相关疑难解决方法(0)

假设一个类有一个public int counter由多个线程访问的字段.这int只是递增或递减.

要增加此字段,应使用哪种方法,为什么？

• lock(this.locker) this.counter++;,
• Interlocked.Increment(ref this.counter);,
• 将访问修饰符更改counter为public volatile.

现在,我发现volatile,我已经删除了许多lock语句和使用Interlocked.但是有理由不这样做吗？

我是.Net 4.0的任务的新手,我无法找到我认为基于任务的替换或实现定时器,例如定期任务.有这样的事吗？

更新 我提出了我认为是我的需求的解决方案,即将"计时器"功能包装在具有子任务的任务中,所有任务都利用CancellationToken并返回任务以便能够参与进一步的任务步骤.

public static Task StartPeriodicTask(Action action, int intervalInMilliseconds, int delayInMilliseconds, CancellationToken cancelToken)
{ 
    Action wrapperAction = () =>
    {
        if (cancelToken.IsCancellationRequested) { return; }

        action();
    };

    Action mainAction = () =>
    {
        TaskCreationOptions attachedToParent = TaskCreationOptions.AttachedToParent;

        if (cancelToken.IsCancellationRequested) { return; }

        if (delayInMilliseconds > 0)
            Thread.Sleep(delayInMilliseconds);

        while (true)
        {
            if (cancelToken.IsCancellationRequested) { break; }

            Task.Factory.StartNew(wrapperAction, cancelToken, attachedToParent, TaskScheduler.Current);

            if (cancelToken.IsCancellationRequested || intervalInMilliseconds == Timeout.Infinite) { break; }

            Thread.Sleep(intervalInMilliseconds);
        }
    };

    return Task.Factory.StartNew(mainAction, cancelToken);
}      

想象一下,我有这样的代码,其中里面的Windows窗体计时器我可以生成一些线程-但我保证只有一个线程使用下面的方法(从答案的一个指示运行位置 -马特·约翰逊):

nb:我们现在假设这种_executing方法有效,我不使用backgroundworker等.

private volatile bool _executing;

private void TimerElapsed(object state)
{
    if (_executing)
        return;

    _executing = true;

    if(smth)
    {
    Thread myThread = new Thread(MainThread1);
    myThread.IsBackground = true;
    myThread.Start();

    }else
    {
    Thread myThread = new Thread(MainThread2);
    myThread.IsBackground = true;
    myThread.Start();
    }
}


 public void MainThread1()
 {
   try
   {
     methodWhichAddelementTomyList(); // e.g., inside list.add();
   }
   finally
   {_executing = false;}
 }
 public void MainThread2()
 {
   try
   {
     methodWhichAddelementTomyList(); // e.g., inside list.add();
   }
   finally
   {_executing = false;} …