Ensure that awaits do not continue on the captured context. (#370)

* Ensure that awaits do not continue on the captured context.

* Make functions async for maintainability.

* Add documentation detailing the use of UIFact.

src/KubernetesClient/Kubernetes.WebSocket.cs

@@ -273,7 +273,7 @@ namespace k8s
             {
                 // Copy the default (credential-related) request headers from the HttpClient to the WebSocket
                 HttpRequestMessage message = new HttpRequestMessage();
-                await this.Credentials.ProcessHttpRequestAsync(message, cancellationToken);
+                await this.Credentials.ProcessHttpRequestAsync(message, cancellationToken).ConfigureAwait(false);
 
                 foreach (var _header in message.Headers)
                 {

src/KubernetesClient/KubernetesClientConfiguration.ConfigFile.cs

@@ -100,7 +100,7 @@ namespace k8s
                 throw new NullReferenceException(nameof(kubeconfig));
             }
 
-            var k8SConfig = await LoadKubeConfigAsync(kubeconfig, useRelativePaths);
+            var k8SConfig = await LoadKubeConfigAsync(kubeconfig, useRelativePaths).ConfigureAwait(false);
             var k8SConfiguration = GetKubernetesClientConfiguration(currentContext, masterUrl, k8SConfig);
 
             return k8SConfiguration;
@@ -139,7 +139,7 @@ namespace k8s
 
             kubeconfig.Position = 0;
 
-            var k8SConfig = await Yaml.LoadFromStreamAsync<K8SConfiguration>(kubeconfig);
+            var k8SConfig = await Yaml.LoadFromStreamAsync<K8SConfiguration>(kubeconfig).ConfigureAwait(false);
             var k8SConfiguration = GetKubernetesClientConfiguration(currentContext, masterUrl, k8SConfig);
 
             return k8SConfiguration;
@@ -486,7 +486,7 @@ namespace k8s
         {
             var fileInfo = new FileInfo(kubeconfigPath ?? KubeConfigDefaultLocation);
 
-            return await LoadKubeConfigAsync(fileInfo, useRelativePaths);
+            return await LoadKubeConfigAsync(fileInfo, useRelativePaths).ConfigureAwait(false);
         }
 
         /// <summary>
@@ -517,7 +517,7 @@ namespace k8s
 
             using (var stream = kubeconfig.OpenRead())
             {
-                var config = await Yaml.LoadFromStreamAsync<K8SConfiguration>(stream);
+                var config = await Yaml.LoadFromStreamAsync<K8SConfiguration>(stream).ConfigureAwait(false);
 
                 if (useRelativePaths)
                 {
@@ -547,7 +547,7 @@ namespace k8s
         /// <returns>Instance of the <see cref="K8SConfiguration"/> class</returns>
         public static async Task<K8SConfiguration> LoadKubeConfigAsync(Stream kubeconfigStream)
         {
-            return await Yaml.LoadFromStreamAsync<K8SConfiguration>(kubeconfigStream);
+            return await Yaml.LoadFromStreamAsync<K8SConfiguration>(kubeconfigStream).ConfigureAwait(false);
         }
 
         /// <summary>

src/KubernetesClient/StreamDemuxer.cs

@@ -57,7 +57,7 @@ namespace k8s
         /// </summary>
         public void Start()
         {
-            this.runLoop = this.RunLoop(this.cts.Token);
+            this.runLoop = Task.Run(async () => await this.RunLoop(this.cts.Token));
         }
 
         /// <inheritdoc/>
@@ -193,9 +193,6 @@ namespace k8s
 
         protected async Task RunLoop(CancellationToken cancellationToken)
         {
-            // This is a background task. Immediately yield to the caller.
-            await Task.Yield();
-
             // Get a 1KB buffer
             byte[] buffer = ArrayPool<byte>.Shared.Rent(1024 * 1024);
             // This maps remembers bytes skipped for each stream.

src/KubernetesClient/Watcher.cs

@@ -57,7 +57,7 @@ namespace k8s
             OnClosed += onClosed;
 
             _cts = new CancellationTokenSource();
-            _watcherLoop = this.WatcherLoop(_cts.Token);
+            _watcherLoop = Task.Run(async () => await this.WatcherLoop(_cts.Token));
         }
 
         /// <inheritdoc/>
@@ -91,14 +91,11 @@ namespace k8s
 
         private async Task WatcherLoop(CancellationToken cancellationToken)
         {
-            // Make sure we run async
-            await Task.Yield();
-
             try
             {
                 Watching = true;
                 string line;
-                _streamReader = await _streamReaderCreator();
+                _streamReader = await _streamReaderCreator().ConfigureAwait(false);
 
