reactive/AsyncRx.NET/System.Reactive.Async/Linq/Operators/Finally.cs

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

using System.Reactive.Disposables;
using System.Threading.Tasks;

namespace System.Reactive.Linq
{
    public partial class AsyncObservable
    {
        public static IAsyncObservable<TSource> Finally<TSource>(this IAsyncObservable<TSource> source, Action finallyAction)
        {
            if (source == null)
                throw new ArgumentNullException(nameof(source));
            if (finallyAction == null)
                throw new ArgumentNullException(nameof(finallyAction));

            return Create(
                source,
                finallyAction,
                static async (source, finallyAction, observer) =>
                {
                    var subscription = await source.SubscribeSafeAsync(observer).ConfigureAwait(false);

                    return AsyncDisposable.Create(async () =>
                    {
                        try
                        {
                            await subscription.DisposeAsync().ConfigureAwait(false);
                        }
                        finally
                        {
                            finallyAction();
                        }
                    });
                });
        }

        public static IAsyncObservable<TSource> Finally<TSource>(this IAsyncObservable<TSource> source, Func<Task> finallyAction)
        {
            if (source == null)
                throw new ArgumentNullException(nameof(source));
            if (finallyAction == null)
                throw new ArgumentNullException(nameof(finallyAction));

            return Create(
                source,
                finallyAction,
                static async (source, finallyAction, observer) =>
                {
                    var subscription = await source.SubscribeSafeAsync(observer).ConfigureAwait(false);

                    return AsyncDisposable.Create(async () =>
                    {
                        try
                        {
                            await subscription.DisposeAsync().ConfigureAwait(false);
                        }
                        finally
                        {
                            await finallyAction().ConfigureAwait(false);
                        }
                    });
                });
        }
    }
}