// cluster.ts
import * as cluster from 'cluster';
import * as os from 'os';

export class Cluster {
    static register(workers: Number, callback: Function): void {
        if (cluster.isMaster) {
            console.log(`Master server started on ${process.pid}`);

            //ensure workers exit cleanly 
            process.on('SIGINT', function () {
                console.log('Cluster shutting down...');
                for (var id in cluster.workers) {
                    cluster.workers[id].kill();
                }
                // exit the master process
                process.exit(0);
            });

            var cpus = os.cpus().length;
            if (workers > cpus)
                workers = cpus;

            for (let i = 0; i < workers; i++) {
                cluster.fork();
            }
            cluster.on('online', function (worker) {
                console.log('Worker %s is online', worker.process.pid);
            });
            cluster.on('exit', (worker, code, signal) => {
                console.log(`Worker ${worker.process.pid} died. Restarting`);
                cluster.fork();
            })
        } else {

            callback();
        }
    }
}