pitrou commented on code in PR #44217: URL: https://github.com/apache/arrow/pull/44217#discussion_r1858142498
########## cpp/src/arrow/compute/kernels/chunked_internal.cc: ########## @@ -0,0 +1,118 @@ +// 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/compute/kernels/chunked_internal.h" + +#include <algorithm> + +#include "arrow/record_batch.h" +#include "arrow/util/logging.h" + +namespace arrow::compute::internal { + +std::vector<const Array*> GetArrayPointers(const ArrayVector& arrays) { + std::vector<const Array*> pointers(arrays.size()); + std::transform(arrays.begin(), arrays.end(), pointers.begin(), + [&](const std::shared_ptr<Array>& array) { return array.get(); }); + return pointers; +} + +std::vector<int64_t> ChunkedIndexMapper::GetChunkLengths( + util::span<const Array* const> chunks) { + std::vector<int64_t> chunk_lengths(chunks.size()); + for (int64_t i = 0; i < static_cast<int64_t>(chunks.size()); ++i) { + chunk_lengths[i] = chunks[i]->length(); + } + return chunk_lengths; +} + +std::vector<int64_t> ChunkedIndexMapper::GetChunkLengths( + const RecordBatchVector& chunks) { + std::vector<int64_t> chunk_lengths(chunks.size()); + for (int64_t i = 0; i < static_cast<int64_t>(chunks.size()); ++i) { + chunk_lengths[i] = chunks[i]->num_rows(); + } + return chunk_lengths; +} + +Result<std::pair<CompressedChunkLocation*, CompressedChunkLocation*>> +ChunkedIndexMapper::LogicalToPhysical() { + // Check that indices would fall in bounds for CompressedChunkLocation + if (ARROW_PREDICT_FALSE(chunk_lengths_.size() > + CompressedChunkLocation::kMaxChunkIndex + 1)) { + return Status::NotImplemented("Chunked array has more than ", + CompressedChunkLocation::kMaxChunkIndex + 1, " chunks"); + } + for (int64_t chunk_length : chunk_lengths_) { + if (ARROW_PREDICT_FALSE(static_cast<uint64_t>(chunk_length) > + CompressedChunkLocation::kMaxIndexInChunk + 1)) { + return Status::NotImplemented("Individual chunk in chunked array has more than ", + CompressedChunkLocation::kMaxIndexInChunk + 1, + " elements"); + } + } + + const int64_t num_indices = static_cast<int64_t>(indices_end_ - indices_begin_); + CompressedChunkLocation* physical_begin = + reinterpret_cast<CompressedChunkLocation*>(indices_begin_); + DCHECK_EQ(physical_begin + num_indices, + reinterpret_cast<CompressedChunkLocation*>(indices_end_)); + + int64_t chunk_offset = 0; + for (int64_t chunk_index = 0; chunk_index < static_cast<int64_t>(chunk_lengths_.size()); + ++chunk_index) { + const int64_t chunk_length = chunk_lengths_[chunk_index]; + for (int64_t i = 0; i < chunk_length; ++i) { + DCHECK_GE(indices_begin_[chunk_offset + i], static_cast<uint64_t>(chunk_offset)); + DCHECK_LT(indices_begin_[chunk_offset + i], + static_cast<uint64_t>(chunk_offset + chunk_length)); + physical_begin[chunk_offset + i] = CompressedChunkLocation{ + static_cast<uint64_t>(chunk_index), + indices_begin_[chunk_offset + i] - static_cast<uint64_t>(chunk_offset)}; + } + chunk_offset += chunk_length; + } + + return std::pair{physical_begin, physical_begin + num_indices}; +} + +Status ChunkedIndexMapper::PhysicalToLogical() { + std::vector<int64_t> chunk_offsets(chunk_lengths_.size()); Review Comment: Hmm, it might (though `chunk_lengths_` is accessed in a debug assertion below). However, we're talking about a small allocation, so I'm not sure it's a problem. -- 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]
