Draft: GeoModelSvc: make MaterialManager methods non-const

This is an attempt to make GeoModelSvc "thread-safe", i.e. pass the thread-checker.

The main problems is that all the StoredMaterialManager interfaces are const and use mutable for the list of materials. Making addMaterial non-const was rather easy (and probably uncontroversial) as it's only used in a few places.

The bigger problem is getMaterial, which is used in pretty much all detector-specific factories. As an example, I applied the necessary fixes to InDetServMatGeoModel. At least for this package this works without problems. Not sure there are any road-blocks in other packages.

But before going further, I would like to have feedback from @tsulaia and @ssnyder if this is the way we want to go. Another option could be to leave getMaterial const and make sure the code is actually thread-safe. Although from what I have seen so far, the code really does not need to be thread-safe/const.

hi Frank -

If making getMaterial non-const works without significant headaches downstream, then i'd just go with that.

Hi @fwinkl , your changes look good to me. The reason why we have there the combination of const and mutable is purely historical.

Since we are on it, perhaps we should also do the same with getElement() and m_elementVector? This can be done in a separate MR later on.

Thanks.

mentioned in merge request !54069 (merged)

OK, thanks for the feedback. I started with the most invasive getMaterial change in !54069 (merged) and will follow-up with the rest. Closing this MR here...

closed

mentioned in merge request !54097 (merged)