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dns_cache: Replace cache timeout mechanism with time wheel algorithm to reduce CPU usage

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This commit is contained in:
Nick Peng
2023-09-23 23:31:19 +08:00
parent b7fb501be9
commit bfacad33ae
10 changed files with 760 additions and 356 deletions
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144
src/dns_server.c
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@@ -1253,6 +1253,43 @@ static int _dns_reply_inpacket(struct dns_request *request, unsigned char *inpac
return ret;
}
static int _dns_server_get_cache_timeout(struct dns_request *request, int ttl)
{
int timeout = 0;
if (dns_conf_prefetch) {
if (dns_conf_serve_expired) {
timeout = dns_conf_serve_expired_prefetch_time;
if (timeout == 0) {
timeout = dns_conf_serve_expired_ttl / 2;
if (timeout == 0 || timeout > EXPIRED_DOMAIN_PREFETCH_TIME) {
timeout = EXPIRED_DOMAIN_PREFETCH_TIME;
}
}
if (request->prefetch == 0) {
timeout += ttl;
}
} else {
timeout = ttl - 3;
}
} else {
timeout = ttl;
if (dns_conf_serve_expired) {
timeout += dns_conf_serve_expired_ttl;
}
}
if (request->prefetch) {
timeout -= 1;
}
if (timeout <= 0) {
timeout = 1;
}
return timeout;
}
static int _dns_server_request_update_cache(struct dns_request *request, dns_type_t qtype,
struct dns_cache_data *cache_data, int has_soa, int cache_ttl)
{
@@ -1293,18 +1330,13 @@ static int _dns_server_request_update_cache(struct dns_request *request, dns_typ
cache_key.query_flag = request->server_flags;
if (request->prefetch) {
if (request->prefetch_expired_domain == 0) {
if (dns_cache_replace(&cache_key, ttl, speed, request->no_serve_expired, cache_data) != 0) {
goto errout;
}
} else {
if (dns_cache_replace_inactive(&cache_key, ttl, speed, request->no_serve_expired, cache_data) != 0) {
goto errout;
}
if (dns_cache_replace(&cache_key, ttl, speed, _dns_server_get_cache_timeout(request, ttl),
!request->prefetch_expired_domain, cache_data) != 0) {
goto errout;
}
} else {
/* insert result to cache */
if (dns_cache_insert(&cache_key, ttl, speed, request->no_serve_expired, cache_data) != 0) {
if (dns_cache_insert(&cache_key, ttl, speed, _dns_server_get_cache_timeout(request, ttl), cache_data) != 0) {
goto errout;
}
}
@@ -1441,18 +1473,13 @@ static int _dns_cache_cname_packet(struct dns_server_post_context *context)
cache_key.query_flag = request->server_flags;
if (request->prefetch) {
if (request->prefetch_expired_domain == 0) {
if (dns_cache_replace(&cache_key, ttl, speed, request->no_serve_expired, cache_packet) != 0) {
goto errout;
}
} else {
if (dns_cache_replace_inactive(&cache_key, ttl, speed, request->no_serve_expired, cache_packet) != 0) {
goto errout;
}
if (dns_cache_replace(&cache_key, ttl, speed, _dns_server_get_cache_timeout(request, ttl),
!request->prefetch_expired_domain, cache_packet) != 0) {
goto errout;
}
} else {
/* insert result to cache */
if (dns_cache_insert(&cache_key, ttl, speed, request->no_serve_expired, cache_packet) != 0) {
if (dns_cache_insert(&cache_key, ttl, speed, _dns_server_get_cache_timeout(request, ttl), cache_packet) != 0) {
goto errout;
}
}
@@ -1484,12 +1511,15 @@ static int _dns_cache_packet(struct dns_server_post_context *context)
cache_key.query_flag = request->server_flags;
if (request->prefetch) {
if (dns_cache_replace(&cache_key, context->reply_ttl, -1, request->no_serve_expired, cache_packet) != 0) {
if (dns_cache_replace(&cache_key, context->reply_ttl, -1,
_dns_server_get_cache_timeout(request, context->reply_ttl),
!request->prefetch_expired_domain, cache_packet) != 0) {
goto errout;
}
} else {
/* insert result to cache */
if (dns_cache_insert(&cache_key, context->reply_ttl, -1, request->no_serve_expired, cache_packet) != 0) {
if (dns_cache_insert(&cache_key, context->reply_ttl, -1,
_dns_server_get_cache_timeout(request, context->reply_ttl), cache_packet) != 0) {
goto errout;
}
}
@@ -3061,9 +3091,9 @@ static int _dns_server_process_answer_AAAA(struct dns_rrs *rrs, struct dns_reque
