Schedule a task based on the specified CRON expression in PHP with Event loops ("dragonmantank/cron-expression" and "revolt/event-loop")

schedule.php

<?php

declare(strict_types=1);

use Revolt\EventLoop;
use Cron\CronExpression;

require implode(DIRECTORY_SEPARATOR, [dirname(__DIR__), 'vendor', 'autoload.php']);

/**
 * Schedule the given task based on the specified CRON expression
 *
 * "dragonmantank/cron-expression" and "revolt/event-loop"
 *
 * e.g.
 *
 * schedule('* * * * *', static function (int $now = 0) {
 *     echo date('Y-m-d H:i:s', $now) . ": Task {$now} running\n\n";
 * });
 *
 * @param callable $task
 * @param CronExpression|string $cron
 */
function schedule(CronExpression|string $cron, callable $task, DateTimeImmutable $now = new DateTimeImmutable()): void
{
    $cron = match (true) {
        is_string($cron) => new CronExpression($cron),
        default => $cron,
    };

    if ($cron->isDue($now)) {
        EventLoop::defer(static fn () => $task($now->getTimestamp()));
    }

    EventLoop::delay(
        $cron->getNextRunDate($now)->getTimestamp() - $now->getTimestamp(),
        static fn () => schedule($cron, $task)
    );
}

EventLoop::run();

// Run example task every minute:
// schedule('* * * * *', static function (int $now = 0) {
//     echo implode(' ', [
//         date('Y-m-d H:i:s', $now),
//         'Memory usage:',
//         number_format(memory_get_usage() / 1024, 3).'K' . PHP_EOL,
//     ]) . \PHP_EOL;
// });