reactive/Ix.NET/Source/System.Interactive.Async/Retry.cs

// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the Apache 2.0 License.
// See the LICENSE file in the project root for more information. 

using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;

namespace System.Linq
{
    public static partial class AsyncEnumerable
    {
        public static IAsyncEnumerable<TSource> Retry<TSource>(this IAsyncEnumerable<TSource> source)
        {
            if (source == null)
                throw new ArgumentNullException(nameof(source));

            return new[] {source}.Repeat()
                                 .Catch();
        }

        public static IAsyncEnumerable<TSource> Retry<TSource>(this IAsyncEnumerable<TSource> source, int retryCount)
        {
            if (source == null)
                throw new ArgumentNullException(nameof(source));
            if (retryCount < 0)
                throw new ArgumentOutOfRangeException(nameof(retryCount));

            return new[] {source}.Repeat(retryCount)
                                 .Catch();
        }

        private static IEnumerable<TSource> Repeat<TSource>(this IEnumerable<TSource> source)
        {
            while (true)
                foreach (var item in source)
                    yield return item;
        }

        private static IEnumerable<TSource> Repeat<TSource>(this IEnumerable<TSource> source, int count)
        {
            for (var i = 0; i < count; i++)
                foreach (var item in source)
                    yield return item;
        }
    }
}