pitrou commented on code in PR #36489:
URL: https://github.com/apache/arrow/pull/36489#discussion_r1260751781
##########
cpp/src/arrow/c/bridge.h:
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@@ -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,
+ struct ArrowSchema* out_schema = NULLPTR);
+
+/// \brief EXPERIMENTAL: Export C++ RecordBatch as an ArrowDeviceArray.
+///
+/// The record batch is exported as if it were a struct array.
+/// The resulting ArrowDeviceArray struct keeps the record batch data and
buffers alive
+/// until its release callback is called by the consumer.
+///
+/// All buffers of all columns in the record batch must have the same
device_type
+/// otherwise an error will be returned. If columns are on different devices,
+/// they should be exported using different ArrowDeviceArray instances.
+///
+/// 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
ignored.
+///
+/// \param[in] batch Record batch 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 where to export the record batch
\param[out]
+/// out_schema optional C struct where to export the record batch schema
+ARROW_EXPORT
+Status ExportDeviceRecordBatch(const RecordBatch& batch, void* sync_event,
+ ReleaseEventFunc sync_release,
+ struct ArrowDeviceArray* out,
+ struct ArrowSchema* out_schema = NULLPTR);
+
+class ARROW_EXPORT DeviceMemoryMgr {
+ public:
+ virtual ~DeviceMemoryMgr() = default;
+
+ virtual Result<std::shared_ptr<MemoryManager>> get_manager(ArrowDeviceType
device_type,
+ int64_t
device_id) const = 0;
+};
Review Comment:
If there's only a single virtual method, just use a `std::function`? Though,
again, I'm not sure having the user implement this makes a very usable API.
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