tqchen commented on a change in pull request #12047: [MXNET-779]Add DLPack
Transformation API
URL: https://github.com/apache/incubator-mxnet/pull/12047#discussion_r209416606
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File path: include/mxnet/c_api.h
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@@ -737,6 +741,57 @@ MXNET_DLL int MXNDArrayGetShape(NDArrayHandle handle,
*/
MXNET_DLL int MXNDArrayGetData(NDArrayHandle handle,
void **out_pdata);
+/*!
+* \brief Create a reference view of NDArray that
+* represents as DLManagedTensor until
+* all the pending writes with respect NDArray are finished.
+* \param handle the handle to the ndarray
+* \param out_dlpack pointer holder to get pointer of DLManagedTensor
+* \return 0 when success, -1 when failure happens
+*/
+MXNET_DLL int MXNDArrayToDLPackForRead(NDArrayHandle handle,
+ DLManagedTensorHandle *out_dlpack);
+
+/*!
+* \brief Create a reference view of NDArray that
+* represents as DLManagedTensor until
+* all the pending reads/writes with respect NDArray are finished.
+* \param handle the handle to the ndarray
+* \param out_dlpack pointer holder to get pointer of DLManagedTensor
+* \return 0 when success, -1 when failure happens
+*/
+MXNET_DLL int MXNDArrayToDLPackForWrite(NDArrayHandle handle,
+ DLManagedTensorHandle *out_dlpack);
+
+/*!
+* \brief Create a NDArray backed by a dlpack tensor.
+*
+* This allows us to create a NDArray using the memory
+* allocated by an external deep learning framework
+* that is DLPack compatible.
+*
+* The memory is retained until the NDArray went out of scope.
+*
+* \param dlpack the pointer of the input DLManagedTensor
+* \param out_handle pointer holder to get pointer of NDArray
+* \return 0 when success, -1 when failure happens
+*/
+MXNET_DLL int MXNDArrayFromDLPack(DLManagedTensorHandle dlpack,
+ NDArrayHandle *out_handle);
+/*!
+ * \brief Delete a dlpack tensor
+ * \param dlpack the pointer of the input DLManagedTensor
+ * \return 0 when success, -1 when failure happens
+ */
+MXNET_DLL int MXNDArrayCallDLPackDeleter(DLManagedTensorHandle dlpack);
+
+/*!
+ * \brief Delete a dlpack tensor
+ * \param dlpack_capsule the pointer of a PyCapsule storing DLManagedTensor
+ * \return 0 when success, -1 when failure happens
+ */
+MXNET_DLL void MXNDArrayCallDLPackCapsuleDeleter(PyObjectHandle
dlpack_capsule);
Review comment:
I see two problems in your particular gist you paste.
- The destructor need to be declared in the global scope(instead of
constructing when passing to the argument)
- THe cstring need to outlive the capsule(construct a global string)
- The function need to outlive the capsule(constructor c func and put it
under global scope)
```python
cfunc = ctypes.CFUNCTYPE(None, ctypes.c_void_p)
def dfunc(dltensor):
pycaps = ctypes.cast(dltensor, ctypes.py_object)
pass
c_destructor = cfunc(dfunc)
c_str_dltensor = ctypes.c_char_p(b"dltensor")
def test():
a = ctypes.pythonapi.PyCapsule_New(1, c_str_dltensor, c_destructor)
test()
```
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