Refactors our use of `slogtest` to instantiate a "standard logger" across most of our tests. This standard logger incorporates https://github.com/coder/slog/pull/217 to also ignore database query canceled errors by default, which are a source of low-severity flakes.
Any test that has set non-default `slogtest.Options` is left alone. In particular, `coderdtest` defaults to ignoring all errors. We might consider revisiting that decision now that we have better tools to target the really common flaky Error logs on shutdown.
This PR is the first in a series aimed at closing
[#15109](https://github.com/coder/coder/issues/15109).
### Changes
- **Template Database Creation:**
`dbtestutil.Open` now has the ability to create a template database if
none is provided via `DB_FROM`. The template database’s name is derived
from a hash of the migration files, ensuring that it can be reused
across tests and is automatically updated whenever migrations change.
- **Optimized Database Handling:**
Previously, `dbtestutil.Open` would spin up a new container for each
test when `DB_FROM` was unset. Now, it first checks for an active
PostgreSQL instance on `localhost:5432`. If none is found, it creates a
single container that remains available for subsequent tests,
eliminating repeated container startups.
These changes address the long individual test times (10+ seconds)
reported by some users, likely due to the time Docker took to start and
complete migrations.
Fixes the flake seen here: https://github.com/coder/coder/runs/25832852690
Linux is not a real time operating system, and so there is no guarantee that subsequent `time.Now()` `time.Since()` calls will return a non-zero time. This assert is mainly there to ensure we don't return `-1`.
fixes#11950https://github.com/coder/coder/issues/11950#issuecomment-1987756088 explains the bug
We were also calling into `Unlisten()` and `Close()` while holding the mutex. I don't believe that `Close()` depends on the notification loop being unblocked, but it's hard to be sure, and the safest thing to do is assume it could block.
So, I added a unit test that fakes out `pq.Listener` and sends a bunch of notifies every time we call into it to hopefully prevent regression where we hold the mutex while calling into these functions.
It also removes the use of a `context.Context` to stop the PubSub -- it must be explicitly `Closed()`. This simplifies a bunch of the logic, and is how we use the pubsub anyway.
Adds prometheus metrics to PGPubsub for monitoring its health and performance in production.
Related to #11950 --- additional diagnostics to help figure out what's happening
