Hello, I am Laszlo

JsonMergePatch and .NET6

12/18/2021

In a previous post I have shown how JsonMergePatch library can be used with console and Asp.Net Core applications.

In this post I will focus on using it with the source generator hand-in-hand of System.Text.Json. Before getting into the details, a new [Patchable] attribute is introduced ease the work:

Patchable

Certain use-cases require to generate wrapper types with the source generation for assemblies that do not directly use Patch<T> (where T is the wrapped source type). This could be a reason for having separate assemblies for entity types, or because of the need of stacking multiple source generators on top of each other. In this case types may be attributed with [Patchable] attribute:

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WaitAsync

11/21/2021

.NET 6 has a new method added to System.Threading.Tasks.Task to wait for a task completion or timeout. WaitAsync method completes with the result of the task it is invoked on, or throws a timeout exception when the given timeout reached or throws a TaskCancelledException if the given cancellation token is set to cancelled state.

The method's primary use-case is to add cancellation or timeout ability for async methods, that inherently don't provide such capability. One use-case could be unit tests, where we explicitly want to time out and fail a test if the method invoked as the system under test is an async operation without a timeout overload. This way we can let other tests to be executed in the test suite.

Previously a poor man (woman)'s implementation for such timeout could look as:

public static async Task<T> TimeoutAfter<T>(this Task<T> task, TimeSpan timeout)
{
    if (task.IsCompleted)
        return await task;
    var cts = new CancellationTokenSource();
    if (task == await Task.WhenAny(task, Task.Delay(timeout, cts.Token)))
    {
        cts.Cancel();
        return await task;
    }
    else
    {
        throw new TimeoutException();
    }
}

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Math Sin with SIMD

10/31/2021

Introduction

In this post I will look into how someone can implement Sin/Cosin functions with SIMD in NET 5. NET 5 does not have a wrapper on SIMD trigonometric functions, so it seems a good exercise to implement it.

Using SIMD, one may gain performance advantage on large data sets. Later in this post I will run a performance benchmark to compare the SIMD implementation with Math.Cos() and MathF.Cos() methods.

Considerations

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String Interpolation and StringBuilder in .NET6

09/26/2021

In a previous post I have looked into what are the performance characteristics of creating interpolated string in .NET 5 and early previews of .NET 6. With .NET 6 preview 7 or better a new approach is used by the C# compiler with support from the BCL to build interpolated strings.

Fortunately the new way provides a faster approach for the most convenient ways for assembling strings, however it makes my previous post completely obsolete.

For details about the new way DefaultInterpolatedStringHandler builds strings, read: https://devblogs.microsoft.com/dotnet/string-interpolation-in-c-10-and-net-6/

Re-running the benchmarks from the previous post, shows much better memory usage:

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String Interpolation and StringBuilder

09/25/2021

This post looks into different approaches and their performance characteristics for appendnng interpolated like strings. I use BenchmarkDotNet to benchmark the different solutions. In case of all benchmarks I have 3 string properties A, B and C each holding one of these values:

• hello
• world
• how are you

The values of these variables are set in a Global setup step of BencharmarkDotNet. In all benchmarks the three string are concatenate with some punctuations.

Implementation

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