Queue - When UserJob has no more tasks, update status & fire hook

[totten]

Overview

Suppose you setup a queue with several tasks and then run them all. What happens to the queue's status?

@eileenmcnaughton - This allows the civicrm_queue.status to actually become completed. This serves a couple purposes:

• On finite/fixed-purpose queues (UserJobs), the queue-status should flip from active to completed so that the background-worker can stop polling for new tasks.
• It's a step toward allowing jobs that can move between AJAX+background. The issue is that background workers don't (and shouldn't) support the same onEnd callback as AJAX. This provides a safer mechanism (hook_queueStatus) which works in both media.

Before

The civicrm_queue.status always remains active.

After

Depends on the use-case:

• If you have an open-ended queue providing an on-going service (no UserJob), then the status remains active.
• If you have a finite/fixed-purpose queue attached to a UserJob, then the status changes from active to completed, and it fires an event:

  function hook_civicrm_queueStatus(CRM_Queue_Queue $queue, string $status)
  

Technical Details

• Also fixes an incidental bug in setStatus().
• There are two main ways that items get removed from a queue (Queue.runNext API and civicrm/queue/ajax/runNext). Both of these fire an internal event (civi.queue.check) to consult the status. The nice thing is that it's easy to incorporate this into both AJAX+background workflows.
• The contact-importer doesn't currently store the queue_id relation, so this doesn't affect statuses on there. For r-run, I used demoqueue, eg

  cv en demoqueue
  cv open civicrm/demo-queue
  cv sql
  ## Periodically run these queries (while job is active; and again after completion)
  ## - select * from civicrm_queue; 
  ## - select id, queue_id, status_id from civicrm_user_job;
  

[civibot]

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[eileenmcnaughton]

I think this seems OK - the full thing will be tested as a thing once it is all working so I'm merging this