node.js rate limite scheduler

Scheduler.js

function ms(input) {
    if(typeof input === 'Number') {
        return input
    }

    var number = parseInt(input, 10);
    var unit = input.replace(number.toString(10), '').trim()
    switch(unit) {
        case 'd':
            number *= 24
        case 'h':
            number *= 60
        case 'm':
            number *= 60
        case 's':
            number *= 1000
    }

    return number
}

function Scheduler(limits) {
    this.smallestDelta = false
    this.timerRunning = false
    this.queueRunning = false

    this.limits = limits.map(function(limitDef) {
        var milis = ms(limitDef.time)
        var limit = {
            maxValue: limitDef.limit,
            totalWindow: milis,
            msPerTick: milis / limitDef.limit,
            ticksLeft: limitDef.limit
        }
        limit.timer = setInterval(function() {
            limit.ticksLeft = Math.min(limit.ticksLeft + 1, limit.maxValue)
        }, limit.msPerTick)

        if(!this.smallestDelta) {
            this.smallestDelta = limit.msPerTick
        }
        else {
            this.smallestDelta = Math.min(limit.msPerTick, this.smallestDelta)
        }

        // dont stay alive for this timer
        limit.timer.unref()
        return limit
    }.bind(this))

    this.queue = []
    this.lastUpdate = Date.now()
}

Scheduler.prototype.push = function(fnc) {
    this.queue.push(fnc)
    this.resumeQueue()
}

Scheduler.prototype.resumeQueue = function() {
    if(!this.queueRunning) {
        console.log(Date.now(), 'resumeQueue')
        setImmediate(this.execute.bind(this))
        this.queueRunning = true;
    }
}

Scheduler.prototype.tickAvailable = function() {
    return this.limits.every(function(limit) {
        return limit.ticksLeft > 0
    })
}

Scheduler.prototype.execute = function() {
    var hasToken = this.tickAvailable()
    if(this.queue.length > 0 && hasToken) {

        var max = this.limits.reduce(function(val, limit) {
            return Math.min(val, limit.ticksLeft)
        }, this.queue.length)
        for(var i=0;i<max;i++) {
            var fnc = this.queue.shift()
            fnc()
        }

        this.limits.forEach(function(limit) {
            limit.ticksLeft -= max
        })

        if(this.queue.length > 0) {
            setImmediate(this.execute.bind(this))
        }
    }
    else if(!hasToken) {

        if(!this.timerRunning) {
            // we still got work to do. keep the timers alive!
            this.limits.forEach(function(limit) {
                limit.timer.ref()
            })
            this.timerRunning = true
        }
        setTimeout(this.execute.bind(this), this.smallestDelta)
    }

    if(this.queue.length === 0) {
        // shutdown queue. everything done!
        this.timerRunning = this.queueRunning = false
        this.limits.map(function(limit) {
            limit.timer.unref()
        })
    }
}

module.exports = Scheduler

Scheduler.test.js

var Scheduler = require('./Scheduler')

var sched = new Scheduler([
    { limit: 10, time: '10s' },
    { limit: 500, time: '10m' }
])

for(var i=0;i<50;i++) {
    sched.push(function() {
        console.log(Date.now() - start, this.x, sched.limits.map(function(l) { return l.ticksLeft }))
    }.bind({ x: i }))
}
var start = Date.now()