class Kredis::Types::Slots

def available?
  failsafe returning: false do
    taken < available
  end
end

def release
  if taken > 0
    decr
    true
  else
    false
  end
end

def reserve
  failsafe returning: false do
    if block_given?
      begin
        if reserve
          yield
          true
        else
          false
        end
      ensure
        release
      end
    else
      if available?
        incr
        true
      else
        false
      end
    end
  end
end

def reset
  del
end

def taken
  get.to_i
end