The `zip_next` function uses a common optimization technique for methods
that generate tuples. The iterator maintains an internal reference to
the returned tuple. When the method is called again, it checks if the
internal tuple's reference count is 1. If so, the tuple can be reused.
However, this approach is not safe under the free-threading build:
after checking the reference count, another thread may perform the same
check and also reuse the tuple. This can result in a double decref on
the items of the replaced tuple and a double incref (memory leak) on
the items of the tuple being set.
This adds a function, `_PyObject_IsUniquelyReferenced` that
encapsulates the stricter logic necessary for the free-threaded build:
the internal tuple must be owned by the current thread, have a local
refcount of one, and a shared refcount of zero.
* Make `weakref.WeakSet` safe against concurrent mutations while it is being iterated.
`_IterationGuard` is no longer used for `WeakSet`, it now relies on copying the underlying set which is an atomic operation while iterating so that it can be modified by other threads.
Remove *ignore* and *on_error* arguments from `pathlib.Path.copy[_into]()`,
because these arguments are under-designed. Specifically:
- *ignore* is appropriated from `shutil.copytree()`, but it's not clear
how it should apply when the user copies a non-directory. We've changed
the callback signature from the `shutil` version, but I'm not confident
the new signature is as good as it can be.
- *on_error* is a generalisation of `shutil.copytree()`'s error handling,
which is to accumulate exceptions and raise a single `shutil.Error` at
the end. It's not obvious which solution is better.
Additionally, this arguments may be challenging to implement in future user
subclasses of `PathBase`, which might utilise a native recursive copying
method.
Per feedback from Paul Moore on GH-123158, it's better to defer making
`Path.delete()` public than ship it with under-designed error handling
capabilities.
We leave a remnant `_delete()` method, which is used by `move()`. Any
functionality not needed by `move()` is deleted.
These two methods accept an *existing* directory path, onto which we join
the source path's base name to form the final target path.
A possible alternative implementation is to check for directories in
`copy()` and `move()` and adjust the target path, which is done in several
`shutil` functions. This behaviour is helpful in a shell context, but
less so in a stored program that explicitly specifies destinations. For
example, a user that calls `Path('foo.py').copy('bar.py')` might not
imagine that `bar.py/foo.py` would be created, but under the alternative
implementation this will happen if `bar.py` is an existing directory.
When display lines above the cursor come from the cache, the first line
to not come from the cache may be a wrapped line, starting half way
through a logical line in the buffer. Detect and handle this case to
avoid accidentally drawing a stray prompt in the middle of a logical
line.
Add a `Path.move()` method that moves a file or directory tree, and returns a new `Path` instance pointing to the target.
This method is similar to `shutil.move()`, except that it doesn't accept a *copy_function* argument, and it doesn't check whether the destination is an existing directory.
`Py_DECREF` and `PyStackRef_CLOSE` are now implemented as macros in the
free-threaded build in ceval.c. There are two motivations;
* MSVC has problems inlining functions in ceval.c in the PGO build.
* We will want to mark escaping calls in order to spill the stack
pointer in ceval.c and we will want to do this around `_Py_Dealloc`
(or `_Py_MergeZeroLocalRefcount` or `_Py_DecRefShared`), not around
the entire `Py_DECREF` or `PyStackRef_CLOSE` call.
Jason R. Coombs
Pieter Eendebak
Irit Katriel
Daniel Hollas
Mark Shannon
Kumar Aditya
Petr Viktorin
Terry Jan Reedy
Kirill Podoprigora
sobolevn
Barney Gale
Victor Stinner
Sergey B Kirpichev
Matt Wozniski
CF Bolz-Tereick
Pablo Galindo Salgado
Adam Turner
Shantanu
Cody Maloney
Anthony Shaw
neonene
Sam Gross
Kevin Evans
blhsing
Bar Harel