[generator] improve *Implementor constructors #1105
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Context: dotnet/maui#12130 Context: https://github.com/angelru/CvSlowJittering Profiling a .NET MAUI customer sample while scrolling on a Pixel 5, I see ~2.2% of the time spent in: (2.2%) mono.android!Android.Views.View.IOnFocusChangeListenerImplementor..ctor() https://github.com/dotnet/maui/blob/2041476e78452891029f4d2bd806c45be42f4878/src/Core/src/Handlers/View/ViewHandler.Android.cs#L14 MAUI subscribes to `Android.Views.View.FocusChange` for every view placed on the screen -- which happens while scrolling in this sample. Reviewing, the generated code for this constructor still uses the outdated `JNIEnv` APIs: public IOnFocusChangeListenerImplementor () : base (global::Android.Runtime.JNIEnv.StartCreateInstance ("mono/android/view/View_OnFocusChangeListenerImplementor", "()V"), JniHandleOwnership.TransferLocalRef) { global::Android.Runtime.JNIEnv.FinishCreateInstance (((global::Java.Lang.Object) this).Handle, "()V"); } Which we can change to use the newer/faster Java.Interop APIs: public unsafe IOnFocusChangeListenerImplementor () : base (IntPtr.Zero, JniHandleOwnership.DoNotTransfer) { const string __id = "()V"; if (((global::Java.Lang.Object) this).Handle != IntPtr.Zero) return; var h = JniPeerMembers.InstanceMethods.StartCreateInstance (__id, ((object) this).GetType (), null); SetHandle (h.Handle, JniHandleOwnership.TransferLocalRef); JniPeerMembers.InstanceMethods.FinishCreateInstance (__id, this, null); } These are better because the equivalent call to `JNIEnv.FindClass()` is cached among other things. After these changes, I instead see: (0.81%) mono.android!Android.Views.View.IOnFocusChangeListenerImplementor..ctor() This should improve the performance of all C# events that wrap Java listeners -- and all .NET MAUI views on Android. These changes also stop emitting the `[Register]` attribute for `*Implementor` classes: [global::Android.Runtime.Register ("mono/android/view/View_OnFocusChangeListenerImplementor")] Which is not needed, because `*Implementor` classes are generated, internal implementation details.
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Changes: dotnet/java-interop@3c2a066...a91ae7f * dotnet/java-interop@a91ae7f9: [generator] improve *Implementor constructors (dotnet/java-interop#1105) * dotnet/java-interop@7d42864d: [Java.Interop.Tools.Cecil] DirectoryAssemblyResolver+MemoryMappedFile (dotnet/java-interop#1103) Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>
This was referenced Oct 9, 2023
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Context: dotnet/maui#12130
Context: https://github.com/angelru/CvSlowJittering
Profiling a .NET MAUI customer sample while scrolling on a Pixel 5, I see ~2.2% of the time spent in:
https://github.com/dotnet/maui/blob/2041476e78452891029f4d2bd806c45be42f4878/src/Core/src/Handlers/View/ViewHandler.Android.cs#L14
MAUI subscribes to
Android.Views.View.FocusChangefor every view placed on the screen -- which happens while scrolling in this sample.Reviewing, the generated code for this constructor still uses the outdated
JNIEnvAPIs:Which we can change to use the newer/faster Java.Interop APIs:
These are better because the equivalent call to
JNIEnv.FindClass()is cached among other things.After these changes, I instead see:
This should improve the performance of all C# events that wrap Java listeners -- and all .NET MAUI views on Android.
These changes also stop emitting the
[Register]attribute for*Implementorclasses:Which is not needed, because
*Implementorclasses are generated, internal implementation details.