Behaviour for ETS-backed shared state with Python-accessible views.

A Store declares tables, their schemas, views for Python access, and a loader for initial data population. Tables use :protected access so reads are lock-free from any BEAM process while writes are serialized through the owning GenServer.

Example

defmodule MyApp.FeatureStore do
  @behaviour Slither.Store

  @impl true
  def tables do
    [
      %{name: :features, type: :set, read_concurrency: true},
      %{name: :user_index, type: :ordered_set, read_concurrency: true}
    ]
  end

  @impl true
  def views do
    [
      %{
        name: :lookup_feature,
        mode: :scalar,
        scope: :session,
        handler: fn %{"key" => key}, _ctx ->
          case Slither.Store.Server.get(MyApp.FeatureStore, :features, key) do
            nil -> %{"error" => "not_found"}
            value -> %{"value" => value}
          end
        end
      },
      %{
        name: :lookup_features_batch,
        mode: :batch,
        scope: :session,
        handler: fn %{"keys" => keys}, _ctx ->
          results = Enum.map(keys, &Slither.Store.Server.get(MyApp.FeatureStore, :features, &1))
          %{"results" => results}
        end
      }
    ]
  end

  @impl true
  def load(tables) do
    # Populate tables from your data source
    data = load_from_database()
    Enum.each(data, fn {key, value} ->
      :ets.insert(tables[:features], {key, value})
    end)
    :ok
  end
end