update .gitignore

node_modules/tx2/src/utils/probes/EWMA.js

@@ -0,0 +1,29 @@
+
+var units = require('./units');
+
+module.exports = ExponentiallyWeightedMovingAverage;
+
+function ExponentiallyWeightedMovingAverage(timePeriod, tickInterval) {
+  this._timePeriod   = timePeriod || 1 * units.MINUTE;
+  this._tickInterval = tickInterval || ExponentiallyWeightedMovingAverage.TICK_INTERVAL;
+  this._alpha        = 1 - Math.exp(-this._tickInterval / this._timePeriod);
+  this._count        = 0;
+  this._rate         = 0;
+};
+
+ExponentiallyWeightedMovingAverage.TICK_INTERVAL = 5 * units.SECONDS;
+
+ExponentiallyWeightedMovingAverage.prototype.update = function(n) {
+  this._count += n;
+};
+
+ExponentiallyWeightedMovingAverage.prototype.tick = function() {
+  var instantRate = this._count / this._tickInterval;
+  this._count     = 0;
+
+  this._rate += (this._alpha * (instantRate - this._rate));
+};
+
+ExponentiallyWeightedMovingAverage.prototype.rate = function(timeUnit) {
+  return (this._rate || 0) * timeUnit;
+};