如何获取 node-http-proxy 完成的每个代理请求的响应时间？

Question

我想计算每个代理请求的响应时间，由 node-http-proxy 完成，如下所示：

var httpProxy = require('http-proxy');
var proxy = httpProxy.createProxyServer();

require('http').createServer(function(req, res) {
   // start-time for one request
   proxy.web(req, res, { target: 'localhost:80' });
}).listen(3000);

proxy.on('proxyRes', function (res) {
  // end-time for one request to calculate the time
  console.log('RAW Response from the target', JSON.stringify(res.headers, true, 2));
});

所以我想得到开始时间和开始时间之间的时间差。我能够捕捉到proxyRes 事件，但是如何将代理响应与正确的客户端请求相匹配？

更新：我尝试了以下方法：

var httpProxy = require('http-proxy');
var http = require('http');

var proxy = new httpProxy.createProxyServer({
    target: {
        host: 'localhost',
        port: 80
    }
});

var start_time = 0;
var proxyServer = http.createServer(function (req, res) {


    start_time = new Date().getTime();

    proxy.web(req, res);

    res.on('finish', function() {
        console.log("The request was proxied in " + (new Date().getTime() - start_time) + "ms");
    });
});

proxyServer.listen(3000);

// Proxy-Target server
var n = 0; sleep = 0;
http.createServer(function (req, res) {

    n++;

    var start_time = new Date().getTime();

    res.writeHead(200, {'Content-Type': 'text/plain'});

    if (n % 2 == 0){
        sleep = 2000;
    } else {
        sleep = 5000;
    }

    setTimeout(function(){
        res.end("...");
    }, sleep);

    res.on('finish', function(d) {
        var diff_time = new Date().getTime() - start_time;
        console.log("The request was processed in " + (new Date().getTime() - start_time) + "ms");
    });

}).listen(80);

因此，目标服务器的时间测量正确，因为一个请求可能持续 2 或 5 秒，但代理有时测量的响应时间仅为几毫秒。 我通过使用 apache-bench 进行了尝试，例如：ab -n 10 -c 3 http://localhost:3000/ 和控制台的结果：

The request was processed in 2007ms
The request was proxied in 2017ms
The request was processed in 2003ms
The request was proxied in 2006ms
The request was processed in 5002ms
The request was processed in 5001ms
The request was proxied in 980ms
The request was proxied in 981ms
The request was processed in 2002ms
The request was proxied in 2006ms
The request was processed in 2002ms
The request was proxied in 2005ms
The request was processed in 5000ms
The request was proxied in 8ms
The request was processed in 5000ms
The request was proxied in 982ms
The request was processed in 2001ms
The request was proxied in 2005ms
The request was processed in 5002ms
The request was proxied in 4998ms

Answer 1

现在可以了，在 nodejs google-gloup 上得到了关键提示，start_time 的 cope 没有在本地设置，所以这里是工作代码：

var httpProxy = require('http-proxy');
var http = require('http');

var proxy = new httpProxy.createProxyServer({});

// before: var start_time = 0;
var proxyServer = http.createServer(function (req, res) {

    // now
    var start_time = new Date().getTime();

    proxy.web(req, res, { target: 'http://localhost:80' });

    res.on('finish', function() {
       console.log("The request was proxied in " + (new Date().getTime() - start_time) + "ms");
    });
});
proxyServer.listen(3000);

Answer 2

（未经测试，但让我们看看这是否有效）

var httpProxy = require('http-proxy');
var proxy = httpProxy.createProxyServer();
var startTime = 0;
var endTime = 0;

require('http').createServer(function(req, res) {
   // start-time for one request
   startTime = new Date().getTime();
   proxy.web(req, res, { 
        target: 'localhost:80' 
   });
}).listen(3000);

proxy.on('proxyRes', function (res) {
  // end-time for one request to calculate the time
  endTime = new Date().getTime();
  console.log(endTime - startTime);
  console.log('RAW Response from the target', JSON.stringify(res.headers, true, 2));
});