在C＃中使用Global Mutex的良好模式是什么？

Z时代
2024-01-10
分类：问答

Mutex类非常容易被误解，而全局互斥体更是如此。

创建全局互斥锁时，可以使用哪种良好，安全的模式？

一个会起作用的

无论我的机器位于哪个区域

保证正确释放互斥锁

如果没有获取互斥，可以选择不永久挂起

处理其他进程放弃互斥锁的情况

回答：

我想确保这是正确的，因为很难正确地做到这一点：

using System.Runtime.InteropServices;   //GuidAttribute
using System.Reflection;                //Assembly
using System.Threading;                 //Mutex
using System.Security.AccessControl;    //MutexAccessRule
using System.Security.Principal;        //SecurityIdentifier
static void Main(string[] args)
{
    // get application GUID as defined in AssemblyInfo.cs
    string appGuid =
        ((GuidAttribute)Assembly.GetExecutingAssembly().
            GetCustomAttributes(typeof(GuidAttribute), false).
                GetValue(0)).Value.ToString();
    // unique id for global mutex - Global prefix means it is global to the machine
    string mutexId = string.Format( "Global\\{{{0}}}", appGuid );
    // Need a place to store a return value in Mutex() constructor call
    bool createdNew;
    // edited by Jeremy Wiebe to add example of setting up security for multi-user usage
    // edited by 'Marc' to work also on localized systems (don't use just "Everyone") 
    var allowEveryoneRule =
        new MutexAccessRule( new SecurityIdentifier( WellKnownSidType.WorldSid
                                                   , null)
                           , MutexRights.FullControl
                           , AccessControlType.Allow
                           );
    var securitySettings = new MutexSecurity();
    securitySettings.AddAccessRule(allowEveryoneRule);
   // edited by MasonGZhwiti to prevent race condition on security settings via VanNguyen
    using (var mutex = new Mutex(false, mutexId, out createdNew, securitySettings))
    {
        // edited by acidzombie24
        var hasHandle = false;
        try
        {
            try
            {
                // note, you may want to time out here instead of waiting forever
                // edited by acidzombie24
                // mutex.WaitOne(Timeout.Infinite, false);
                hasHandle = mutex.WaitOne(5000, false);
                if (hasHandle == false)
                    throw new TimeoutException("Timeout waiting for exclusive access");
            }
            catch (AbandonedMutexException)
            {
                // Log the fact that the mutex was abandoned in another process,
                // it will still get acquired
                hasHandle = true;
            }
            // Perform your work here.
        }
        finally
        {
            // edited by acidzombie24, added if statement
            if(hasHandle)
                mutex.ReleaseMutex();
        }
    }
}