mirror of
https://github.com/vercel-labs/scriptc.git
synced 2026-10-28 06:53:42 +08:00
Chris Tate
ee49946d32
InternTable keys can be arrays of numbers or of strings, compared by their elements: numbers by SameValueZero, strings by content, and holes equal to each other only. The runtime stores an array key as one byte string that encodes its elements; the Node.js implementation encodes it into a Map key the same way. Replaced table indexes are now freed. Every thread that uses a table records the epoch it read at the start of each lookup and insert, and an index retired in an earlier epoch than every recorded one is freed. Worker threads stop holding retirements back when they exit. Number indexes keep a tag byte per slot ahead of the key and value pairs, so a lookup of an absent key reads the dense tag bytes instead of pairs. getOrInsertComputed lowers an arrow callback with an expression body in place, with its parameter bound to the key, so interning through `(key) => new T(...)` creates no closure.
80 lines
3.1 KiB
TypeScript
80 lines
3.1 KiB
TypeScript
import { Worker, isMainThread, parentPort, workerData } from "node:worker_threads";
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import { InternTable } from "@scriptc/experimental";
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// InternTable (@scriptc/experimental) with array keys: arrays of numbers or
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// of strings compare by their elements (numbers by SameValueZero, strings
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// by content), so a freshly built key finds the value stored under an equal
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// one. Workers intern list types keyed by their member ids. Node.js prints
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// the same.
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class List {
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readonly members: readonly number[];
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readonly label: string;
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constructor(members: readonly number[], label: string) {
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this.members = members;
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this.label = label;
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}
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}
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const lists = new InternTable<readonly number[], List>("arrays.lists");
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const paths = new InternTable<readonly string[], number>("arrays.paths");
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function listOf(members: readonly number[]): List {
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return lists.getOrInsertComputed(members, (key) => new List([...key], key.join("|")));
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}
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if (isMainThread) {
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const a = listOf([1, 2, 3]);
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const b = listOf([1, 2, 3]);
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const c = listOf([1, 2]);
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const d = listOf([3, 2, 1]);
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console.log(a === b, a === c, a === d, a.label, c.label, d.label, lists.size);
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console.log(lists.get([1, 2, 3]) === a, lists.get([1, 2, 3, 4]), lists.has([1, 2]), lists.has([2, 1]));
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// SameValueZero elements.
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const z = listOf([-0, NaN]);
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console.log(listOf([0, 0 / 0]) === z, lists.has([0, NaN]), lists.has([NaN, 0]), lists.size);
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// Empty and long keys.
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const empty = listOf([]);
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const long: number[] = [];
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for (let i = 0; i < 500; i++) long.push(i * 1.5);
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const big = listOf(long);
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console.log(listOf([]) === empty, empty.label === "", listOf([...long]) === big, big.members.length);
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long.push(1);
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console.log(lists.has(long), lists.size);
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// Holes differ from numbers.
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const holed = new Array<number>(3);
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holed[0] = 1;
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const again = new Array<number>(3);
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again[0] = 1;
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console.log(listOf(holed).members.length, listOf(again) === listOf(holed), lists.has([1, 0, 0]), lists.has([1]));
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// String arrays compare by content, element by element.
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console.log(paths.getOrInsert(["ab", "c"], 1), paths.getOrInsert(["a", "bc"], 2), paths.getOrInsert(["ab", "c"], 3));
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console.log(paths.get(["a" + "b", "c"]), paths.get(["abc"]), paths.get([]), paths.getOrInsert([], 4), paths.get([""]));
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console.log(paths.getOrInsert([""], 5), paths.getOrInsert(["", ""], 6), paths.get([""]), paths.size);
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const results: string[] = [];
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let pending = 3;
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for (let w = 0; w < 3; w++) {
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const worker = new Worker(new URL(import.meta.url), { workerData: { seed: w } });
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worker.on("message", (message: unknown) => {
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results[w] = message as string;
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});
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worker.on("exit", () => {
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if (--pending === 0) for (const line of results) console.log(line);
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});
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}
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} else {
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const { seed } = workerData as { seed: number };
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let total = 0;
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let bad = 0;
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for (let n = 0; n < 5000; n++) {
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const k = (n * 13 + seed * 1667) % 5000;
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const members = [k % 7, k % 11, k];
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const list = listOf(members);
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if (list.label !== members.join("|")) bad++;
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total += list.members[2]!;
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}
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parentPort!.postMessage(`worker ${seed}: total=${total} bad=${bad}`);
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}
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