refactor RingBuffer

.gitignore

@@ -1,2 +1,4 @@
 node_modules
 dist
+tsconfig.tsbuildinfo
+

engine/lib/RingBuffer.test.ts

@@ -0,0 +1,20 @@
+import { expect, test } from "vitest";
+import { claim, createRingBuffer } from "./RingBuffer.ts";
+
+test("RingBuffer", () => {
+	expect(() => createRingBuffer(3, () => ({}))).toThrow(
+		"size must be a power of two",
+	);
+
+	const pooled = createRingBuffer(4, () => ({}));
+
+	expect(pooled.size).toBe(4);
+	expect(pooled.cursor).toBe(0);
+	expect(pooled.buffer.length).toBe(4);
+
+	for (let i = 0; i < 8; i++) {
+		expect(claim(pooled)).toBe(pooled.buffer[i % 4]);
+	}
+
+	expect(pooled.cursor).toBe(0);
+});

engine/lib/RingBuffer.ts

@@ -1,25 +1,34 @@
-export default class RingBuffer<T> {
+export type Pooled<T> = {
 	size: number;
 	mask: number;
 	cursor: number;
 	buffer: Array<T>;
+};
 
-	constructor(size: number, blueprint: T) {
-		if ((size & (size - 1)) !== 0) {
-			throw new Error("size must be a power of two");
-		}
-
-		this.size = size;
-		this.mask = size - 1;
-		this.cursor = 0;
-		this.buffer = [];
-
-		for (let i = 0; i < size; i++) {
-			this.buffer.push(structuredClone(blueprint));
-		}
+export function createRingBuffer<T extends object>(
+	size: number,
+	create: () => T,
+): Pooled<T> {
+	if ((size & (size - 1)) !== 0) {
+		throw new Error("size must be a power of two");
 	}
 
-	next(): T {
-		return this.buffer[this.cursor++ & this.mask];
+	const buffer = new Array<T>(size);
+	for (let i = 0; i < size; i++) {
+		buffer[i] = create();
 	}
+
+	return {
+		size,
+		mask: size - 1,
+		cursor: 0,
+		buffer,
+	};
+}
+
+export function claim<T>(pooled: Pooled<T>): T {
+	const slot = pooled.buffer[pooled.cursor];
+	pooled.cursor = (pooled.cursor + 1) & pooled.mask;
+
+	return slot;
 }