Supervising 3rd party modules

Questions / Help
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1

What’s the best way to add 3rd party modules in your supervisor tree?

For example, I’m using the following code which successfully starts a supervised mariaex process that I can send queries to, but I can’t name it because the start link implementation in mariaex doesn’t take a name argument.

defmodule ElixirMysql.Application do
  use Application

  def start(_type, _args) do
    import Supervisor.Spec, warn: false
    config = Application.get_env(:elixir_mysql, :db)
    children = [
      worker(Mariaex, [config])
    ]
    opts = [strategy: :one_for_one, name: ElixirMysql.Supervisor]
    Supervisor.start_link(children, opts)
  end
end

Is there a way to name processes in situations like this? I thought about wrapping it around a custom genserver, but I don’t know if that’s even possible, I couldn’t find any examples.

2

I just skimmed over the sources, and it seems as if MariaEx uses :dbconnect to manage itselfs lifecycle. So it is probably already supervised. If not just add it. You can use tools like erlangs :observer to see if there is a supervision tree spun up. Of course you can supervise the supervisor. It won’t need a name though, and I’m not sure how you could grab that supervisir into yours, since it will be probably started in the application start up of :mariaex (or even earlier by one of its dependencies).

Also, you are not meant to send messages directly to any of :mariaexs processes, so you don’t need to know their names. Just use the exposed functions of the application. This is true regardless if a process is supervised or not. If you need to send directly to a process of a dependency, then there is probably an issue with the design of the dependency.

Last but not least, a minor nitpick about your wording: You don’t add “modules” into a supervision tree, but “processes”.

3

Mariaex query functions require the pid of the Mariaex process.

iex(1)> {:ok, p} = Mariaex.start_link(username: “user”, database: “db”)
{:ok, #PID<0.108.0>}

iex(2)> Mariaex.query(p, “CREATE TABLE test1 (id serial, title text)”)
{:ok, %Mariaex.Result{columns: [], command: :create, num_rows: 0, rows: []}}

I’m just trying to figure out how I can start a mariaex process and keep track of it’s pid so I can use it throughout my Application.

Maybe trying to supervise it was the wrong way to go about it, but it seems I still need to keep track of it’s pid somehow, and I’m not able to name it,because the Mariaex.start_link/1 doesn’t take a process name option.

So how would I go about doing this?