mock_snowflake.rb

module MockSnowflake
  TWEPOCH = 1142974214000
  WORKERIDBITS = 5
  DATACENTERIDBITS = 5
  MAXWORKERID = -1 ^ (-1 << WORKERIDBITS)
  SEQUENCEBITS = 12

  WORKERIDSHIFT = SEQUENCEBITS
  DATACENTERIDSHIFT = SEQUENCEBITS + WORKERIDBITS
  TIMESTAMPLEFTSHIFT = SEQUENCEBITS + WORKERIDBITS + DATACENTERIDBITS
  SEQUENCEMASK = -1 ^ (-1 << SEQUENCEBITS)

  WORKER_ID = 0
  DATACENTER_ID = 0

  def self.get_id(agent)
    @sequence ||= 0

    t = self.get_timestamp

    until !(t < (@last_timestamp || 0))
      sleep 0.001
      t = self.get_timestamp
    end

    if @last_timestamp == t
      @sequence = (@sequence + 1) & SEQUENCEMASK
      if @sequence == 0
        t = til_next_millis(@last_timestamp)
      end
    else
      @sequence = 0
    end

    @last_timestamp = t
    ((t - TWEPOCH) << TIMESTAMPLEFTSHIFT) |
      (DATACENTER_ID << DATACENTERIDSHIFT) |
      (WORKER_ID << WORKERIDSHIFT) |
      @sequence
  end

  def self.til_next_millis(last_timestamp)
    while last_timestamp == (t = self.get_timestamp)
    end
    t
  end

  def self.get_timestamp
    ((t = Time.now).to_i * 1000) + (t.usec / 1000).to_i
  end
end