From 878dfe6e30b7d55bd37d08a46eca9506b4ac38c7 Mon Sep 17 00:00:00 2001
From: "Collin M. Barrett" <collinbarrett@users.noreply.github.com>
Date: Thu, 27 Jun 2019 14:18:45 -0500
Subject: [PATCH] consume tasks from TransformBlock so app doesn't hang

---
 src/FilterLists.Agent/ListArchiver/DownloadLists.cs | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/src/FilterLists.Agent/ListArchiver/DownloadLists.cs b/src/FilterLists.Agent/ListArchiver/DownloadLists.cs
index ce1fd0b9c..107e48b26 100644
--- a/src/FilterLists.Agent/ListArchiver/DownloadLists.cs
+++ b/src/FilterLists.Agent/ListArchiver/DownloadLists.cs
@@ -29,15 +29,20 @@ public Handler(IMediator mediator)
                 _mediator = mediator;
             }
 
+            // https://stackoverflow.com/a/22492731/2343739
             protected override async Task Handle(Command request, CancellationToken cancellationToken)
             {
                 var downloader = new TransformBlock<ListInfo, Task>(
                     l => _mediator.Send(new DownloadList.Command(l), cancellationToken),
                     new ExecutionDataflowBlockOptions {MaxDegreeOfParallelism = MaxDegreeOfParallelism});
+                var buffer = new BufferBlock<Task>();
+                downloader.LinkTo(buffer);
                 foreach (var list in request.Lists)
                     await downloader.SendAsync(list, cancellationToken);
                 downloader.Complete();
                 await downloader.Completion;
+                if (buffer.TryReceiveAll(out var tasks))
+                    await Task.WhenAll(tasks);
             }
         }
     }