How to inject behavior into Phoenix Endpoint?

In my app, I have

defmodule MyWebApp.Endpoint do
  use Phoenix.Endpoint, otp_app: :my_web_app
  use Absinthe.Phoenix.Endpoint

which generates subscribe(), ubsubscribe(), broadcast!() etc functions with use.

How can I inject behavior, e.g. logging or presence tracking, into these functions?

Also, subscribe/2 just gets topic and opts keyword list as arguments. Wouldn’t the topic name be generated/resolved in absinthe schema when we configure subscriptions to mutations, e.g.

  object :lock_subscriptions do
    field :lock_changed, non_null(:lock_result) do
      arg(:lock_input, :lock_input)

        %{lock_input: %{id: target_id, target_type: target_type}}, _ ->
          {:ok, topic: "#{@lock_changed_prefix}:#{target_type}:#{target_id}"}

        _, _ ->
          {:ok, topic: "#{@lock_changed_prefix}:*"}

      trigger([:acquire_lock, :release_lock],
        topic: fn
          %{success: true, id: target_id, target_type: target_type} ->

          _ ->

The subscribe function,

  @doc """
  Subscribes the caller to the given topic.

  See `Phoenix.PubSub.subscribe/3` for options.
  @callback subscribe(topic, opts :: Keyword.t) :: :ok | {:error, term}

doesn’t need to be aware of the users that subscribes, right? If I really wanted, I’d incorporate user id into topic name, e.g. “#{@lock_changed_prefix}:#{target_type}:#{target_id}:#{}”. Maybe all it knows is process id, namely self().

BTW if the server dies and the supervisor restarts it, the PIDs will be all invalid, so how will PubSub know whom to notify?

Anyway, the main question is how to add behavior to these callbacks?
The use macro generates something like

    quote do
      def subscribe(topic, opts \\ []) when is_binary(topic) do
        Phoenix.PubSub.subscribe(pubsub_server!(), topic, opts)

How do I inject, for example, logging of arguments or adding topic to Phoenix.Tracker?