NGX_LOWLEVEL_BUFFERED  186 http/ngx_http_write_filter_module.c     if (size == 0 && !(c->buffered & NGX_LOWLEVEL_BUFFERED)) {
NGX_LOWLEVEL_BUFFERED  296 http/ngx_http_write_filter_module.c     if ((c->buffered & NGX_LOWLEVEL_BUFFERED) && r->postponed == NULL) {