TRACE logging improvements

[galderz]

Infinispan uses this idiom where it caches whether trace is enabled in a static final field. In native testing it has been shown that this field is true even if trace has not been enabled. @Sanne already predicted the issue. The linked issue also explains the reason why this happens. In Hibernate's case, they worked around it by making the cached field non static.

After much discussion, an agreement has been reached that isTraceEanbled calls should be computed at build time (only enable it if it has been configured) and if not enabled, all the code that adds/maintains trace logging should be dead code eliminated if possible. This way, for code that uses isTraceEnabled to return true, it would require using a native executable that has been built with this option enabled. If this option was not enabled, the native executable would remove code to isTraceEnabled true paths, reducing its size both in terms of code and strings used within it.

Once this is in place, Hibernate could go back to having TRACE enabled check cached as static field and you could get the benefits above. The recommendation would be for instance or to use on the fly isTraceEnabled(). By folding this colds, they'd precomputed at build time and replaced, so no need for static fields. In fact, static fields caching trace enabled should be avoided since they'll always return true.

This change would require an update to the Quarkus logging documentation.

[quarkusbot]

/cc @kenfinnigan, @Ladicek

[galderz]

The solution described can be achieved by using gizmo to generate bytecode at build time for a class that substitutes BasicLogger.isTraceEnabled method, if any categories have been enabled for TRACE. Then, the substituted method would check whether the log name is equals too, or starts with, the category to trace in which case it would return true. Then, by adding @Fold annotation, it should force these isTraceEnabled calls to happen at build time hence enabling dead code elimination.

[galderz]

Updated the description to better match the expected behaviour. PR incoming.