互斥量时如何避免竞争条件？

我正在使用一个命名的系统互斥锁来同步2个进程.这是我目前在应用程序中获取互斥量的方式：

using System.Threading;

public static bool AcquireMutex()
{
    // Protect against double acquisitions
    if (MyMutex != null)
    {
        throw new ApplicationException("Failed to acquire mutex");
    }

    try
    {
        // See if a named system mutex has already been created - if it has,
        // wait a short amount of time for its release.
        MyMutex = Mutex.OpenExisting(MutexName);
        if (!MyMutex.WaitOne(TimeSpan.FromSeconds(2), false))
        {
            // MyMutex still being held
            MyMutex = null;
            return false;
        }
    }
    catch
    {
        // MyMutex doesn't exist so create it
        MyMutex = new Mutex(true, MutexName);
    }

    return true;
}

如果具有MutexName的命名系统互斥锁不存在,OpenExisting将引发异常,从而允许我的应用程序创建它.

但是,这里似乎存在竞争条件-如果OpenExisting抛出,则在调用新Mutex之前会有一个小窗口,其他应用程序可能已在该窗口中获取了互斥体.

避免这种竞争情况并使此代码更可靠的最佳方法是什么？

一位同事提到他在代码中使用了Win32 Platform SDK中的CreateMutex(另一个需要同步的过程).但是,.NET Framework似乎并未对此提供支持.所以我不确定这是我代码的最佳解决方案.

更新资料

根据@David Schwartz的回答,这是我的新代码：

public static bool AcquireMutex()
{
    // Protect against double acquisitions
    if (MyMutex != null)
    {
        throw new ApplicationException("Failed to acquire mutex");
    }

    bool createdNew;
    MyMutex = new Mutex(true, MutexName, out createdNew);
    if (createdNew)
    {
        // Mutex was created so ownership is guaranteed; no need to wait on it.
        return true;
    }

    try
    {
        if (!MyMutex.WaitOne(TimeSpan.FromSeconds(2), false))
        {
            MyMutex = null;
            return false;
        }
    }
    catch (AbandonedMutexException)
    {
        // Other application was aborted, which led to an abandoned mutex.
        // This is fine, as we have still successfully acquired the mutex.
    }

    return true;
}

解决方法:

有一个专门为此目的设计的构造函数.从docs：

createdNew
Type: System.Boolean
When this method returns, contains a Boolean that is true if a local mutex was created (that is, if name is null or an empty string) or if the specified named system mutex was created; false if the specified named system mutex already existed. This parameter is passed uninitialized.

标签：mutex,race-condition,c,net
来源： https://codeday.me/bug/20191101/1985678.html