Replace pthread_self with pthread_threadid_np on macOS

[SpriteOvO]

This PR changes the implementation of fn get_current_tid() on macOS.

The previous used pthread_self() returns an opaque type pthread_t with a large value. Instead, pthread_threadid_np returns a system-wide unique integral ID of thread in the location specified by thread_id.

Note that pthread_threadid_np doesn't seem to exist before macOS 10.6 as mentioned from C++ spdlog comment, we can use pthread_mach_thread_np(pthread_self()) for earlier versions. But considering it's a fairly early version (wikipedia says its initial release date is August 28, 2009), I don't have a condition to test it. So ignoring this for now until a user reports it.

I ran the 3 ways of getting TID on macOS from GitHub Action and this is results:

pthread_self: 4567832064
pthread_threadid_np: 9037
pthread_mach_thread_np(pthread_self()): 259

Obviously, pthread_self returns a large value that doesn't quite match our perception of common TID. pthread_threadid_np and pthread_mach_thread_np both look good, but semantically I prefer the former, whose function name implies what we're doing.

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Other projects also use pthread_threadid_np to get TID on macOS:

• LLVM compiler-rt

  • https://reviews.llvm.org/D18951
  • https://github.com/llvm/llvm-project/blob/4c6f95be29c6ce0f89663a5103c58ee63d76cda3/compiler-rt/lib/sanitizer_common/sanitizer_mac.cpp#L406

• C++ spdlog

  • https://github.com/gabime/spdlog/blob/7e635fca68d014934b4af8a1cf874f63989352b7/include/spdlog/details/os-inl.h#L370

[Lancern]

LGTM.

[Lancern]

Is the thread ID returned from pthread_threadid_np the same as the system thread ID?

[SpriteOvO]

Is the thread ID returned from pthread_threadid_np the same as the system thread ID?

@Lancern From what I learned from Google results - macOS doesn't seem to have a definition for TID. There are different debugging tools that use different ways to get a value to use as a TID.

[blog] gettid on Mac OS
[blog] How to get the thread ID correctly?

Refer to this SO answer, pthread_threadid_np produces the same value as in the system tools.