added parallel executor

Author: alkampfergit

src/KernelMemory.Extensions.FunctionalTests/QueryPipeline/ParallelQueryHandlerTests.cs

@@ -0,0 +1,63 @@
+using Moq;
+
+namespace KernelMemory.Extensions.FunctionalTests.QueryPipeline;
+
+public class ParallelQueryHandlerTests
+{
+    [Fact]
+    public void Constructor_WithValidParameters_CreatesInstance()
+    {
+        // Arrange & Act
+        var handler = new ParallelQueryHandler("test");
+
+        // Assert
+        Assert.Equal("test", handler.Name);
+    }
+
+    [Fact]
+    public async Task HandleAsync_WithMultipleHandlers_CallsAllHandlers()
+    {
+        // Arrange
+        var mock1 = new Mock<IQueryHandler>();
+        var mock2 = new Mock<IQueryHandler>();
+        var handler = new ParallelQueryHandler("test", mock1.Object, mock2.Object);
+        var question = GetQuestion();
+
+        // Act
+        await handler.HandleAsync(question, CancellationToken.None);
+
+        // Assert
+        mock1.Verify(x => x.HandleAsync(question, CancellationToken.None), Times.Once);
+        mock2.Verify(x => x.HandleAsync(question, CancellationToken.None), Times.Once);
+    }
+
+    private static UserQuestion GetQuestion()
+    {
+        return new UserQuestion(new UserQueryOptions("test index"), "question");
+    }
+
+    [Fact]
+    public async Task HandleAsync_WithNoHandlers_CompletesSuccessfully()
+    {
+        // Arrange
+        var handler = new ParallelQueryHandler("test");
+        var question = GetQuestion();
+
+        // Act & Assert
+        await handler.HandleAsync(question, CancellationToken.None);
+    }
+
+    [Fact]
+    public async Task HandleAsync_WhenHandlerThrows_PropagatesException()
+    {
+        // Arrange
+        var mock = new Mock<IQueryHandler>();
+        mock.Setup(x => x.HandleAsync(It.IsAny<UserQuestion>(), It.IsAny<CancellationToken>()))
+            .ThrowsAsync(new InvalidOperationException());
+        var handler = new ParallelQueryHandler("test", mock.Object);
+
+        // Act & Assert
+        await Assert.ThrowsAsync<InvalidOperationException>(() => 
+            handler.HandleAsync(GetQuestion(), CancellationToken.None));
+    }
+}

src/KernelMemory.Extensions/QueryPipeline/ParallelQueryHandler.cs

@@ -0,0 +1,30 @@
+using System.Collections.Generic;
+using System.Linq;
+using System.Threading;
+using System.Threading.Tasks;
+
+namespace KernelMemory.Extensions;
+
+/// <summary>
+/// Useful when you want to wrap multiple query handlers
+/// and you want them to execute concurrently
+/// </summary>
+public class ParallelQueryHandler : BasicQueryHandler
+{
+    private readonly IEnumerable<IQueryHandler> _handlers;
+    private readonly string _name;
+
+    public ParallelQueryHandler(string name, params IQueryHandler[] handlers)
+    {
+        _name = name;
+        _handlers = handlers;
+    }
+
+    public override string Name => _name;
+
+    protected override async Task OnHandleAsync(UserQuestion userQuestion, CancellationToken cancellationToken)
+    {
+        var tasks = _handlers.Select(h => h.HandleAsync(userQuestion, cancellationToken));
+        await Task.WhenAll(tasks);
+    }
+}