Ducktype instance type check (#6373)

DataDog · Nov 28, 2024 · 7f5fb56 · 7f5fb56
1 parent 959f006
commit 7f5fb56
Show file tree

Hide file tree

Showing 2 changed files with 38 additions and 10 deletions.
diff --git a/tracer/src/Datadog.Trace/DuckTyping/DuckType.cs b/tracer/src/Datadog.Trace/DuckTyping/DuckType.cs
@@ -1350,7 +1350,7 @@ public static CreateTypeResult GetProxy(Type targetType)
                     return default;
                 }
 
-                return GetProxy(instance.GetType()).CreateInstance<T>(instance);
+                return instance is T tInst ? tInst : GetProxy(instance.GetType()).CreateInstance<T>(instance);
             }
 
             /// <summary>
@@ -1368,7 +1368,7 @@ public static CreateTypeResult GetProxy(Type targetType)
                     return default;
                 }
 
-                return GetProxy(typeof(TOriginal)).CreateInstance<T, TOriginal>(instance);
+                return instance is T tInst ? tInst : GetProxy(typeof(TOriginal)).CreateInstance<T, TOriginal>(instance);
             }
 
             /// <summary>
@@ -1384,7 +1384,7 @@ public static bool CanCreate(object? instance)
                     return false;
                 }
 
-                return GetProxy(instance.GetType()).CanCreate();
+                return instance is T || GetProxy(instance.GetType()).CanCreate();
             }
 
             /// <summary>

diff --git a/tracer/src/Datadog.Trace/DuckTyping/DuckTypeExtensions.cs b/tracer/src/Datadog.Trace/DuckTyping/DuckTypeExtensions.cs
@@ -48,6 +48,12 @@ public static object DuckCast(this object instance, Type targetType)
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
         public static bool TryDuckCast<T>(this object? instance, [NotNullWhen(true)] out T? value)
         {
+            if (instance is T tInst)
+            {
+                value = tInst;
+                return true;
+            }
+
             if (instance is not null &&
                 DuckType.CreateCache<T>.GetProxy(instance.GetType()) is { Success: true } proxyResult)
             {
@@ -71,11 +77,20 @@ public static bool TryDuckCast(this object? instance, Type targetType, [NotNullW
         {
             if (targetType is null) { ThrowHelper.ThrowArgumentNullException(nameof(targetType)); }
 
-            if (instance is not null &&
-                DuckType.GetOrCreateProxyType(targetType, instance.GetType()) is { Success: true } proxyResult)
+            if (instance is not null)
             {
-                value = proxyResult.CreateInstance(instance);
-                return true;
+                var instanceType = instance.GetType();
+                if (instanceType == targetType)
+                {
+                    value = instance;
+                    return true;
+                }
+
+                if (DuckType.GetOrCreateProxyType(targetType, instanceType) is { Success: true } proxyResult)
+                {
+                    value = proxyResult.CreateInstance(instance);
+                    return true;
+                }
             }
 
             value = default;
@@ -92,6 +107,11 @@ public static bool TryDuckCast(this object? instance, Type targetType, [NotNullW
         public static T? DuckAs<T>(this object? instance)
             where T : class
         {
+            if (instance is T tInst)
+            {
+                return tInst;
+            }
+
             if (instance is not null &&
                 DuckType.CreateCache<T>.GetProxy(instance.GetType()) is { Success: true } proxyResult)
             {
@@ -112,10 +132,18 @@ public static bool TryDuckCast(this object? instance, Type targetType, [NotNullW
         {
             if (targetType is null) { ThrowHelper.ThrowArgumentNullException(nameof(targetType)); }
 
-            if (instance is not null &&
-                DuckType.GetOrCreateProxyType(targetType, instance.GetType()) is { Success: true } proxyResult)
+            if (instance is not null)
             {
-                return proxyResult.CreateInstance(instance);
+                var instanceType = instance.GetType();
+                if (instanceType == targetType)
+                {
+                    return instance;
+                }
+
+                if (DuckType.GetOrCreateProxyType(targetType, instanceType) is { Success: true } proxyResult)
+                {
+                    return proxyResult.CreateInstance(instance);
+                }
             }
 
             return null;