Implement ULID.generate/0, ULID.generate/1 and ULID.decode/1

[unnawut]

Issue/Task Number: T147

Overview

Implements the main logic for ULID.generate/0, ULID.generate_at/1 and ULID.decode/1.

Changes

• Implemented the Crockford base32 encoder module
• Implemented logic for ULID.generate/0
• Implemented logic for ULID.generate_at/1
• Implemented logic for ULID.decode/1
• Added benchmarking

Implementation Details

N/A

Usage

Try the instructions provided in the README.md

Impact

N/A

[sirn]

def decode(<<time::bytes-size(10), id::bytes-size(16)>>)

[sirn]

Let's have generate/0 and generate/1 instead of generate_at/1

def generate do
  :milli_seconds
  |> :os.system_time()
  |> generate()
end

def generate(time) do
   # ...
end

[unnawut]

I was thinking that there might be generate(opts) in the future and this won't work:

def generate(opts \\ [])
def generate(time, opts \\ [])

Thoughts?

[sirn]

Let's not code for something that won't come :-)

[sirn]

I not sure about the rescue pattern (in Erlang we almost never do this) because it obscure where the error can happen in the stack. Can we instead return {:error, "message"} directly?

[sirn]

I think maybe something like:

case encode(time, 10) do
  {:error, error} -> {:error, error}
  encoded_time ->
    rand = :crypto.strong_rand_bytes(10)
    case encode(rand, 16) do
      {:error, error} -> {:error, error}
      encoded_rand -> encoded_time <> encoded_rand
    end
end

It should make it clear where can the error raise.

[sirn]

Following the above comment, I think this is something better handled in generate/1 when time is passed, rather than deep down in the stack (whereas encode itself doesn't care about max_time and I think it shouldn't be aware of)

[unnawut]

@sirn Please review again

P.S. I need your help setting up CI for this one. There's probaly more to do than just copy & edit the Jenkinsfile.

[sirn]

Awesome! 🎉