浅谈C#中取消令牌CancellationTokenSource

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浅谈C#中取消令牌CancellationTokenSource

基础操作

            CancellationTokenSource cancellationTokenSource = new CancellationTokenSource();
            cancellationTokenSource.Token.Register(() =>
            {
                Console.WriteLine("取消了1111");
            });
            cancellationTokenSource.Token.Register(() =>
            {
                Console.WriteLine("取消了2222");
            });
            cancellationTokenSource.Cancel();

取消了2222
取消了1111

超时自动取消

```
new CancellationTokenSource(3000);
```

cancellationTokenSource.CancelAfter(3000);

关联取消

            CancellationTokenSource cancellationTokenSource = new CancellationTokenSource();
            CancellationTokenSource cancellationTokenSource2 = new CancellationTokenSource();
            cancellationTokenSource.Token.Register(() =>
            {
                Console.WriteLine("取消了1111");
            });
            cancellationTokenSource2.Token.Register(() =>
            {
                Console.WriteLine("取消了2222");
            });
            var linkedTokenSource = CancellationTokenSource.CreateLinkedTokenSource(cancellationTokenSource.Token,
                cancellationTokenSource2.Token);
            linkedTokenSource.Token.Register(() =>
            {
                Console.WriteLine("关联令牌被取消了");
            });
            //cancellationTokenSource.Cancel();
            cancellationTokenSource2.Cancel();

关联令牌被取消了
取消了2222

令牌1和2的任意一个取消，关联令牌linkedTokenSource就会被取消。但是关联令牌linkedTokenSource取消，令牌1和2并不会取消。

判断取消

            CancellationTokenSource cancellationTokenSource = new CancellationTokenSource();
            cancellationTokenSource.Token.Register(() =>
            {
                Console.WriteLine("取消了1111");
            });
            Task.Run(async () =>
            {
                while (!cancellationTokenSource.IsCancellationRequested)
                {
                    Console.WriteLine("一直在执行...");
                    await Task.Delay(1000);
                }
            });
            cancellationTokenSource.CancelAfter(3000);

一直在执行...
一直在执行...
一直在执行...
取消了1111

            CancellationTokenSource cancellationTokenSource = new CancellationTokenSource();
            Task.Run(async () =>
            {
                try
                {
                    while (true)
                    {
                        //如果操作被取消则直接抛出异常
                        cancellationTokenSource.Token.ThrowIfCancellationRequested();
                        Console.WriteLine("一直在执行...");
                        await Task.Delay(1000);
                    }
                }
                catch (OperationCanceledException ex)
                {
                    Console.WriteLine("取消了！");
                }
            });
            cancellationTokenSource.CancelAfter(3000);

一直在执行...
一直在执行...
一直在执行...
取消了！

使用ThrowIfCancellationRequested会抛出OperationCanceledException异常，需要自己捕获处理

出处：https://www.cnblogs.com/log9527blog/p/17571326.html

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