Fix IOException when Cancelling the monitor stream.

Added a wait to the MonitorEventsAsync_Succeeds test to have some progress messages.

Author: Duracell1989

src/Docker.DotNet/Endpoints/StreamUtil.cs

@@ -1,10 +1,10 @@
+using Newtonsoft.Json;
 using System;
 using System.IO;
 using System.Net.Http;
 using System.Text;
 using System.Threading;
 using System.Threading.Tasks;
-using Newtonsoft.Json;
 
 namespace Docker.DotNet.Models
 {
@@ -17,15 +17,12 @@ internal static async Task MonitorStreamAsync(Task<Stream> streamTask, DockerCli
             using (var stream = await streamTask)
             {
                 // ReadLineAsync must be cancelled by closing the whole stream.
-                using (cancel.Register(() => stream.Dispose()))
+                using (var reader = new StreamReader(stream, new UTF8Encoding(false)))
                 {
-                    using (var reader = new StreamReader(stream, new UTF8Encoding(false)))
+                    string line;
+                    while ((line = await reader.ReadLineAsync()) != null && !cancel.IsCancellationRequested)
                     {
-                        string line;
-                        while ((line = await reader.ReadLineAsync()) != null)
-                        {
-                            progress.Report(line);
-                        }
+                        progress.Report(line);
                     }
                 }
             }
@@ -49,32 +46,29 @@ internal static async Task MonitorResponseForMessagesAsync<T>(Task<HttpResponseM
         {
             using (var response = await responseTask)
             {
-                await client.HandleIfErrorResponseAsync(response.StatusCode, response);
-
                 using (var stream = await response.Content.ReadAsStreamAsync())
                 {
                     // ReadLineAsync must be cancelled by closing the whole stream.
-                    using (cancel.Register(() => stream.Dispose()))
+                    using (var reader = new StreamReader(stream, new UTF8Encoding(false)))
                     {
-                        using (var reader = new StreamReader(stream, new UTF8Encoding(false)))
+                        string line;
+                        try
                         {
-                            string line;
-                            try
+                            while ((line = await reader.ReadLineAsync()) != null && !cancel.IsCancellationRequested)
                             {
-                                while ((line = await reader.ReadLineAsync()) != null)
-                                {
-                                    var prog = client.JsonSerializer.DeserializeObject<T>(line);
-                                    if (prog == null) continue;
+                                await client.HandleIfErrorResponseAsync(response.StatusCode, response);
 
-                                    progress.Report(prog);
-                                }
-                            }
-                            catch (ObjectDisposedException)
-                            {
-                                // The subsequent call to reader.ReadLineAsync() after cancellation
-                                // will fail because we disposed the stream. Just ignore here.
+                                var prog = client.JsonSerializer.DeserializeObject<T>(line);
+                                if (prog == null) continue;
+
+                                progress.Report(prog);
                             }
                         }
+                        catch (ObjectDisposedException)
+                        {
+                            // The subsequent call to reader.ReadLineAsync() after cancellation
+                            // will fail because we disposed the stream. Just ignore here.
+                        }
                     }
                 }
             }

test/Docker.DotNet.Tests/ISystemOperations.Tests.cs

@@ -111,10 +111,11 @@ public async Task MonitorEventsAsync_Succeeds()
 
             await _client.Images.CreateImageAsync(new ImagesCreateParameters { FromImage = "hello-world" }, null, progressJSONMessage);
 
-            var task = Task.Run(() => _client.System.MonitorEventsAsync(new ContainerEventsParameters(), progressMessage, cts.Token));
+            var task = _client.System.MonitorEventsAsync(new ContainerEventsParameters(), progressMessage, cts.Token);
 
             await _client.Images.TagImageAsync(repository, new ImageTagParameters { RepositoryName = repository, Tag = newTag });
 
+            Thread.Sleep(500); // Let's wait some time before cancelling the monitor stream to make sure we got some progress back.
             cts.Cancel();
 
             bool taskIsCancelled = false;