等待一段时间，直到满足条件 [英] Waiting for some time until a condition is met

问题描述

我有一个这样的代码，它在与主线程不同的线程中执行。

  if  （_isSTminStarted&&（_stMinExpired ==  false ））
 {
  //  等到stMin到期 
 字符串 message = 字符串 .Empty; 
 执行 
 {
 message =  等待STmin到期 + DateTime.Now.ToString（  h：mm： SS.FFF）; 
 _logger.Info（message）; 
 
 
}  while （_stMinExpired ==  false ）; 
 
 _isSTminStarted =  true ; 
 _timer.STminTimerStarted（_stMinRecieved）; 
 
 CanFrame consecutiveFrame = _fragmentedFrameQueue.Dequeue（）; 
 PublishFrame（consecutiveFrame）; 
} 

请参阅do while循环，我已添加，因为我必须等到计时器到期并且_stMinExpired设置为true。然后我只发送下一帧。



当System.threading.timer到期时设置此标志。但我不认为这是等到那个时候的理想方式。你可以建议一些方法，我可以在这个线程中等待，直到设置该标志，而不是在循环时放置。

解决方案

尝试使用 AutoResetEvent [ ^ ]。

正如Firo所提到的，你想要使用其中一个基于事件的等待处理程序（AutoResetEvent或ManualResetEvent）。它们的设计正是你在这里要求的：等到未知时间在另一个线程中发生的事情。

 class Test {
 AutoResetEvent waitHandle = new AutoResetEvent（false）; 
 
 void SpawnThread（）{
 Thread t = new Thread（ThreadMethod）; 
 t.Start（）; 
} 
 
 void ThreadMethod（）{
  waitHandle.WaitOne（）;  
 CanFrame consecutiveFrame = _fragmentedFrameQueue.Dequeue（）; 
 PublishFrame（consecutiveFrame）; 
} 
 
 void SomeLongOtherMethod（）{
 DoStuffThatTakesAWhile（）; 
  waitHandle.Set（）;  //这将释放线程。 
} 
} 

你永远不要等待使用紧密循环。这将以100％的CPU运行核心并使您的应用程序不受欢迎。等待句柄和Thread.Sleep也是操作系统级触发器，并将您的线程置于不使用CPU时间的非运行状态。

使用 Thread.Sleep [ ^ ] - 它可以在您的任务执行任何其他操作之前等待特定时间。

I have a code like this which executes in a different thread than main thread.

if(_isSTminStarted && (_stMinExpired == false))
            {
                //wait till stMin is expired
                String message = string.Empty;
                do
                {
                    message = "Waiting till STmin expires " + DateTime.Now.ToString("h:mm:ss.fff");
                    _logger.Info(message);
                    

                } while (_stMinExpired == false);               
           
                _isSTminStarted = true;
                _timer.STminTimerStarted(_stMinRecieved);

                CanFrame consecutiveFrame = _fragmentedFrameQueue.Dequeue();
                PublishFrame(consecutiveFrame);
            }

Please see the do while loop , i have added that because i have to wait until a timer expires and _stMinExpired is set to true. Then only i should send next frame.

This flag is set when a System.threading.timer expires. But i don't think this is the ideal way to wait till that time. can you suggest some ways in which i can wait in this thread till that flag is set rather than putting do while loop.

解决方案

Try using AutoResetEvent[^].

As Firo mentions, you want to use one of the event based wait handlers (AutoResetEvent or ManualResetEvent) for this. They are designed for exactly what you ask here: waiting until something happens in another thread at an unknown time.

class Test {
  AutoResetEvent waitHandle = new AutoResetEvent(false);

 void SpawnThread(){
  Thread t = new Thread(ThreadMethod);
  t.Start();
 }
 
 void ThreadMethod(){
  waitHandle.WaitOne();
  CanFrame consecutiveFrame = _fragmentedFrameQueue.Dequeue();
  PublishFrame(consecutiveFrame);
 }

 void SomeLongOtherMethod(){
  DoStuffThatTakesAWhile();
  waitHandle.Set(); // This will release the thread.
 }
}

You should never wait by using a tight loop. That will run a core at 100% CPU and make your app unpopular. Wait handles, and Thread.Sleep as well, are OS level triggers and put your thread into a non-running state that doesn't use CPU time.

Use Thread.Sleep[^] instead - it can wait for a specific time before your task does anything else.

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