references        712 http/ngx_http_upstream_round_robin.c                    ssl_session, ssl_session ? ssl_session->references : 0);
references        736 http/ngx_http_upstream_round_robin.c                    "save session: %p:%d", ssl_session, ssl_session->references);
references        752 http/ngx_http_upstream_round_robin.c                        old_ssl_session, old_ssl_session->references);