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index.js
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index.js
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var cluster = require('cluster')
var http = require('http')
var numCPUs = require('os').cpus().length
var net = require('net')
var EventEmitter = require('events').EventEmitter
var split = require('split')
var parse = require('through-parse')
var through = require('through')
var fs = require('fs')
var path = require('path')
var headpath = path.join(__dirname + '/HEAD')
var ee = new EventEmitter
function readHEAD() {
return fs.readFileSync(headpath).toString()
}
function writeHEAD(value) {
return fs.writeFileSync(headpath, value)
}
function reply(cmd, value) {
ee.emit('reply', { cmd: cmd, value: value || 'OK' })
}
module.exports = function(opts) {
if (typeof opts == 'string') {
opts = { target: opts }
}
if (typeof opts['zero-downtime'] === 'undefined') {
opts['zero-downtime'] = true
}
if (opts.head) {
headpath = opts.head
}
if (!cluster.isMaster) {
try {
require(readHEAD())
}
catch(ex) {
console.error(ex)
}
return
}
writeHEAD(opts.target)
cluster.on('exit', function(worker, code, signal) {
if (worker.suicide === true) return
console.log('Worker process crashed! (%d/%d/%s)',
worker.process.pid, code, signal)
if (opts['zero-downtime']) {
var fork = cluster.fork()
console.log('Restarting fork. New pid:', fork.process.pid)
}
})
function sig(cmd, value) {
if (cmd !== 'upgrade') return broadcast()
var mpath = path.resolve(value)
fs.stat(mpath, function(err, stat) {
if (err) return reply(cmd, err)
writeHEAD(mpath)
broadcast()
})
function broadcast() {
var keys = Object.keys(cluster.workers)
keys.forEach(function(id, index) {
var worker = cluster.workers[id]
if (cmd === 'message') {
worker.send(value)
}
else if (cmd === 'upgrade' && opts['zero-downtime']) {
if (index % 2 === 0 && !isLast(index)) {
cluster.fork()
setImmediate(function() {
disconnect(worker)
})
}
else {
disconnect(worker, function() {
cluster.fork()
})
}
}
else if (cmd === 'upgrade' || cmd === 'kill') {
worker.kill()
cluster.fork()
}
else if (cmd === 'die') {
worker.kill()
if (isLast(index)) {
reply(cmd)
process.kill()
}
}
})
reply(cmd)
function disconnect(worker, cb) {
worker.disconnect()
var timeout = setTimeout(function() {
worker.kill()
cb && cb()
}, 60000)
worker.on('disconnect', function() {
clearTimeout(timeout)
worker.kill()
cb && cb()
})
}
function isLast(i) { return i === keys.length - 1 }
}
}
//
// create a server to listen for out of process
// instructions to kill, disconnect or message workers.
//
var server = net.createServer(function(conn) {
var cmd
function onReply(d) {
conn.write(JSON.stringify(d) + '\n')
}
ee.on('reply', onReply)
conn.on('close', function() { ee.removeListener('reply', onReply) })
conn.on('error', function(err) { reply(cmd, err) })
conn
.pipe(split())
.pipe(parse())
.pipe(through(function(data) {
if (!data || !data.cmd) return
cmd = data.cmd
switch(cmd) {
case 'upgrade':
if (opts['pre-upgrade']) {
return require(opts['pre-upgrade'])(data, function(err, value) {
if (err) return reply(cmd, err)
sig('upgrade', value || data.value || opts.target)
})
}
sig('upgrade', data.value || opts.target)
break
case 'die':
sig('die')
break
case 'kill':
sig('kill')
break
case 'message':
if (data.value) {
sig('message', data.value)
}
break
}
}))
})
server.listen(opts.port || 3000, opts.address, function() {
console.log('Starting on port %d', opts.port)
})
var forks = opts.forks || numCPUs
for (var i = 0; i < forks; i++) {
cluster.fork()
}
}