[12.x] feat: allow queued listeners to be unique

[calebdw]

Hello!

This PR allows queued listeners to implement ShouldBeUnique and ShouldBeUniqueUntilProcessing, similar to jobs. E.g,

<?php

namespace App\Listeners;

use App\Events\LicenseSaved;
use Illuminate\Contracts\Queue\ShouldBeUnique;
use Illuminate\Contracts\Queue\ShouldQueue;

class AcquireProductKey implements ShouldQueue, ShouldBeUnique
{
    public function uniqueId(LicenseSaved $event): string
    {
        return $event->license->id;
    }

    public function shouldQueue(LicenseSaved $event): bool
    {
        return $event->license->product_key === null;
    }

    public function __invoke(LicenseSaved $event): void
    {
        // ...
    }
}

Motivation

I just had a bug in production where a listener was dispatched to the queue in rapid succession when it should not have been. Unfortunately, queued listeners could not implement the ShouldBeUnique and ShouldBeUniqueUntilProcessing contracts---they can only use the WithoutOverlapping middleware which prevents two jobs from running at the same time, but this does nothing to prevent duplicate jobs from being dispatched to the queue in the first place.

Thanks!

[taylorotwell]

@calebdw should we actually serialize the cache repository onto the queue in CallQueuedListener? Feels like that could cause issues with connections that can't be serialized, etc.? Any other options there?

Just storing docs PR here for myself for reference: laravel/docs#10996

[calebdw]

@taylorotwell, apologies for the delayed reply---I was without power for several days.

Good catch on not serializing the cache, I was just following the job pattern without thinking too much 😅

I updated the CallQueuedListener to pass through to the listener method at runtime instead of serializing the property on the job

[calebdw]

Thanks!