// Worker affinity via a custom balancer + isTask().
//
// Each worker keeps its own in-memory counter map. The keyAffinity balancer
// uses isTask() to inspect a task's args and route by a consistent hash of
// the key, so successive operations on the same key always hit the worker
// that already has that key's state.
//
// Requires Node v24+.
// Run: node examples/worker-affinity/main.ts

import { workers, roundRobin } from '../../src/index.ts';
import type { Balancer } from '../../src/index.ts';
import { increment, read } from './counter.ts';
import { keyAffinity } from './key-affinity.ts';

const operations = [
  ['a', 1],
  ['b', 1],
  ['a', 2],
  ['c', 1],
  ['b', 3],
  ['a', 1],
  ['c', 4],
  ['b', 1],
] as const;
const expected = { a: 4, b: 5, c: 5 };

async function demo(label: string, balance: Balancer) {
  using run = workers(4, { balance });
  await run(operations.map(([k, n]) => increment(k, n)));
  const [a, b, c] = await run([read('a'), read('b'), read('c')]);
  const got = { a, b, c };
  const ok = got.a === expected.a && got.b === expected.b && got.c === expected.c;
  console.log(`${label.padEnd(16)} got=${JSON.stringify(got)}  ${ok ? 'OK' : 'WRONG (counts split across workers)'}`);
}

await demo('round-robin', roundRobin());
await demo('keyAffinity()', keyAffinity());