Copilot commented on code in PR #51122:
URL: https://github.com/apache/arrow/pull/51122#discussion_r3932596902
##########
python/pyarrow/array.pxi:
##########
@@ -2269,6 +2274,51 @@ cdef class Array(_PandasConvertible):
return pyarrow_wrap_array(array)
+ @staticmethod
+ def from_dlpack(x, /, *, device=None, copy=None):
+ """
+ Construct an Array from an object implementing the DLPack protocol.
+
+ Parameters
+ ----------
+ x : object
+ The input object containing array data, following the DLPack
+ protocol (has a ``__dlpack__`` method).
+ device : tuple[enum.Enum, int], optional
+ Designates where the resulting Array should reside, in the
+ format returned by :meth:`Array.__dlpack_device__`. When None,
+ the output Array occupies the same device as the source.
+ Default: None.
+ copy : bool, optional
+ Controls duplication behavior. True mandates copying; False
+ prohibits copying and raises ``BufferError`` if unavoidable;
+ None duplicates only when necessary. Default: None.
+
+ Returns
+ -------
+ Array
+ An Array housing the data from the input object, potentially
+ as a copy or view.
+ """
+ version = (DLPACK_VERSION.major, DLPACK_VERSION.minor)
+ pycapsule = x.__dlpack__(max_version=version, dl_device=device,
copy=copy)
+ if not PyCapsule_CheckExact(pycapsule):
+ raise TypeError("DLPack producer did not return a PyCapsule")
+ cdef DLManagedTensorVersioned* ptr =
<DLManagedTensorVersioned*>PyCapsule_GetPointer(
+ pycapsule, "dltensor_versioned")
+ if ptr == NULL:
+ raise ValueError(
+ 'DLPack producer did not produce a "dltensor_versioned"
PyCapsule')
+ # Mark the capsule as consumed so its destructor does not also invoke
the deleter.
+ # ImportArrayVersionedFromDLPack will take ownership even if it errors
(calling
+ # the deleter in that case).
+ PyCapsule_SetName(pycapsule, "used_dltensor_versioned")
+ with nogil:
+ # Copy handled on producer side
+ result = ImportArrayVersionedFromDLPack(ptr, False)
+ carray = GetResultValue(result)
Review Comment:
In `Array.from_dlpack()`, `result` is assigned inside a `with nogil:` block
but isn’t declared as a Cython cdef variable, which will fail to compile (and
can’t use a Python variable without the GIL). Also check `PyCapsule_SetName`
for failure; if it fails and you proceed, the capsule destructor may still call
the DLPack deleter, risking double-free.
##########
python/pyarrow/tensor.pxi:
##########
@@ -300,7 +306,52 @@ strides: {self.strides}"""
buffer.strides = <Py_ssize_t *>
cp.PyBytes_AsString(self._ssize_t_strides)
buffer.suboffsets = NULL
- def __dlpack__(self, stream=None, max_version=None, dl_device=None,
copy=None):
+ @staticmethod
+ def from_dlpack(x, /, *, device=None, copy=None):
+ """
+ Construct a Tensor from an object implementing the DLPack protocol.
+
+ Parameters
+ ----------
+ x : object
+ The input object containing array data, following the DLPack
+ protocol (has a ``__dlpack__`` method).
+ device : tuple[enum.Enum, int], optional
+ Designates where the resulting Tensor should reside, in the
+ format returned by :meth:`Tensor.__dlpack_device__`. When None,
+ the output Tensor occupies the same device as the source.
+ Default: None.
+ copy : bool, optional
+ Controls duplication behavior. True mandates copying; False
+ prohibits copying and raises ``BufferError`` if unavoidable;
+ None duplicates only when necessary. Default: None.
+
+ Returns
+ -------
+ Tensor
+ A Tensor housing the data from the input object, potentially
+ as a copy or view.
+ """
+ version = (DLPACK_VERSION.major, DLPACK_VERSION.minor)
+ pycapsule = x.__dlpack__(max_version=version, dl_device=device,
copy=copy)
+ if not PyCapsule_CheckExact(pycapsule):
+ raise TypeError("DLPack producer did not return a PyCapsule")
+ cdef DLManagedTensorVersioned* ptr =
<DLManagedTensorVersioned*>PyCapsule_GetPointer(
+ pycapsule, "dltensor_versioned")
+ if ptr == NULL:
+ raise ValueError(
+ 'DLPack producer did not produce a "dltensor_versioned"
PyCapsule')
+ # Mark the capsule as consumed so its destructor does not also invoke
the deleter.
+ # ImportTensorVersionedFromDLPack will take ownership even if it
errors (calling
+ # the deleter in that case).
+ PyCapsule_SetName(pycapsule, "used_dltensor_versioned")
+ with nogil:
+ # Copy handled on producer side
+ result = ImportTensorVersionedFromDLPack(ptr, False)
+ ctensor = GetResultValue(result)
Review Comment:
In `Tensor.from_dlpack()`, `result` is assigned inside a `with nogil:` block
but isn’t declared as a Cython cdef variable, which will fail to compile (and
can’t use a Python variable without the GIL). Also check `PyCapsule_SetName`
for failure; if it fails and you proceed, the capsule destructor may still call
the DLPack deleter, risking double-free.
##########
python/pyarrow/tests/test_dlpack.py:
##########
@@ -339,3 +339,81 @@ def test_dlpack_cuda_not_supported():
with pytest.raises(NotImplementedError, match="DLPack support is
implemented "
"only for buffers on CPU device."):
carr.__dlpack_device__()
+
+
+@check_bytes_allocated
[email protected]('np_type',
+ [np.uint8, np.uint16, np.uint32, np.uint64,
+ np.int8, np.int16, np.int32, np.int64,
+ np.float16, np.float32, np.float64])
+def test_tensor_from_dlpack(np_type):
+ if Version(np.__version__) < Version("2.1.0"):
+ pytest.skip("Versioned DLPack capsules require numpy 2.1.0 or later")
+
+ # Non-contiguous, strided slice: DLPack carries explicit strides, so this
+ # should not need a copy on export.
Review Comment:
Comment says “copy on export” but this test is exercising *import* via
`from_dlpack`.
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