cachex

defmodule Cachex.Actions.Clear do
  @moduledoc false
  # This module controls the action of clearing a cache. Clearing a cache means

  # removing all items from inside the cache, regardless of whether they should

  # have been evicted or not.


  # we need our imports

  use Cachex.Actions

  # add some aliases

  alias Cachex.Actions.Size
  alias Cachex.LockManager
  alias Cachex.State

  @doc """

  Clears all items in a cache.



  We return the number of items current inside the cache when we clear it. This

  action executes inside a Transaction to ensure that there are no keys currently

  under a lock - thus ensuring consistency.



  There are currently no recognised options, the argument only exists for future

  proofing.

  """
  defaction clear(%State{ cache: cache } = state, options) do
    LockManager.transaction(state, [], fn ->
      evicted =
        state
        |> Size.execute(@notify_false)
        |> handle_evicted

      true = :ets.delete_all_objects(cache)

      evicted
    end)
  end

  # Handles the result of the size call and transforms the result into something

  # we can safely return to the user to represent how many items were cleared.

  defp handle_evicted({ :ok, _size } = res), do: res
  defp handle_evicted(_other_result), do: { :ok, 0 }

end