Retry logic for tasks

TaskExtensions.cs

namespace YourProduct
{
    /// <summary>
    /// Task retry logic
    /// </summary>
    public static class TaskHelper
    {
        /// <summary>
        /// Returns a task which retries the task returned by the specified task provider.
        /// </summary>
        /// <typeparam name="TResult"></typeparam>
        /// <param name="taskProvider">The task returning function.</param>
        /// <param name="maxAttemps">The maximum number of retries.</param>
        /// <param name="shouldRetry">A predicate function which determines whether an exception should cause a retry. The default returns true for all exceptions.</param>
        /// <returns></returns>
        /// <exception cref="System.ArgumentNullException"></exception>
        /// <exception cref="System.ArgumentOutOfRangeException"></exception>
    	[DebuggerStepThrough]
        public static Task<TResult> Retry<TResult>(Func<Task<TResult>> taskProvider, int maxAttemps, Func<Exception, bool> shouldRetry = null)
        {
            if (shouldRetry == null)
                shouldRetry = ex => true;
            return taskProvider()
                .ContinueWith(task => 
					RetryContinuation(task, taskProvider, maxAttemps, shouldRetry));
        }

        /// <summary>
        /// A task continuation which attempts a retry if a task is faulted.
        /// </summary>
        /// <typeparam name="TResult"></typeparam>
        /// <param name="task"></param>
        /// <param name="taskProvider"></param>
        /// <param name="attemptsRemaining"></param>
        /// <param name="shouldRetry"></param>
        /// <returns></returns>
        static TResult RetryContinuation<TResult>(Task<TResult> task, Func<Task<TResult>> taskProvider, int attemptsRemaining, Func<Exception, bool> shouldRetry)
        {
            if (task.IsFaulted)
            {
                if (attemptsRemaining > 0 && shouldRetry(task.Exception.InnerException))
                {
                    return taskProvider()
                        .ContinueWith(retryTask => RetryContinuation(retryTask, taskProvider, --attemptsRemaining, shouldRetry))
                        .Result;
                }
                else
                {
                    // will throw AggregateException
                    return task.Result;
                }
            }
            else
            {
                return task.Result;
            }
        }
    }

}