c# mutex使用示例

来自：http://outofmemory.cn/code-snippet/1631/c-mutex-usage-example

Mutex：/mjuteks/互斥(体) 又称同步基元使用了System.Threading 命名空间。
当创建一个应用程序类时，将同时创建一个系统范围内的命名的Mutex对象。这个互斥元在整个操作系统中都是可见的。当已经存在一个同名的互斥元时，构造函数将会输出一个布尔值。程序代码通过检测这个布尔值来判断指定的程序实例是否启动，如果已经存在同名互斥元的话，则显示一个对话框，告知用户应用程序已经启动，并退出应用程序

using System.Runtime.InteropServices;   //GuidAttribute
using System.Reflection;                //Assembly
using System.Threading;                 //Mutex
using System.Security.AccessControl;    //MutexAccessRule
using System.Security.Principal;        //SecuirtyIdentifier

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 );

using (var mutex = new Mutex(false, mutexId))
{
// 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);
mutex.SetAccessControl(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 the mutex was abandoned in another process, it will still get aquired
hasHandle = true;
}

// Perform your work here.
}
finally
{
// edited by acidzombie24, added if statemnet
if(hasHandle)
mutex.ReleaseMutex();
}
}
}