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Extend JNI to Managed type map caching #9818

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Extend JNI to Managed type map caching #9818

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13 changes: 12 additions & 1 deletion src/Mono.Android/Java.Interop/TypeManager.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -243,15 +243,26 @@ static Exception CreateJavaLocationException ()
Type? type = null;
IntPtr class_ptr = JNIEnv.GetObjectClass (handle);
string? class_name = GetClassName (class_ptr);
List<string>? class_names = null;
lock (TypeManagerMapDictionaries.AccessLock) {
while (class_ptr != IntPtr.Zero && !TypeManagerMapDictionaries.JniToManaged.TryGetValue (class_name, out type)) {

type = GetJavaToManagedType (class_name);
if (type != null) {
TypeManagerMapDictionaries.JniToManaged.Add (class_name, type);

// cache shortcuts for the class names of the subclasses in the hierarchy we just explored
if (class_names is not null) {
foreach (var subclass_name in class_names) {
TypeManagerMapDictionaries.JniToManaged.Add (subclass_name, type);

@jonathanpeppers jonathanpeppers Feb 21, 2025

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Is the type here actually the correct one? It seems like it would be the final type it found and not the one that matches the class_name earlier in the loop.

Do you need to store a (string, Type) tuple, so you have the previous Type instance?

@simonrozsival simonrozsival Feb 22, 2025

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You're right that it is not an exact match. On the other hand, by inspecting the superclasses in the type hierarchy we should always arraive at the same type. So my idea was to cache this "shortcut".

The only problem I can think of is if we stored this "shortcut", any later call to TypeManager.RegisterType with a more specific mapping would be ignored. This could break dynamic registration. I will need to give this some more thought.

}
}

break;
}

class_names ??= new List<string> ();
class_names.Add (class_name);

IntPtr super_class_ptr = JNIEnv.GetSuperclass (class_ptr);
JNIEnv.DeleteLocalRef (class_ptr);
class_name = null;
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