Adding RunAsync.

AsyncRx.NET/System.Reactive.Async.Linq/System/Reactive/Linq/Operators/RunAsync.cs

@@ -0,0 +1,107 @@
+// 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.Reactive.Disposables;
+using System.Reactive.Subjects;
+using System.Threading;
+
+namespace System.Reactive.Linq
+{
+    // REVIEW: Consider using these for GetAwaiter.
+
+    partial class AsyncObservable
+    {
+        public static AsyncAsyncSubject<TSource> RunAsync<TSource>(this IAsyncObservable<TSource> source, CancellationToken token)
+        {
+            if (source == null)
+                throw new ArgumentNullException(nameof(source));
+
+            var subject = new SequentialAsyncAsyncSubject<TSource>();
+
+            if (token.IsCancellationRequested)
+            {
+                var ignored = subject.OnErrorAsync(new OperationCanceledException(token));
+                return subject;
+            }
+
+            var subscribeTask = source.SubscribeSafeAsync(subject);
+
+            subscribeTask.ContinueWith(t =>
+            {
+                if (t.Exception != null)
+                {
+                    subject.OnErrorAsync(t.Exception); // NB: Should not occur due to use of SubscribeSafeAsync.
+                }
+            });
+
+            if (token.CanBeCanceled)
+            {
+                var d = new SingleAssignmentAsyncDisposable();
+
+                subscribeTask.ContinueWith(t =>
+                {
+                    if (t.Exception == null)
+                    {
+                        var ignored = d.AssignAsync(t.Result);
+                    }
+                });
+
+                token.Register(() =>
+                {
+                    var ignored = d.DisposeAsync();
+                });
+            }
+
+            return subject;
+        }
+
+        public static AsyncAsyncSubject<TSource> RunAsync<TSource>(this IConnectableAsyncObservable<TSource> source, CancellationToken token)
+        {
+            if (source == null)
+                throw new ArgumentNullException(nameof(source));
+
+            var subject = new SequentialAsyncAsyncSubject<TSource>();
+
+            if (token.IsCancellationRequested)
+            {
+                var ignored = subject.OnErrorAsync(new OperationCanceledException(token));
+                return subject;
+            }
+
+            var d = new CompositeAsyncDisposable();
+
+            var subscribeTask = source.SubscribeSafeAsync(subject);
+
+            subscribeTask.ContinueWith(t =>
+            {
+                if (t.Exception != null)
+                {
+                    subject.OnErrorAsync(t.Exception); // NB: Should not occur due to use of SubscribeSafeAsync.
+                }
+                else
+                {
+                    var ignored = d.AddAsync(t.Result);
+
+                    source.ConnectAsync().ContinueWith(t2 =>
+                    {
+                        if (t2.Exception == null)
+                        {
+                            var ignored2 = d.AddAsync(t2.Result);
+                        }
+                    });
+                }
+            });
+
+            if (token.CanBeCanceled)
+            {
+                token.Register(() =>
+                {
+                    var ignored = d.DisposeAsync();
+                });
+            }
+
+            return subject;
+        }
+    }
+}