Offload functions to worker threads with shared memory primitives for Node.js.
feat: add sqlite example demonstrating task-arg caching for shared db
Opens a SQLite database once on the worker via a task-arg. All
subsequent queries receive the cached db instance — the DatabaseSync
object never crosses thread boundaries.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
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README.md
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README.md
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- [`examples/shared-state`](examples/shared-state) -- mutex-protected shared struct
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- [`examples/multi-module`](examples/multi-module) -- moroutines from multiple modules on one worker
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- [`examples/transfer`](examples/transfer) -- zero-copy buffer transfer to and from a worker
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- [`examples/sqlite`](examples/sqlite) -- shared SQLite database on a worker via task-arg caching
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examples/sqlite/db.ts
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examples/sqlite/db.ts
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import { DatabaseSync } from 'node:sqlite';
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import { mo } from '../../src/index.ts';
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export const openDb = mo(import.meta, (filename: string): DatabaseSync => {
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const db = new DatabaseSync(filename);
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db.exec(`
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CREATE TABLE IF NOT EXISTS users (
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id INTEGER PRIMARY KEY AUTOINCREMENT,
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name TEXT NOT NULL,
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email TEXT NOT NULL
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)
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`);
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return db;
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});
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export const insertUser = mo(import.meta, (db: DatabaseSync, name: string, email: string): number => {
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const stmt = db.prepare('INSERT INTO users (name, email) VALUES (?, ?)');
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const result = stmt.run(name, email);
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return Number(result.lastInsertRowid);
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});
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export const getUser = mo(import.meta, (db: DatabaseSync, id: number): { id: number; name: string; email: string } | undefined => {
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const stmt = db.prepare('SELECT id, name, email FROM users WHERE id = ?');
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return stmt.get(id) as { id: number; name: string; email: string } | undefined;
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});
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export const listUsers = mo(import.meta, (db: DatabaseSync): { id: number; name: string; email: string }[] => {
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const stmt = db.prepare('SELECT id, name, email FROM users');
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return stmt.all() as { id: number; name: string; email: string }[];
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});
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export const countUsers = mo(import.meta, (db: DatabaseSync): number => {
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const stmt = db.prepare('SELECT COUNT(*) as count FROM users');
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const row = stmt.get() as { count: number };
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return row.count;
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});
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examples/sqlite/main.ts
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examples/sqlite/main.ts
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// Shared SQLite database across multiple moroutine calls on a single worker.
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// The db is opened once via a task-arg and cached for all subsequent queries.
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// Requires Node v24+.
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//
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// Run: node examples/sqlite/main.ts
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import { workers } from '../../src/index.ts';
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import { openDb, insertUser, getUser, listUsers, countUsers } from './db.ts';
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// openDb(':memory:') is a task — it runs once on the worker and is cached.
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// Every query receives the cached db instance without re-opening it.
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const db = openDb(':memory:');
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{
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using run = workers(1);
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const id1 = await run(insertUser(db, 'Alice', 'alice@example.com'));
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const id2 = await run(insertUser(db, 'Bob', 'bob@example.com'));
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const id3 = await run(insertUser(db, 'Charlie', 'charlie@example.com'));
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console.log(`Inserted users with ids: ${id1}, ${id2}, ${id3}`);
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const alice = await run(getUser(db, id1));
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console.log('Get Alice:', alice);
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const count = await run(countUsers(db));
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console.log(`Total users: ${count}`);
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const all = await run(listUsers(db));
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console.log('All users:', all);
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}