Add LockFile

PowerKit.Tests/LockFileTests.cs

@@ -0,0 +1,52 @@
+using System.IO;
+using FluentAssertions;
+using PowerKit;
+using Xunit;
+
+namespace PowerKit.Tests;
+
+public class LockFileTests
+{
+    [Fact]
+    public void TryAcquire_Test()
+    {
+        // Arrange
+        using var tempFile = TempFile.Create();
+
+        // Act
+        using var lockFile = LockFile.TryAcquire(tempFile.Path);
+
+        // Assert
+        lockFile.Should().NotBeNull();
+        File.Exists(tempFile.Path).Should().BeTrue();
+    }
+
+    [Fact]
+    public void TryAcquire_AlreadyLocked_Test()
+    {
+        // Arrange
+        using var tempFile = TempFile.Create();
+        using var lockFile = LockFile.TryAcquire(tempFile.Path);
+
+        // Act
+        using var lockFile2 = LockFile.TryAcquire(tempFile.Path);
+
+        // Assert
+        lockFile2.Should().BeNull();
+    }
+
+    [Fact]
+    public void Dispose_Test()
+    {
+        // Arrange
+        using var tempFile = TempFile.Create();
+        var lockFile = LockFile.TryAcquire(tempFile.Path);
+
+        // Act
+        lockFile!.Dispose();
+
+        // Assert: lock can be reacquired after disposal
+        using var lockFile2 = LockFile.TryAcquire(tempFile.Path);
+        lockFile2.Should().NotBeNull();
+    }
+}

PowerKit/LockFile.cs

@@ -0,0 +1,40 @@
+using System;
+using System.IO;
+
+namespace PowerKit;
+
+/// <summary>
+/// Represents a file-based lock that prevents concurrent access to a shared resource.
+/// </summary>
+internal partial class LockFile(FileStream fileStream) : IDisposable
+{
+    /// <inheritdoc />
+    public void Dispose() => fileStream.Dispose();
+}
+
+internal partial class LockFile
+{
+    /// <summary>
+    /// Tries to acquire a lock on the specified file path.
+    /// Returns <see langword="null" /> if the lock could not be acquired.
+    /// </summary>
+    public static LockFile? TryAcquire(string filePath)
+    {
+        try
+        {
+            var fileStream = File.Open(
+                filePath,
+                FileMode.OpenOrCreate,
+                FileAccess.ReadWrite,
+                FileShare.None
+            );
+
+            return new LockFile(fileStream);
+        }
+        // This is the most specific exception for "access denied"
+        catch (IOException)
+        {
+            return null;
+        }
+    }
+}