Using an ETS table to share the state

In the Creating a stateful server process (messages with counters) and Using agents as an abstraction around states recipes, we saw that in order to maintain the state in our processes, we had to be passing the function calls to the state.

This solves the problem when a process needs to maintain states, but what if we need to share some data between multiple processes?

One of the solutions is the use of a structure that allows concurrent access and is really effective in the retrieval of data. This structure is called ETS.

Note

ETS means Erlang Term Storage, and it is an in-memory store.

In this recipe, we will create a small wrapper around an ETS table that can be used as a key/value store.

Getting ready

To create our key/value store, let's create new module ets_store.ex and add the following code:

defmodule EtsStore do
  @table_id __MODULE__

  def init do
    :ets.new(@table_id, [:public, :named_table])
  end

  def insert(key, value) do
    :ets.insert...