86 lines
1.4 KiB
JavaScript
86 lines
1.4 KiB
JavaScript
|
|
||
|
|
/**
|
||
|
|
* 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;
|
||
|
|
};
|
||
|
|
|