// Compare load balancing strategies with variable-cost work.
// Requires Node v24+.
//
// Run: node examples/load-balancing/main.ts

import { setTimeout } from 'node:timers/promises';
import { workers, roundRobin, leastBusy } from '../../src/index.ts';
import { Balancer, Runner, WorkerHandle, Task } from '../../src/index.ts';
import { work } from './work.ts';

// Lopsided task costs (ms) — round-robin assigns by position and
// ignores how long each worker has been busy, so one worker gets
// all the heavy items.  Least-busy routes to whichever worker has
// fewer in-flight tasks, spreading the load more evenly.
const tasks = [300, 30, 300, 30, 300, 30];

async function bench(label: string, run: Runner): Promise<void> {
  const promises: Promise<number>[] = [];
  const start = performance.now();
  for (const ms of tasks) {
    promises.push(run(work(ms)));
    // Small delay so short tasks can complete between dispatches,
    // giving least-busy useful active-count information.
    await setTimeout(40);
  }
  await Promise.all(promises);
  const elapsed = (performance.now() - start).toFixed(0);
  console.log(`${label}: ${elapsed}ms`);
}

{
  using run = workers(2, { balance: roundRobin() });
  await bench('Round-robin', run);
}

{
  using run = workers(2, { balance: leastBusy() });
  await bench('Least-busy', run);
}