Update DependentHandle on Mono runtime

dotnet · stephentoub · Jun 26, 2021 · Jun 15, 2021 · Jun 15, 2021 · Jun 15, 2021
commit a96fa3fb19ae72411b6ab34bcfb1721f7ccbc6b3
@@ -240,8 +240,8 @@
       <Compile Include="$(BclSourcesRoot)\System\Reflection\Emit\UnmanagedMarshal.cs" />
       <Compile Include="$(BclSourcesRoot)\System\Reflection\Metadata\AssemblyExtensions.cs" />
       <Compile Include="$(BclSourcesRoot)\System\Resources\ManifestBasedResourceGroveler.Mono.cs" />
+      <Compile Include="$(BclSourcesRoot)\System\Runtime\DependentHandle.cs" />
       <Compile Include="$(BclSourcesRoot)\System\Runtime\GCSettings.Mono.cs" />
-      <Compile Include="$(BclSourcesRoot)\System\Runtime\CompilerServices\DependentHandle.cs" />
       <Compile Include="$(BclSourcesRoot)\System\Runtime\CompilerServices\JitHelpers.cs" />
       <Compile Include="$(BclSourcesRoot)\System\Runtime\CompilerServices\RuntimeHelpers.Mono.cs" />
       <Compile Include="$(BclSourcesRoot)\System\Runtime\CompilerServices\RuntimeFeature.Mono.cs" />

@@ -1,73 +1,100 @@
 // Licensed to the .NET Foundation under one or more agreements.
 // The .NET Foundation licenses this file to you under the MIT license.
 
+using System.Runtime.CompilerServices;
+
 namespace System.Runtime.CompilerServices
 {
     internal struct Ephemeron
     {
         public object? key;
         public object? value;
     }
+}
 
+namespace System.Runtime
+{
     //
     // Instead of dependent handles, mono uses arrays of Ephemeron objects.
     //
-    internal struct DependentHandle
+    public struct DependentHandle : IDisposable
     {
         private Ephemeron[] data;
 
-        public DependentHandle(object? primary, object? secondary)
+        public DependentHandle(object? target, object? dependent)
         {
             data = new Ephemeron[1];
-            data[0].key = primary;
-            data[0].value = secondary;
+            data[0].key = target;
+            data[0].value = dependent;
             GC.register_ephemeron_array(data);
         }
 
         public bool IsAllocated => data != null;
 
-        // Getting the secondary object is more expensive than getting the first so
-        // we provide a separate primary-only accessor for those times we only want the
-        // primary.
-        public object? GetPrimary()
+        public object? Target
+        {
+            get => GetTarget();
+            set => SetTarget(value);
+        }
+
+        public object? Dependent
+        {
+            get => GetDependent();
+            set => SetDependent(value);
+        }
+
+        public (object? Target, object? Dependent) GetTargetAndDependent()
         {
             if (!IsAllocated)
                 throw new NotSupportedException();
             if (data[0].key == GC.EPHEMERON_TOMBSTONE)
-                return null;
-            return data[0].key;
+            {
+                return default;
+            }
+            return (data[0].key, data[0].value);
         }
 
-        public object? GetPrimaryAndSecondary(out object? secondary)
+        public void Dispose()
         {
+            data = null!;
+        }
+
+        private object? GetTarget()
+        {
+            // Getting the secondary object is more expensive than getting the first so
+            // we provide a separate primary-only accessor for those times we only want the
+            // primary.
+
             if (!IsAllocated)
                 throw new NotSupportedException();
             if (data[0].key == GC.EPHEMERON_TOMBSTONE)
-            {
-                secondary = null;
                 return null;
-            }
-            secondary = data[0].value;
             return data[0].key;
         }
 
-        public void SetPrimary(object? primary)
+        private void SetTarget(object? primary)
         {
             if (!IsAllocated)
                 throw new NotSupportedException();
             data[0].key = primary;
         }
 
-        public void SetSecondary(object? secondary)
+        private object? GetDependent()
         {
             if (!IsAllocated)
                 throw new NotSupportedException();
-            data[0].value = secondary;
+            if (data[0].key == GC.EPHEMERON_TOMBSTONE)
+            {
+                return null;
+            }
+            return data[0].value;
         }
 
-        public void Free()
+        private void SetDependent(object? secondary)
         {
-            data = null!;
+            if (!IsAllocated)
+                throw new NotSupportedException();
+            data[0].value = secondary;
         }
     }
 }