the great bench

bench/churn-sweep.ts

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+// bench/churn-sweep.ts
+import { Bench } from "tinybench";
+import { type Box, box } from "../engine/lib/box.ts";
+import {
+	createDictionary,
+	deleteEntry,
+	setEntry,
+} from "../engine/lib/Dictionary.ts";
+import MapArray from "../engine/lib/MapArray.ts";
+
+const SIZES = [100, 250, 500, 999, 2500, 5000, 10000];
+const CHURN_N = 100;
+const churnKeys = Array.from({ length: CHURN_N }, (_, i) => `churn-${i}`);
+
+let sink = 0;
+
+function makeBaseData(size: number): Array<[string, Box<number>]> {
+	const data: Array<[string, Box<number>]> = [];
+	let i = size;
+	while (i-- > 0) data.push([String(i), box(i)]);
+	return data;
+}
+
+type Row = {
+	structure: string;
+	size: number;
+	latencyNsAvg: number;
+	latencyNsMed: number;
+};
+const rows: Row[] = [];
+
+for (const size of SIZES) {
+	const baseData = makeBaseData(size);
+
+	const ma = new MapArray(structuredClone(baseData));
+	const dict = createDictionary(structuredClone(baseData));
+	const map = new Map(structuredClone(baseData));
+
+	const bench = new Bench({ name: `churn @ size=${size}`, time: 500 });
+
+	bench
+		.add("MapArray", () => {
+			for (const key of churnKeys) ma.set(key, box(1));
+			for (const key of churnKeys) ma.delete(key);
+			sink += ma.entries().length;
+		})
+		.add("Dictionary", () => {
+			for (const key of churnKeys) setEntry(dict, [key, box(1)]);
+			for (const key of churnKeys) deleteEntry(dict, key);
+			sink += dict.entries.length;
+		})
+		.add("Map", () => {
+			for (const key of churnKeys) map.set(key, box(1));
+			for (const key of churnKeys) map.delete(key);
+			sink += map.size;
+		});
+
+	await bench.run();
+
+	for (const task of bench.tasks) {
+		const res = task.result;
+		if (!res) continue;
+		rows.push({
+			structure: task.name,
+			size,
+			latencyNsAvg: res.latency.mean,
+			latencyNsMed: res.latency.p50 ?? res.latency.mean,
+		});
+	}
+
+	console.log(`-- size=${size} done --`);
+	console.table(bench.table());
+}
+
+// CSV output
+const header = "structure,size,latency_ns_avg,latency_ns_med";
+const csvLines = rows.map(
+	(r) =>
+		`${r.structure},${r.size},${r.latencyNsAvg.toFixed(2)},${r.latencyNsMed.toFixed(2)}`,
+);
+const csv = [header, ...csvLines].join("\n");
+
+(await Deno.writeTextFile?.("churn-sweep.csv", csv)) ??
+	(await import("node:fs/promises")).then((fs) =>
+		fs.writeFile("churn-sweep.csv", csv),
+	);
+
+console.log("\nWrote churn-sweep.csv");
+console.log("sink (ignore):", sink);