Method: Uniqid::ClassMethods#generate

Defined in:
lib/uniqid.rb

#generate(worker_value, server_value, timestamp = nil) ⇒ Object

Generate ID



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# File 'lib/uniqid.rb', line 88

def generate(worker_value, server_value, timestamp = nil)
  server_value = server_value(server_value)
  worker_value = worker_value(worker_value)

  # The reserved position is temporarily random, shifted by 7 bits to the left
  bak_value = (rand(MAX_BAK_NUM) << LOCAL_ID_LEN)

  local_timestamp =
    if timestamp
      (timestamp * 1000).to_i
    else
      (Time.now.to_f * 1000).to_i
    end

  # If the last generation time is the same as the current time, the sequence within milliseconds
  if local_timestamp == @last_timestamp

    # The sequence is self-increasing and only has 7 bits,
    # so it is ANDed with MAX_LOCAL_NUM and removes the high bits
    sequence = (@sequence + 1) & MAX_LOCAL_NUM

    # Check for overflow: whether the sequence exceeds 127 per millisecond,
    # when 127, it is equal to 0 after AND with MAX_LOCAL_NUM
    if sequence.zero?
      # Wait until the next millisecond
      local_timestamp = next_timestamp(@last_timestamp)
    end

  else
    # If it is different from the last generation time, reset the sequence
    # In order to ensure that the mantissa is more random, set a random number in the last digit
    @sequence = rand(1 << LOCAL_ID_LEN)
    sequence = @sequence
  end

  @last_timestamp = local_timestamp

  # Save the difference of timestamp(current timestamp - start timestamp)
  local_timestamp -= TIMESTAMP_START

  (local_timestamp << (TOTAL_LEN - TIMESTAMP_LEN)) | server_value | worker_value | bak_value | sequence
end