ets_vs_process.exs

defmodule PCache do
  def start do
    # data = for i <- 0..1_000, do: {i, i}, into: %{}
    spawn(fn ->
      accept_reads()
    end)
  end

  def get(pid) do
    us = self()
    send(pid, {:get, us})
    receive do
      val ->
        val
    end
  end

  def time do
    pid = start()
    {time, _} = :timer.tc(fn -> get(pid) end)
    time
  end

  def accept_reads() do
    receive do
      {:get, them} ->
        send(them, 42)
        accept_reads()
    end
  end
end

defmodule EtsCache do
  def start do
    :ets.new(:test, [:named_table, :public, :set])
    :ets.insert(:test, {:get, 42})
  end

  def get(tab) do
    case :ets.lookup(tab, :get) do
      [{:get, val}] -> val
      [] -> nil
    end
  end

  def time do
    start()
    {time, _} = :timer.tc(fn -> get(:test) end)
    time
  end
end