Express middleware to emit end event on res.end()
res object has following events:
header- when HTTP Header is written,close- when connection is closed from client sidefinish- when request processing finished (*)
(*) Unfortunately, if client has closed its connection, there is no event signalling that the server side finished the processing of the request as finish event does not fires in this case.
It may be correct from abstract framework perspective as the request to be terminated without response to the client (and network connection is closed) and looks like it's does not matter whether the server finished the processing or not.
However, there are several negative outcomes of this approach. One of them is that middleware has no information when the server has really finished the processing of the request.
This module overrides res.end() function to emit end when res.end() is called, i.e. when processing by server is finished independently of whether the connection was closed by client or not.
Usage example:
'use strict';
var express = require('express');
var http = require('http');
var endMw = require('express-end');
//var endMw = require('../');
var app = express();
app.use(endMw);
var count = 0;
app.use(function(req, res, next) {
var current = ++count;
console.log('[%d] app.use()', current);
res.once('close', function() {
console.log('[%d] app.use(): res.once(close)', current);
});
res.once('end', function() {
console.log('[%d] app.use(): res.once(end)', current);
});
res.once('finish', function() {
console.log('[%d] app.use(): res.once(finish)', current);
});
next();
});
var httpPort = 8080;
var RESPONSE_DELAY = 1000; // Milliseconds
app.get('/test1', function (req, res) {
var result = { test: 'test' };
setTimeout(function() {
res
.status(200)
.send(result);
}, RESPONSE_DELAY);
});
var server = http.createServer(app);
server.listen(httpPort, function () {
console.log('* Server listening at %s:%d', server.address().address, server.address().port);
});Log (first request completed by server, second request cancelled by client):
$ node app.js
* Server listening at :::8080
[1] app.use()
[1] app.use(): res.once(end)
[1] app.use(): res.once(finish)
[2] app.use()
[2] app.use(): res.once(close)
[2] app.use(): res.once(end)
The source code for this example is located in demo/ subdirectory of package
In order to run it you need to:
cd demo;- start
run_demo.shin one terminal to imitate server withexpress-endmiddleware; - start
run_batches.shin another terminal; when started, pressCtrl+Cto interrupt active HTTP requests imitating close from client side.
$ ./run_batches.sh
This is ApacheBench, Version 2.3 <$Revision: 1663405 $>
Copyright 1996 Adam Twiss, Zeus Technology Ltd, http://www.zeustech.net/
Licensed to The Apache Software Foundation, http://www.apache.org/
Benchmarking 127.0.0.1 (be patient).....done
Server Software:
Server Hostname: 127.0.0.1
Server Port: 8080
Document Path: /test1
Document Length: 15 bytes
Concurrency Level: 10
Time taken for tests: 1.007 seconds
Complete requests: 10
Failed requests: 0
Total transferred: 2160 bytes
HTML transferred: 150 bytes
Requests per second: 9.93 [#/sec] (mean)
Time per request: 1007.159 [ms] (mean)
Time per request: 100.716 [ms] (mean, across all concurrent requests)
Transfer rate: 2.09 [Kbytes/sec] received
Connection Times (ms)
min mean[+/-sd] median max
Connect: 0 0 0.1 0 0
Processing: 1006 1006 0.3 1006 1007
Waiting: 1003 1004 1.1 1005 1006
Total: 1006 1006 0.2 1006 1007
Percentage of the requests served within a certain time (ms)
50% 1006
66% 1007
75% 1007
80% 1007
90% 1007
95% 1007
98% 1007
99% 1007
100% 1007 (longest request)
$ ./run_demo.sh
* Server listening at :::8080
[1] app.use()
[2] app.use()
[3] app.use()
[4] app.use()
[5] app.use()
[6] app.use()
[7] app.use()
[8] app.use()
[9] app.use()
[10] app.use()
[1] app.use(): res.once(end)
[1] app.use(): res.once(finish)
[2] app.use(): res.once(end)
[3] app.use(): res.once(end)
[4] app.use(): res.once(end)
[5] app.use(): res.once(end)
[6] app.use(): res.once(end)
[7] app.use(): res.once(end)
[8] app.use(): res.once(end)
[9] app.use(): res.once(end)
[10] app.use(): res.once(end)
[2] app.use(): res.once(finish)
[3] app.use(): res.once(finish)
[4] app.use(): res.once(finish)
[5] app.use(): res.once(finish)
[6] app.use(): res.once(finish)
[7] app.use(): res.once(finish)
[8] app.use(): res.once(finish)
[9] app.use(): res.once(finish)
[10] app.use(): res.once(finish)
$ ./run_batches.sh
This is ApacheBench, Version 2.3 <$Revision: 1663405 $>
Copyright 1996 Adam Twiss, Zeus Technology Ltd, http://www.zeustech.net/
Licensed to The Apache Software Foundation, http://www.apache.org/
Benchmarking 127.0.0.1 (be patient)...^C
Server Software:
Server Hostname: 127.0.0.1
Server Port: 8080
Document Path: /test1
Document Length: 0 bytes
Concurrency Level: 10
Time taken for tests: 0.956 seconds
Complete requests: 0
Failed requests: 0
Total transferred: 0 bytes
HTML transferred: 0 bytes
$ ./run_demo.sh
* Server listening at :::8080
[1] app.use()
[2] app.use()
[3] app.use()
[4] app.use()
[5] app.use()
[6] app.use()
[7] app.use()
[8] app.use()
[9] app.use()
[10] app.use()
[10] app.use(): res.once(close)
[1] app.use(): res.once(close)
[2] app.use(): res.once(close)
[3] app.use(): res.once(close)
[4] app.use(): res.once(close)
[5] app.use(): res.once(close)
[6] app.use(): res.once(close)
[7] app.use(): res.once(close)
[8] app.use(): res.once(close)
[9] app.use(): res.once(close)
[1] app.use(): res.once(end)
[2] app.use(): res.once(end)
[3] app.use(): res.once(end)
[4] app.use(): res.once(end)
[5] app.use(): res.once(end)
[6] app.use(): res.once(end)
[7] app.use(): res.once(end)
[8] app.use(): res.once(end)
[9] app.use(): res.once(end)
[10] app.use(): res.once(end)
You may also have a look on the discussion on the topic at stackexchange: http://codereview.stackexchange.com/questions/20069/monkey-patching-extra-events-in-node-js-http-express
If you have different needs regarding the functionality, please add a feature request.
npm install --save express-endgithub.com npmjs.com travis-ci.org coveralls.io inch-ci.org
MIT