pitrou commented on code in PR #36489:
URL: https://github.com/apache/arrow/pull/36489#discussion_r1261420080
##########
cpp/src/arrow/c/bridge.h:
##########
@@ -166,6 +166,140 @@ Result<std::shared_ptr<RecordBatch>>
ImportRecordBatch(struct ArrowArray* array,
/// @}
+/// \defgroup c-data-device-interface Functions for working with the C data
device
+/// interface.
+///
+/// @{
+
+/// \brief EXPERIMENTAL: Type for freeing a sync event
+///
+/// If synchronization is necessary for accessing the data on a device,
+/// a pointer to an event needs to be passed when exporting the device
+/// array. It's the responsibility of the release function for the array
+/// to release the event.
+using ReleaseEventFunc = void (*)(void*);
+
+/// \brief EXPERIMENTAL: Export C++ Array as an ArrowDeviceArray.
+///
+/// The resulting ArrowDeviceArray struct keeps the array data and buffers
alive
+/// until its release callback is called by the consumer. All buffers in
+/// the provided array MUST have the same device_type, otherwise an error
+/// will be returned.
+///
+/// If a non-null sync_event is provided, then the sync_release func must also
be
+/// non-null. If the sync_event is null, then the sync_release parameter is
not called.
+///
+/// \param[in] array Array object to export
+/// \param[in] sync_event A pointer to an event-like object if necessary for
+/// synchronization, otherwise null.
+/// \param[in] sync_release Function pointer to release the sync event
+/// \param[out] out C struct to export the array to
+/// \param[out] out_schema optional C struct to export the array type to
+ARROW_EXPORT
+Status ExportDeviceArray(const Array& array, void* sync_event,
+ ReleaseEventFunc sync_release, struct
ArrowDeviceArray* out,
Review Comment:
I think having the user devise the `void*` and release func themselves is
just making it easier for them to shoot themselves in the foot. That said,
you're right that we can _start_ with that in this PR.
In any case, for the sake of type-proofing, perhaps we want to introduce an
intermediate struct? (there are too many things that may cast silently to
`void*` :-)).
```c++
struct RawSyncEvent {
void* sync_event = nullptr;
std::function<void(void*)> release_func;
};
```
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