pitrou commented on code in PR #38472: URL: https://github.com/apache/arrow/pull/38472#discussion_r1415635359
########## cpp/src/arrow/c/dlpack.cc: ########## @@ -0,0 +1,151 @@ +// Licensed to the Apache Software Foundation (ASF) under one +// or more contributor license agreements. See the NOTICE file +// distributed with this work for additional information +// regarding copyright ownership. The ASF licenses this file +// to you under the Apache License, Version 2.0 (the +// "License"); you may not use this file except in compliance +// with the License. You may obtain a copy of the License at +// +// http://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, +// software distributed under the License is distributed on an +// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY +// KIND, either express or implied. See the License for the +// specific language governing permissions and limitations +// under the License. + +#include "arrow/c/dlpack.h" + +#include "arrow/array/array_base.h" +#include "arrow/c/dlpack_abi.h" +#include "arrow/device.h" +#include "arrow/type.h" + +namespace arrow { + +namespace dlpack { + +Status getDLDataType(const std::shared_ptr<DataType>& type, DLDataType* out) { + DLDataType dtype; + dtype.lanes = 1; + dtype.bits = type->bit_width(); + switch (type->id()) { + case Type::INT8: + case Type::INT16: + case Type::INT32: + case Type::INT64: + dtype.code = DLDataTypeCode::kDLInt; + *out = dtype; + return Status::OK(); + case Type::UINT8: + case Type::UINT16: + case Type::UINT32: + case Type::UINT64: + dtype.code = DLDataTypeCode::kDLUInt; + *out = dtype; + return Status::OK(); + case Type::HALF_FLOAT: + case Type::FLOAT: + case Type::DOUBLE: + dtype.code = DLDataTypeCode::kDLFloat; + *out = dtype; + return Status::OK(); + case Type::BOOL: + // DLPack supports byte-packed boolean values + return Status::TypeError("Bit-packed boolean data type not supported by DLPack."); + default: + return Status::TypeError( + "Can only use __dlpack__ on primitive arrays without NullType and Decimal " + "types."); + } +} + +struct DLMTensorCtx { + std::shared_ptr<ArrayData> ref; + std::vector<int64_t> shape; + DLManagedTensor tensor; +}; + +static void deleter(DLManagedTensor* arg) { + delete static_cast<DLMTensorCtx*>(arg->manager_ctx); +} + +Status ExportArray(const std::shared_ptr<Array>& arr, DLManagedTensor** out) { + if (arr->null_count() > 0) { + return Status::TypeError("Can only use __dlpack__ on arrays with no nulls."); + } + + // Define the DLDataType struct + // Supported data types: int, uint, float + DLDataType arr_type; + RETURN_NOT_OK(getDLDataType(arr->type(), &arr_type)); + + // Create DLMTensorCtx struct with the reference to + // the data of the array + std::shared_ptr<ArrayData> array_ref = arr->data(); + DLMTensorCtx* DLMTensor = new DLMTensorCtx; + DLMTensor->ref = array_ref; + + // Define DLManagedTensor struct defined by + // DLPack (dlpack_structure.h) + DLManagedTensor* dlm_tensor = &DLMTensor->tensor; + dlm_tensor->manager_ctx = DLMTensor; + dlm_tensor->deleter = &deleter; + + // Define the data pointer to the DLTensor + // If array is of length 0, data pointer should be NULL Review Comment: Hmm, that is weird. @kkraus14 Do you know the rationale for this? Allowing the data to be NULL for 0-sized arrays is one thing, but mandating that it is NULL seems silly. -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: [email protected] For queries about this service, please contact Infrastructure at: [email protected]
