cyx-6 commented on code in PR #593:
URL: https://github.com/apache/tvm-ffi/pull/593#discussion_r3585767140
##########
tests/python/test_function.py:
##########
@@ -177,40 +177,46 @@ def echo(x: Any) -> Any:
assert tvm_ffi.get_global_func("mytest.echo", allow_missing=True) is None
[email protected](
+ hasattr(sys, "_is_gil_enabled") and not sys._is_gil_enabled(),
+ reason="PyObject-tying (wrapper aliasing) is disabled on free-threaded
Python",
+)
def test_rvalue_ref() -> None:
+ # Under universal cache-on the callback's arg aliases the caller's
+ # wrapper, so use_count inside is 1 (one wrapper, one chandle ref).
+ # ``_move()`` on either side detaches that wrapper's binding before
+ # the C++ AnyViewToOwnedAny transfer nulls the source chandle.
use_count = tvm_ffi.get_global_func("testing.object_use_count")
def callback(x: Any, expected_count: int) -> Any:
- # The use count of TVM FFI objects is decremented as part of
- # `ObjectRef.__del__`, which runs when the Python object is
- # destructed. However, Python object destruction is not
- # deterministic, and even CPython's reference-counting is
- # considered an implementation detail. Therefore, to ensure
- # correct results from this test, `gc.collect()` must be
- # explicitly called.
+ # ``gc.collect()`` ensures Python destructors have run so
+ # use_count reflects only live wrappers.
gc.collect()
assert expected_count == use_count(x)
return x._move()
f = tvm_ffi.convert(callback)
- def check0() -> None:
+ def check_caller_move() -> None:
+ # Caller passes ``x._move()``: callback receives a fresh canonical
+ # wrapper for the moved-in chandle.
x = tvm_ffi.convert([1, 2])
assert use_count(x) == 1
- f(x, 2)
f(x._move(), 1)
assert x.__ctypes_handle__().value is None
- def check1() -> None:
+ def check_callback_move() -> None:
+ # Callback returns ``x._move()``: caller sees a fresh canonical
+ # wrapper, distinct from the now-empty ``x``.
x = tvm_ffi.convert([1, 2])
assert use_count(x) == 1
- y = f(x, 2)
- f(x._move(), 2)
+ y = f(x, 1)
+ assert y is not x
assert x.__ctypes_handle__().value is None
assert y.__ctypes_handle__().value is not None
- check0()
- check1()
+ check_caller_move()
Review Comment:
Not swapped, I renamed to `check_caller_move` / `check_callback_move` so the
two cases read clearly.
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