Method constructor

lib/histogram.js:19–65

(config)

class Histogram extends Metric {
	constructor(config) {
		super(config, {
			buckets: [0.005, 0.01, 0.025, 0.05, 0.1, 0.25, 0.5, 1, 2.5, 5, 10],
		});

		this.type = 'histogram';
		this.defaultLabels = {};
		this.defaultExemplarLabelSet = {};
		this.enableExemplars = false;

		for (const label of this.labelNames) {
			if (label === 'le') {
				throw new Error('le is a reserved label keyword');
			}
		}

		this.upperBounds = this.buckets;
		this.bucketValues = this.upperBounds.reduce((acc, upperBound) => {
			acc[upperBound] = 0;
			return acc;
		}, {});

		if (config.enableExemplars) {
			this.enableExemplars = true;
			this.bucketExemplars = this.upperBounds.reduce((acc, upperBound) => {
				acc[upperBound] = null;
				return acc;
			}, {});
			Object.freeze(this.bucketExemplars);
			this.observe = this.observeWithExemplar;
		} else {
			this.observe = this.observeWithoutExemplar;
		}

		Object.freeze(this.bucketValues);
		Object.freeze(this.upperBounds);

		if (this.labelNames.length === 0) {
			this.hashMap = {
				[hashObject({})]: createBaseValues(
					{},
					this.bucketValues,
					this.bucketExemplars,
				),
			};
		}
	}

	/**
	 * Observe a value in histogram