06 June 2023

How Async/Await Really Works in C#

Very detailed history of async programming in C#, which has always been hard to get right. This describes the problems, the solutions, and everything in between.

How to start using .NET Background Services

I’m not sure if this is new to me, but I’ll keep this here as a reference. To run a background service in .Net:

In Program.cs:

services.AddHostedService<Worker>();

Where Worker is a class that extends BackgroundService. The core method is ExecuteAsync, and there are also lifecycle event methods StartAsync and StopAsync.

Feature toggle management in .NET Core

Neatly following on from that is .Net’s feature management package. They demo it with a Worker, although that’s just a coincidence that I happened to read this article after the one above:

var host = Host.CreateDefaultBuilder(args)
               .ConfigureServices(services =>
               {
                   services.AddHostedService<Worker>();

                   services.AddFeatureManagement();
               })
               .Build();

public class Worker : BackgroundService
{
    private readonly ILogger<Worker> _logger;
    private readonly IFeatureManager _featureManager;

    public Worker(ILogger<Worker> logger,
                  IFeatureManager featureManager)
    {
        _logger = logger;
        _featureManager = featureManager;
    }

    protected override async Task ExecuteAsync(CancellationToken stoppingToken)
    {
        if (await _featureManager.IsEnabledAsync("ExperimentalAlgorithm"))
        {
             _logger.LogInformation("I'm using some experimental algorithm!");

            // do experimental stuff...
        }
    }
}

As well as calling _featureManager.IsEnabledAsync directly, you can also add it as an attribute on Asp.Net Core controllers:

[FeatureGate(FeatureFlags.ExperimentalAlgorithm)]
public class ExperimentalController()
{
    // ...
}

And there’s lot more configuration and usage possibilities.

Refactor your .NET HTTP Clients to Typed HTTP Clients

This article explains about using IHttpClientFactory and typed clients instead of new HttpClient(), which I assume you already know by now, but it goes on to describe in detail how you should really use named/typed clients.

6 useful extensions for IEnumerable

Exactly what it says:

var isEmpty = numbers.Empty<int>().IsNullOrEmpty();
var (even, odd) = numbers.Partition(n => n % 2 == 0);
var median = numbers.Median();
var mode = numbers.Mode();
var standardDeviation = numbers.StandardDeviation();
var random = numbers.Shuffle();

How to detect Globalization-Invariant mode in .NET

I wish I’d known earlier that Globalization-Invariant mode was a thing. I assume it means that instead of writing Invariant("blah") all the time in the code, you can set an environment variable DOTNET_SYSTEM_GLOBALIZATION_INVARIANT to true.

Six ways to shoot yourself in the foot with healthchecks

Health checks are nice, but don’t let them cascade into disaster.

Where are Objects Allocated in C#? Understanding Heap and Stack

Understanding the difference between the heap and the stack, and how to change it (ref, in, out keywords).