[Xamarin.Android.Build.Tasks] reduce System.Linq usage in ManifestDocument #9281
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Profiling an incremental build of a `dotnet new maui` project with a
XAML change, one thing I saw was time spent in `<GenerateJavaStubs/>`
MSBuild task, and the `ManifestDocument` class:
67.57ms (1.80%) xamarin.android.build.tasks!Xamarin.Android.Tasks.ManifestDocument.Merge(class Microsoft.Build.Utilities.TaskLoggingHel
19.99ms (0.53%) xamarin.android.build.tasks!Xamarin.Android.Tasks.ManifestDocument.CreateApplicationElement(class System.Xml.Linq.XEleme...
Reviewing the code, there was a decent amount of LINQ usage that would
create extra allocations for closures, such as:
var properties =
Assemblies.SelectMany (path => PropertyAttribute.FromCustomAttributeProvider (Resolver.GetAssembly (path), cache))
I unrolled the System.Linq usage, and just used plain `foreach` loops
instead.
I also found some places that did:
if (!attrs.Any ())
yield break;
We could just remove these as the `yield return` wouldn't return if
`attrs` is empty *anyway*.
After removing this code, I see a small improvement:
62.56ms (1.80%) xamarin.android.build.tasks!Xamarin.Android.Tasks.ManifestDocument.Merge(class Microsoft.Build.Utilities.TaskLoggingHe...
16.03ms (0.46%) xamarin.android.build.tasks!Xamarin.Android.Tasks.ManifestDocument.CreateApplicationElement(class System.Xml.Linq.XEleme...
This probably saves ~5ms to incremental builds, but seems like a
straightforward change.
jonathanpeppers
commented
Sep 3, 2024
Comment on lines
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to
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| var ull1 = usesLibraryAttr ?? Array.Empty<UsesLibraryAttribute> (); | ||
| var ull2 = typeUsesLibraryAttr.AsEnumerable () ?? Array.Empty<UsesLibraryAttribute> (); | ||
| var usesLibraryAttrs = ull1.Concat (ull2); | ||
| var ucl1 = usesConfigurationAttr ?? Array.Empty<UsesConfigurationAttribute>(); | ||
| var ucl2 = typeUsesConfigurationAttr.AsEnumerable () ?? Array.Empty<UsesConfigurationAttribute> (); | ||
| var usesConfigurationattrs = ucl1.Concat (ucl2); |
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It seems like this made lots of locals before, and we didn't really need them?
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Yup looks like this code above was just to concatinate the lists. But you already do that in the new foreach loop replacement.
Comment on lines
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| AddUsesLibraries (application, usesLibraryAttrs, cache); | ||
| AddUsesConfigurations (application, usesConfigurationattrs, cache); | ||
| AddUsesLibraries (application, usesLibraryAttr, cache); | ||
| AddUsesConfigurations (application, usesConfigurationAttr, cache); |
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I just used the original list instead.
Comment on lines
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to
+910
| void AddUsesConfigurations (XElement application, IEnumerable<UsesConfigurationAttribute> configs, TypeDefinitionCache cache) | ||
| void AddUsesConfigurations (XElement application, List<UsesConfigurationAttribute> configs, TypeDefinitionCache cache) | ||
| { | ||
| foreach (var uca in configs) | ||
| application.Add (uca.ToElement (PackageName, cache)); | ||
| } | ||
|
|
||
| void AddUsesLibraries (XElement application, IEnumerable<UsesLibraryAttribute> libraries, TypeDefinitionCache cache) | ||
| void AddUsesLibraries (XElement application, List<UsesLibraryAttribute> libraries, TypeDefinitionCache cache) |
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These might allow the C# compiler to automatically turn the foreach into for, if the List<T> type is known.
dellis1972
approved these changes
Sep 4, 2024
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Profiling an incremental build of a
dotnet new mauiproject with a XAML change, one thing I saw was time spent in<GenerateJavaStubs/>MSBuild task, and theManifestDocumentclass:Reviewing the code, there was a decent amount of LINQ usage that would create extra allocations for closures, such as:
I unrolled the System.Linq usage, and just used plain
foreachloops instead.I also found some places that did:
We could just remove these as the
yield returnwouldn't return ifattrsis empty anyway.After removing this code, I see a small improvement:
This probably saves ~5ms to incremental builds, but seems like a straightforward change.