                 // ReadLineAsync will return null when we've reached the end of the stream.
                 while ((line = await _streamReader.ReadLineAsync().ConfigureAwait(false)) != null)
@@ -164,7 +161,7 @@ namespace k8s
             Action onClosed = null)
         {
             return new Watcher<T>(async () => {
-                var response = await responseTask;
+                var response = await responseTask.ConfigureAwait(false);
 
                 if (!(response.Response.Content is WatcherDelegatingHandler.LineSeparatedHttpContent content))
                 {

src/KubernetesClient/WatcherDelegatingHandler.cs

@@ -19,7 +19,7 @@ namespace k8s
         protected override async Task<HttpResponseMessage> SendAsync(HttpRequestMessage request,
             CancellationToken cancellationToken)
         {
-            var originResponse = await base.SendAsync(request, cancellationToken);
+            var originResponse = await base.SendAsync(request, cancellationToken).ConfigureAwait(false);
 
             if (originResponse.IsSuccessStatusCode)
             {
@@ -47,18 +47,18 @@ namespace k8s
 
             protected override async Task SerializeToStreamAsync(Stream stream, TransportContext context)
             {
-                _originStream = await _originContent.ReadAsStreamAsync();
+                _originStream = await _originContent.ReadAsStreamAsync().ConfigureAwait(false);
 
                 StreamReader = new PeekableStreamReader(_originStream);
 
-                var firstLine = await StreamReader.PeekLineAsync();
+                var firstLine = await StreamReader.PeekLineAsync().ConfigureAwait(false);
 
                 var writer = new StreamWriter(stream);
 
 //                using (writer) // leave open
                 {
-                    await writer.WriteAsync(firstLine);
+                    await writer.WriteAsync(firstLine).ConfigureAwait(false);
-                    await writer.FlushAsync();
+                    await writer.FlushAsync().ConfigureAwait(false);
                 }
             }
 
@@ -94,7 +94,7 @@ namespace k8s
             }
             public async Task<string> PeekLineAsync()
             {
-                var line = await ReadLineAsync();
+                var line = await ReadLineAsync().ConfigureAwait(false);
                 _buffer.Enqueue(line);
                 return line;
             }

src/KubernetesClient/Yaml.cs

@@ -29,7 +29,7 @@ namespace k8s
         /// </param>
         public static async Task<List<object>> LoadAllFromStreamAsync(Stream stream, Dictionary<String, Type> typeMap) {
             var reader = new StreamReader(stream);
-            var content = await reader.ReadToEndAsync();
+            var content = await reader.ReadToEndAsync().ConfigureAwait(false);
             return LoadAllFromString(content, typeMap);
         }
 
@@ -95,13 +95,13 @@ namespace k8s
 
         public static async Task<T> LoadFromStreamAsync<T>(Stream stream) {
             var reader = new StreamReader(stream);
-            var content = await reader.ReadToEndAsync();
+            var content = await reader.ReadToEndAsync().ConfigureAwait(false);
             return LoadFromString<T>(content);
         }
 
         public static async Task<T> LoadFromFileAsync<T> (string file) {
             using (FileStream fs = File.OpenRead(file)) {
-                return await LoadFromStreamAsync<T>(fs);
+                return await LoadFromStreamAsync<T>(fs).ConfigureAwait(false);
             }
         }
 

tests/KubernetesClient.Tests/KubernetesClient.Tests.csproj

@@ -33,6 +33,7 @@
     <PackageReference Include="Microsoft.NET.Test.Sdk" Version="16.0.1" />
     <PackageReference Include="xunit" Version="2.4.1" />
     <PackageReference Include="xunit.runner.visualstudio" Version="2.4.1" />
+    <PackageReference Include="Xunit.StaFact" Version="0.3.18" />
     <PackageReference Include="Moq" Version="4.13.1" />
 
     <DotNetCliToolReference Include="dotnet-xunit" Version="2.3.1" />

tests/KubernetesClient.Tests/KubernetesClientConfigurationTests.cs

@@ -1,5 +1,6 @@
 using System.IO;
 using System.Linq;
+using System.Threading;
 using k8s.Exceptions;
 using k8s.KubeConfigModels;
 using Xunit;
@@ -406,6 +407,17 @@ namespace k8s.Tests
             AssertConfigEqual(expectedCfg, cfg);
         }
 
+        /// <summary>
+        ///     Ensures Kube config file can be loaded from within a non-default <see cref="SynchronizationContext"/>.
+        ///     The use of <see cref="UIFactAttribute"/> ensures the test is run from within a UI-like <see cref="SynchronizationContext"/>.
+        /// </summary>
+        [UIFact]
+        public void BuildConfigFromConfigFileInfoOnNonDefaultSynchronizationContext()
+        {
+            var fi = new FileInfo("assets/kubeconfig.yml");
+            KubernetesClientConfiguration.BuildConfigFromConfigFile(fi, "federal-context", useRelativePaths: false);
+        }
+
         private void AssertConfigEqual(K8SConfiguration expected, K8SConfiguration actual)
         {
             Assert.Equal(expected.ApiVersion, actual.ApiVersion);