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Use try...finally... to ensure buffer is released #728

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Merged
merged 2 commits into from
May 22, 2025
Merged

Use try...finally... to ensure buffer is released #728

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3e5feb1
Use `try...finally...` to ensure buffer is released
jakirkham May 22, 2025
ef55e3c
Remove spaces on blank lines
jakirkham May 22, 2025
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51 changes: 26 additions & 25 deletions python/kvikio/kvikio/_lib/arr.pyx
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Original file line number Diff line number Diff line change
Expand Up @@ -130,36 +130,37 @@ cdef class Array:
self.strides_mv = None
else:
PyObject_GetBuffer(obj, &pybuf, PyBUF_FULL_RO)

if pybuf.suboffsets != NULL:
raise NotImplementedError("Suboffsets are not supported")

self.ptr = <uintptr_t>pybuf.buf
self.obj = pybuf.obj
self.readonly = <bint>pybuf.readonly
self.ndim = <Py_ssize_t>pybuf.ndim
self.itemsize = <Py_ssize_t>pybuf.itemsize

if self.ndim > 0:
self.shape_mv = new_Py_ssize_t_array(self.ndim)
memcpy(
&self.shape_mv[0],
pybuf.shape,
self.ndim * sizeof(Py_ssize_t)
)
if not PyBuffer_IsContiguous(&pybuf, b"C"):
self.strides_mv = new_Py_ssize_t_array(self.ndim)
try:
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@jakirkham jakirkham May 22, 2025

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The core of this change involves adding a try for the block of code right after PyObject_GetBuffer

if pybuf.suboffsets != NULL:
raise NotImplementedError("Suboffsets are not supported")
Comment on lines +134 to +135
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@jakirkham jakirkham May 22, 2025

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For example here is one exception we raise

Though it is also possible to wind up with an exception due to some bug in the code below

In any event we want to make sure normal resource cleanup can proceed as usual (without potentially causing segfaults)


self.ptr = <uintptr_t>pybuf.buf
self.obj = pybuf.obj
self.readonly = <bint>pybuf.readonly
self.ndim = <Py_ssize_t>pybuf.ndim
self.itemsize = <Py_ssize_t>pybuf.itemsize

if self.ndim > 0:
self.shape_mv = new_Py_ssize_t_array(self.ndim)
memcpy(
&self.strides_mv[0],
pybuf.strides,
&self.shape_mv[0],
pybuf.shape,
self.ndim * sizeof(Py_ssize_t)
)
if not PyBuffer_IsContiguous(&pybuf, b"C"):
self.strides_mv = new_Py_ssize_t_array(self.ndim)
memcpy(
&self.strides_mv[0],
pybuf.strides,
self.ndim * sizeof(Py_ssize_t)
)
else:
self.strides_mv = None
else:
self.shape_mv = None
self.strides_mv = None
else:
self.shape_mv = None
self.strides_mv = None
PyBuffer_Release(&pybuf)
finally:
PyBuffer_Release(&pybuf)
Comment on lines +162 to +163
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@jakirkham jakirkham May 22, 2025

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Then moving the PyBuffer_Release into a finally block

That way we still release the underlying Py_buffer object if an exception is raised


cpdef bint _c_contiguous(self):
return _c_contiguous(
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