Sorted set rank and score.

rank_and_score.rb

require 'sorted_set_adapter'

set = SortedSetAdapter.new

set.flush

set.add 1, 'foo'
set.add 2, 'bar'

p set.all # -> ["foo", "bar"]

set.add 3, 'foo'

p set.all # -> ["bar", "foo"]

set.add -1, 'baz'

p set.all # -> ["baz", "bar", "foo"]

set.add -1, 'foo'
set.add -1, 'bar'

p set.all # -> ["bar", "baz", "foo"]

sorted_set_adapter.rb

require 'redis'

class SortedSetAdapter
  @key = :scheduler

  class << self
    attr :key
  end

  def redis
    @redis ||= Redis.new
  end

  def add score, member
    redis.zadd self.class.key, score, member
  end

  def rem_first
    member = redis.zrange(self.class.key, 0, 0).first

    # try to remove the first member from the set so it doesn't
    # get processed by another job. If it's already been
    # removed then try and get the next member
    if redis.zrem(self.class.key, member)
      member
    else
      # get the next member
      rem_first
    end
  end

  def count
    redis.zcard self.class.key
  end

  def flush
    redis.zremrangebyrank self.class.key, 0, -1
  end

  def top size
    redis.zrange self.class.key, 0, size - 1
  end

  def rank member
    redis.zrank self.class.key, member
  end

  def all
    redis.zrange self.class.key, 0, -1
  end

end