Make Disposable.Create produce idempotent disposables

PowerKit.Tests/DisposableTests.cs

@@ -1,6 +1,7 @@
 using System;
 using System.Collections.Generic;
 using System.Linq;
+using System.Threading;
 using FluentAssertions;
 using Xunit;
 
@@ -21,6 +22,22 @@ public void Create_Test()
         invoked.Should().BeTrue();
     }
 
+    [Fact]
+    public void Create_Idempotent_Test()
+    {
+        // Arrange
+        var count = 0;
+        var disposable = Disposable.Create(() => Interlocked.Increment(ref count));
+
+        // Act
+        disposable.Dispose();
+        disposable.Dispose();
+        disposable.Dispose();
+
+        // Assert
+        count.Should().Be(1);
+    }
+
     [Fact]
     public void Merge_Test()
     {

PowerKit/Disposable.cs

@@ -1,11 +1,16 @@
 using System;
 using System.Collections.Generic;
+using System.Threading;
 
 namespace PowerKit;
 
 file class DelegateDisposable(Action dispose) : IDisposable
 {
-    public void Dispose() => dispose();
+    private Action? _dispose = dispose;
+
+    public void Dispose() =>
+        // Idempotency
+        Interlocked.Exchange(ref _dispose, null)?.Invoke();
 }
 
 /// <summary>
@@ -21,6 +26,9 @@ public static class Disposable
     /// <summary>
     /// Creates a disposable that invokes the specified action when disposed.
     /// </summary>
+    /// <remarks>
+    /// The returned disposable is idempotent and invokes the action at most once.
+    /// </remarks>
     public static IDisposable Create(Action dispose) => new DelegateDisposable(dispose);
 
     /// <summary>