Add cancel abilities to Deferred Callbacks

[rbadillap]

Note

A PR was created with the purpose to mention the forget method in the documentation: laravel/docs#9902.

Hello Laravel team,

In this PR I'm adding capabilities to the new defer() helper to be cancelled.

What is defer()?

Check this announcement out.

Proposed change

Add the ability to cancel deferred callbacks before they are executed. This can be achieved in two ways:

Option 1: Cancelling by name

defer(fn() => performTask(), 'task-name');
// Later...
defer()->cancel('task-name');

Option 2: Cancelling directly

$task = defer(fn() => performTask());
// Later...
$task->cancel();

Important

I've opened a discussion thread about this topic here.

Recreation instructions

The best way to recreate this feature is by using routes.

Route::get('/500', function () {
    $a = defer(function () {
        usleep(microseconds: 250000);
        info(message: 'executing defer: a');
    }, name: 'a');

    $b = defer(function () {
        usleep(microseconds: 500000);
        info(message: 'executing defer: b');
    }, name: 'b');

    $c = defer(function () {
        usleep(microseconds: 750000);
        info(message: 'executing defer: c');
    }, name: 'c');

    $d = defer(function () {
        usleep(microseconds: 1000000);
        info(message: 'executing defer: d');
    }, name: 'd');

    $a->always()->cancel('a'); // this cancels $a
    $b->always();
    $c->always();
    $d->always(); // this never got cancelled

    // this cancels $b
    if ( true ) {
        $b->cancel();
    }

    // this cancels $c
    defer()->cancel('c');

    return response([ 'status' => '500'], 500);
});

The expected result of the code above is:

Pending

Depending on the feedback received and whether the community takes this approach positively, I need to complete this feature by adding:

• Code and details about the feature
• Test cases (?)
• Documentation

Thanks,
Ronny

[github-actions]

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[devajmeireles]

I don't know about the format, but the cancel concept sounds pretty useful.

[rbadillap]

I think this PR is ready for review.

All test cases are green, and don't see much more functionality to be added, keeping the more simple approach as possible.

ICYM, I've opened a discussion thread just in case you consider it necessary.
#52817

PD: sorry about the unverified commits, I fixed that in my last commit.
PD2: I'm aware about this PR: #52801, I don't see any particular impact on choosing which PR should be merged first, if you move defer to Support, I can do the changes real quick if necessary.

[taylorotwell]

You can already defer()->forget('callback-name'); 👍