Convert MqttClient._connectState to enum

Source/MQTTnet/Client/MqttClient.cs

@@ -39,10 +39,15 @@ namespace MQTTnet.Client
         IMqttChannelAdapter _adapter;
         bool _cleanDisconnectInitiated;
         volatile int _connectState;
-        const int CONNECT_STATED_DISCONNECTED = 0;
-        const int CONNECT_STATED_DISCONNECTING = 1;
-        const int CONNECT_STATED_CONNECTED = 2;
-        const int CONNECT_STATED_CONNECTING = 3;
+
+        enum ConnectState
+        {
+            Disconnected = 0,
+            Disconnecting,
+            Connected,
+            Connecting
+        }
+
         MqttClientDisconnectReason _disconnectReason;
 
         DateTime _lastPacketSentTimestamp;
@@ -61,7 +66,7 @@ namespace MQTTnet.Client
 
         public IMqttApplicationMessageReceivedHandler ApplicationMessageReceivedHandler { get; set; }
 
-        public bool IsConnected => _connectState == CONNECT_STATED_CONNECTED;
+        public bool IsConnected => (ConnectState)_connectState == ConnectState.Connected;
 
         public IMqttClientOptions Options { get; private set; }
 
@@ -74,7 +79,7 @@ namespace MQTTnet.Client
 
             ThrowIfDisposed();
 
-            if (Interlocked.CompareExchange(ref _connectState, CONNECT_STATED_CONNECTING, CONNECT_STATED_DISCONNECTED) != CONNECT_STATED_DISCONNECTED)
+            if (CompareExchangeConnectState(ConnectState.Connecting, ConnectState.Disconnected) != ConnectState.Disconnected)
                 throw new InvalidOperationException("Not allowed to connect while connect/disconnect is pending.");
 
             MqttClientAuthenticateResult authenticateResult = null;
@@ -113,7 +118,7 @@ namespace MQTTnet.Client
                     _keepAlivePacketsSenderTask = Task.Run(() => TrySendKeepAliveMessagesAsync(backgroundCancellationToken), backgroundCancellationToken);
                 }
 
-                Interlocked.CompareExchange(ref _connectState, CONNECT_STATED_CONNECTED, CONNECT_STATED_CONNECTING);
+                CompareExchangeConnectState(ConnectState.Connected, ConnectState.Connecting);
 
                 _logger.Info("Connected.");
 
@@ -365,7 +370,7 @@ namespace MQTTnet.Client
             {
                 Cleanup();
                 _cleanDisconnectInitiated = false;
-                Interlocked.CompareExchange(ref _connectState, CONNECT_STATED_DISCONNECTED, CONNECT_STATED_DISCONNECTING);
+                CompareExchangeConnectState(ConnectState.Disconnected, ConnectState.Disconnecting);
 
                 _logger.Info("Disconnected.");
 
@@ -800,20 +805,20 @@ namespace MQTTnet.Client
 
         bool DisconnectIsPendingOrFinished()
         {
-            var connectState = _connectState;
+            var connectState = (ConnectState)_connectState;
             do
             {
                 switch (connectState)
                 {
-                    case CONNECT_STATED_DISCONNECTING:
-                    case CONNECT_STATED_DISCONNECTED:
+                    case ConnectState.Disconnected:
+                    case ConnectState.Disconnecting:
                         return true;
-                    case CONNECT_STATED_CONNECTING:
-                    case CONNECT_STATED_CONNECTED:
+                    case ConnectState.Connected:
+                    case ConnectState.Connecting:
                         // This will compare the _connectState to old value and set it to "CONNECT_STATED_DISCONNECTING" afterwards.
                         // So the first caller will get a "false" and all subsequent ones will get "true".
-                        var newState = Interlocked.CompareExchange(ref _connectState, CONNECT_STATED_DISCONNECTING, connectState);
-                        if (newState != connectState)
+                        var newState = CompareExchangeConnectState(ConnectState.Disconnecting, connectState);
+                        if (newState == connectState)
                         {
                             return false;
                         }
@@ -822,5 +827,10 @@ namespace MQTTnet.Client
                 }
             } while (true);
         }
+
+        ConnectState CompareExchangeConnectState(ConnectState value, ConnectState comparand)
+        {
+            return (ConnectState)Interlocked.CompareExchange(ref _connectState, (int)value, (int)comparand);
+        }
     }
 }