[5.8] Prevent a job from firing if it's been marked as deleted

[gms8994]

During queue job processing an Events\JobProcessing event is fired, which makes it possible to $job->delete(), however, $job->fire() still happens even on the deleted job.

This adds a check to the processing of the job to prevent that, and fires an Events\JobDeleted event that can be listened for.

Also adds output to the WorkCommand to allow seeing that a job was deleted before processing completed.

Tests included.

[taylorotwell]

Interesting. What was your use case for deleting jobs in the Processing event?

[gms8994]

@taylorotwell I was trying to find a way to prevent "duplicated" jobs (same Job::class on the same connection with the same parameters) from running. For example, due to some legacy code, we have something that will fire Job::class, that through some unfortunate series of events can also fire Job::class later. There isn't a great way of solving that problem in our environment short of something like this.

I did look to see if there was a way to throw a specific exception that would remove the job without failing it, but couldn't find anything, and then came across deleting the job, but noticed the missing piece.

I appreciate you taking the time to look over the PR!

[gms8994]

Specifically, see https://github.com/expanse/laravel-distinct-jobs for the anticipated use of this functionality.

[taylorotwell]

Do you actually need the event or can we get rid of that part?

[gms8994]

I think at least one of JobDeleted or JobProcessed should be fired, if not for my pending package then for the output of the queue:work console command to not "feel" like errors are occurring. I think JobProcessed would suffice for my needs, and would work if the code were updated to fire it - I was simply trying to stick to semantics, since the job technically wasn't processed.

[taylorotwell]

Please remove the deleted event and re-submit. From what I can tell it doesn't fire if I just let a job process, even though that does delete the job after processing. I find it confusing.