Cancel the task instead of changing @running

lib/concurrent-ruby/concurrent/timer_task.rb

@@ -256,6 +256,16 @@ def timeout_interval=(value)
       warn 'TimerTask timeouts are now ignored as these were not able to be implemented correctly'
     end
 
+    def shutdown
+      @task.cancel if @task # must happen outside of synchronization
+      super
+    end
+
+    def kill
+      @task.cancel if @task # must happen outside of synchronization
+      super
+    end
+
     private :post, :<<
 
     private
@@ -270,6 +280,7 @@ def ns_initialize(opts, &task)
       @run_now = opts[:now] || opts[:run_now]
       @executor = Concurrent::SafeTaskExecutor.new(task)
       @running = Concurrent::AtomicBoolean.new(false)
+      @task = nil
       @value = nil
 
       self.observers = Collection::CopyOnNotifyObserverSet.new
@@ -278,26 +289,24 @@ def ns_initialize(opts, &task)
     # @!visibility private
     def ns_shutdown_execution
       @running.make_false
-      @running = Concurrent::AtomicBoolean.new(false)
       super
     end
 
     # @!visibility private
     def ns_kill_execution
       @running.make_false
-      @running = Concurrent::AtomicBoolean.new(false)
       super
     end
 
     # @!visibility private
     def schedule_next_task(interval = execution_interval)
-      ScheduledTask.execute(interval, args: [Concurrent::Event.new, @running], &method(:execute_task))
+      @task = ScheduledTask.execute(interval, args: [Concurrent::Event.new], &method(:execute_task))
       nil
     end
 
     # @!visibility private
-    def execute_task(completion, continue_running)
-      return nil unless continue_running.true?
+    def execute_task(completion)
+      return nil unless @running.true?
       _success, value, reason = @executor.execute(self)
       if completion.try?
         self.value = value