@pm2/io
Version:
PM2.io NodeJS APM
160 lines (159 loc) • 4.69 kB
JavaScript
"use strict";
Object.defineProperty(exports, "__esModule", { value: true });
const EDS_1 = require("../EDS");
class Histogram {
constructor(opts) {
this._sample = new EDS_1.default();
this._count = 0;
this._sum = 0;
this._varianceM = 0;
this._varianceS = 0;
this._ema = 0;
this.used = false;
opts = opts || {};
this._measurement = opts.measurement;
this._callFn = null;
const methods = {
min: this.getMin,
max: this.getMax,
sum: this.getSum,
count: this.getCount,
variance: this._calculateVariance,
mean: this._calculateMean,
ema: this.getEma()
};
if (methods.hasOwnProperty(this._measurement)) {
this._callFn = methods[this._measurement];
}
else {
this._callFn = function () {
const percentiles = this.percentiles([0.5, 0.75, 0.95, 0.99, 0.999]);
const medians = {
median: percentiles[0.5],
p75: percentiles[0.75],
p95: percentiles[0.95],
p99: percentiles[0.99],
p999: percentiles[0.999]
};
return medians[this._measurement];
};
}
}
update(value) {
this.used = true;
this._count++;
this._sum += value;
this._sample.update(value);
this._updateMin(value);
this._updateMax(value);
this._updateVariance(value);
this._updateEma(value);
}
percentiles(percentiles) {
const values = this._sample
.toArray()
.sort(function (a, b) {
return (a === b)
? 0
: a - b;
});
const results = {};
for (let i = 0; i < percentiles.length; i++) {
const percentile = percentiles[i];
if (!values.length) {
results[percentile] = null;
continue;
}
const pos = percentile * (values.length + 1);
if (pos < 1) {
results[percentile] = values[0];
}
else if (pos >= values.length) {
results[percentile] = values[values.length - 1];
}
else {
const lower = values[Math.floor(pos) - 1];
const upper = values[Math.ceil(pos) - 1];
results[percentile] = lower + (pos - Math.floor(pos)) * (upper - lower);
}
}
return results;
}
val() {
if (typeof (this._callFn) === 'function') {
return this._callFn();
}
else {
return this._callFn;
}
}
getMin() {
return this._min;
}
getMax() {
return this._max;
}
getSum() {
return this._sum;
}
getCount() {
return this._count;
}
getEma() {
return this._ema;
}
fullResults() {
const percentiles = this.percentiles([0.5, 0.75, 0.95, 0.99, 0.999]);
return {
min: this._min,
max: this._max,
sum: this._sum,
variance: this._calculateVariance(),
mean: this._calculateMean(),
count: this._count,
median: percentiles[0.5],
p75: percentiles[0.75],
p95: percentiles[0.95],
p99: percentiles[0.99],
p999: percentiles[0.999],
ema: this._ema
};
}
_updateMin(value) {
if (this._min === undefined || value < this._min) {
this._min = value;
}
}
_updateMax(value) {
if (this._max === undefined || value > this._max) {
this._max = value;
}
}
_updateVariance(value) {
if (this._count === 1)
return this._varianceM = value;
const oldM = this._varianceM;
this._varianceM += ((value - oldM) / this._count);
this._varianceS += ((value - oldM) * (value - this._varianceM));
}
_updateEma(value) {
if (this._count <= 1)
return this._ema = this._calculateMean();
const alpha = 2 / (1 + this._count);
this._ema = value * alpha + this._ema * (1 - alpha);
}
_calculateMean() {
return (this._count === 0)
? 0
: this._sum / this._count;
}
_calculateVariance() {
return (this._count <= 1)
? null
: this._varianceS / (this._count - 1);
}
isUsed() {
return this.used;
}
}
exports.default = Histogram;