学步园

 通知正在等待的线程已发生事件。无法继承此类。

AutoResetEvent 允许线程通过发信号互相通信。通常，此通信涉及线程需要独占访问的资源。

线程通过调用 AutoResetEvent 上的 WaitOne 来等待信号。如果 AutoResetEvent 处于非终止状态，则该线程阻塞，并等待当前控制资源的线程通过调用 Set 发出资源可用的信号。

调用 Set 向 AutoResetEvent 发信号以释放等待线程。AutoResetEvent 将保持终止状态，直到一个正在等待的线程被释放，然后自动返回非终止状态。如果没有任何线程在等待，则状态将无限期地保持为终止状态。

可以通过将一个布尔值传递给构造函数来控制 AutoResetEvent 的初始状态，如果初始状态为终止状态，则为 true；否则为 false。

 namespace ConsoleApplicationTEST<br /> {<br /> class Program<br /> {<br /> static void Main(string[] args)<br /> {<br /> Calculate calc = new Calculate();<br /> Console.WriteLine("Result = {0}.",<br /> calc.Result(234).ToString());<br /> Console.WriteLine("Result = {0}.",<br /> calc.Result(55).ToString());<br /> }<br /> }<br /> class Calculate<br /> {<br /> double baseNumber, firstTerm, secondTerm, thirdTerm;<br /> AutoResetEvent[] autoEvents;<br /> ManualResetEvent manualEvent;</p> <p> // Generate random numbers to simulate the actual calculations.<br /> Random randomGenerator;</p> <p> public Calculate()<br /> {<br /> autoEvents = new AutoResetEvent[]<br /> {<br /> new AutoResetEvent(false),<br /> new AutoResetEvent(false),<br /> new AutoResetEvent(false)<br /> };</p> <p> manualEvent = new ManualResetEvent(false);<br /> }</p> <p> void CalculateBase(object stateInfo)<br /> {<br /> baseNumber = randomGenerator.NextDouble();</p> <p> // Signal that baseNumber is ready.<br /> manualEvent.Set();<br /> }</p> <p> // The following CalculateX methods all perform the same<br /> // series of steps as commented in CalculateFirstTerm.</p> <p> void CalculateFirstTerm(object stateInfo)<br /> {<br /> // Perform a precalculation.<br /> double preCalc = randomGenerator.NextDouble();</p> <p> // Wait for baseNumber to be calculated.<br /> manualEvent.WaitOne();</p> <p> // Calculate the first term from preCalc and baseNumber.<br /> firstTerm = preCalc * baseNumber *<br /> randomGenerator.NextDouble();</p> <p> // Signal that the calculation is finished.<br /> autoEvents[0].Set();<br /> }</p> <p> void CalculateSecondTerm(object stateInfo)<br /> {<br /> double preCalc = randomGenerator.NextDouble();<br /> manualEvent.WaitOne();<br /> secondTerm = preCalc * baseNumber *<br /> randomGenerator.NextDouble();<br /> autoEvents[1].Set();<br /> }</p> <p> void CalculateThirdTerm(object stateInfo)<br /> {<br /> double preCalc = randomGenerator.NextDouble();<br /> manualEvent.WaitOne();<br /> thirdTerm = preCalc * baseNumber *<br /> randomGenerator.NextDouble();<br /> autoEvents[2].Set();<br /> }</p> <p> public double Result(int seed)<br /> {<br /> randomGenerator = new Random(seed);</p> <p> // Simultaneously calculate the terms.<br /> ThreadPool.QueueUserWorkItem(<br /> new WaitCallback(CalculateBase));<br /> ThreadPool.QueueUserWorkItem(<br /> new WaitCallback(CalculateFirstTerm));<br /> ThreadPool.QueueUserWorkItem(<br /> new WaitCallback(CalculateSecondTerm));<br /> ThreadPool.QueueUserWorkItem(<br /> new WaitCallback(CalculateThirdTerm));</p> <p> // Wait for all of the terms to be calculated.<br /> WaitHandle.WaitAll(autoEvents);</p> <p> // Reset the wait handle for the next calculation.<br /> manualEvent.Reset();</p> <p> return firstTerm + secondTerm + thirdTerm;<br /> }<br /> }<br /> }<br />

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