Silence p4est output

[efaulhaber]

Right now, there is a lot of output from p4est when running bigger AMR examples with P4estMesh (not merged yet, see #584).
I don't see how this could be done without using sc_package_is_registered and sc_package_set_verbosity, so it seems like trixi-framework/P4est.jl#32 needs to be resolved first.

[sloede]

Can you do a workaround for now, e.g., by directly calling p4est_init without checking for an existing initialization?

[efaulhaber]

This will crash Julia if P4est.jl has been used before in the same session.

[sloede]

Can you maybe put it in the __init__() method of Trixi as a workaround for now? That should ensure that it is only run at most once when using Trixi, unless someone uses Trixi and another package together that also initializes P4est without checking whether it is initialized.

[efaulhaber]

Can we somehow check in the init function if P4est.jl has been used before? Otherwise

using P4est
using Trixi

would crash Julia.

[efaulhaber]

I solved it like this now:

if p4est_package_id()[] < 0
  p4est_init(C_NULL, SC_LP_ERROR)
end

p4est_package_id reliably returns -1 if p4est hasn't been initialized (at least in the current p4est version).
This initializes p4est if it hasn't been done before. If a user initialized p4est with a different log level before using Trixi, we won't touch the log level.