CancellationTokenExtensions.cs

using System;
using System.Collections.Concurrent;
using System.Threading;

public static class CancellationTokenExtensions
{
    private static readonly ConcurrentDictionary<CancellationToken, string> _reasons = new();
    private static readonly ConcurrentDictionary<CancellationToken, CancellationTokenSource> _sources = new();

    // Method to create a CancellationToken with a reason
    public static CancellationToken CreateCancellationToken(string reason)
    {
        var cts = new CancellationTokenSource();
        var token = cts.Token;
        _reasons[token] = reason;
        _sources[token] = cts;
        return token;
    }

    // Method to create a CancellationToken from an existing CancellationTokenSource with a reason
    public static CancellationToken CreateCancellationToken(CancellationTokenSource cts, string reason)
    {
        var token = cts.Token;
        _reasons[token] = reason;
        _sources[token] = cts;
        return token;
    }

    // Method to create a CancellationToken that will be canceled after a delay with a reason
    public static CancellationToken CreateCancellationToken(int millisecondsDelay, string reason)
    {
        var cts = new CancellationTokenSource(millisecondsDelay);
        var token = cts.Token;
        _reasons[token] = reason;
        _sources[token] = cts;
        return token;
    }

    // Method to create a linked CancellationToken with a reason
    public static CancellationToken CreateLinkedCancellationToken(CancellationToken token1, CancellationToken token2, string reason)
    {
        var linkedCts = CancellationTokenSource.CreateLinkedTokenSource(token1, token2);
        var token = linkedCts.Token;
        _reasons[token] = reason;
        _sources[token] = linkedCts;
        return token;
    }

    // Extension method to get the reason from an OperationCanceledException
    public static string? GetReason(this OperationCanceledException exception)
    {
        return exception.CancellationToken != default && _reasons.TryGetValue(exception.CancellationToken, out var reason)
            ? reason
            : null;
    }

    // Method to get the CancellationTokenSource associated with a CancellationToken
    public static CancellationTokenSource? GetCancellationTokenSource(CancellationToken token)
    {
        return _sources.TryGetValue(token, out var cts) ? cts : null;
    }
}