TypeManager.CreateProxy does not cache constructor reflection

[jeromelaban]

Android application type

Android for .NET (net6.0-android, etc.)

Affected platform version

.NET 6 and 7

Description

The following piece of code is very expensive when manipulating native objects:

https://github.com/xamarin/xamarin-android/blob/91669a4e489104668fdd07382e40cf070aa559ac/src/Mono.Android/Java.Interop/TypeManager.cs#L327-L348

As there is no caching for getting constructors, in the worst case, twice:

Steps to Reproduce

Get ShapeDrawable.Paint in a loop.

Did you find any workaround?

None.

Relevant log output

No response

[jonathanpeppers]

I can still see this in a recent .NET MAUI app:

It looks like any API that returns a new instance of a Java.Lang.Object subclass would look up the constructor again.

1. First call, Java object A: looks up constructor
2. Second call, Java object A: already has a C# object, reuses object, doesn't call constructor at all
3. Third call, Java object B: looks up constructor again

I think this could happen for commonly called APIs like View.Background that return unique Drawable instances. MAUI calls these a lot.