Fix data race thread sanitiser warnings

Author: abnegate

templates/swift/Sources/WebSockets/WebSocketClient.swift.twig

@@ -7,6 +7,8 @@ import NIOFoundationCompat
 import NIOSSL
 
 public let WEBSOCKET_LOCKER_QUEUE = "SyncLocker"
+public let WEBSOCKET_THREAD_QUEUE = "ThreadLocker"
+public let WEBSOCKET_CHANNEL_QUEUE = "ChannelLocker"
 
 /// Creates and manages connections to a WebSocket server.
 ///
@@ -20,16 +22,35 @@ public class WebSocketClient {
     let query: String
     let headers: HTTPHeaders
     let frameKey: String
-    
+
     public private(set) var maxFrameSize: Int
-    
-    var channel: Channel? = nil
+
     var tlsEnabled: Bool = false
     var closeSent: Bool = false
 
-    let locker = DispatchQueue(label: WEBSOCKET_LOCKER_QUEUE, qos: .background)
+    private let locker = DispatchQueue(label: WEBSOCKET_LOCKER_QUEUE, qos: .background)
+    private let channelQueue = DispatchQueue(label: WEBSOCKET_CHANNEL_QUEUE)
+    private let threadGroupQueue = DispatchQueue(label: WEBSOCKET_THREAD_QUEUE)
 
-    var threadGroup: MultiThreadedEventLoopGroup? = nil
+    var channel: Channel? {
+        get {
+            return channelQueue.sync { _channel }
+        }
+        set {
+            channelQueue.sync { _channel = newValue }
+        }
+    }
+    private var _channel: Channel? = nil
+
+    var threadGroup: MultiThreadedEventLoopGroup? {
+        get {
+            return threadGroupQueue.sync { _threadGroup }
+        }
+        set {
+            threadGroupQueue.sync { _threadGroup = newValue }
+        }
+    }
+    private var _threadGroup: MultiThreadedEventLoopGroup?
 
     weak var delegate: WebSocketClientDelegate? = nil