wjones127 commented on code in PR #34133: URL: https://github.com/apache/arrow/pull/34133#discussion_r1138787644
########## csharp/src/Apache.Arrow/C/CArrowSchemaExporter.cs: ########## @@ -0,0 +1,265 @@ +// 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. + + +using System; +using System.Collections.Generic; +using System.IO; +using System.Linq; +using System.Runtime.InteropServices; +using Apache.Arrow.Types; + +namespace Apache.Arrow.C +{ + public static class CArrowSchemaExporter + { + /// <summary> + /// Export a type to a <see cref="CArrowSchema"/>. + /// </summary> + /// <param name="datatype">The datatype to export</param> + /// <param name="schema">An allocated but uninitialized CArrowSchema pointer.</param> + /// <example> + /// <code> + /// CArrowSchema* exportPtr = CArrowSchema.Create(); + /// CArrowSchemaExporter.ExportType(dataType, exportPtr); + /// foreign_import_function(exportPtr); + /// CArrowSchema.Free(exportPtr); Review Comment: Here, we're implicitly assuming that `foreign_import_function` called `release` already and is done with it. Because we allocated the `CArrowSchema*` pointer, we must free it. It's supposed to be that when exporting the consumer will allocate the `CArrowSchema*`, but that seems impossible in cases like Python. Although when we get to exporting Arrays, I'm not sure how the lifetime is handled. Because the buffers do need to be kept alive, so the call to `Free` in that case needs to be deferred until after the Python process is done with it. But how does C# know when that is? -- 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]
