Reduce memory allocations/improve perf of Counter

lib/counter.js

@@ -17,20 +17,36 @@ class Counter extends Metric {
 	 * @returns {void}
 	 */
 	inc(labels, value) {
-		if (!isObject(labels)) {
-			return inc.call(this, null)(labels, value);
+		let hash;
+		if (isObject(labels)) {
+			hash = hashObject(labels);
+			validateLabel(this.labelNames, labels);
+		} else {
+			value = labels;
+			labels = {};
 		}
 
-		const hash = hashObject(labels);
-		return inc.call(this, labels, hash)(value);
+		if (value && !Number.isFinite(value)) {
+			throw new TypeError(`Value is not a valid number: ${util.format(value)}`);
+		}
+		if (value < 0) {
+			throw new Error('It is not possible to decrease a counter');
+		}
+
+		if (value === null || value === undefined) value = 1;
+
+		setValue(this.hashMap, value, labels, hash);
 	}
 
 	/**
 	 * Reset counter
 	 * @returns {void}
 	 */
 	reset() {
-		return reset.call(this);
+		this.hashMap = {};
+		if (this.labelNames.length === 0) {
+			setValue(this.hashMap, 0);
+		}
 	}
 
 	async get() {
@@ -47,12 +63,10 @@ class Counter extends Metric {
 		};
 	}
 
-	labels() {
-		const labels = getLabels(this.labelNames, arguments) || {};
-		validateLabel(this.labelNames, labels);
-		const hash = hashObject(labels);
+	labels(...args) {
+		const labels = getLabels(this.labelNames, args) || {};
 		return {
-			inc: inc.call(this, labels, hash),
+			inc: this.inc.bind(this, labels),
 		};
 	}
 
@@ -63,38 +77,11 @@ class Counter extends Metric {
 	}
 }
 
-const reset = function () {
-	this.hashMap = {};
-
-	if (this.labelNames.length === 0) {
-		this.hashMap = setValue({}, 0);
-	}
-};
-
-const inc = function (labels, hash) {
-	return value => {
-		if (value && !Number.isFinite(value)) {
-			throw new TypeError(`Value is not a valid number: ${util.format(value)}`);
-		}
-		if (value < 0) {
-			throw new Error('It is not possible to decrease a counter');
-		}
-
-		labels = labels || {};
-		validateLabel(this.labelNames, labels);
-
-		const incValue = value === null || value === undefined ? 1 : value;
-
-		this.hashMap = setValue(this.hashMap, incValue, labels, hash);
-	};
-};
-
-function setValue(hashMap, value, labels, hash) {
-	hash = hash || '';
+function setValue(hashMap, value, labels = {}, hash = '') {
 	if (hashMap[hash]) {
 		hashMap[hash].value += value;
 	} else {
-		hashMap[hash] = { value, labels: labels || {} };
+		hashMap[hash] = { value, labels };
 	}
 	return hashMap;
 }