Use _Atomic for configuration.isFinished

Author: inamiy

SwiftTask/SwiftTask.swift

@@ -32,13 +32,13 @@ public class TaskConfiguration
     public var cancel: (Void -> Void)?
 
     /// useful to terminate immediate-infinite-sequence while performing `initClosure`
-    public private(set) var isFinished: Bool = false
-    
-    public init()
+    public var isFinished : Bool
     {
-        
+        return _isFinished.rawValue
     }
 
+    private var _isFinished = _Atomic(false)
+    
     internal func finish()
     {
         //
@@ -53,7 +53,7 @@ public class TaskConfiguration
         self.pause = nil
         self.resume = nil
         self.cancel = nil
-        self.isFinished = true
+        self._isFinished.rawValue = true
     }
 }