Add polyfills for SystemException, ThreadAbortException, and impr…

…ove `Lock` resilience (#14)
Tyrrrz · Sep 30, 2024 · 694424d · 694424d
1 parent 13499d2
commit 694424d
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Showing 5 changed files with 63 additions and 6 deletions.
diff --git a/PolyShim/Net60/EnumerableExtensions.cs b/PolyShim/Net60/EnumerableExtensions.cs
@@ -17,7 +17,7 @@ public static T ElementAt<T>(this IEnumerable<T> source, Index index)
         if (index.IsFromEnd)
         {
             var asCollection =
-#if !NET45_OR_GREATER
+#if NETFRAMEWORK && !NET45_OR_GREATER
                 source as ICollection<T> ??
 #else
                 source as IReadOnlyCollection<T> ??
@@ -38,7 +38,7 @@ source as IReadOnlyCollection<T> ??
         if (index.IsFromEnd)
         {
             var asCollection =
-#if !NET45_OR_GREATER
+#if NETFRAMEWORK && !NET45_OR_GREATER
                 source as ICollection<T> ??
 #else
                 source as IReadOnlyCollection<T> ??
@@ -154,7 +154,7 @@ T defaultValue
     public static IEnumerable<T> Take<T>(this IEnumerable<T> source, Range range)
     {
         var asCollection =
-#if !NET45_OR_GREATER
+#if NETFRAMEWORK && !NET45_OR_GREATER
             source as ICollection<T> ??
 #else
             source as IReadOnlyCollection<T> ??

diff --git a/PolyShim/Net90/Lock.cs b/PolyShim/Net90/Lock.cs
@@ -31,8 +31,30 @@ public bool TryEnter(int millisecondsTimeout) =>
 
     public Scope EnterScope()
     {
-        Enter();
+#if NETFRAMEWORK && !NET40_OR_GREATER
+        // Older versions of the framework don't have the overload of Monitor.Enter(...) that accepts a ref bool
+        Monitor.Enter(this);
         return new Scope(this);
+#else
+        var acquiredLock = false;
+        try
+        {
+            Monitor.Enter(this, ref acquiredLock);
+            return new Scope(this);
+        }
+        // Ensure that the lock is released if the owning thread is aborted.
+        // Implementation reference:
+        // https://github.com/MarkCiliaVincenti/Backport.System.Threading.Lock/blob/c28041f1e22e561d5cde040704abeeb8d9a18649/Backport.System.Threading.Lock/PreNet5Lock.cs#L112-L125
+        // MIT License, Mark Cilia Vincenti
+        // https://github.com/Tyrrrz/PolyShim/pull/10#issuecomment-2381456516
+        catch (ThreadAbortException)
+        {
+            if (acquiredLock)
+                Monitor.Exit(this);
+
+            throw;
+        }
+#endif
     }
 }
 

diff --git a/PolyShim/NetCore10/AggregateException.cs b/PolyShim/NetCore10/AggregateException.cs
@@ -18,8 +18,6 @@ namespace System;
 [ExcludeFromCodeCoverage]
 internal class AggregateException : Exception
 {
-    public ReadOnlyCollection<Exception> InnerExceptions { get; } = new(new Exception[0]);
-
     public AggregateException(string? message, params Exception[] innerExceptions)
         : base(message, innerExceptions.FirstOrDefault())
     {
@@ -47,6 +45,8 @@ public AggregateException()
     public AggregateException(SerializationInfo info, StreamingContext context)
         : base(info, context) { }
 
+    public ReadOnlyCollection<Exception> InnerExceptions { get; } = new(new Exception[0]);
+
     public AggregateException Flatten()
     {
         var innerExceptions = new List<Exception>();

diff --git a/PolyShim/NetCore20/SystemException.cs b/PolyShim/NetCore20/SystemException.cs
@@ -0,0 +1,15 @@
+#if (NETCOREAPP && !NETCOREAPP2_0_OR_GREATER) || (NETSTANDARD && !NETSTANDARD2_0_OR_GREATER)
+#nullable enable
+// ReSharper disable RedundantUsingDirective
+// ReSharper disable CheckNamespace
+// ReSharper disable InconsistentNaming
+// ReSharper disable PartialTypeWithSinglePart
+using System.Diagnostics.CodeAnalysis;
+
+namespace System;
+
+// https://learn.microsoft.com/en-us/dotnet/api/system.systemexception
+[ExcludeFromCodeCoverage]
+internal class SystemException(string? message = null, Exception? innerException = null)
+    : Exception(message, innerException);
+#endif
diff --git a/PolyShim/NetCore20/ThreadAbortException.cs b/PolyShim/NetCore20/ThreadAbortException.cs
@@ -0,0 +1,20 @@
+#if (NETCOREAPP && !NETCOREAPP2_0_OR_GREATER) || (NETSTANDARD && !NETSTANDARD2_0_OR_GREATER)
+#nullable enable
+// ReSharper disable RedundantUsingDirective
+// ReSharper disable CheckNamespace
+// ReSharper disable InconsistentNaming
+// ReSharper disable PartialTypeWithSinglePart
+using System.Diagnostics.CodeAnalysis;
+
+namespace System.Threading;
+
+// https://learn.microsoft.com/en-us/dotnet/api/system.threading.threadabortexception
+[ExcludeFromCodeCoverage]
+internal class ThreadAbortException : SystemException
+{
+    // This exception cannot be instantiated by user code
+    private ThreadAbortException() => HResult = unchecked((int)0x80131530);
+
+    public object? ExceptionState => null;
+}
+#endif