[fea] Expose the arena mr to the Python interface.

[trivialfis]

Description

Close #830 .

• Add the arena allocator to the public Python interface.
• Small changes to the logger initialization to avoid exposing spdlog in the shared objects.

Checklist

• I am familiar with the Contributing Guidelines.
• New or existing tests cover these changes.
• The documentation is up to date with these changes.

[wence-]

This changes the __attribute__((visibility)) of this namespace from "default" to "hidden". Is this deliberate, or an inadvertent editor-induced change?

[trivialfis]

It's deliberate.

[trivialfis]

See the second error in https://github.com/rapidsai/rmm/actions/runs/11531514933/job/32102372109 .

[wence-]

Ah, OK, can we just hide that one symbol? Add RMM_HIDDEN for that symbol.

See discussion in #1652, particularly, we need to be careful about visibility of objects that might make it in to the public namespace.

[trivialfis]

Thank you for sharing. I will check whether the exception can be thrown from there. Considering that the namespace is detail and is only used by the MR, which is exposed in the public, it should be fine. That said, I will double check.
Who doesn't love c++ linking, so much fun.

[trivialfis]

The visibility is controlled by namespace instead of translation unit.

[harrism]

oh I had it backwards. I thought this change was exposing more, but it's actually hiding more.

[wence-]

May I suggest that we make the hiding explicit?

namespace RMM_HIDDEN rmm::mr::detail::arena {

?

[trivialfis]

I'm more than happy to make the change. But do you want to do it for the entire repository or do you want me to make the change to this specific file? Or maybe the CMake hidden visibility option is sufficient?

[trivialfis]

Switched to hiding only the spdlog function as suggested offline.

[wence-]

Thanks!