Clean-up pyatomic headers

[colesbury]

Feature or enhancement

Now that #108337 is done, we have three atomic headers. We should be able to remove pycore_atomic.h and pycore_atomic_funcs.h and replace their usages with calls to pyatomic.h.

cc @vstinner

Linked PRs

• gh-109693: Remove pycore_atomic_funcs.h #109694
• gh-109693: Use pyatomic.h for signal module #110477
• gh-109693: Use pyatomic.h for signal module #110480
• gh-109693: Update pycore_interp.h to use pyatomic.h #110604
• gh-109693: Update _gil_runtime_state.last_holder to use pyatomic.h #110605
• gh-109693: Update _gil_runtime_state.locked to use pyatomic.h #110836
• gh-109693: Update pyruntimestate._finalizing to use pyatomic.h #110837
• gh-109693: Remove pycore_atomic.h #110992

[colesbury]

@vstinner, For pycore_atomic.h, I'm not sure whether to keep _Py_atomic_address and _Py_atomic_int or not.

[vstinner]

I was fine to remove pycore_atomic_funcs.h at once since it's only used by _PyUnicode_FromId() which is... no longer used by Python itself!

To remove pycore_atomic.h, I would prefer to make baby steps: convert usage one by one. For example, you can start by converting signal handlers: get_handler() and set_handler() in Modules/signalmodule.c, and also the two "tripped" variables.

If someone goes wrong, it would be easier to revert changes if they have limited scope. Also, smaller PRs are easier to review :-)

[corona10]

@colesbury @vstinner
I am working on the following fields.

cpython/Include/internal/pycore_gil.h

Lines 28 to 31 in 67e8d41

	_Py_atomic_address last_holder;
	/* Whether the GIL is already taken (-1 if uninitialized). This is
	atomic because it can be read without any lock taken in ceval.c. */
	_Py_atomic_int locked;

[vstinner]

The last part seems to be about annotations:

vstinner@mona$ git grep pycore_atomic.h

Makefile.pre.in:                $(srcdir)/Include/internal/pycore_atomic.h \
PCbuild/pythoncore.vcxproj:    <ClInclude Include="..\Include\internal\pycore_atomic.h" />
PCbuild/pythoncore.vcxproj.filters:    <ClInclude Include="..\Include\internal\pycore_atomic.h">

Python/ceval_gil.c:#include "pycore_atomic.h"        // _Py_ANNOTATE_RWLOCK_CREATE
Python/thread_pthread.h:#include "pycore_atomic.h"        // _Py_ANNOTATE_PURE_HAPPENS_BEFORE_MUTEX

[vstinner]

Python/ceval_gil.c:#include "pycore_atomic.h"        // _Py_ANNOTATE_RWLOCK_CREATE
Python/thread_pthread.h:#include "pycore_atomic.h"        // _Py_ANNOTATE_PURE_HAPPENS_BEFORE_MUTEX

Hum, in fact, these symbols come from dynamic_annotations.h. It seems like pycore_pyatomic.h is no longer needed.

@corona10: Do you want to prepare a PR to remove it?

[corona10]

@corona10: Do you want to prepare a PR to remove it?

Yeah, I am preparing the PR

[corona10]

@colesbury @vstinner I think that now we can close this issue.
Please let me know if you want to reopen this issue :)

[colesbury]

Thanks @corona10!

[vstinner]

Well done. One less legacy API in Python C API :-)