Question about supporting runtime packs for "parent" RIDs

[pjcollins]

The Android (32) workload currently ships four runtime packs, one for each Android architecture:

• Microsoft.Android.Runtime.32.android-arm
• Microsoft.Android.Runtime.32.android-arm64
• Microsoft.Android.Runtime.32.android-x86
• Microsoft.Android.Runtime.32.android-x64

In order to reduce our installation footprint we have a desire to introduce a new runtime pack for managed assemblies that are not architecture specific, but are still only intended to be used with the parent android RID. Right now these managed assemblies are duplicated in all four packs mentioned above. Ideally, we would move the non-architecture specific assemblies into a new pack:

• Microsoft.Android.Runtime.32.android

I tried to get this to work by adding a second RuntimePackNamePatterns value to the KnownFrameworkReference we declare:

<KnownFrameworkReference
    Include="Microsoft.Android"
    TargetFramework="net6.0"
    RuntimeFrameworkName="Microsoft.Android"
    LatestRuntimeFrameworkVersion="**FromWorkload**"
    TargetingPackName="Microsoft.Android.Ref.32"
    TargetingPackVersion="**FromWorkload**"
-   RuntimePackNamePatterns="Microsoft.Android.Runtime.32.**RID**"
+   RuntimePackNamePatterns="Microsoft.Android.Runtime.32.android;Microsoft.Android.Runtime.32.**RID**"
    RuntimePackRuntimeIdentifiers="android-arm;android-arm64;android-x86;android-x64"
    Profile="Android"
/>

The ProcessFrameworkReferences task handles this approach, but the ResolveFrameworkReferences task breaks as it only allows for a 1:1 relationship between runtime pack and framework reference:

Microsoft.NET.Sdk.FrameworkReferenceResolution.targets(326,5): error MSB4018: System.ArgumentException: An item with the same key has already been added. Key: Microsoft.Android

I'm wondering how risky or big of a breaking change it would be to change the RuntimePack* metadata on ResolvedFrameworkReferences, and do something like this instead:

--- a/src/Tasks/Microsoft.NET.Build.Tasks/ResolveFrameworkReferences.cs
+++ b/src/Tasks/Microsoft.NET.Build.Tasks/ResolveFrameworkReferences.cs
@@ -26,7 +26,6 @@ protected override void ExecuteCore()
             }

             var resolvedTargetingPacks = ResolvedTargetingPacks.ToDictionary(tp => tp.ItemSpec, StringComparer.OrdinalIgnoreCase);
-            var resolvedRuntimePacks = ResolvedRuntimePacks.ToDictionary(rp => rp.GetMetadata(MetadataKeys.FrameworkName), StringComparer.OrdinalIgnoreCase);

             var resolvedFrameworkReferences = new List<TaskItem>(FrameworkReferences.Length);

@@ -48,12 +47,11 @@ protected override void ExecuteCore()
                 resolvedFrameworkReference.SetMetadata("TargetingPackVersion", targetingPack.GetMetadata(MetadataKeys.NuGetPackageVersion));
                 resolvedFrameworkReference.SetMetadata("Profile", targetingPack.GetMetadata("Profile"));

-                ITaskItem runtimePack;
-                if (resolvedRuntimePacks.TryGetValue(frameworkReference.ItemSpec, out runtimePack))
-                {
-                    resolvedFrameworkReference.SetMetadata("RuntimePackPath", runtimePack.GetMetadata(MetadataKeys.PackageDirectory));
-                    resolvedFrameworkReference.SetMetadata("RuntimePackName", runtimePack.GetMetadata(MetadataKeys.NuGetPackageId));
-                    resolvedFrameworkReference.SetMetadata("RuntimePackVersion", runtimePack.GetMetadata(MetadataKeys.NuGetPackageVersion));
+                var matchingPacks = ResolvedRuntimePacks.Where(rp => rp.GetMetadata(MetadataKeys.FrameworkName).Equals(frameworkReference.ItemSpec, StringComparison.OrdinalIgnoreCase));
+                if (matchingPacks.Any()) {
+                    resolvedFrameworkReference.SetMetadata("RuntimePackPath", string.Join (";", matchingPacks.Select (mp => mp.GetMetadata(MetadataKeys.PackageDirectory))));
+                    resolvedFrameworkReference.SetMetadata("RuntimePackName", string.Join (";", matchingPacks.Select (mp => mp.GetMetadata(MetadataKeys.NuGetPackageId))));
+                    resolvedFrameworkReference.SetMetadata("RuntimePackVersion", string.Join (";", matchingPacks.Select (mp => mp.GetMetadata(MetadataKeys.NuGetPackageVersion))));
                 }

                 resolvedFrameworkReferences.Add(resolvedFrameworkReference);

We may also want to update the metadata names, but that might cause more breakage. These changes would produce ; separated RuntimePack* metadata values, for example:

RuntimePackName = Microsoft.Android.Runtime.32.android;Microsoft.Android.Runtime.32.android-x64

These changes to ResolveFrameworkReferences appear to work as needed for the Android use case. I've also got something working on the workload side by introducing a new FrameworkReference for Android, but I am not convinced that this FrameworkReference addition is the most sane or desirable approach.