return -1;
}
snprintf(ip, sizeof(ip), "[%.2x%.2x:%.2x%.2x:%.2x%.2x:%.2x%.2x:%.2x%.2x:%.2x%.2x:%.2x%.2x:%.2x%.2x]", paddr[0], paddr[1],
paddr[2], paddr[3], paddr[4], paddr[5], paddr[6], paddr[7], paddr[8], paddr[9], paddr[10], paddr[11],
paddr[12], paddr[13], paddr[14], paddr[15]);
snprintf(ip, sizeof(ip), "[%.2x%.2x:%.2x%.2x:%.2x%.2x:%.2x%.2x:%.2x%.2x:%.2x%.2x:%.2x%.2x:%.2x%.2x]", paddr[0],
paddr[1], paddr[2], paddr[3], paddr[4], paddr[5], paddr[6], paddr[7], paddr[8], paddr[9], paddr[10],
paddr[11], paddr[12], paddr[13], paddr[14], paddr[15]);
/* start ping */
_dns_server_request_get(request);
@@ -6450,13 +6480,13 @@ static int _dns_server_second_ping_check(struct dns_request *request)
return ret;
}
static void _dns_server_prefetch_domain(struct dns_cache *dns_cache)
static int _dns_server_prefetch_domain(struct dns_cache *dns_cache)
{
/* If there are still hits, continue pre-fetching */
struct dns_server_query_option server_query_option;
int hitnum = dns_cache_hitnum_dec_get(dns_cache);
if (hitnum <= 0) {
return;
return -1;
}
/* start prefetch domain */
@@ -6467,11 +6497,19 @@ static void _dns_server_prefetch_domain(struct dns_cache *dns_cache)
server_query_option.ecs_enable_flag = 0;
if (_dns_server_prefetch_request(dns_cache->info.domain, dns_cache->info.qtype, 0, &server_query_option) != 0) {
tlog(TLOG_ERROR, "prefetch domain %s, qtype %d, failed.", dns_cache->info.domain, dns_cache->info.qtype);
return -1;
}
return 0;
}
static void _dns_server_prefetch_expired_domain(struct dns_cache *dns_cache)
static int _dns_server_prefetch_expired_domain(struct dns_cache *dns_cache)
{
time_t ttl = dns_cache->info.insert_time + dns_cache->info.ttl + dns_conf_serve_expired_ttl - time(NULL);
if (ttl < 0) {
return -1;
}
/* start prefetch domain */
tlog(TLOG_DEBUG, "expired domain, prefetch by cache %s, qtype %d, ttl %d", dns_cache->info.domain,
dns_cache->info.qtype, dns_cache->info.ttl);
@@ -6483,7 +6521,23 @@ static void _dns_server_prefetch_expired_domain(struct dns_cache *dns_cache)
if (_dns_server_prefetch_request(dns_cache->info.domain, dns_cache->info.qtype, 1, &server_query_option) != 0) {
tlog(TLOG_DEBUG, "prefetch domain %s, qtype %d, failed.", dns_cache->info.domain, dns_cache->info.qtype);
return -1;
}
return 0;
}
static int _dns_server_cache_expired(struct dns_cache *dns_cache)
{
if (dns_conf_prefetch == 1) {
if (dns_conf_serve_expired == 1) {
return _dns_server_prefetch_expired_domain(dns_cache);
} else {
return _dns_server_prefetch_domain(dns_cache);
}
}
return -1;
}
static void _dns_server_tcp_idle_check(void)
@@ -6592,44 +6646,8 @@ static void _dns_server_save_cache_to_file(void)
static void _dns_server_period_run_second(void)
{
static unsigned int sec = 0;
static time_t last = 0;
time_t now = 0;
sec++;
time(&now);
if (last == 0) {
last = now;
}
if (now - 180 > last) {
dns_cache_invalidate(NULL, 0, 0, NULL, 0);
tlog(TLOG_WARN, "Service paused for 180s, force invalidate cache.");
}
last = now;
if (sec % 2 == 0) {
if (dns_conf_prefetch) {
/* do pre-fetching */
if (dns_conf_serve_expired) {
int prefetch_time = dns_conf_serve_expired_prefetch_time;
if (prefetch_time == 0) {
prefetch_time = dns_conf_serve_expired_ttl / 2;
if (prefetch_time == 0 || prefetch_time > EXPIRED_DOMAIN_PREFETCH_TIME) {
prefetch_time = EXPIRED_DOMAIN_PREFETCH_TIME;
}
}
dns_cache_invalidate(NULL, 0, DNS_MAX_DOMAIN_REFETCH_NUM, _dns_server_prefetch_expired_domain,
prefetch_time);
} else {
dns_cache_invalidate(_dns_server_prefetch_domain, 3, DNS_MAX_DOMAIN_REFETCH_NUM, NULL, 0);
}
} else {
dns_cache_invalidate(NULL, 0, 0, NULL, 0);
}
}
_dns_server_tcp_idle_check();
_dns_server_check_need_exit();
@@ -7212,7 +7230,7 @@ static int _dns_server_audit_init(void)
static int _dns_server_cache_init(void)
{
if (dns_cache_init(dns_conf_cachesize, dns_conf_serve_expired, dns_conf_serve_expired_ttl) != 0) {
if (dns_cache_init(dns_conf_cachesize, _dns_server_cache_expired) != 0) {
tlog(TLOG_ERROR, "init cache failed.");
return -1;
}