Initial commit

.gitignore

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+/.bundle/
+/.yardoc
+/_yardoc/
+/coverage/
+/doc/
+/pkg/
+/spec/reports/
+/tmp/
+
+# rspec failure tracking
+.rspec_status

.rspec

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+--format documentation
+--color
+--require spec_helper

.rubocop.yml

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+AllCops:
+  TargetRubyVersion: 2.5
+  NewCops: enable
+
+Style/StringLiterals:
+  Enabled: true
+  EnforcedStyle: single_quotes
+
+Style/StringLiteralsInInterpolation:
+  Enabled: true
+  EnforcedStyle: double_quotes
+
+Style/ClassAndModuleChildren:
+  Enabled: true
+  EnforcedStyle: compact
+
+Style/RedundantSelf:
+  Enabled: false
+
+Layout/LineLength:
+  Max: 120
+
+Metrics/AbcSize:
+  Max: 20

CHANGELOG.md

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+## [Unreleased]
+
+## [0.1.0] - 2021-11-21
+
+- Initial release

Gemfile

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+# frozen_string_literal: true
+
+source 'https://rubygems.org'
+
+# Specify your gem's dependencies in lsuuid.gemspec
+gemspec
+
+gem 'rake', '~> 13.0'
+
+gem 'rspec', '~> 3.0'
+
+gem 'rubocop', '~> 1.7'

LICENSE.txt

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+The MIT License (MIT)
+
+Copyright (c) 2021 Karthick
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in
+all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+THE SOFTWARE.

README.md

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+# LSUUID (Lexicographically Sortable Universally Unique Identifier)
+
+LSUUID is a lexicographically sortable identifier with format similar to UUIDv4. 
+UUID has some limitations which are already listed and addressed by [ULID](https://github.com/ulid/spec).
+
+LSUUID provides the following improvements over ulid :-
+- The timestamp component in ulid is in milliseconds whereas LSUUID uses nanoseconds so that chance of collision is reduced 1000 times
+- Ability to bucket the generated identifiers with a prefix is provided by LSUUID
+- LSUUID adheres to the UUIDv4 format there by allowing the storage of the identifier in the UUID datatype of data stores which is more efficient than a string which is required for ulid.
+
+*Note: For use cases where format of the identifier is not a matter of concern, using ULID over LSUUID might be a better choice.*
+
+## Specification
+Below is the structure of LSUUID.
+
+**Without Prefix:**
+```
+ Sample LSUUID: 619bd0ef-2a04-5068-d3c4-f6fac6809edb
+
+ 619bd0ef-2a04-5068-      d3c4-f6fac6809edb
+
+|------------------|     |-----------------|
+     Timestamp                Randomness
+       64bits                   64bits
+```
+
+**With Prefix:**
+```
+ Sample LSUUID: 619bd0ef-2a04-5068-d3c4-f6fac6809edb
+
+ 619bd0      ef-2a04-5068-d3c4-f6      fac6809edb
+
+|------|    |--------------------|    |----------|
+ Prefix            Timestamp           Randomness
+ 24bits             64bits               40bits
+```
+
+### Components:
+
+**Timestamp**
+- 64 bit integer
+- UNIX-time in nanoseconds
+
+**Randomness**
+- 64 bits (40 bits in case a prefix is specified)
+- Cryptographically secure source of randomness, if possible
+
+## Installation
+
+Add this line to your application's Gemfile:
+
+```ruby
+gem 'lsuuid'
+```
+
+And then execute:
+
+    $ bundle install
+
+Or install it yourself as:
+
+    $ gem install lsuuid
+
+## Usage
+
+### Generate a UUID:
+```ruby
+irb(main):001:0> LSUUID.generate
+=> "619bd0ef-2a04-5068-d3c4-f6fac6809edb"
+```
+Generates a UUID based on the method call time.
+### Timestamp specific UUIDs:
+```ruby
+irb(main):001:0> t = Time.now     
+=> 2021-11-22 22:49:02 +0530
+irb(main):002:0> LSUUID.generate(time: t)
+=> "619bd106-0c6b-ba28-7811-f5787dab02d4"
+```
+### Modes:
+#### **ceil**
+```ruby
+irb(main):001:0> LSUUID.generate(time: t, mode: :ceil)
+=> "619bd106-0c6b-ba28-ffff-ffffffffffff"
+irb(main):002:0>  LSUUID.generate(time: t, mode: :ceil, prefix: 0)
+=> "00000061-9bd1-060c-6bba-28ffffffffff"
+```
+
+#### **floor**
+```ruby
+irb(main):001:0> LSUUID.generate(time: t, mode: :floor)
+=> "619bd106-0c6b-ba28-0000-000000000000"
+irb(main):002:0>  LSUUID.generate(time: t, mode: :ceil, prefix: 0)
+=> "00000061-9bd1-060c-6bba-280000000000"
+```
+
+### Prefix
+```ruby
+irb(main):001:0> LSUUID.generate(prefix: 0, time: t)
+=> "00000061-9bd1-060c-6bba-28428c7e196d"
+irb(main):002:0> LSUUID.generate(prefix: 1000, time: t)
+=> "0003e861-9bd1-060c-6bba-28d9cb973352"
+irb(main):003:0> LSUUID.generate(prefix: 16_777_215, time: t)
+=> "ffffff61-9bd1-060c-6bba-2826264c51e0"
+```
+**Note:** Prefix can be an integer between 0 and 16,777,215
+
+## Contributing
+
+Bug reports and pull requests are welcome on GitHub at https://github.com/hwslabs/lsuuid.
+
+## License
+
+The gem is available as open source under the terms of the [MIT License](https://opensource.org/licenses/MIT).

