Improve performance of hashObject

CHANGELOG.md

@@ -12,6 +12,7 @@ project adheres to [Semantic Versioning](http://semver.org/).
 ### Changed
 
 - remove unnecessary loop from `osMemoryHeapLinux`
+- Improve performance of `hashObject` by using pre-sorted array of label names
 
 ### Added
 

lib/counter.js

@@ -40,7 +40,7 @@ class Counter extends Metric {
 	incWithoutExemplar(labels, value) {
 		let hash = '';
 		if (isObject(labels)) {
-			hash = hashObject(labels);
+			hash = hashObject(labels, this.sortedLabelNames);
 			validateLabel(this.labelNames, labels);
 		} else {
 			value = labels;
@@ -130,7 +130,7 @@ class Counter extends Metric {
 	remove(...args) {
 		const labels = getLabels(this.labelNames, args) || {};
 		validateLabel(this.labelNames, labels);
-		return removeLabels.call(this, this.hashMap, labels);
+		return removeLabels.call(this, this.hashMap, labels, this.sortedLabelNames);
 	}
 }
 

lib/gauge.js

@@ -120,7 +120,7 @@ class Gauge extends Metric {
 	}
 
 	_getValue(labels) {
-		const hash = hashObject(labels || {});
+		const hash = hashObject(labels || {}, this.sortedLabelNames);
 		return this.hashMap[hash] ? this.hashMap[hash].value : 0;
 	}
 
@@ -139,7 +139,7 @@ class Gauge extends Metric {
 	remove(...args) {
 		const labels = getLabels(this.labelNames, args);
 		validateLabel(this.labelNames, labels);
-		removeLabels.call(this, this.hashMap, labels);
+		removeLabels.call(this, this.hashMap, labels, this.sortedLabelNames);
 	}
 }
 
@@ -158,7 +158,7 @@ function setDelta(gauge, labels, delta) {
 	}
 
 	validateLabel(gauge.labelNames, labels);
-	const hash = hashObject(labels);
+	const hash = hashObject(labels, gauge.sortedLabelNames);
 	setValueDelta(gauge.hashMap, delta, labels, hash);
 }
 

lib/histogram.js

@@ -83,7 +83,7 @@ class Histogram extends Metric {
 	}
 
 	updateExemplar(labels, value, exemplarLabels) {
-		const hash = hashObject(labels);
+		const hash = hashObject(labels, this.sortedLabelNames);
 		const bound = findBound(this.upperBounds, value);
 		const { bucketExemplars } = this.hashMap[hash];
 		let exemplar = bucketExemplars[bound];
@@ -132,7 +132,7 @@ class Histogram extends Metric {
 	 * @returns {void}
 	 */
 	zero(labels) {
-		const hash = hashObject(labels);
+		const hash = hashObject(labels, this.sortedLabelNames);
 		this.hashMap[hash] = createBaseValues(
 			labels,
 			this.bucketValues,
@@ -167,7 +167,7 @@ class Histogram extends Metric {
 	remove(...args) {
 		const labels = getLabels(this.labelNames, args);
 		validateLabel(this.labelNames, labels);
-		removeLabels.call(this, this.hashMap, labels);
+		removeLabels.call(this, this.hashMap, labels, this.sortedLabelNames);
 	}
 }
 
@@ -214,7 +214,7 @@ function observe(labels) {
 			);
 		}
 
-		const hash = hashObject(labelValuePair.labels);
+		const hash = hashObject(labelValuePair.labels, this.sortedLabelNames);
 		let valueFromMap = this.hashMap[hash];
 		if (!valueFromMap) {
 			valueFromMap = createBaseValues(

lib/metric.js

@@ -39,10 +39,17 @@ class Metric {
 		if (!validateLabelName(this.labelNames)) {
 			throw new Error('Invalid label name');
 		}
+
 		if (this.collect && typeof this.collect !== 'function') {
 			throw new Error('Optional "collect" parameter must be a function');
 		}
 
+		if (this.labelNames) {
+			this.sortedLabelNames = [...this.labelNames].sort();
+		} else {
+			this.sortedLabelNames = [];
+		}
+
 		this.reset();
 
 		for (const register of this.registers) {

lib/summary.js

@@ -115,7 +115,7 @@ class Summary extends Metric {
 	remove(...args) {
 		const labels = getLabels(this.labelNames, args);
 		validateLabel(this.labelNames, labels);
-		removeLabels.call(this, this.hashMap, labels);
+		removeLabels.call(this, this.hashMap, labels, this.sortedLabelNames);
 	}
 }
 
@@ -170,7 +170,7 @@ function observe(labels) {
 			);
 		}
 
-		const hash = hashObject(labelValuePair.labels);
+		const hash = hashObject(labelValuePair.labels, this.sortedLabelNames);
 		let summaryOfLabel = this.hashMap[hash];
 		if (!summaryOfLabel) {
 			summaryOfLabel = {

lib/util.js

@@ -14,8 +14,12 @@ exports.getValueAsString = function getValueString(value) {
 	}
 };
 
-exports.removeLabels = function removeLabels(hashMap, labels) {
-	const hash = hashObject(labels);
+exports.removeLabels = function removeLabels(
+	hashMap,
+	labels,
+	sortedLabelNames,
+) {
+	const hash = hashObject(labels, sortedLabelNames);
 	delete hashMap[hash];
 };
 
@@ -59,32 +63,44 @@ exports.getLabels = function (labelNames, args) {
 	return acc;
 };
 
-function hashObject(labels) {
-	// We don't actually need a hash here. We just need a string that
-	// is unique for each possible labels object and consistent across
-	// calls with equivalent labels objects.
-	let keys = Object.keys(labels);
+function fastHashObject(keys, labels) {
 	if (keys.length === 0) {
 		return '';
 	}
-	// else
-	if (keys.length > 1) {
-		keys = keys.sort(); // need consistency across calls
-	}
 
 	let hash = '';
-	let i = 0;
-	const size = keys.length;
-	for (; i < size - 1; i++) {
-		hash += `${keys[i]}:${labels[keys[i]]},`;
+
+	for (let i = 0; i < keys.length; i++) {
+		const key = keys[i];
+		const value = labels[key];
+		if (value === undefined) continue;
+
+		hash += `${key}:${value},`;
 	}
-	hash += `${keys[i]}:${labels[keys[i]]}`;
+
 	return hash;
 }
+
+function hashObject(labels, labelNames) {
+	// We don't actually need a hash here. We just need a string that
+	// is unique for each possible labels object and consistent across
+	// calls with equivalent labels objects.
+
+	if (labelNames) {
+		return fastHashObject(labelNames, labels);
+	}
+
+	const keys = Object.keys(labels);
+	if (keys.length > 1) {
+		keys.sort(); // need consistency across calls
+	}
+
+	return fastHashObject(keys, labels);
+}
 exports.hashObject = hashObject;
 
 exports.isObject = function isObject(obj) {
-	return obj === Object(obj);
+	return obj !== null && typeof obj === 'object';
 };
 
 exports.nowTimestamp = function nowTimestamp() {