27 线程执行上下文和取消

27.3 执行上下文

            CallContext.LogicalSetData("Name", "Jeffrey");
            ThreadPool.QueueUserWorkItem(obj =>
            {
                Console.WriteLine($"Name={CallContext.LogicalGetData("Name")}");
            });
            ExecutionContext.SuppressFlow();
            ThreadPool.QueueUserWorkItem(obj =>
            {
                Console.WriteLine($"Name={CallContext.LogicalGetData("Name")}");
            });
            ExecutionContext.RestoreFlow();

 27.4 协作式取消和超时

        static void Main(string[] args)
        {
            CancellationTokenSource cts = new CancellationTokenSource();
            ThreadPool.QueueUserWorkItem(o => Count(cts.Token, 1000));
            Console.WriteLine("press enter to cancel the operation");
            Console.ReadLine();
            cts.Cancel();
            Console.ReadKey();
        }
        private static void Count(CancellationToken token, int countTo)
        {
            for (int count = 0; count < countTo; count++)
            {
                if (token.IsCancellationRequested)
                {
                    Console.WriteLine("Count is cancel");
                    break;
                }
                Console.WriteLine(count);
                Thread.Sleep(200);
            }
            Console.WriteLine("Count is done");
        }

            CancellationTokenSource cts = new CancellationTokenSource();
            cts.Token.Register(() => { Console.WriteLine("Canceled 1"); });
            cts.Token.Register(() => { Console.WriteLine("Canceled 2"); });
            cts.Cancel();

            CancellationTokenSource cts1 = new CancellationTokenSource();
            cts1.Token.Register(() => { Console.WriteLine("Cts1 canceled"); });

            CancellationTokenSource cts2 = new CancellationTokenSource();
            cts2.Token.Register(() => { Console.WriteLine("Cts2 canceled"); });

            var linkedCts = CancellationTokenSource.CreateLinkedTokenSource(cts1.Token, cts2.Token);
            linkedCts.Token.Register(() => { Console.WriteLine("linked cancel"); });

            cts2.Cancel();

            Console.WriteLine("cts1={0} cts2={1} linked={2}", cts1.IsCancellationRequested, cts2.IsCancellationRequested, linkedCts.IsCancellationRequested);
            /*  Canceled 2
            Canceled 1
            linked cancel
            Cts2 canceled
            cts1=False cts2=True linked=True    */