key);
return 0;
}
int dns_question_add(DnsQuestion *q, DnsResourceKey *key) {
size_t i;
int r;
assert(key);
@ -41,7 +53,7 @@ int dns_question_add(DnsQuestion *q, DnsResourceKey *key) {
if (!q)
return -ENOSPC;
for (i = 0; i < q->n_keys; i++) {
for (size_t i = 0; i < q->n_keys; i++) {
r = dns_resource_key_equal(q->keys[i], key);
if (r < 0)
return r;
@ -49,11 +61,7 @@ int dns_question_add(DnsQuestion *q, DnsResourceKey *key) {
return 0;
}
if (q->n_keys >= q->n_allocated)
return -ENOSPC;
q->keys[q->n_keys++] = dns_resource_key_ref(key);
return 0;
return dns_question_add_raw(q, key);
}
int dns_question_matches_rr(DnsQuestion *q, DnsResourceRecord *rr, const char *search_domain) {

1
src/resolve/resolved-dns-question.h
View File

@ -22,6 +22,7 @@ int dns_question_new_address(DnsQuestion **ret, int family, const char *name, bo
int dns_question_new_reverse(DnsQuestion **ret, int family, const union in_addr_union *a);
int dns_question_new_service(DnsQuestion **ret, const char *service, const char *type, const char *domain, bool with_txt, bool convert_idna);
int dns_question_add_raw(DnsQuestion *q, DnsResourceKey *key);
int dns_question_add(DnsQuestion *q, DnsResourceKey *key);
int dns_question_matches_rr(DnsQuestion *q, DnsResourceRecord *rr, const char *search_domain);