Author: mdounin
Date: 2012-09-28 18:28:38 +0000 (Fri, 28 Sep 2012)
New Revision: 4872
URL: http://trac.nginx.org/nginx/changeset/4872/nginx

Log:
Resolver: cached addresses are returned with random rotation now.

This ensures balancing when working with dynamically resolved upstream
servers with multiple addresses.

Based on patch by Anton Jouline.


Modified:
trunk/src/core/ngx_resolver.c

Modified: trunk/src/core/ngx_resolver.c
===================================================================
--- trunk/src/core/ngx_resolver.c 2012-09-28 13:49:26 UTC (rev 4871)
+++ trunk/src/core/ngx_resolver.c 2012-09-28 18:28:38 UTC (rev 4872)
@@ -88,6 +88,8 @@
static void ngx_resolver_free(ngx_resolver_t *r, void *p);
static void ngx_resolver_free_locked(ngx_resolver_t *r, void *p);
static void *ngx_resolver_dup(ngx_resolver_t *r, void *src, size_t size);
+static in_addr_t *ngx_resolver_rotate(ngx_resolver_t *r, in_addr_t *src,
+ ngx_uint_t n);
static u_char *ngx_resolver_log_error(ngx_log_t *log, u_char *buf, size_t len);


@@ -445,8 +447,7 @@

if (naddrs != 1) {
addr = 0;
- addrs = ngx_resolver_dup(r, rn->u.addrs,
- naddrs * sizeof(in_addr_t));
+ addrs = ngx_resolver_rotate(r, rn->u.addrs, naddrs);
if (addrs == NULL) {
return NGX_ERROR;
}
@@ -2135,6 +2136,28 @@
}


+static in_addr_t *
+ngx_resolver_rotate(ngx_resolver_t *r, in_addr_t *src, ngx_uint_t n)
+{
+ void *dst, *p;
+ ngx_uint_t j;
+
+ dst = ngx_resolver_alloc(r, n * sizeof(in_addr_t));
+
+ j = ngx_random() % n;
+
+ if (j == 0) {
+ ngx_memcpy(dst, src, n * sizeof(in_addr_t));
+ return dst;
+ }
+
+ p = ngx_cpymem(dst, &src[j], (n - j) * sizeof(in_addr_t));
+ ngx_memcpy(p, src, j * sizeof(in_addr_t));
+
+ return dst;
+}
+
+
char *
ngx_resolver_strerror(ngx_int_t err)
{

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