Maybe there are other approaches that would support a "generic RID" runtime pack that I am not considering?

I couldn't figure out the best area label to add to this issue. If you have write-permissions please help me learn by adding exactly one area label.

[pjcollins]

Adding @dsplaisted and @jonathanpeppers to help weigh in on this, I think it would be something we may want to do for .NET 7.

[dsplaisted]

This makes sense to me, and I think the multiple runtime pack approach per FrameworkReference approach is preferrable to the multiple FrameworkReference approach.

[baronfel]

We'd love to see this for 7.0! Of course we'd accept a PR, but otherwise the team will work it in as time/scheduling allows.

[jonathanpeppers]

@pjcollins it might work without any code changes if we did:

<KnownFrameworkReference
    Include="Microsoft.Android"
    TargetFramework="net6.0"
    RuntimeFrameworkName="Microsoft.Android"
    LatestRuntimeFrameworkVersion="**FromWorkload**"
    TargetingPackName="Microsoft.Android.Ref.32"
    TargetingPackVersion="**FromWorkload**"
    RuntimePackNamePatterns="Microsoft.Android.Runtime.32.**RID**"
    RuntimePackRuntimeIdentifiers="android"
    Profile="Android"
/>

Then put native libraries for every RID inside? Release apps use all 4 architectures by default anyway -- don't need them split into separate packs?

This is similar to what Maui does as there are no native libraries:

https://github.com/dotnet/maui/blob/4a0f92458da62006b347f5eb7e29e06e8d7b5f97/src/Workload/Microsoft.Maui.Sdk/Sdk/BundledVersions.in.targets#L18-L31

%(RuntimePackRuntimeIdentifiers) is just android for this one.

[pjcollins]

Thanks that is a good point given how small our architecture specific libraries are, I will try to play around with that option as well. I can probably open a PR against ResolveFrameworkReferences at some point next week if it ends up still being needed.

[pjcollins]

I spent some time seeing if we could fit everything into a single runtime pack:

31.0.200-ci.runtime-dedupe-prototype.107
│
├───data
│       RuntimeList.xml
│
└───runtimes
    ├───android
    │   └───lib
    │       └───net6.0
    │               Java.Interop.dll
    │               Java.Interop.pdb
    │               Mono.Android.dll
    │               Mono.Android.Export.dll
    │               Mono.Android.Export.pdb
    │               Mono.Android.pdb
    │
    ├───android-arm
    │   └───native
    │           libmono-android.debug.so
    │           libmono-android.release.so
    │           libxamarin-debug-app-helper.so
    │
    ├───android-arm64
    │   └───native
    │           libmono-android.debug.so
    │           libmono-android.release.so
    │           libxamarin-debug-app-helper.so
    │
    ├───android-x64
    │   └───native
    │           libmono-android.debug.so
    │           libmono-android.release.so
    │           libxamarin-debug-app-helper.so
    │
    └───android-x86
        └───native
                libmono-android.debug.so
                libmono-android.release.so
                libxamarin-debug-app-helper.so

With this approach I've ran into an issue with the ResolveRuntimePackAssets task, which generally doesn't support nested files with the same name:

"C:\Users\Peter\test\android\android.csproj" (_ComputeFilesToPublishForRuntimeIdentifiers target) (1:11) ->
    C:\Users\Peter\android-toolchain\dotnet\sdk\6.0.300-preview.22128.2\Sdks\Microsoft.NET.Sdk\targets\Microsoft.NET.Sdk.FrameworkReferenceResolution.targets(427,5): error NETSDK1110: More than one asset in the runtime pack has the same destination sub-path of 'libmono-android.debug.so'. Report this error to the .NET team here: https://aka.ms/dotnet-sdk-issue.

To move forward with the single runtime pack suggestion we could try to update this task to handle this case, or alternatively rename the architecture specific components so that they are unique and add custom processing tasks/targets to our Android SDK.

I think I am still leaning towards the approach of adding a new runtime pack for managed assemblies and adding support for multiple runtime packs per framework reference.