[XABT] Create separate assembly preparation tasks.

src/Xamarin.Android.Build.Tasks/Tasks/CompressAssemblies.cs

@@ -0,0 +1,108 @@
+#nullable enable
+
+using System;
+using System.Collections.Generic;
+using System.IO;
+using System.Linq;
+using Microsoft.Android.Build.Tasks;
+using Microsoft.Build.Framework;
+using Xamarin.Android.Tools;
+
+namespace Xamarin.Android.Tasks;
+
+/// <summary>
+/// Compresses assemblies using LZ4 compression before placing them in the APK.
+/// Note this is independent of whether they are stored compressed with ZIP in the APK.
+/// Our runtime bits will LZ4 decompress them at assembly load time.
+/// </summary>
+public class CompressAssemblies : AndroidTask
+{
+	public override string TaskPrefix => "CAS";
+
+	[Required]
+	public string ApkOutputPath { get; set; } = "";
+
+	public bool EmbedAssemblies { get; set; }
+
+	[Required]
+	public bool EnableCompression { get; set; }
+
+	public bool IncludeDebugSymbols { get; set; }
+
+	[Required]
+	public string ProjectFullPath { get; set; } = "";
+
+	[Required]
+	public ITaskItem [] ResolvedFrameworkAssemblies { get; set; } = [];
+
+	[Required]
+	public ITaskItem [] ResolvedUserAssemblies { get; set; } = [];
+
+	[Required]
+	public string [] SupportedAbis { get; set; } = [];
+
+	[Output]
+	public ITaskItem [] ResolvedFrameworkAssembliesOutput { get; set; } = [];
+
+	[Output]
+	public ITaskItem [] ResolvedUserAssembliesOutput { get; set; } = [];
+
+	public override bool RunTask ()
+	{
+		if (IncludeDebugSymbols || !EnableCompression || !EmbedAssemblies) {
+			ResolvedFrameworkAssembliesOutput = ResolvedFrameworkAssemblies;
+			ResolvedUserAssembliesOutput = ResolvedUserAssemblies;
+			return true;
+		}
+
+		var compressed_assemblies_info = GetCompressedAssemblyInfo ();
+
+		// Get all the user and framework assemblies we may need to compresss
+		var assemblies = ResolvedFrameworkAssemblies.Concat (ResolvedUserAssemblies).Where (asm => !(ShouldSkipAssembly (asm))).ToArray ();
+		var per_arch_assemblies = MonoAndroidHelper.GetPerArchAssemblies (assemblies, SupportedAbis, true);
+		var compressed_output_dir = Path.GetFullPath (Path.Combine (Path.GetDirectoryName (ApkOutputPath), "..", "lz4"));
+
+		foreach (var kvp in per_arch_assemblies) {
+			Log.LogDebugMessage ($"Compressing assemblies for architecture '{kvp.Key}'");
+
+			foreach (var asm in kvp.Value.Values) {
+				MonoAndroidHelper.LogIfReferenceAssembly (asm, Log);
+
+				var compressed_assembly = AssemblyCompression.Compress (Log, asm, compressed_assemblies_info, compressed_output_dir);
+
+				if (compressed_assembly.HasValue ()) {
+					Log.LogDebugMessage ($"Compressed '{asm.ItemSpec}' to '{compressed_assembly}'.");
+					asm.SetMetadata ("CompressedAssembly", compressed_assembly);
+				}
+			}
+		}
+
+		ResolvedFrameworkAssembliesOutput = ResolvedFrameworkAssemblies;
+		ResolvedUserAssembliesOutput = ResolvedUserAssemblies;
+
+		return !Log.HasLoggedErrors;
+	}
+
+	IDictionary<AndroidTargetArch, Dictionary<string, CompressedAssemblyInfo>> GetCompressedAssemblyInfo ()
+	{
+		var key = CompressedAssemblyInfo.GetKey (ProjectFullPath);
+		Log.LogDebugMessage ($"Retrieving assembly compression info with key '{key}'");
+
+		var compressedAssembliesInfo = BuildEngine4.UnregisterTaskObjectAssemblyLocal<IDictionary<AndroidTargetArch, Dictionary<string, CompressedAssemblyInfo>>> (key, RegisteredTaskObjectLifetime.Build);
+
+		if (compressedAssembliesInfo is null)
+			throw new InvalidOperationException ($"Assembly compression info not found for key '{key}'. Compression will not be performed.");
+
+		return compressedAssembliesInfo;
+	}
+
+	bool ShouldSkipAssembly (ITaskItem asm)
+	{
+		var should_skip = asm.GetMetadataOrDefault ("AndroidSkipAddToPackage", false);
+
+		if (should_skip)
+			Log.LogDebugMessage ($"Skipping {asm.ItemSpec} due to 'AndroidSkipAddToPackage' == 'true' ");
+
+		return should_skip;
+	}
+}