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Merge of r4872, r4893: resolver cached addresses random rotation.

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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.
This commit is contained in:
Maxim Dounin 2012-11-12 18:47:07 +00:00
parent 033598bc07
commit 0e6c7b0614
1 changed files with 29 additions and 2 deletions
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31
src/core/ngx_resolver.c
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@ -88,6 +88,8 @@ static void *ngx_resolver_calloc(ngx_resolver_t *r, size_t size);
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 @@ ngx_resolve_name_locked(ngx_resolver_t *r, ngx_resolver_ctx_t *ctx)
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 +2136,32 @@ 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)
{
void *dst, *p;
ngx_uint_t j;
dst = ngx_resolver_alloc(r, n * sizeof(in_addr_t));
if (dst == NULL) {
return dst;
}
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)
{