在Azure函数中不会触发CancellationToken [英] CancellationToken doesn't get triggered in the Azure Functions

问题描述

我有这个简单的Azure函数:

I've got this simple Azure Function:

public static class MyCounter
{
    public static int _timerRound = 0;
    public static bool _isFirst = true;

    [FunctionName("Counter")]
    //[TimeoutAttribute("00:00:05")]
    public async static Task Run([TimerTrigger("*/10 * * * * *")]TimerInfo myTimer, TraceWriter log, CancellationToken token)
    {
        try
        {
            log.Info($"C# Timer trigger function executed at: {DateTime.UtcNow}");
            if (_isFirst)
            {
                log.Info("Cancellation token registered");
                token.Register(async () =>
                {
                    log.Info("Cancellation token requested");
                    return;
                });
                _isFirst = false;
            }
            Interlocked.Increment(ref _timerRound);
            for (int i = 0; i < 10; i++)
            {
                log.Info($"Round: {_timerRound}, Step: {i}, cancel request:{token.IsCancellationRequested}");
                await Task.Delay(500, token).ConfigureAwait(false);
            }
        }
        catch (Exception ex)
        {
            log.Error("hold on, exception!", ex);
        }
    }
}

我想做的是在应用停止或发生代码重新部署(主机关闭事件)时捕获CancellationToken请求事件.

What I'm trying to do is capturing the CancellationToken request event when the app stops or a code redeploy happened (host shutdown event).

顺便说一句，我也尝试过在for循环中检查IsCancellationRequested属性.永远不会成真.

BTW, I've also tried to check the IsCancellationRequested property in the for loop as well. Never turns true.

主要要求是在功能部署期间不要丢失任何操作/数据，我想知道该应用程序正在停止，因此一旦主机在更新后再次启动，我将保留一些要处理的数据.

The main requirement is not to loose any operation/data during the function deployments, I want to know that the app is being stopped so that I persist some data to be processed once host started again after update.

推荐答案

根据您的代码，我在我这边进行了测试，这是我的测试结果:

Based on your code, I tested it on my side, here are my test result:

从以上屏幕截图中，我们可以发现，除了第一轮以外，随后的几轮都无法处理取消回调.正如法比奥·卡瓦坎特(Fabio Cavalcante)所说，我删除了_isFirst逻辑检查，发现它可以在所有回合中工作，如下所示:

From the above screenshots, we could find that the subsequent rounds could not handle the cancellation callback except the first round. As Fabio Cavalcante commented, I removed the _isFirst logical checking and found it could work for all rounds as follows:

注意:我通过在触发TimerTrigger时禁用功能来模拟主机的关闭.

Note: I simulated the shutdown of my host by disabling my function when the TimerTrigger is triggered.

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