Useful extensions examples

TaskExtension.cs

public static class TaskExtensions
    {
        public static Task Ignore<TException>(this Task task) where TException : Exception
        {
            return task.ContinueWith(x =>
            {
                if (x.IsCanceled || !x.IsFaulted)
                {
                    return Task.CompletedTask;
                }

                if (x.Exception != null && x.Exception.InnerException is TException)
                {
                    return Task.CompletedTask;
                }

                throw x.Exception.InnerException;
            }, TaskContinuationOptions.AttachedToParent);
        }

        public static Task<TResult> Ignore<TResult, TException>(this Task<TResult> task, TResult defaultValue = default(TResult)) where TException : Exception
        {
            return task.ContinueWith(x =>
            {
                if (x.IsCanceled || !x.IsFaulted)
                {
                    return defaultValue;
                }

                if (x.Exception != null && x.Exception.InnerException is TException)
                {
                    return defaultValue;
                }

                throw x.Exception.InnerException;
            }, TaskContinuationOptions.AttachedToParent);
        }

        public static Task On<TException>(this Task task, Func<TException, Task> onException) where TException : Exception
        {
            return task.ContinueWith(x =>
            {
                if (x.IsCanceled || !x.IsFaulted)
                {
                    return Task.CompletedTask;
                }

                if (x.Exception != null && x.Exception.InnerException is TException ex)
                {
                    return onException(ex);
                }

                throw x.Exception.InnerException;
            }, TaskContinuationOptions.AttachedToParent).Unwrap();
        }
    }

TaskFactoryExtension.cs

public static class TaskFactoryExtensions
    {
        public static Task StartNewNeverEndingTask(this TaskFactory factory, Action action, CancellationToken cancellationToken, TaskCreationOptions creationOptions = TaskCreationOptions.LongRunning, int delayMilisseconds = 1000)
        {
            if (action == null) 
                throw new ArgumentNullException(nameof(action));
            
            if (cancellationToken == default)
                throw new ArgumentNullException(nameof(cancellationToken));

            return factory.StartNew(async () =>
            {
                while (!cancellationToken.IsCancellationRequested)
                {
                    action();
                    await Task.Delay(delayMilisseconds, cancellationToken);
                }
            }, cancellationToken, creationOptions, TaskScheduler.Default);
        }

        public static Task StartNewNeverEndingTask(this TaskFactory factory, Func<Task> func, CancellationToken cancellationToken, TaskCreationOptions creationOptions = TaskCreationOptions.LongRunning, int delayMilisseconds = 1000)
        {
            if (func == null)
                throw new ArgumentNullException(nameof(func));

            if (cancellationToken == default)
                throw new ArgumentNullException(nameof(cancellationToken));

            return factory.StartNew(async () =>
            {
                while (!cancellationToken.IsCancellationRequested)
                {
                    await func();
                    await Task.Delay(delayMilisseconds, cancellationToken);
                }
            }, cancellationToken, creationOptions, TaskScheduler.Default);
        }
    }