Description
Based on discussion in dmlc/dlpack#57, array.__dlpack__ method supports stream keyword, implementing @tqchen's suggestion for synchronization semantics.
The from_dlpack command in array API does not support it at present though, requiring users to explicitly synchronize at the exporter's side.
The from_dlpack function has acquired device keyword (see #626) to permit porting device data to host, e.g. from_dlpack(gpu_arr, device=(kDLCPU, 0)) and, potentially, to allow exchanges between different APIs targeting the same device (e.g., between kDLOneAPI and kDLCUDA for oneAPI devices targeting NVidia GPUs) down the road.
It is tempting to want to add support for stream keyword to from_dlpack, but this keyword value must make sense for importing library, while stream value passed to __dlpack__ must make sense for exporting library. So it seems that from_dlpack should only allow specifying non-default value stream keyword when it can make sense for both. Maybe when device type of requested device is the same as the type indicated in arr.__dlpack_device__.