Function connection_at 

pub fn connection_at(address: &str) -> PgConnection

Constructs a new Task store representation from a Postgres DB address.

A transient connect failure — a momentary too many clients / a DB restarting — is retried a few times with linear backoff before giving up, so a blip doesn’t become an instant fatal panic (the robustness mandate: degrade through transients, fail fast only when the DB is truly down).