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/**
* Expose `Backoff`.
*/
module.exports = Backoff;
/**
* Initialize backoff timer with `opts`.
*
* - `min` initial timeout in milliseconds [100]
* - `max` max timeout [10000]
* - `jitter` [0]
* - `factor` [2]
*
* @param {Object} opts
* @api public
*/
function Backoff(opts) {
opts = opts || {};
this.ms = opts.min || 100;
this.max = opts.max || 10000;
this.factor = opts.factor || 2;
this.jitter = opts.jitter > 0 && opts.jitter <= 1 ? opts.jitter : 0;
this.attempts = 0;
}
/**
* Return the backoff duration.
*
* @return {Number}
* @api public
*/
Backoff.prototype.duration = function(){
var ms = this.ms * Math.pow(this.factor, this.attempts++);
if (this.jitter) {
var rand = Math.random();
var deviation = Math.floor(rand * this.jitter * ms);
ms = (Math.floor(rand * 10) & 1) == 0 ? ms - deviation : ms + deviation;
}
return Math.min(ms, this.max) | 0;
};
/**
* Reset the number of attempts.
*
* @api public
*/
Backoff.prototype.reset = function(){
this.attempts = 0;
};
/**
* Set the minimum duration
*
* @api public
*/
Backoff.prototype.setMin = function(min){
this.ms = min;
};
/**
* Set the maximum duration
*
* @api public
*/
Backoff.prototype.setMax = function(max){
this.max = max;
};
/**
* Set the jitter
*
* @api public
*/
Backoff.prototype.setJitter = function(jitter){
this.jitter = jitter;
};
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