Prevent triggering queries from logging

Prevent triggering queries from logging

This will raise an exception in development and log it in production when logging an application context would trigger an exception.

The lazy attributes are put in place to prevent just that. But this means that calling the lazy attribute should query for it. We can do that by reading a variable inside the proc, rather than calling a method that would load the object.

Because we're sometimes logging early in the request cycle, before resources are loaded, we need to make sure we don't memoize these nils. So now, the LazyAttributes only memoize nils when they had received an invalid type. In other cases, when the value was still nil it will retrigger the block.

We also include the context in error logging, so we need to exclude enforcing the limit there, to avoid the recursion it would cause.

Lazily push user & project into logging-context

This avoids some queries triggered when logging the ApplicationContext from an internal API call. By using the ivar to access @project or @actor we avoid loading the information. We'll still log the information if it was already loaded at the time we want to log.

Preload logging attributes before logging context

We do this so the logging itself would not trigger any queries. Most of the time, we just need to preload the route on a group or project. We can do this through the new Routable#preload_for_logging.

In the case of runner-client, we deduct the context from either the project linked to the runner, or the group linked to it.

Add documentation to Gitlab::Utils::LazyAttributes