routemaster/lua/batch_load_and_count.lua
--
-- Increments the attempts counter on a batch and returns all its data.
--
-- KEYS[1]: the batch key
--
local attempts = redis.call('LINDEX', KEYS[1], 2)
if not attempts then
return nil
else
redis.call('LSET', KEYS[1], 2, tonumber(attempts) + 1)
return redis.call('LRANGE', KEYS[1], 0, -1)
end