Author: ru
Date: 2011-11-16 13:11:39 +0000 (Wed, 16 Nov 2011)
New Revision: 4296

Log:
Now nginx uses TTL of a DNS response when calculating cache validity.

Previously it used a hardcoded value of 300 seconds. Also added the
"valid=" parameter to the "resolver" directive that can be used to
override the cache validity time.

Patch by Kirill A. Korinskiy with minor changes.


Modified:
trunk/src/core/ngx_resolver.c

Modified: trunk/src/core/ngx_resolver.c
===================================================================
--- trunk/src/core/ngx_resolver.c 2011-11-16 12:51:27 UTC (rev 4295)
+++ trunk/src/core/ngx_resolver.c 2011-11-16 13:11:39 UTC (rev 4296)
@@ -93,6 +93,7 @@
ngx_resolver_t *
ngx_resolver_create(ngx_conf_t *cf, ngx_str_t *names, ngx_uint_t n)
{
+ ngx_str_t s;
ngx_url_t u;
ngx_uint_t i;
ngx_resolver_t *r;
@@ -146,12 +147,27 @@

r->resend_timeout = 5;
r->expire = 30;
- r->valid = 300;
+ r->valid = 0;

r->log = &cf->cycle->new_log;
r->log_level = NGX_LOG_ERR;

for (i = 0; i < n; i++) {
+ if (ngx_strncmp(names[i].data, "valid=", 6) == 0) {
+ s.len = names[i].len - 6;
+ s.data = names[i].data + 6;
+
+ r->valid = ngx_parse_time(&s, 1);
+
+ if (r->valid == NGX_ERROR) {
+ ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,
+ "invalid parameter: %V", &names[i]);
+ return NULL;
+ }
+
+ continue;
+ }
+
ngx_memzero(&u, sizeof(ngx_url_t));

u.host = names[i];
@@ -1149,6 +1165,7 @@
char *err;
u_char *cname;
size_t len;
+ int32_t ttl;
uint32_t hash;
in_addr_t addr, *addrs;
ngx_str_t name;
@@ -1258,7 +1275,13 @@

qtype = (an->type_hi << 8) + an->type_lo;
len = (an->len_hi << 8) + an->len_lo;
+ ttl = (an->ttl[0] << 24) + (an->ttl[1] << 16)
+ + (an->ttl[2] << 8) + (an->ttl[3]);

+ if (ttl < 0) {
+ ttl = 0;
+ }
+
if (qtype == NGX_RESOLVE_A) {

i += sizeof(ngx_resolver_an_t);
@@ -1287,8 +1310,9 @@
}
}

- ngx_log_debug2(NGX_LOG_DEBUG_CORE, r->log, 0,
- "resolver naddrs:%ui cname:%p", naddrs, cname);
+ ngx_log_debug3(NGX_LOG_DEBUG_CORE, r->log, 0,
+ "resolver naddrs:%ui cname:%p ttl:%d",
+ naddrs, cname, ttl);

if (naddrs) {

@@ -1357,7 +1381,7 @@

ngx_queue_remove(&rn->queue);

- rn->valid = ngx_time() + r->valid;
+ rn->valid = ngx_time() + (r->valid ? r->valid : ttl);
rn->expire = ngx_time() + r->expire;

ngx_queue_insert_head(&r->name_expire_queue, &rn->queue);
@@ -1399,7 +1423,8 @@

rn->cnlen = (u_short) name.len;
rn->u.cname = name.data;
- rn->valid = ngx_time() + r->valid;
+
+ rn->valid = ngx_time() + (r->valid ? r->valid : ttl);
rn->expire = ngx_time() + r->expire;

ngx_queue_insert_head(&r->name_expire_queue, &rn->queue);
@@ -1450,6 +1475,7 @@
char *err;
size_t len;
in_addr_t addr;
+ int32_t ttl;
ngx_int_t digit;
ngx_str_t name;
ngx_uint_t i, mask, qident;
@@ -1545,7 +1571,13 @@
an = (ngx_resolver_an_t *) &buf[i + 2];

len = (an->len_hi << 8) + an->len_lo;
+ ttl = (an->ttl[0] << 24) + (an->ttl[1] << 16)
+ + (an->ttl[2] << 8) + (an->ttl[3]);

+ if (ttl < 0) {
+ ttl = 0;
+ }
+
ngx_log_debug3(NGX_LOG_DEBUG_CORE, r->log, 0,
"resolver qt:%ui cl:%ui len:%uz",
(an->type_hi << 8) + an->type_lo,
@@ -1581,7 +1613,7 @@

ngx_queue_remove(&rn->queue);

- rn->valid = ngx_time() + r->valid;
+ rn->valid = ngx_time() + (r->valid ? r->valid : ttl);
rn->expire = ngx_time() + r->expire;

ngx_queue_insert_head(&r->addr_expire_queue, &rn->queue);

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