# `Nebulex.Adapter.Keyslot`
[🔗](https://github.com/elixir-nebulex/nebulex/blob/v2.6.6/lib/nebulex/adapter/keyslot.ex#L1)

This behaviour provides a callback to compute the hash slot for a specific
key based on the number of slots (partitions, nodes, ...).

The purpose of this module is to allow users to implement a custom
hash-slot function to distribute the keys. It can be used to select
the node/slot where a specific key is supposed to be.

> It is highly recommended to use a **Consistent Hashing** algorithm.

## Example

    defmodule MyApp.Keyslot do
      use Nebulex.Adapter.Keyslot

      @impl true
      def hash_slot(key, range) do
        key
        |> :erlang.phash2()
        |> :jchash.compute(range)
      end
    end

This example uses [Jumping Consistent Hash](https://github.com/cabol/jchash).

# `hash_slot`

```elixir
@callback hash_slot(key :: any(), range :: pos_integer()) :: non_neg_integer()
```

Returns an integer within the range `0..range-1` identifying the hash slot
the specified `key` hashes to.

## Example

    iex> MyKeyslot.hash_slot("mykey", 10)
    2

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*Consult [api-reference.md](api-reference.md) for complete listing*