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.
diff --git a/src/core/ngx_resolver.c b/src/core/ngx_resolver.c
index 178e083..dcdbe0c 100644
--- a/src/core/ngx_resolver.c
+++ b/src/core/ngx_resolver.c
@@ -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)
{