Rakefile

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+# frozen_string_literal: true
+
+require 'bundler/gem_tasks'
+require 'rspec/core/rake_task'
+
+RSpec::Core::RakeTask.new(:spec)
+
+require 'rubocop/rake_task'
+
+RuboCop::RakeTask.new
+
+task default: %i[spec rubocop]

bin/console

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+#!/usr/bin/env ruby
+# frozen_string_literal: true
+
+require 'bundler/setup'
+require 'lsuuid'
+
+# You can add fixtures and/or initialization code here to make experimenting
+# with your gem easier. You can also use a different console, if you like.
+
+# (If you use this, don't forget to add pry to your Gemfile!)
+# require 'pry'
+# Pry.start
+
+require 'irb'
+IRB.start(__FILE__)

bin/setup

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+#!/usr/bin/env bash
+set -euo pipefail
+IFS=$'\n\t'
+set -vx
+
+bundle install
+
+# Do any other automated setup that you need to do here

lib/lsuuid.rb

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+# frozen_string_literal: true
+
+require_relative 'lsuuid/version'
+
+if RUBY_VERSION >= '2.5'
+  require 'securerandom'
+else
+  require 'sysrandom/securerandom'
+end
+
+module LSUUID # :nodoc:
+  PREFIX_LEN = 6
+  PAD_CHAR = '0'
+  FLOOR_CHAR = '0'
+  CEIL_CHAR = 'f'
+  DEFAULT_RAND_LEN = 16
+
+  class << self
+    # We allow 6 chars (24 bits) of UUID to be customizable as per requirement.
+    def generate(prefix: nil, time: Time.now, mode: :random)
+      prefix_hex = validate_prefix_and_get_hex(prefix)
+      result = prefix_hex +
+               time.to_i.to_s(16).rjust(8, PAD_CHAR) + time.nsec.to_s(16).rjust(8, PAD_CHAR) +
+               random_hex(prefix_hex, mode)
+      [result[0..7], result[8..11], result[12..15], result[16..19], result[20..31]].join('-')
+    end
+
+    private
+
+    def random_hex(prefix_hex, mode)
+      rand_len = DEFAULT_RAND_LEN - prefix_hex.size
+      case mode
+      when :random then SecureRandom.hex(rand_len / 2)
+      when :ceil then ''.rjust(rand_len, CEIL_CHAR)
+      when :floor then ''.rjust(rand_len, FLOOR_CHAR)
+      else raise "Unknown mode [#{mode}]"
+      end
+    end
+
+    def validate_prefix_and_get_hex(prefix)
+      return '' if prefix.nil?
+
+      raise "Expecting integer Got #{prefix.class.name}" unless prefix.is_a? Integer
+
+      if (prefix > 16_777_215) || prefix.negative?
+        raise "Integer prefix out of range. Allowed: min - 0, max - 16,777,215 (hex: ffffff). Got: #{prefix}."
+      end
+
+      prefix.to_s(16).rjust(PREFIX_LEN, PAD_CHAR)
+    end
+  end
+end

lib/lsuuid/version.rb

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+# frozen_string_literal: true
+
+module LSUUID
+  VERSION = '0.1.0'
+end

