Dynamic worker_args within the same pool

[hickscorp]

Hello,

Requirements

The requirements of my request would sound like this:

• As a user of Poolex who would like to have different arguments passed for workers within the same pool,
• I would like to have an option to pass a function or MFA to worker_args,
• So that I could round-robin things without having to spin-up more pools.

TL;DR

Here's an interesting use-case. Imagine having a bunch of Antivirus hosts. Say 4. They are identified within Elixir land by a {host, port} tuple. I'm looking for a way to do something like this?

  def pool_spec(hosts)
      when is_list(hosts),
      do: [
        pool_id: pool_id(),
        worker_module: @me,
        worker_args: WHAT_GOES_HERE?,
        workers_count: 4,
        max_overflow: 4
      ]

My goal would be to maybe pass a function rather than a literal in worker_args, expecting that it would be called by Poolex at runtime when starting each worker along with some sort of identifier for that worker, so that I could "round-robin" the hosts - imagine something like this:

  def pool_spec(hosts)
      when is_list(hosts),
      do: [
        pool_id: pool_id(),
        worker_module: @me,
        worker_args: &[Enum.at(rem(length(hosts), &1))],
        workers_count: 4,
        max_overflow: 4
      ]

Or something like that... I saw that there's a PR about this (maybe?) and I was wondering if there was already a way to do so?