node.js，http代理请求结束时的回调？

我正在尝试学习node.js，我的上下文是来自nodejitsu的http代理模块

我想访问代理事件的结尾，以便记录目标服务器响应所用的时间。但是，我不知道如何创建适当的回调或事件处理程序。我查看了http代理的源代码，它似乎没有采用传统的回调方法

下面是一个示例，我相信这对呼吸节点的人来说是一个简单的修复：

/* demonstrate a basic proxy server that can log the time 
it takes to execute a given hit on the destination server
*/
var http = require('http'),
    httpProxy = require('http-proxy');

// Create the proxy server
httpProxy.createServer(function (req, res, proxy) {
    var startTime = ( new Date()).getTime();

    // NEED HELP HERE. 
    // something like this should do it?
    proxy.addListener("end",function() {
        var endTime = (new Date()).getTime();
        console.log("request took " + (endTime - startTime) + "ms");
    });

    proxy.proxyRequest(req, res, {
        host: 'localhost',
        port: 9000
    });
}).listen(8000);

// the destination server
http.createServer(function (req, res) {
    res.writeHead(200, { 'Content-Type': 'text/plain' });
    res.write('request successfully proxied: ' + req.url +'\n' + JSON.stringify(req.headers, true, 2));
    // make the hit slow by pausing the end()
    setTimeout(function() {
        res.end();
    },2000);
}).listen(9000);

---

一种方法是拦截res.end（）调用。我有3天的快递经验，所以我不知道这会搞砸什么：

var proxy = new httpProxy.RoutingProxy();
app.get("/foo", function (req, res) {
    var realEnd = res.end;
    var start = +new Date();
    res.end = function () {
        var elapsed = +new Date() - start;
        console.log("elapsed", elapsed);
        realEnd.apply(res);
    }
    proxy.proxyRequest(req, res, {
        host: 'localhost',
        port: 9000
    });
});

---

一种方法是拦截res.end（）调用。我有3天的快递经验，所以我不知道这会搞砸什么：

var proxy = new httpProxy.RoutingProxy();
app.get("/foo", function (req, res) {
    var realEnd = res.end;
    var start = +new Date();
    res.end = function () {
        var elapsed = +new Date() - start;
        console.log("elapsed", elapsed);
        realEnd.apply(res);
    }
    proxy.proxyRequest(req, res, {
        host: 'localhost',
        port: 9000
    });
});