PHP Process

Pausing

If you need to pause your program to wait for external thing to happen (or any other reason), you can pause it this way:

use Innmind\TimeContinuum\Period;

$os
    ->process()
    ->halt(Period::second(10));

You can use any unit of period except months because it's not an absolute value.

Info

If you want to wait for years it will compute that as 365 days. But if you need to do this there may be a design problem in your program.

Handling CLI Signals

Any process can receive signals to tell them a user (or the system) wants to shut them down allowing the process to terminate gracefully (1).

1. This is the prevalent usage, but there are more.

For example let's say you need to import a large csv file into a database but you want to be able to stop it gracefully. You can do:

use Innmind\Signals\Signal;
use Innmind\Filesystem\{
    File,
    File\Content\Line,
    Name,
};
use Innmind\Url\Path;
use Innmind\Immutable\{
    Sequence,
    Predicate\Instance,
};

$signaled = false;
$stop = static function() use (&$signaled): void {
    $signaled = true;
};

$os
    ->process()
    ->signals()
    ->listen(Signal::interrupt, $stop);

$os
    ->filesystem()
    ->mount(Path::of('data/'))
    ->unwrap()
    ->get(Name::of('users.csv'))
    ->keep(Instance::of(File::class))
    ->map(static fn(File $file) => $file->content()->lines())
    ->toSequence() #(1)
    ->flatMap(static fn(Sequence $lines) => $lines)
    ->takeWhile(static function() use (&$signaled) {
        return !$signaled;
    })
    ->foreach(static fn(Line $line) => importToDb($line));

$os
    ->process()
    ->signals()
    ->remove($stop);

1. Maybe<Sequence>->toSequence()->flatMap(fn($sequence) => $sequence) is a way to swallow the fact that the file may not exist.

This way if a user sends a signal to interrupt the script, it will:

• pause the execution
• call the $stop function
• modify the $signaled flag
• resume the execution
• the next line that is attempted to be read won't be done because of takeWhile

Tip

You can specify multiple listeners for a single signal and they'll be executed in the order you added them.