No need to make gchandles for permits at all

Author: Sushisource

src/Temporalio/Bridge/CustomSlotSupplier.cs

@@ -15,7 +15,7 @@ internal class CustomSlotSupplier : NativeInvokeableClass<Interop.CustomSlotSupp
     {
         private readonly ILogger logger;
         private readonly Temporalio.Worker.Tuning.ICustomSlotSupplier userSupplier;
-        private readonly Dictionary<uint, GCHandle> permits = new();
+        private readonly Dictionary<uint, Temporalio.Worker.Tuning.ISlotPermit> permits = new();
         private uint permitId = 1;
 
         /// <summary>
@@ -167,11 +167,10 @@ private void Release(Interop.SlotReleaseCtx ctx)
 
         private uint AddPermitToMap(Temporalio.Worker.Tuning.ISlotPermit permit)
         {
-            var handle = GCHandle.Alloc(permit);
             lock (permits)
             {
                 var usedPermitId = permitId;
-                permits.Add(permitId, handle);
+                permits.Add(permitId, permit);
                 permitId += 1;
                 return usedPermitId;
             }

src/Temporalio/Worker/Tuning/SlotMarkUsedContext.cs

@@ -14,14 +14,11 @@ public class SlotMarkUsedContext
         /// Initializes a new instance of the <see cref="SlotMarkUsedContext"/> class.
         /// </summary>
         /// <param name="ctx">The bridge version of the slot mark used context.</param>
-        /// <param name="userData">The user data associated with the slot.</param>
-        internal SlotMarkUsedContext(Temporalio.Bridge.Interop.SlotMarkUsedCtx ctx, GCHandle userData)
+        /// <param name="permit">The user-create permit instance.</param>
+        internal SlotMarkUsedContext(Temporalio.Bridge.Interop.SlotMarkUsedCtx ctx, ISlotPermit permit)
         {
             this.SlotInfo = SlotInfo.FromBridge(ctx.slot_info);
-            unsafe
-            {
-                this.Permit = (ISlotPermit)userData.Target!;
-            }
+            this.Permit = permit;
         }
 
         /// <summary>

src/Temporalio/Worker/Tuning/SlotReleaseContext.cs

@@ -1,5 +1,3 @@
-using System.Runtime.InteropServices;
-
 namespace Temporalio.Worker.Tuning
 {
     /// <summary>
@@ -14,14 +12,14 @@ public class SlotReleaseContext
         /// Initializes a new instance of the <see cref="SlotReleaseContext"/> class.
         /// </summary>
         /// <param name="ctx">The bridge version of the slot release context.</param>
-        /// <param name="userData">The user data associated with the slot.</param>
-        internal SlotReleaseContext(Temporalio.Bridge.Interop.SlotReleaseCtx ctx, GCHandle userData)
+        /// <param name="permit">The user-create permit instance.</param>
+        internal SlotReleaseContext(Temporalio.Bridge.Interop.SlotReleaseCtx ctx, ISlotPermit permit)
         {
             unsafe
             {
                 this.SlotInfo = ctx.slot_info is null ? null : SlotInfo.FromBridge(*ctx.slot_info);
-                this.Permit = (ISlotPermit)userData.Target!;
             }
+            this.Permit = permit;
         }
 
         /// <summary>