Run function for a Node cron job

cron.coffee

require './schema.js'
mongoose    = require "mongoose"
mongodb     = require "mongodb"
sys         = require 'sys'
lock        = require './lock.js'
run         = require './run.js'

# Sample cron
# * * * * * /usr/local/bin/node /var/some/dir/cron.js > /var/log/cronjs.log
run.attempt('every 1 minute', () ->
    lock.check('one', (conflict) ->
        return false if conflict

        # Pull all the links that expire today
        # This is done by selecting links via <date logged> - timeframe
        # Then sending out emails

        db = mongoose.connect(mongurl)
        Link = mongoose.model('links', LinkSchema)
        date = new Date()

        # Iterate through items
        Link.find(
            date_expire:
                $gte: new Date()
        ).sort('date','descending').execFind((err,docs)->
            console.log(err) if err
            // Do something with docs

            lock.destroy()
            process.kill(process.pid, 'SIGTERM');
        )
    )
)

lock.coffee

fs = require 'fs'
path = require 'path'
lockPath = "/var/www/some/dir/"
lockFile = ''

process.on('SIGTERM', () ->
    process.exit(1)
)

exports.check = (filename, contents..., callback) ->
    lockFile = "#{lockPath}/#{filename}.lock"
    path.exists lockFile, (exists) ->
        fs.writeFileSync(lockFile, contents.join('')) unless exists
        console.log "Lock file #{filename} already exists. Exiting..." if exists
        callback exists

exports.destroy = () ->
    path.exists(lockFile, (exists) ->
        fs.unlinkSync(lockFile) if exists
    )

run.coffee

exports.attempt = (time, callback) ->
    d = new Date
    hours = d.getHours()
    minutes = d.getMinutes()

    m = time.match(/every ([0-9]+) hours?/)
    if(minutes == 0 && m && hours % m[1] == 0) then return(callback())
    m = time.match(/every ([0-9]+) minutes?/)
    if(m && minutes % m[1] == 0) then return(callback())
    false