IdGenerator

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This gem provides uniq and random ids generation in distributed services but at the same time gives some ordering (timestamp) and debug (context) information

The gem is inspired by Twitter Snowflake and other algorithms.

The main difference is that ids generated by gem are not fully sequenced. We want to have large random part that can be used as a simple guard against enumeration attack.

Goals & Assumptions

While we designed format and gem we used these as requirements:

  • Every system should be able to independently (without coordination) generate id that will never (with reasonable chances) be duplicated
  • ID allows partial time ordering (timestamp in seconds)
  • ID has easy system identifier (context)
  • ID is human readable
  • ID size is not a concern
  • ID format should not be used for business/application logic - thus it remains flexible for future changes

ID Format

Suggested algorithm is based on the Twitter snowflake and other similar alghorithms:

TTTTTTTT-II-RRRRRRRRRRRRRRRRRRRRRR

  • TTTTTTTT - time in seconds since 2000 (just cool number) represented as hex - Gives us ~150 years of uniq sequences
  • II - 1 byte for System Identification in hex
  • RRRRRRRRRRRRRRRRRRRRRR - 11 bytes secure random number as hex

Code to generate is pretty straightforward: 

time = format('%08x', Time.now.to_i - Time.new(2000).to_i)
id = '6a'
random = SecureRandom.hex(11)
id = "#{time}-#{id}-#{random}" # "21dc3680-6a-910df0665e5e29b9f89e21"

Installation

Add gem to your application's Gemfile:

gem 'id_generator'

Usage

# Somewhere during project start
context_id = 165 # value from 0 to 255
ID_GENERATOR = IdGenerator.new(context_id)

#Inside of the actual code
ID_GENERATOR.generate

Contributing

Bug reports and pull requests are welcome on GitHub at https://github.com/matic-insurance/id_generator.

License

The gem is available as open source under the terms of the MIT License.