little node.js reloader

launcher.js

/*
 * This file is part of the Spludo Framework.
 * Copyright (c) 2009-2010 DracoBlue, http://dracoblue.net/
 *
 * Licensed under the terms of MIT License. For the full copyright and license
 * information, please see the LICENSE file in the root folder.
 */

/*
 * based on https://github.com/DracoBlue/spludo/blob/master/build/run_dev_server.js
 * Rewritten by marcello@cellosoft.com
 */

var child_process = require('child_process'),
    fs = require("fs"),
    util = require("util"),
    path = require("path"),
    log = require('log4js')().getLogger('launcher')

if (process.ARGV.length < 3) {
    log.error("usage: %s %s <server.js>", process.ARGV[0], process.ARGV[1])
    process.exit(1)
}

var child = null,
    watchedFiles = [],
    restarting = false,
    shuttingDown = false,
    selfPath = path.resolve(__filename),
    pidPath = selfPath + '.pid',
    mainScript = process.ARGV[2],
    mainPath = path.dirname(path.resolve(mainScript))+'/',
    currentDirectory = path.resolve(process.cwd())+'/',
    changedFiles = [],
    addedFiles = [],
    removedFiles = [],
    lastFailure = 0

fs.watchFile(selfPath, {interval:500}, function(current, previous) {
    if (current.mtime.valueOf() != previous.mtime.valueOf() ||
        current.ctime.valueOf() != previous.ctime.valueOf()) {
        log.warn("!!! " + selfPath + " has been modified (i.e. this hot swap code) Shutting down...")
        shutdown()
    }
})

function restart() {
    if (!restarting) {
        restarting = true
        changedFiles.forEach(function(file) {
            log.info('/// ' + file)
        })
        addedFiles.forEach(function(file) {
            log.info('+++ ' + file)
        })
        removedFiles.forEach(function(file) {
            log.info('--- ' + file)
        })
        if (child) {
            stop()
        } else {
            start()
        }
    }
}

function start() {
    try {
        var pidData = fs.readFileSync(pidPath);
        var oldPid = parseInt(pidData)
        if (oldPid) {
            log.info('Killing old server ('+oldPid+')')
            process.kill(oldPid)
        }
    } catch (e) {}

    restarting = false
    
    watchFiles()

    child = child_process.spawn(process.ARGV[0], ['--debug', mainScript])

    log.info("<"+ mainScript + "> Started... (pid = "+child.pid+")")

    fs.writeFileSync(pidPath, String(child.pid))

    child.stdout.on('data', function (data) {
        process.stdout.write(data)
    })

    child.stderr.on('data', function (data) {
        util.print(data)
    })

    child.on('exit', function (code, signal) {
        child = null
        try {
            fs.unlinkSync(pidPath)
        } catch (e) {}
        if (shuttingDown) {
            process.exit(0)
        }
        log.warn("<" + mainScript + "> Exited with code " + code + (signal ? " ("+signal+")" : ""))
        if (!restarting && (new Date - lastFailure) < 2000) {
            log.warn("Two exits in a row, waiting for file change...")
            return
        }
        lastFailure = new Date
        start()
    })

}

function stop() {
    child && child.kill()
}

function findFiles(callback) {
    child_process.exec('find '+mainPath, function(error, stdout, stderr) {
        callback(null, stdout.trim().split("\n").filter(function(file) {
            return !/\.(pid|sock)$/.test(file) && file != selfPath
        }).map(function(file) {
            return path.resolve(file)
        }))
    })
}

function watchFiles() {
    findFiles(function(err, files) {
        // Unwatch any file in watchedFiles that's not in files
        watchedFiles = watchedFiles.filter(function(watchedFile) {
            if (files.some(function(file) { return file == watchedFile })) {
                return true
            }
            log.debug("unwatching "+watchedFile)
            fs.unwatchFile(watchedFile)
            return false
        })

        changedFiles = []
        addedFiles = []
        removedFiles = []
        
        files.forEach(function(fullFile) {
            // Don't watch a file we're already watching
            if (watchedFiles.some(function(watchedFile) { return fullFile == watchedFile })) {
                return
            }

            watchedFiles.push(fullFile)
            var stats = fs.statSync(fullFile)
            var isDirectory = stats.isDirectory()
            var file = fullFile.replace(currentDirectory, "")
            log.debug("watching "+file)

            fs.watchFile(file, {interval:500}, function(current, previous) {
                if (shuttingDown) return
                
                if (current.mtime.valueOf() != previous.mtime.valueOf() ||
                    current.ctime.valueOf() != previous.ctime.valueOf()) {
                    if (isDirectory) {
                        findFiles(function(err,newFiles) {
                            if (newFiles.length != watchedFiles.length) {
                                var originals = {}
                                files.forEach(function(file) { originals[file] = true })
                                newFiles.forEach(function(file) {
                                    if (originals[file]) {
                                        delete originals[file]
                                    } else {
                                        addedFiles.push(file)
                                    }
                                })
                                for (var file in originals) {
                                    removedFiles.push(file)
                                }
                                process.nextTick(restart)
                            }
                        })
                    } else {
                        changedFiles.push(file)
                        process.nextTick(restart)
                    }
                }
            })
        })
    })
}

function shutdown() {
    shuttingDown = true
    stop()
    watchedFiles.forEach(function(file) { fs.unwatchFile(file) })
}

process.on('exit', shutdown)

start()

I LIKE.

I should eventually steal your features and add them to github.com/dtrejo/run.js ;)

Cheers!
-David

by all means