Question

我在一个进程中执行：

_eventWaitHandle.Set();
_eventWaitHandle.Reset();

在另一个进程中：

_eventWaitHandle.WaitOne();
Console.WriteLine("Hello");

但永远不会得到通知（没有控制台输出）。它似乎是异步设置。

我怎能等到所有服务员都在发出重置（）之前发出信号？

我创建了等待句柄（ NAMED进程间等待句柄）：

    internal static EventWaitHandle OpenExistingOrCreateEventWaitHandle(string name)
    {
        try
        {
            return EventWaitHandle.OpenExisting(name);
        }
        catch (WaitHandleCannotBeOpenedException)
        {
            return new EventWaitHandle(false, EventResetMode.ManualReset, name);
        }
    }

更新

现在我有一个“解决方案”

_eventWaitHandle.Set();
Thread.Sleep(10);
_eventWaitHandle.Reset();

第二种可能 - 为每个进程提供许多句柄。但是此代码应该适用于任何Office应用程序加载项或独立应用程序。因此，应该如何生成名称和发现。

第三 - 使用WCF p2p（netPeerTcpBinding）或命名管道与UdpDiscoveryEndpoint-但这些使用“IP”，因此在部署到最终用户时可能会遇到一些安全问题？

Answer 1

是的，Set()函数会立即退出，因此调用Set()和Reset()时，基本上什么都不做，或者随机执行某些操作。您可以通过在WaitOne()。

之后重置监听线程上的事件来解决问题

Answer 2

您可以将EventResetMode设置为EventResetMode.AutoReset，这样做，当其中一个进程接受事件时，它会自动重置事件。你不必在以后手动重置它。

有多个进程，您可以为每个侦听器创建一个事件，并在必须发出事件信号时触发它们。

foreach(var process in _myProcesses)
{
    waitHandles.Add(OpenExistingOrCreateEventWaitHandle(process.SharedWaitHandleName);
}

...

internal static EventWaitHandle OpenExistingOrCreateEventWaitHandle(string name)
{
    try
    {
        return EventWaitHandle.OpenExisting(name);
    }
    catch (WaitHandleCannotBeOpenedException)
    {
        return new EventWaitHandle(false, EventResetMode.AutoReset, name);
    }
}


...


foreach(var waitHandle in waitHandles)
{
    waitHandle.Set();
}

Answer 3

如果您想知道如何等待所有服务员在执行Reset（）之前发出信号，其中服务员是同一进程中的不同线程，那么请查看EventWaitHandle的MSDN页面中的此示例类

using System;
using System.Threading;

public class Example
{
    // The EventWaitHandle used to demonstrate the difference
    // between AutoReset and ManualReset synchronization events.
    //
    private static EventWaitHandle ewh;

    // A counter to make sure all threads are started and
    // blocked before any are released. A Long is used to show
    // the use of the 64-bit Interlocked methods.
    //
    private static long threadCount = 0;

    // An AutoReset event that allows the main thread to block
    // until an exiting thread has decremented the count.
    //
    private static EventWaitHandle clearCount = 
        new EventWaitHandle(false, EventResetMode.AutoReset);

    [MTAThread]
    public static void Main()
    {
        // Create an AutoReset EventWaitHandle.
        //
        ewh = new EventWaitHandle(false, EventResetMode.AutoReset);

        // Create and start five numbered threads. Use the
        // ParameterizedThreadStart delegate, so the thread
        // number can be passed as an argument to the Start 
        // method.
        for (int i = 0; i <= 4; i++)
        {
            Thread t = new Thread(
                new ParameterizedThreadStart(ThreadProc)
            );
            t.Start(i);
        }

        // Wait until all the threads have started and blocked.
        // When multiple threads use a 64-bit value on a 32-bit
        // system, you must access the value through the
        // Interlocked class to guarantee thread safety.
        //
        while (Interlocked.Read(ref threadCount) < 5)
        {
            Thread.Sleep(500);
        }

        // Release one thread each time the user presses ENTER,
        // until all threads have been released.
        //
        while (Interlocked.Read(ref threadCount) > 0)
        {
            Console.WriteLine("Press ENTER to release a waiting thread.");
            Console.ReadLine();

            // SignalAndWait signals the EventWaitHandle, which
            // releases exactly one thread before resetting, 
            // because it was created with AutoReset mode. 
            // SignalAndWait then blocks on clearCount, to 
            // allow the signaled thread to decrement the count
            // before looping again.
            //
            WaitHandle.SignalAndWait(ewh, clearCount);
        }
        Console.WriteLine();

        // Create a ManualReset EventWaitHandle.
        //
        ewh = new EventWaitHandle(false, EventResetMode.ManualReset);

        // Create and start five more numbered threads.
        //
        for(int i=0; i<=4; i++)
        {
            Thread t = new Thread(
                new ParameterizedThreadStart(ThreadProc)
            );
            t.Start(i);
        }

        // Wait until all the threads have started and blocked.
        //
        while (Interlocked.Read(ref threadCount) < 5)
        {
            Thread.Sleep(500);
        }

        // Because the EventWaitHandle was created with
        // ManualReset mode, signaling it releases all the
        // waiting threads.
        //
        Console.WriteLine("Press ENTER to release the waiting threads.");
        Console.ReadLine();
        ewh.Set();

    }

    public static void ThreadProc(object data)
    {
        int index = (int) data;

        Console.WriteLine("Thread {0} blocks.", data);
        // Increment the count of blocked threads.
        Interlocked.Increment(ref threadCount);

        // Wait on the EventWaitHandle.
        ewh.WaitOne();

        Console.WriteLine("Thread {0} exits.", data);
        // Decrement the count of blocked threads.
        Interlocked.Decrement(ref threadCount);

        // After signaling ewh, the main thread blocks on
        // clearCount until the signaled thread has 
        // decremented the count. Signal it now.
        //
        clearCount.Set();
    }
}

Answer 4

我解决了问题。我使用内存映射文件来存储事件等待句柄名称列表。超时无法稳定工作。目前的解决方案在2年内投入生产。

要像我在下一张收据中使用的IPC桌面事件那样p2p：

1个共享的互斥锁
每个进程1个唯一的服务员和1个唯一的响应者事件等待句柄（事件参与者）
1个内存映射文件，用于存储等待参与者的注册表（可以使用真正的注册表）
1个用于交换事件数据的内存映射文件

Answer 5

使用EventResetMode.Manual并将EventWaitHandle存储在静态中。消费者应该从这个静态读取句柄。每当您要调用Set（）时，首先创建一个新的EventWaitHandle并将其存储在该静态中。下一次消费者想要处理时，他会得到新的，这很清楚。

等到EventWaitHandle.Set（）之后通知所有进程

5 个答案: