SnowflakeId

Snowflake Identifier in Elixir, based on Rust's rs-snowflake

Generates SnowflakeId's. This struct implements the Enumerable protocol, so you can use this with all the functions from Enum and Stream modules.

This implementation is functional and does not use any GenServer to store the state.

# override the time function for the test
iex> get_time = fn -> 1630163558780 end
iex> generator = SnowflakeId.new(1, 1, get_time: get_time)
iex> Enum.at(generator, 0)
6837401535245324288
iex> generator |> Enum.at(0) |> Integer.to_string(2)
"101111011100011010101000111100001011111000000100001000000000000"
#^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^xxxxxyyyyyzzzzzzzzzzzz
#^: timestamp
#x: machine_id
#y: node_id
#z: index

More realistic example:

iex> my_data =
...>   SnowflakeId.new(1, 1)
...>   |> Enum.take(10)
...>   |> Enum.map(fn id ->
...>     # insert your data in your database
...>     %{id: id, name: "my_id_#{id}"}
...>   end)
iex> length(my_data)
10

If you want to not use the Enumerable protocol you can do it yourself by:

# override the time function for the test
iex> get_time = fn -> 1630163558780 end
iex> generator = SnowflakeId.new(1, 1, get_time: get_time)
iex> SnowflakeId.format_id(generator)
6837401535245324288
iex> generator = SnowflakeId.next(generator)
iex> SnowflakeId.format_id(generator)
6837401535245324289

Small warning, because the timestamp only uses 41 bits and the default timestamp starts from 1970. The maximum time that can be stored is:

iex> bits = 0b11111111111111111111111111111111111111111
iex> DateTime.from_unix(bits, :millisecond)
{:ok, ~U[2039-09-07 15:47:35.551Z]}

You can mitigate this by using your own timestamp function or use the helper function:

# from the start of 2000
iex> from = ~U[2000-01-01T00:00:00Z]
iex> get_time = SnowflakeId.timestamp_factory(from)
iex> with_own_get_time = SnowflakeId.new(1, 1, get_time: get_time)
iex> default_get_time = SnowflakeId.new(1, 1)
iex> Enum.at(with_own_get_time, 0) < Enum.at(default_get_time, 0)
true

we can now use this longer:

iex> bits = 0b11111111111111111111111111111111111111111
iex> ~U[2000-01-01T00:00:00Z] |> DateTime.add(bits, :millisecond) |> DateTime.truncate(:second)
~U[2069-09-06 15:47:35Z]

Installation

def deps do
  [
    {:snowflake_id, "~> 0.1.0"}
  ]
end

Documentation

https://hexdocs.pm/snowflake_id