pitrou commented on code in PR #39091: URL: https://github.com/apache/arrow/pull/39091#discussion_r1489200380
########## swift/Arrow/Sources/Arrow/ArrowCExporter.swift: ########## @@ -0,0 +1,110 @@ +// 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. + +import Foundation +import ArrowC +import Atomics + +extension String { + var cstring: UnsafePointer<CChar> { + (self as NSString).cString(using: String.Encoding.utf8.rawValue)! + } +} + +// The memory used by UnsafeAtomic is not automatically +// reclaimed. Since this value is initialized once +// and used until the program/app is closed it's +// memory will be released on program/app exit +let exportDataCounter: UnsafeAtomic<Int> = .create(0) + +public class ArrowCExporter { + private class ExportData { + let id: Int + var cArray = ArrowC.ArrowArray() + private let arrowData: ArrowData + private(set) var data = [UnsafeRawPointer?]() + private(set) var buffers: UnsafeMutablePointer<UnsafeRawPointer?> + init(_ arrowData: ArrowData) { + id = exportDataCounter.loadThenWrappingIncrement(ordering: .relaxed) + + // keep a reference to the ArrowData + // obj so the memory doesn't get + // deallocated + self.arrowData = arrowData + for arrowBuffer in arrowData.buffers { + data.append(arrowBuffer.rawPointer) + } + + self.buffers = UnsafeMutablePointer(mutating: data) + ArrowCExporter.exportedData[id] = self + } + + func release() { + // the data associated with this export data + // does not need to be released as they are + // still associated with the ArrowBuffer + // and it will deallocate this memory + ArrowCExporter.exportedData.removeValue(forKey: id.hashValue) + } + } + + private static var exportedData = [Int: ExportData]() + + public init() {} + + public func exportType(_ cSchema: inout ArrowC.ArrowSchema, arrowType: ArrowType, name: String = "") -> + Result<Bool, ArrowError> { + do { + cSchema.format = try arrowType.cDataFormatId.cstring + cSchema.name = name.cstring Review Comment: Unless, I'm misunderstanding, this exports a pointer that is not guaranteed to remain valid until the `release` function is called. What you most certainly need to do is: 1. allocate a copy of the utf8 contents 2. have the `release` function deallocate that copy -- 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]
