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elixir driver for cassandra/scylla

elixir, Cassandra

TokenAware LB Policy for Xandra and Shard Awareness

Python Examples

Java Reference

Elixir NIF

  • https://github.com/lpgauth/murmur

  • Possibly something like this? -

    defmodule ShardCalculator do
  @min_token -1 <<< 63
  @token_max 1 <<< 64

  def calculate_shard(token, ignore_msb, nr_shards) do
    # Bias the token
    biased_token = token - @min_token

    # Left shift by ignore_msb bits
    biased_token = biased_token <<< ignore_msb

    # Multiply by number of shards and perform truncating division
    shard = div(biased_token * nr_shards, @token_max)
    shard
  end
end

    defmodule ShardCalculator do
  @min_token -1 <<< 63
  @token_max 1 <<< 64

  def calculate_shard(token, ignore_msb, nr_shards) do
    token = token - @min_token
    token = token <<< ignore_msb

    tok_lo = token &&& 0xFFFFFFFF
    tok_hi = token >>> 32

    mul1 = tok_lo * nr_shards
    mul2 = tok_hi * nr_shards

    sum = (mul1 >>> 32) + mul2
    sum >>> 32
  end
end

Existing Xandra

Worklist