// Multiple workers updating shared struct state protected by a mutex.
// Without the mutex, the read-modify-write would race and lose updates.
// Requires Node v24+.
//
// Run: node examples/shared-state/main.ts

import { workers, shared, int32, mutex } from '../../src/index.ts';
import { updatePosition } from './update-position.ts';

const mu = mutex();
const pos = shared({ x: int32, y: int32 });

const steps = 1000;

{
  using run = workers(4);

  // 4 workers each move the position (1, 2) per step, 1000 steps each
  await run([
    updatePosition(mu, pos, 1, 2, steps),
    updatePosition(mu, pos, 1, 2, steps),
    updatePosition(mu, pos, 1, 2, steps),
    updatePosition(mu, pos, 1, 2, steps),
  ]);
}

const final = pos.load();
console.log(`Expected: { x: ${4 * steps}, y: ${4 * steps * 2} }`);
console.log(`Actual:   { x: ${final.x}, y: ${final.y} }`);
console.log(final.x === 4 * steps && final.y === 4 * steps * 2 ? 'PASS — mutex prevented races' : 'FAIL — data race!');