Feature request: Add message priorities to Redis queues

I think it would be interesting to add queues with priority functionality. In the sense that you could add a message with a specific priority score, and consumers would always consume in order. This would be easy to implement on redis using a sorted set. Operations would take O(ln(N)) instead of O(1), but it is still very acceptable for many cases.

A simpler version of this feature would be having the option to add a given message on the front of the queue (simply using lpush instead of rpush).

We can use the message_id string to store information so that the message is consistently added on requeues.

What do you think?