origin nginx ngx_http_do_read_client_request_body did not limit upload rate , how did you do it ?

[ygm521]

origin nginx ngx_http_do_read_client_request_body did not limit upload rate , if in function ngx_http_do_read_client_request_body limit upload rate, the cpu is 100%， how did you do it ?
whats the meanning of xxx , thanks!

static void /* {{{ ngx_http_read_upload_client_request_body_handler */
ngx_http_read_upload_client_request_body_handler(ngx_http_request_t *r)
{
    ngx_int_t  rc;
    ngx_http_upload_ctx_t     *u = ngx_http_get_module_ctx(r, ngx_http_upload_module);
    ngx_event_t               *rev = r->connection->read;
    ngx_http_core_loc_conf_t  *clcf;

    if (rev->timedout) {
        if(!rev->delayed) {
            r->connection->timedout = 1;
            upload_shutdown_ctx(u);
            ngx_http_finalize_request(r, NGX_HTTP_REQUEST_TIME_OUT);
            return;
        }

        //xxx
        rev->timedout = 0;
        rev->delayed = 0;

        if (!rev->ready) {
            clcf = ngx_http_get_module_loc_conf(r, ngx_http_core_module);
            ngx_add_timer(rev, clcf->client_body_timeout);

            if (ngx_handle_read_event(rev, clcf->send_lowat) != NGX_OK) {
                upload_shutdown_ctx(u);
                ngx_http_finalize_request(r, NGX_HTTP_INTERNAL_SERVER_ERROR);
            }

            return;
        }
    }
    else{
        // xxx
        if (r->connection->read->delayed) {
            clcf = ngx_http_get_module_loc_conf(r, ngx_http_core_module);
            ngx_log_debug0(NGX_LOG_DEBUG_HTTP, rev->log, 0,
                           "http read delayed");

            if (ngx_handle_read_event(rev, clcf->send_lowat) != NGX_OK) {
                upload_shutdown_ctx(u);
                ngx_http_finalize_request(r, NGX_HTTP_INTERNAL_SERVER_ERROR);
            }

            return;
        }
    }

    //读取请求的包体
    rc = ngx_http_do_read_upload_client_request_body(r);

    if (rc >= NGX_HTTP_SPECIAL_RESPONSE) {
        upload_shutdown_ctx(u);
        ngx_http_finalize_request(r, rc);
    }
} /* }}} */