[Xamarin.Android.Build.Tasks] _CopyIntermediateAssemblies uses CopyIfChanged (#2128)

jonathanpeppers · dellis1972 · commit c2d36812ed3d · 2018-09-03T12:26:10.000+01:00
Context: #2088 970da9e was a good step towards "correctness" in building incrementally in the following scenario: - File | New Xamarin.Forms project | NetStandard library - Build - Change XAML - Build In this scenario, there is now a new target rising to the surface we can improve: 276 ms _CopyIntermediateAssemblies 1 calls Looking at the target, it seems we could use the `CopyIfChanged` task here more effectively. This task will automaticaly set the timestamps of files that have been copied, and so we don't need any subsequent `<ItemGroup />` or `<Touch />` elements. It was also touching *all* files instead of just the ones that were changed. After this change: 33 ms _CopyIntermediateAssemblies 1 calls The overall build went from 7.058s to 6.652s, so there must be some other targets that benefit from the timestamps not changing on *all* of these files.
diff --git a/src/Xamarin.Android.Build.Tasks/Xamarin.Android.Common.targets b/src/Xamarin.Android.Build.Tasks/Xamarin.Android.Common.targets
@@ -1943,20 +1943,15 @@ because xbuild doesn't support framework reference assemblies.
 	Outputs="@(ResolvedUserAssemblies->'$(MonoAndroidLinkerInputDir)%(Filename)%(Extension)')"
 	DependsOnTargets="_ResolveAssemblies;_ResolveSatellitePaths;_CreatePackageWorkspace;_CreateIntermediateAssembliesDir;_CopyConfigFiles">
 	<!-- Make a copy of every assembly we need in assemblies -->
-	<Copy
+	<CopyIfChanged
 		SourceFiles="@(ResolvedAssemblies)"
 		DestinationFiles="@(ResolvedAssemblies->'$(MonoAndroidLinkerInputDir)%(Filename)%(Extension)')"
-		SkipUnchangedFiles="true" />
-	<Copy
+	/>
+	<CopyIfChanged
 		SourceFiles="@(_AndroidResolvedSatellitePaths)"
 		DestinationFiles="@(_AndroidResolvedSatellitePaths->'$(MonoAndroidLinkerInputDir)%(DestinationSubDirectory)%(Filename)%(Extension)')"
-		SkipUnchangedFiles="true"
 	/>
 	<Delete Files="@(ResolvedAssemblies->'$(MonoAndroidLinkerInputDir)%(Filename)%(Extension).mdb')" />
-	<ItemGroup>
-		<_IntermediateAssemblyFiles Include="$(MonoAndroidLinkerInputDir)*" />
-	</ItemGroup>
-	<Touch Files="@(_IntermediateAssemblyFiles)" />
 </Target>
 
 <Target Name="_CollectConfigFiles"
