Yae/exitHook.js

// https://github.com/sindresorhus/exit-hook

const callbacks = new Set();
let isCalled = false;
let isRegistered = false;

function exit(shouldManuallyExit, signal) {
    if (isCalled) {
        return;
    }

    isCalled = true;

    for (const callback of callbacks) {
        callback();
    }

    if (shouldManuallyExit === true) {
        process.exit(128 + signal);
    }
}

function exitHook(onExit) {
    callbacks.add(onExit);

    if (!isRegistered) {
        isRegistered = true;

        process.once('exit', exit);
        process.once('SIGINT', exit.bind(undefined, true, 2));
        process.once('SIGTERM', exit.bind(undefined, true, 15));

        // PM2 Cluster shutdown message. Caught to support async handlers with pm2, needed because
        // explicitly calling process.exit() doesn't trigger the beforeExit event, and the exit
        // event cannot support async handlers, since the event loop is never called after it.
        process.on('message', message => {
            if (message === 'shutdown') {
                exit(true, -128);
            }
        });
    }

    return () => {
        callbacks.delete(onExit);
    };
}

module.exports = {
    exitHook
}