Day 11: Higher-level API.

StephenClearyExamples · Mar 5, 2022 · 4d52ad1 · 4d52ad1
1 parent 97918f1
commit 4d52ad1
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Showing 3 changed files with 62 additions and 12 deletions.
diff --git a/Chat/ChatApi/ChatConnection.cs b/Chat/ChatApi/ChatConnection.cs
@@ -2,6 +2,7 @@
 using System;
 using System.Buffers;
 using System.Buffers.Binary;
+using System.Collections.Concurrent;
 using System.Collections.Generic;
 using System.IO.Pipelines;
 using System.Linq;
@@ -21,6 +22,7 @@ public sealed class ChatConnection
         private readonly Channel<IMessage> _inputChannel;
         private readonly Channel<IMessage> _outputChannel;
         private readonly Timer _timer;
+        private readonly ConcurrentDictionary<Guid, TaskCompletionSource> _outstandingRequests = new();
 
         public ChatConnection(PipelineSocket pipelineSocket, TimeSpan keepaliveTimeSpan = default)
         {
@@ -40,6 +42,20 @@ public ChatConnection(PipelineSocket pipelineSocket, TimeSpan keepaliveTimeSpan
 
         public void Complete() => _outputChannel.Writer.Complete();
 
+        public Task SetNicknameAsync(string nickname)
+        {
+            var setNicknameRequestMessage = new SetNicknameRequestMessage(Guid.NewGuid(), nickname);
+            var tcs = new TaskCompletionSource(TaskCreationOptions.RunContinuationsAsynchronously);
+            _outstandingRequests.TryAdd(setNicknameRequestMessage.RequestId, tcs);
+            return SendMessageAndWaitForResponseAsync();
+
+            async Task SendMessageAndWaitForResponseAsync()
+            {
+                await SendMessageAsync(setNicknameRequestMessage);
+                await tcs.Task;
+            }
+        }
+
         public async Task SendMessageAsync(IMessage message)
         {
             await _outputChannel.Writer.WriteAsync(message);
@@ -102,7 +118,36 @@ private async void PipelineToChannelAsync()
                     var data = await _pipelineSocket.InputPipe.ReadAsync();
 
                     foreach (var message in ParseMessages(data.Buffer))
-                        await _inputChannel.Writer.WriteAsync(message);
+                    {
+                        if (message is KeepaliveMessage)
+                        {
+                            // Ignore
+                        }
+                        else if (message is AckResponseMessage ackResponseMessage)
+                        {
+                            if (!_outstandingRequests.TryRemove(ackResponseMessage.RequestId, out var tcs))
+                            {
+                                // The server sent us an ack response for a request we didn't send.
+                                throw new InvalidOperationException("Protocol violation.");
+                            }
+
+                            tcs.TrySetResult();
+                        }
+                        else if (message is NakResponseMessage nakResponseMessage)
+                        {
+                            if (!_outstandingRequests.TryRemove(nakResponseMessage.RequestId, out var tcs))
+                            {
+                                // The server sent us an ack response for a request we didn't send.
+                                throw new InvalidOperationException("Protocol violation.");
+                            }
+
+                            tcs.TrySetException(new Exception("Request was rejected."));
+                        }
+                        else
+                        {
+                            await _inputChannel.Writer.WriteAsync(message);
+                        }
+                    }
 
                     if (data.IsCompleted)
                     {

diff --git a/Chat/ChatApi/MessageSerialization.cs b/Chat/ChatApi/MessageSerialization.cs
@@ -91,6 +91,11 @@ public static int GetMessageLengthPrefixValue(IMessage message)
                 message = new BroadcastMessage(from, text);
                 return true;
             }
+            else if (messageType == 2)
+            {
+                message = new KeepaliveMessage();
+                return true;
+            }
             else if (messageType == 3)
             {
                 if (!sequenceReader.TryReadGuid(out var requestId))

diff --git a/Chat/ChatClient/MainWindow.xaml.cs b/Chat/ChatClient/MainWindow.xaml.cs
@@ -75,14 +75,6 @@ await foreach (var message in chatConnection.InputMessages)
                     {
                         Chat.Text += $"{broadcastMessage.From}: {broadcastMessage.Text}\n";
                     }
-                    else if (message is AckResponseMessage ackResponseMessage)
-                    {
-                        Log.Text += $"Got ack from {chatConnection.RemoteEndPoint} for request {ackResponseMessage.RequestId}.\n";
-                    }
-                    else if (message is NakResponseMessage nakResponseMessage)
-                    {
-                        Log.Text += $"Got nak from {chatConnection.RemoteEndPoint} for request {nakResponseMessage.RequestId}.\n";
-                    }
                     else
                         Log.Text += $"Got unknown message from {chatConnection.RemoteEndPoint}.\n";
                 }
@@ -103,9 +95,17 @@ private async void Button_Click_3(object sender, RoutedEventArgs e)
             }
             else
             {
-                var message = new SetNicknameRequestMessage(Guid.NewGuid(), nicknameTextBox.Text);
-                await _chatConnection.SendMessageAsync(message);
-                Log.Text += $"Sent nickname request {message.RequestId} for {message.Nickname}\n";
+                var nickname = nicknameTextBox.Text;
+                try
+                {
+                    Log.Text += $"Sending nickname request for {nickname}\n";
+                    await _chatConnection.SetNicknameAsync(nickname);
+                    Log.Text += $"Successfully set nickname to {nickname}\n";
+                }
+                catch (Exception ex)
+                {
+                    Log.Text += $"Unable to set nickname to {nickname}: {ex.Message}\n";
+                }
             }
         }
     }