adamreeve opened a new pull request, #33603: URL: https://github.com/apache/arrow/pull/33603
# Which issue does this PR close? Closes https://issues.apache.org/jira/browse/ARROW-16921 # What changes are included in this PR? This PR implements decompression support for Arrow IPC format files and streams in the dotnet/C# library. The main concern raised in the above Jira issue was that we don't want to add new NuGet package dependencies to support decompression formats that won't be needed by most users, so a default `CompressionProvider` implementation has been added that uses reflection to use the `ZstdNet` package for ZSTD decompression and `K4os.Compression.LZ4.Streams` and `CommunityToolkit.HighPerformance` for LZ4 Frame support if they are available. The `netstandard1.3` target has decompression support disabled due to some reflection functionality being missing, and neither `ZstdNet` or `K4os.Compression.LZ4.Streams` support `netstandard1.3`. The `ArrowFileReader` and `ArrowStreamReader` constructors accept an `ICompressionProvider` parameter to allow users to provide their own compression provider if they want to use different dependencies. ### Alternatives to consider An alternative approach that could be considered instead of reflection is to use these extra dependencies as build time dependencies but not make them dependencies of the NuGet package. I tested this out in https://github.com/adamreeve/arrow/commit/4544afde6fef12337c7b188cc497da0bc1bf829d and it seems to work reasonably well too but required bumping the version of `System.Runtime.CompilerServices.Unsafe` under the `netstandard2.0` and `netcoreapp3.1` targets. This reduces all the reflection boilerplate but seems pretty hacky as now Apache.Arrow.dll depends on these extra dlls and we rely on the dotnet runtime behaviour of not trying to load them until they're used. So I think the reflection approach is better. Another alternative would be to move decompression support into a separate NuGet package (eg. `Apache.Arrow.Compression`) that depends on `Apache.Arrow` and has an implementation of `ICompressionProvider` that users can pass in to the `ArrowFileReader` constructor, or maybe has a way to register itself with the `Apache.Arrow` package so it only needs to be configured once. That would seem cleaner to me but I'm not sure how much work it would be to set up a whole new package. # Are these changes tested? Yes, new unit tests have been added. Test files have been created with a Python script that is included in the PR due to only decompression support being added and not compression support. # Are there any user-facing changes? Yes, this implements a new feature but in a backwards compatible way. -- 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: github-unsubscr...@arrow.apache.org For queries about this service, please contact Infrastructure at: us...@infra.apache.org
