Reduce memory allocations/improve perf of Gauge

Author: zbjornson

CHANGELOG.md

@@ -12,9 +12,10 @@ project adheres to [Semantic Versioning](http://semver.org/).
 ### Changed
 
 - Don't add event listener to `process` if cluster module is not used.
-- fix: set labels for default memory metrics on linux
-- fix: fix DEP0152 deprecation warning in Node.js v16+
+- fix: set labels for default memory metrics on linux.
+- fix: fix DEP0152 deprecation warning in Node.js v16+.
 - fix: Set aggregation mode for newer event loop metrics. (Fixes [#418](https://github.com/siimon/prom-client/issues/418))
+- Improve performance of/reduce memory allocations in Gauge.
 
 ### Added
 

benchmarks/gauge.js

@@ -0,0 +1,42 @@
+'use strict';
+
+const { getLabelNames, labelCombinationFactory } = require('./utils/labels');
+
+module.exports = setupGaugeSuite;
+
+function setupGaugeSuite(suite) {
+	suite.add(
+		'inc',
+		labelCombinationFactory([], (client, { Gauge }, labels) =>
+			Gauge.inc(labels, 1),
+		),
+		{ teardown, setup: setup(0) },
+	);
+
+	suite.add(
+		'inc with labels',
+		labelCombinationFactory([8, 8], (client, { Gauge }, labels) =>
+			Gauge.inc(labels, 1),
+		),
+		{ teardown, setup: setup(2) },
+	);
+}
+
+function setup(labelCount) {
+	return client => {
+		const registry = new client.Registry();
+
+		const Gauge = new client.Gauge({
+			name: 'Gauge',
+			help: 'Gauge',
+			labelNames: getLabelNames(labelCount),
+			registers: [registry],
+		});
+
+		return { registry, Gauge };
+	};
+}
+
+function teardown(client, { registry }) {
+	registry.clear();
+}

benchmarks/index.js

@@ -9,6 +9,7 @@ const benchmarks = createRegressionBenchmark(currentClient, [
 
 benchmarks.suite('registry', require('./registry'));
 benchmarks.suite('histogram', require('./histogram'));
+benchmarks.suite('gauge', require('./gauge'));
 benchmarks.suite('summary', require('./summary'));
 benchmarks.run().catch(err => {
 	console.error(err.stack);

lib/gauge.js

@@ -24,18 +24,20 @@ class Gauge extends Metric {
 	 * @returns {void}
 	 */
 	set(labels, value) {
-		if (!isObject(labels)) {
-			return set.call(this, null)(labels, value);
-		}
-		return set.call(this, labels)(value);
+		value = getValueArg(labels, value);
+		labels = getLabelArg(labels);
+		set(this, labels, value);
 	}
 
 	/**
 	 * Reset gauge
 	 * @returns {void}
 	 */
 	reset() {
-		return reset.call(this);
+		this.hashMap = {};
+		if (this.labelNames.length === 0) {
+			setValue(this.hashMap, 0, {});
+		}
 	}
 
 	/**
@@ -45,7 +47,10 @@ class Gauge extends Metric {
 	 * @returns {void}
 	 */
 	inc(labels, value) {
-		inc.call(this, labels)(value);
+		value = getValueArg(labels, value);
+		labels = getLabelArg(labels);
+		if (value === undefined) value = 1;
+		set(this, labels, this._getValue(labels) + value);
 	}
 
 	/**
@@ -55,7 +60,10 @@ class Gauge extends Metric {
 	 * @returns {void}
 	 */
 	dec(labels, value) {
-		dec.call(this, labels)(value);
+		value = getValueArg(labels, value);
+		labels = getLabelArg(labels);
+		if (value === undefined) value = 1;
+		set(this, labels, this._getValue(labels) - value);
 	}
 
 	/**
@@ -64,7 +72,12 @@ class Gauge extends Metric {
 	 * @returns {void}
 	 */
 	setToCurrentTime(labels) {
-		return setToCurrentTime.call(this, labels)();
+		const now = Date.now() / 1000;
+		if (labels === undefined) {
+			this.set(now);
+		} else {
+			this.set(labels, now);
+		}
 	}
 
 	/**
@@ -78,7 +91,11 @@ class Gauge extends Metric {
 	 * });
 	 */
 	startTimer(labels) {
-		return startTimer.call(this, labels)();
+		const start = process.hrtime();
+		return endLabels => {
+			const delta = process.hrtime(start);
+			this.set(Object.assign({}, labels, endLabels), delta[0] + delta[1] / 1e9);
+		};
 	}
 
 	async get() {
@@ -104,11 +121,11 @@ class Gauge extends Metric {
 		const labels = getLabels(this.labelNames, arguments);
 		validateLabel(this.labelNames, labels);
 		return {
-			inc: inc.call(this, labels),
-			dec: dec.call(this, labels),
-			set: set.call(this, labels),
-			setToCurrentTime: setToCurrentTime.call(this, labels),
-			startTimer: startTimer.call(this, labels),
+			inc: this.inc.bind(this, labels),
+			dec: this.dec.bind(this, labels),
+			set: this.set.bind(this, labels),
+			setToCurrentTime: this.setToCurrentTime.bind(this, labels),
+			startTimer: this.startTimer.bind(this, labels),
 		};
 	}
 
@@ -119,78 +136,21 @@ class Gauge extends Metric {
 	}
 }
 
-function setToCurrentTime(labels) {
-	return () => {
-		const now = Date.now() / 1000;
-		if (labels === undefined) {
-			this.set(now);
-		} else {
-			this.set(labels, now);
-		}
-	};
-}
-
-function startTimer(startLabels) {
-	return () => {
-		const start = process.hrtime();
-		return endLabels => {
-			const delta = process.hrtime(start);
-			this.set(
-				Object.assign({}, startLabels, endLabels),
-				delta[0] + delta[1] / 1e9,
-			);
-		};
-	};
-}
-
-function dec(labels) {
-	return value => {
-		const data = convertLabelsAndValues(labels, value);
-		if (data.value === undefined) data.value = 1;
-		this.set(data.labels, this._getValue(data.labels) - data.value);
-	};
-}
-
-function inc(labels) {
-	return value => {
-		const data = convertLabelsAndValues(labels, value);
-		if (data.value === undefined) data.value = 1;
-		this.set(data.labels, this._getValue(data.labels) + data.value);
-	};
-}
-
-function set(labels) {
-	return value => {
-		if (typeof value !== 'number') {
-			throw new TypeError(`Value is not a valid number: ${util.format(value)}`);
-		}
-
-		labels = labels || {};
+function set(gauge, labels, value) {
+	if (typeof value !== 'number') {
+		throw new TypeError(`Value is not a valid number: ${util.format(value)}`);
+	}
 
-		validateLabel(this.labelNames, labels);
-		this.hashMap = setValue(this.hashMap, value, labels);
-	};
+	validateLabel(gauge.labelNames, labels);
+	setValue(gauge.hashMap, value, labels);
 }
 
-function reset() {
-	this.hashMap = {};
-
-	if (this.labelNames.length === 0) {
-		this.hashMap = setValue({}, 0, {});
-	}
+function getLabelArg(labels) {
+	return isObject(labels) ? labels : {};
 }
 
-function convertLabelsAndValues(labels, value) {
-	if (!isObject(labels)) {
-		return {
-			value: labels,
-			labels: {},
-		};
-	}
-	return {
-		labels,
-		value,
-	};
+function getValueArg(labels, value) {
+	return isObject(labels) ? value : labels;
 }
 
 module.exports = Gauge;