ngx_int_t
ngx_http_upstream_create_round_robin_peer(ngx_http_request_t *r,
    ngx_http_upstream_resolved_t *ur)
{
    u_char                            *p;
    size_t                             len;
    ngx_uint_t                         i, n;
    struct sockaddr_in                *sin;
    ngx_http_upstream_rr_peers_t      *peers;
    ngx_http_upstream_rr_peer_data_t  *rrp;

    rrp = r->upstream->peer.data;

    if (rrp == NULL) {
        rrp = ngx_palloc(r->pool, sizeof(ngx_http_upstream_rr_peer_data_t));
        if (rrp == NULL) {
            return NGX_ERROR;
        }

        r->upstream->peer.data = rrp;
    }

    peers = ngx_pcalloc(r->pool, sizeof(ngx_http_upstream_rr_peers_t)
                     + sizeof(ngx_http_upstream_rr_peer_t) * (ur->naddrs - 1));
    if (peers == NULL) {
        return NGX_ERROR;
    }

    peers->single = (ur->naddrs == 1);
    peers->number = ur->naddrs;
    peers->name = &ur->host;

    if (ur->sockaddr) {
        peers->peer[0].sockaddr = ur->sockaddr;
        peers->peer[0].socklen = ur->socklen;
        peers->peer[0].name = ur->host;
        peers->peer[0].weight = 1;
        peers->peer[0].effective_weight = 1;
        peers->peer[0].current_weight = 0;
        peers->peer[0].max_fails = 1;
        peers->peer[0].fail_timeout = 10;

    } else {

        for (i = 0; i < ur->naddrs; i++) {

            len = NGX_INET_ADDRSTRLEN + sizeof(":65536") - 1;

            p = ngx_pnalloc(r->pool, len);
            if (p == NULL) {
                return NGX_ERROR;
            }

            len = ngx_inet_ntop(AF_INET, &ur->addrs[i], p, NGX_INET_ADDRSTRLEN);
            len = ngx_sprintf(&p[len], ":%d", ur->port) - p;

            sin = ngx_pcalloc(r->pool, sizeof(struct sockaddr_in));
            if (sin == NULL) {
                return NGX_ERROR;
            }

            sin->sin_family = AF_INET;
            sin->sin_port = htons(ur->port);
            sin->sin_addr.s_addr = ur->addrs[i];

            peers->peer[i].sockaddr = (struct sockaddr *) sin;
            peers->peer[i].socklen = sizeof(struct sockaddr_in);
            peers->peer[i].name.len = len;
            peers->peer[i].name.data = p;
            peers->peer[i].weight = 1;
            peers->peer[i].effective_weight = 1;
            peers->peer[i].current_weight = 0;
            peers->peer[i].max_fails = 1;
            peers->peer[i].fail_timeout = 10;
        }
    }

    rrp->peers = peers;
    rrp->current = 0;

    if (rrp->peers->number <= 8 * sizeof(uintptr_t)) {
        rrp->tried = &rrp->data;
        rrp->data = 0;

    } else {
        n = (rrp->peers->number + (8 * sizeof(uintptr_t) - 1))
                / (8 * sizeof(uintptr_t));

        rrp->tried = ngx_pcalloc(r->pool, n * sizeof(uintptr_t));
        if (rrp->tried == NULL) {
            return NGX_ERROR;
        }
    }

    r->upstream->peer.get = ngx_http_upstream_get_round_robin_peer;
    r->upstream->peer.free = ngx_http_upstream_free_round_robin_peer;
    r->upstream->peer.tries = rrp->peers->number;
#if (NGX_HTTP_SSL)
    r->upstream->peer.set_session = ngx_http_upstream_empty_set_session;
    r->upstream->peer.save_session = ngx_http_upstream_empty_save_session;
#endif

    return NGX_OK;
}