fix #1358 (#1359)

Author: Khitiara

src/Core/Silk.NET.Core/Native/GlobalMemory.cs

@@ -14,11 +14,14 @@ public sealed class GlobalMemory : IDisposable
     {    
         // Actual object
         private readonly object _memoryObject;
+        private          int    _stringArrayCount;
+        private          bool   _freed = false;
 
-        private GlobalMemory(object memoryObject, int length)
+        private GlobalMemory(object memoryObject, int length, int stringArrayCount = 0)
         {
             _memoryObject = memoryObject;
             Length = length;
+            _stringArrayCount = stringArrayCount;
         }
 
         /// <summary>
@@ -120,6 +123,17 @@ public unsafe ref byte GetPinnableReference()
 
         private unsafe void Free()
         {
+            if (_stringArrayCount != 0)
+            {
+                var span = AsSpan<IntPtr>();
+                for (var index = 0; index < _stringArrayCount; index++)
+                {
+                    var intPtr = span[index];
+                    SilkMarshal.Free(intPtr);
+                }
+
+                _stringArrayCount = 0;
+            }
             switch (_memoryObject)
             {
                 case HGlobal hGlobal:
@@ -145,6 +159,8 @@ private unsafe void Free()
                 }
 #endif
             }
+
+            _freed = true;
         }
 
         /// <inheritdoc />
@@ -174,6 +190,15 @@ public static GlobalMemory Allocate(int length) =>
             new GlobalMemory(new GCHandleByteArray(length), length > 0 ? length : 1);
 #endif
 
+        internal static GlobalMemory AllocateForStringArray(int length, int count) =>
+#if NET6_0_OR_GREATER
+            new GlobalMemory(new NativeMemoryPtr(length), length > 0 ? length : 1, count);
+#elif NET5_0
+            new GlobalMemory(GC.AllocateUninitializedArray<byte>(length > 0 ? length : 1, true), length, count);
+#else
+            new GlobalMemory(new GCHandleByteArray(length), length > 0 ? length : 1, count);
+#endif
+
         // Encapsulations different kinds of memory
         private interface IGlobalMemory
         {

src/Core/Silk.NET.Core/Native/SilkMarshal.cs

@@ -53,10 +53,6 @@ static SilkMarshal()
         // This means that the GlobalMemory is only freed when the user calls Free.
         private static readonly ConcurrentDictionary<nint, GlobalMemory> _marshalledMemory = new();
 
-        // In addition, we should keep track of the memory we allocate dedicated to string arrays. If we don't, we won't
-        // know to free the individual strings allocated within memory.
-        private static readonly ConcurrentDictionary<GlobalMemory, int> _stringArrays = new();
-
         // Other kinds of GCHandle-pinned pointers may be passed into Free, like delegate pointers for example which
         // must have GCHandles allocated on older runtimes to avoid an ExecutionEngineException.
         // We should keep track of those.
@@ -96,15 +92,6 @@ public static bool Free(nint ptr)
                 return ret;
             }
 
-            if (_stringArrays.TryRemove(val, out var numStrings))
-            {
-                var span = val.AsSpan<nint>();
-                for (var i = 0; i < numStrings; i++)
-                {
-                    Free(span[i]);
-                }
-            }
-
             val.Dispose();
             return ret;
         }
@@ -364,7 +351,7 @@ public static GlobalMemory StringArrayToMemory
             NativeStringEncoding e = NativeStringEncoding.Ansi
         )
         {
-            var memory = GlobalMemory.Allocate(input.Count * IntPtr.Size);
+            var memory = GlobalMemory.AllocateForStringArray(input.Count * IntPtr.Size, input.Count);
             var span = memory.AsSpan<nint>();
             for (var i = 0; i < input.Count; i++)
             {
@@ -386,7 +373,7 @@ public static GlobalMemory StringArrayToMemory
             Func<string, nint> customStringMarshaller
         )
         {
-            var memory = GlobalMemory.Allocate(input.Count * IntPtr.Size);
+            var memory = GlobalMemory.AllocateForStringArray(input.Count * IntPtr.Size, input.Count);
             var span = memory.AsSpan<nint>();
             for (var i = 0; i < input.Count; i++)
             {
@@ -409,7 +396,6 @@ public static nint StringArrayToPtr
         )
         {
             var memory = StringArrayToMemory(input, encoding);
-            _stringArrays.TryAdd(memory, input.Count);
             return RegisterMemory(memory);
         }
 
@@ -426,7 +412,6 @@ Func<string, nint> customStringMarshaller
         )
         {
             var memory = StringArrayToMemory(input, customStringMarshaller);
-            _stringArrays.TryAdd(memory, input.Count);
             return RegisterMemory(memory);
         }