Gracefully shutdown

Since a task is a function that can be run synchronously or asynchronously, it uses the same mechanism to know that it needs to gracefully stop what it's doing.

This mechanism is process signals.

Task.php

use Innmind\OperatingSystem\OperatingSystem;
use Innmind\Signals\Signal;

final class Task
{
    public function __invoke(OperatingSystem $os)
    {
        $signaled = false;
        $os
            ->process()
            ->signals()
            ->listen(Signal::terminate, function() use (&$signaled) {
                $signaled = true;
            });

        while (!$signaled) {
            // do something
        }
    }
}

The $signaled variable will be flipped in 2 cases:

• the PHP process receives the signal (that will be dispatched to all tasks that listened to it)
• the scope calls $continuation->terminate()

If the scope asks to terminate then it will send the signal to all tasks. This means that if you call this method in your scope you should add a listener to all your tasks otherwise the system may never terminate.