Implement locked iteration for PyList (#4789)

* implement locked iteration for PyList * fix limited API and PyPy support * fix formatting of safety docstrings * only define fold and rfold on not(feature = "nightly") * add missing try_fold implementation on nightly * Use split borrows for locked iteration for PyList Inline ListIterImpl implementations by using split borrows and destructuring let Self { .. } = self destructuring inside BoundListIterator impls. Signed-off-by: Manos Pitsidianakis <manos@pitsidianak.is> * use a function to do the split borrow * add changelog entries * fix clippy on limited API and PyPy * use a macro for the split borrow * add a test that mutates the list during a fold * enable next_unchecked on PyPy * fix incorrect docstring for locked_for_each * simplify borrows by adding BoundListIterator::with_critical_section * fix build on GIL-enabled and limited API builds * fix docs build on MSRV --------- Signed-off-by: Manos Pitsidianakis <manos@pitsidianak.is> Co-authored-by: Manos Pitsidianakis <manos@pitsidianak.is>
PyO3 · Jan 8, 2025 · c0f08c2 · c0f08c2
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diff --git a/newsfragments/4789.added.md b/newsfragments/4789.added.md
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+* Added `PyList::locked_for_each`, which is equivalent to `PyList::for_each` on
+  the GIL-enabled build and uses a critical section to lock the list on the
+  free-threaded build, similar to `PyDict::locked_for_each`.
diff --git a/newsfragments/4789.changed.md b/newsfragments/4789.changed.md
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+* Operations that process a PyList via an iterator now use a critical section
+  on the free-threaded build to amortize synchronization cost and prevent race conditions.
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		* Operations that process a PyList via an iterator now use a critical section
		on the free-threaded build to amortize synchronization cost and prevent race conditions.