chore: use after_connect hook within connection pool for each new connection

[kamilpavlicko]

Motivation

Use after_connect hook in the proper way with each connection within the connection pool (sequel doc)

Actual behavior

Currently, there is after_connect executed only once for the Sequel connection instance, but it's not executed when creating new connection within connection pool

Issue

With using sequel-rails with rails and multithreaded webserver (for example Puma) there is a need to utilize a connection pool for multiple connections.
Let's say that we want to set statement_timeout for all connections in the connection pool.

config.sequel.after_connect = proc do |db|
  db.execute('SET statement_timeout = 30000;')
end

So with max_connections => 5 and running

5.times{ Thread.new{ puts DB['SHOW statement_timeout'].to_a }}

there should be the same timeout -> 30s for all connections in the connection pool

@JonathanTron @JosephHalter
Could you please take a look at that to verify all the changes? :)

[JonathanTron]

Hi @kamilpavlicko, thanks for the PR.

My only concern is that we're changing the behaviour for after_connect in sequel-rails.

It's been a long time, but from what I recall, at the time, we intentionally didn't implement it using sequel after_connect. The current behaviour means this hook is called only once when we start a new rails process, while the new behaviour would make those existing hooks called once per new connection (which is not necessarily on rails boot, if I recall correctly).

What I propose is:

1. keep the existing after_connect as it is, called once per rails process.
2. add a new after_each_connect (or after_every_connect, or whatever else you prefer) which we can hook into sequel's after_connect.

What do you think?

[kamilpavlicko]

@JonathanTron
Yep, totally agree.
Then I would go with after_new_connection approach. Will change the code and will update Readme.

[kamilpavlicko]

@JonathanTron
PR updated 👍

[JonathanTron]

Thanks for the changes @kamilpavlicko !

[kamilpavlicko]

Is there any date or plan, when it is going to be released?

[JonathanTron]

@kamilpavlicko I can make a new release next week. My concern is that we don't have CI running anymore since TravisCI is no longer free for OSS, I started a branch to migrate to Github Actions... but I never finished.

[kamilpavlicko]

@JonathanTron
I've noticed new release there ... awesome job, thank you 👍