upstream_response_time 是否包含 tcp 三次握手？

[Heysexyboy]

查看官方针对 upstream_response_time 的解释很模糊，因此想请教一下 upstream_response_time 是否包含 tcp 三次握手和四次挥手？

https://nginx.org/en/docs/http/ngx_http_upstream_module.html
$upstream_response_time
keeps time spent on receiving the response from the upstream server; the time is kept in seconds with millisecond resolution. Times of several responses are separated by commas and colons like addresses in the $upstream_addr variable.

https://docs.nginx.com/nginx/admin-guide/monitoring/logging/
$upstream_response_time – The time between establishing a connection and receiving the last byte of the response body from the upstream server

[Heysexyboy]

在代码中看到的 response_time 是在 ngx_close_connection(u->peer.connection); 之后，是否可以证实是包含tcp三次握手和四次挥手的耗时？
//如果响应时间未设置，更新响应时间为当前时间减去开始时间
if (u->state && u->state->response_time == (ngx_msec_t) -1) {
u->state->response_time = ngx_current_msec - u->start_time;
//更新接收和发送的字节数。
if (u->pipe && u->pipe->read_length) {
u->state->bytes_received += u->pipe->read_length
- u->pipe->preread_size;
u->state->response_length = u->pipe->read_length;
}

    if (u->peer.connection) {
        u->state->bytes_sent = u->peer.connection->sent;
    }
}

//调用上游模块的结束请求函数。
u->finalize_request(r, rc);
//释放上游服务器的地址信息
if (u->peer.free && u->peer.sockaddr) {
u->peer.free(&u->peer, u->peer.data, 0);
u->peer.sockaddr = NULL;
}

if (u->peer.connection) {

#if (NGX_HTTP_SSL)

    /* TODO: do not shutdown persistent connection */

    if (u->peer.connection->ssl) {

        /*
         * We send the "close notify" shutdown alert to the upstream only
         * and do not wait its "close notify" shutdown alert.
         * It is acceptable according to the TLS standard.
         */

        u->peer.connection->ssl->no_wait_shutdown = 1;

        (void) ngx_ssl_shutdown(u->peer.connection);
    }

#endif

    ngx_log_debug1(NGX_LOG_DEBUG_HTTP, r->connection->log, 0,
                   "close http upstream connection: %d",
                   u->peer.connection->fd);

    if (u->peer.connection->pool) {
        ngx_destroy_pool(u->peer.connection->pool);
    }

    ngx_close_connection(u->peer.connection);
}

[chobits]

$upstream_response_time 记录的是从建立连接到接收完响应主体的最后一个字节之间的时间。
该时间包括：
TCP 三次握手的时间（连接建立时间）。
发送请求到接收到完整响应的时间（即请求处理时间和数据传输时间）。