lsuuid.gemspec

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+# frozen_string_literal: true
+
+require_relative 'lib/lsuuid/version'
+
+Gem::Specification.new do |spec|
+  spec.name          = 'lsuuid'
+  spec.version       = LSUUID::VERSION
+  spec.authors       = ['Hypto Engineering Team']
+  spec.email         = ['engineering@hypto.in']
+
+  spec.summary       = 'Universally Unique Lexicographically Sortable Identifier'
+  spec.description   = 'Universally Unique Lexicographically Sortable Identifier'
+  spec.homepage      = 'https://github.com/hwslabs/lsuuid'
+  spec.license       = 'MIT'
+  spec.required_ruby_version = '>= 2.4.0'
+
+  # spec.metadata['allowed_push_host'] = 'TODO: Set to 'https://mygemserver.com''
+
+  spec.metadata['homepage_uri'] = spec.homepage
+  spec.metadata['source_code_uri'] = 'https://github.com/hwslabs/lsuuid'
+  spec.metadata['changelog_uri'] = 'https://github.com/hwslabs/lsuuid/blob/main/CHANGELOG.md'
+  spec.metadata['rubygems_mfa_required'] = 'true'
+
+  # Specify which files should be added to the gem when it is released.
+  # The `git ls-files -z` loads the files in the RubyGem that have been added into git.
+  spec.files = Dir.chdir(File.expand_path(__dir__)) do
+    `git ls-files -z`.split("\x0").reject do |f|
+      (f == __FILE__) || f.match(%r{\A(?:(?:test|spec|features)/|\.(?:git|travis|circleci)|appveyor)})
+    end
+  end
+  spec.bindir        = 'exe'
+  spec.executables   = spec.files.grep(%r{\Aexe/}) { |f| File.basename(f) }
+  spec.require_paths = ['lib']
+
+  # Uncomment to register a new dependency of your gem
+  # spec.add_dependency "example-gem", "~> 1.0"
+
+  # For more information and examples about making a new gem, checkout our
+  # guide at: https://bundler.io/guides/creating_gem.html
+end

spec/lsuuid_spec.rb

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+# frozen_string_literal: true
+
+UUID_REGEXP = /\A[0-9a-f]{8}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{12}\z/i.freeze
+
+RSpec.describe LSUUID do # rubocop:disable  Metrics/BlockLength
+  it 'has a version number' do
+    expect(LSUUID::VERSION).not_to be nil
+  end
+
+  it 'should generate identifier in a valid UUID format' do
+    lsuuid = LSUUID.generate
+    expect(lsuuid.size).to eq(36)
+    expect(!(UUID_REGEXP =~ lsuuid).nil?).to eq(true)
+  end
+
+  it 'should generate least possible uuid for given params in floor mode' do
+    lsuuid = LSUUID.generate(mode: :floor)
+    expect(lsuuid[26..-1]).to eq('0000000000')
+  end
+
+  it 'should generate highest possible uuid for given params in ceil mode' do
+    lsuuid = LSUUID.generate(mode: :ceil)
+    expect(lsuuid[26..-1]).to eq('ffffffffff')
+  end
+
+  it 'should generate uuid with first 6 chars as 0s for prefix 0 ' do
+    lsuuid = LSUUID.generate(prefix: 0)
+    expect(lsuuid[0..5]).to eq('000000')
+  end
+
+  it 'should generate uuid with first 6 chars as fs for max prefix[16_777_215]' do
+    lsuuid = LSUUID.generate(prefix: 16_777_215)
+    expect(lsuuid[0..5]).to eq('ffffff')
+  end
+
+  it 'should generate same identifier for same input except for random suffix' do
+    time = Time.now
+    test_prefix = 15_332
+    lsuuid1 = LSUUID.generate(prefix: test_prefix, time: time, mode: :random)
+    lsuuid2 = LSUUID.generate(prefix: test_prefix, time: time, mode: :random)
+    expect(lsuuid1[0..25]).to eq(lsuuid2[0..25])
+    expect(lsuuid1[26..-1]).not_to eq(lsuuid2[26..-1])
+  end
+end

spec/spec_helper.rb

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+# frozen_string_literal: true
+
+require 'lsuuid'
+
+RSpec.configure do |config|
+  # Enable flags like --only-failures and --next-failure
+  config.example_status_persistence_file_path = '.rspec_status'
+
+  # Disable RSpec exposing methods globally on `Module` and `main`
+  config.disable_monkey_patching!
+
+  config.expect_with :rspec do |c|
+    c.syntax = :expect
+  end
+end