Implement metrics

metrics/circularBuffer.js

@@ -0,0 +1,30 @@
+class CircularBuffer {
+	constructor(size) {
+		this.buffer = new Array(size);
+		this.size = size;
+		this.head = 0;
+		this.tail = 0;
+	}
+
+	push(item) {
+		this.buffer[this.head] = item;
+		this.head = (this.head + 1) % this.size;
+		if (this.head === this.tail) {
+			this.tail = (this.tail + 1) % this.size;
+		}
+	}
+
+	toArray() {
+		const result = [];
+		let current = this.tail;
+		for (let i = 0; i < this.size; i++) {
+			if (this.buffer[current] !== undefined) {
+				result.push(this.buffer[current]);
+			}
+			current = (current + 1) % this.size;
+		}
+		return result;
+	}
+}
+
+module.exports = { CircularBuffer };