Retry now script needs to LPUSH before ZREM

[edgurgel]

https://github.com/edgurgel/verk/blob/master/priv/requeue_job_now.lua

  local removed = redis.call("ZREM", KEYS[1], job)
    if removed == 1 then
      redis.call("LPUSH", queue_key, job)
    else

If the ZREM succeeds but something happens afterwards that LPUSH is not called we may never enqueue again this job. We would rather have 2 jobs than 0 jobs to be processed.

cc/ @keyan

I'm not sure if we want to try to LREM if the ZREM failed? What do you think?

[edgurgel]

It is supposed to be a rare case that Redis fails to LPUSH after a successful ZREM but if we can avoid this case by ordering the commands we might as well do it.

[keyan]

Hey Ed, thanks for the write up.

We would rather have 2 jobs than 0 jobs to be processed.

I used this ordering because I was afraid a job might be processed right before we asked to requeue it. But yeah your concern sounds reasonable.