handle_continue_blogpost_03.ex

defmodule MyServer do
  # ...

  # Some sort of async operation that needs to be done on the data
  def handle_cast({:increment, id}, state) do
    Logger.info("#{state.type} - increment #{id}")
    updated_data = Map.update(state.data, id, 1, fn v -> v + 1 end)
    updated_state = Map.put(state, :data, updated_data)
    {:noreply, updated_state}
  end
  
  # ...
end


# Our new process which continuously sends messages to the other process
defmodule Spammer do
  use GenServer

  def start_link([]) do
    GenServer.start_link(__MODULE__, :ok)
  end

  def init(:ok) do
    loop()
    {:ok, :state}
  end

  def handle_info(:send_message, state) do
    Enum.each([:users, :messages, :items], fn name ->
      :ok = GenServer.cast(name, {:increment, "id"})
    end)
    loop()
    {:noreply, state}
  end

  defp loop() do
    self() |> send(:send_message)
  end
end