Rename our "client-server" variables/functions?

[sbastrakov]

Some examples of renamings done in other produts are here

[PrometheusPi]

What would you prefer @ComputationalRadiationPhysics/picongpu-developers?

[sbastrakov]

Just as a note, we use it in several places with different contexts. I feel some usage was also technically imprecise (if not incorrect) to begin with. So it is very possible there should be different renaming in different situations.

[n01r]

I like

• main / worker
• controller / agent
• primary / replica

that's still multiple, I know

[sbastrakov]

After #3822 is merged, we will have the following things to consider wrt this renaming. They are all quite common in the code, all involve master, but in different context and meaning:

• The main multi-plugin (that is basically an aggrenate of instances per species). I think this may become Main<> instead of Master<>
• MPI rank doing some aggregation (e.g. reduction) and/or output. E.g. like this, similar code and naming in several other places. Here it is maybe okay to keep, but we can consider calling it root as MPI reduce and gather call the target process like that.
• Lockstep programming. We need operations to be done by thread 0 of each block like this. This is logically similar to #pragma omp master which also make it easier understandible by this analogy. Note that in OpenMP 5.1 it became deprecated. Here i do not have a good renaming option.