Add DiagnosticsClientConnector to support creating a DiagnosticsClien…

…t from a diagnostic port (#5073)

Followup of #5070 that introduced a non-viable approach (Comment
#5070 (comment))

This PR adds `DiagnosticsClientConnector` that is `IAsyncDisposable` and
offers the method `FromDiagnosticPort`.

src/Microsoft.Diagnostics.NETCore.Client/DiagnosticsClient/DiagnosticsClient.cs

@@ -381,47 +381,6 @@ internal async Task DisablePerfMapAsync(CancellationToken token)
             ValidateResponseMessage(response, nameof(DisablePerfMapAsync));
         }
 
-        /// <summary>
-        /// Create a new DiagnosticsClient instance using the specified diagnostic port.
-        /// </summary>
-        /// <param name="diagnosticPort">The diagnostic port.</param>
-        /// <param name="ct">The token to monitor for cancellation requests.</param>
-        public static async Task<DiagnosticsClient> FromDiagnosticPort(string diagnosticPort, CancellationToken ct)
-        {
-            if (diagnosticPort is null)
-            {
-                throw new ArgumentNullException(nameof(diagnosticPort));
-            }
-
-            IpcEndpointConfig portConfig = IpcEndpointConfig.Parse(diagnosticPort);
-
-            if (portConfig.IsListenConfig)
-            {
-                string fullPort = RuntimeInformation.IsOSPlatform(OSPlatform.Windows) ? portConfig.Address : Path.GetFullPath(portConfig.Address);
-                ReversedDiagnosticsServer server = new(fullPort);
-                server.Start();
-
-                try
-                {
-                    IpcEndpointInfo endpointInfo = await server.AcceptAsync(ct).ConfigureAwait(false);
-                    return new DiagnosticsClient(endpointInfo.Endpoint);
-                }
-                catch (TaskCanceledException)
-                {
-                    //clean up the server
-                    await server.DisposeAsync().ConfigureAwait(false);
-                    if (!ct.IsCancellationRequested)
-                    {
-                        throw;
-                    }
-                    return null;
-                }
-            }
-
-            Debug.Assert(portConfig.IsConnectConfig);
-            return new DiagnosticsClient(portConfig);
-        }
-
         /// <summary>
         /// Get all the active processes that can be attached to.
         /// </summary>

src/Microsoft.Diagnostics.NETCore.Client/DiagnosticsClient/DiagnosticsClientConnector.cs

@@ -0,0 +1,90 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+using System;
+using System.Diagnostics;
+using System.IO;
+using System.Runtime.InteropServices;
+using System.Threading;
+using System.Threading.Tasks;
+
+namespace Microsoft.Diagnostics.NETCore.Client
+{
+    /// <summary>
+    /// A connector that allows to create a <see cref="DiagnosticsClient"/> from a diagnostic port.
+    /// </summary>
+    public sealed class DiagnosticsClientConnector : IAsyncDisposable
+    {
+        private bool _disposed;
+        private readonly IAsyncDisposable _server;
+
+        internal DiagnosticsClientConnector(DiagnosticsClient diagnosticClient, IAsyncDisposable server)
+        {
+            _server = server;
+            Instance = diagnosticClient;
+        }
+
+        /// <summary>
+        /// Gets the <see cref="DiagnosticsClient"/> instance.
+        /// </summary>
+        public DiagnosticsClient Instance { get; }
+
+        /// <inheritdoc />
+        public async ValueTask DisposeAsync()
+        {
+            if (_disposed)
+            {
+                return;
+            }
+
+            if (_server != null)
+            {
+                await _server.DisposeAsync().ConfigureAwait(false);
+            }
+
+            _disposed = true;
+        }
+
+        /// <summary>
+        /// Create a new <see cref="DiagnosticsClientConnector"/> instance using the specified diagnostic port.
+        /// </summary>
+        /// <param name="diagnosticPort">The diagnostic port.</param>
+        /// <param name="ct">The token to monitor for cancellation requests.</param>
+        /// <returns>A <see cref="DiagnosticsClientConnector"/> instance</returns>
+        public static async Task<DiagnosticsClientConnector> FromDiagnosticPort(string diagnosticPort, CancellationToken ct)
+        {
+            if (diagnosticPort is null)
+            {
+                throw new ArgumentNullException(nameof(diagnosticPort));
+            }
+
+            IpcEndpointConfig portConfig = IpcEndpointConfig.Parse(diagnosticPort);
+
+            if (portConfig.IsListenConfig)
+            {
+                string fullPort = RuntimeInformation.IsOSPlatform(OSPlatform.Windows) ? portConfig.Address : Path.GetFullPath(portConfig.Address);
+                ReversedDiagnosticsServer server = new(fullPort);
+                server.Start();
+
+                try
+                {
+                    IpcEndpointInfo endpointInfo = await server.AcceptAsync(ct).ConfigureAwait(false);
+                    return new DiagnosticsClientConnector(new DiagnosticsClient(endpointInfo.Endpoint), server);
+                }
+                catch (TaskCanceledException)
+                {
+                    //clean up the server
+                    await server.DisposeAsync().ConfigureAwait(false);
+                    if (!ct.IsCancellationRequested)
+                    {
+                        throw;
+                    }
+                    return null;
+                }
+            }
+
+            Debug.Assert(portConfig.IsConnectConfig);
+            return new DiagnosticsClientConnector(new DiagnosticsClient(portConfig), null);
+        }
+    }
+}