notes.txt

http://antirez.com/news/88
http://www.rediscookbook.org/implement_a_fifo_queue.html
http://www.rediscookbook.org/get_and_delete.html
http://redis.io/commands/rpoplpush <<<

http://stackoverflow.com/questions/16517439/redis-how-to-delete-all-keys-older-than-3-months

https://github.com/heureka/php-rq
https://github.com/heureka/php-rq/blob/master/src/Command/UniqueQueue/ReEnqueue.php
	too complex

http://big-elephants.com/2013-09/building-a-message-queue-using-redis-in-go/
	does not handle failures

http://redis.io/topics/notifications
	expired notifications cannot be used because we have no guarantee the message will be handled

two lists, QUEUE and PROCESSING, hashmap of inverted timeouts
enqueue: lpush to QUEUE
processing: rpoplpush QUEUE to PROCESSING, insert key to hashmap with TTL of timeout
retry: foreach item in processing that does NOT have hash in hashmap, atomically move to QUEUE with decreased retry count


problem: guarantee items are never lost AND never processed twice: this is probably not solvable

todo persistent redis