Hello, I am Laszlo

Singletons with DI Container

04/08/2023

A typical discussion topic about Dependency Injection (DI) Containers is creating singleton classes. Although many discussions come to the conclusion that the singleton pattern can be converted directly to singleton with a DI container, that is not entirely true.

First concern is that many DI containers support creating a child or scoped containers. Singleton registrations are instantiated with different rules based on the contract of the container. In that case it is possible that a child container creates its own singleton instance - but this is generally not the case. Today most containers differentiate scoped registrations from singletons to handle this case.

Second concern is that most DI containers require the user to implement the singleton type with a public constructor. This ensures that the DI container can invoke the constructor. However, it also implies that any user code may just as well instantiate further objects from the type. Even worse, the declaration of the type does not reflect its intended use.

The third concern is that a user can create multiple DI containers in an application. Each container can have its own singletons, as nothing restricts not to register the same (singleton) type with multiple containers.

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Method Size and CPU

03/18/2023

Usually, assembly code size is good measure to have for performance optimizations. In this post I plan to gain an understanding why smaller assembly code size might be beneficial and how this affects the performance.

Problem

To answer this question, I prepare two methods to compare. How can I create two methods that do the same operations in essence but differ in code size that is executed?

Instead of writing 2 methods to compare, I decided to write ~2000 methods:

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The Best Way to ArgumentValidation

02/25/2023

Introduction to Argument Validation

In .NET7 we can do 3 different style of argument validation against null arguments. In this post I will check which one is the most performant.

The first example is the poor man's validation. We check if the input parameter is null, and if so an ArgumentNullException object is instantiated and thrown. This style of argument validation has been around for an awfully long time in .NET.

public int CustomArgumentValidationImpl(Data? input)
{
    if (input == null)
        throw new ArgumentNullException(nameof(input));
    return input.Value;
}

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Understanding RuntimeHelpers.IsKnownConstant Method

02/04/2023

In this post my goal is to gain understanding of the RuntimeHelpers.IsKnownConstant method. I have come across it in the Performance Improvements in .NET 7 blog post. There are two examples presented in the post:

• bool StartsWith(char value)

• Math.Round with MidpointRounding mode is specified

I will learn about JIT optimization including RuntimeHelpers.IsKnownConstant through a simple and slightly artificial example. A bool IsPalindromePosition(int position) method is part of a type which has a static property ReadOnlySpan<char> Text. The method returns true when the given position from the beginning of the string returns the same character as one from the end. For the sake of simplicity this method omits all input validation.

public static ReadOnlySpan<char> Text => "hellobolleh";

[MethodImpl(MethodImplOptions.AggressiveInlining | MethodImplOptions.AggressiveOptimization)]
public bool IsPalindromePosition(int position)
{
    if (int.IsOddInteger(Text.Length) && position == Text.Length / 2 + 1)
        return true;

    return Text[position] == Text[Text.Length - position - 1];
}

[MethodImpl(MethodImplOptions.NoInlining | MethodImplOptions.AggressiveOptimization)]
public bool Work()
{
    var result = IsPalindromePosition(0);
    return result;
}

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Kestrel Serving Requests

01/15/2023

In this post I review the way Kestrel serves HTTP requests. Please note, that the architecture described here may change from release to release of ASP.NET Core. At the time of writing .NET 7 and the corresponding ASP.NET Core is a month away from release.

Accepting connection on HTTP2 and HTTP3

ASP.NET Core's Kestrel opens IConnectionListener<T>s upon startup. For each ASPNETCORE_URLS set, a connection listener is instantiated. A base IConnectionListener implementation is a SocketConnectionListener. Connection listeners implement the decorator pattern. For example, GenericConnectionListener expects another connection listener as a constructor parameter.Connection listeners provide basic functionality to bind/unbind to a given port and to accept new connection requests.

ConnectionDispatcher also initiated during startup. It starts to run an infinite while loop in AcceptConnectionsAsync() method to accept new connections on a given listener. When a client sends a request, a new connection in initialized. In this case a KestrelConnection<T>, that also implements IThreadPoolWorkItem.Execute().

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