每台计算机的应用程序的一个实例，如何？

Question

我试图让我的应用程序只运行一次在电脑上，我的应用程序需要comunicate到WebService所以它是坏让它运行多次，使用互斥这个目前即时通讯：

MyMsg := RegisterWindowMessage('My_Unique_App_Message_Name'); 
Mutex := CreateMutex(nil, True, 'My_Unique_Application_Mutex_Name'); 
if (Mutex = 0) OR (GetLastError = ERROR_ALREADY_EXISTS) then 
exit; 

目前这可以限制每个用户1个应用程序的实例，但是我的应用程序正在Windows Server环境中使用，其中一次有20多个用户在使用，所以我需要严格限制每个服务器只运行一次，我试图做的是将Mutex声明为全局互斥体，但是当我执行下一个代码时，它无法工作。

MyMsg := RegisterWindowMessage('My_Unique_App_Message_Name'); 
Mutex := CreateMutex(nil, True, 'Global\My_Unique_Application_Mutex_Name'); 
if (Mutex = 0) OR (GetLastError = ERROR_ALREADY_EXISTS) then 
begin 
exit 

所以我做错了什么？有没有其他可靠的方式不让我的应用程序的第二个实例运行？

Answer 1

默认情况下，lpMutexAttributes = nil创建的互斥锁只能由运行该进程的用户访问。所有用户都需要访问互斥锁。

空DACL安全描述符

通过使用安全描述符具有空DACL执行此操作。请在下面找到我用于单实例应用程序/服务的代码

//Creates a mutex to see if the program is already running. 
function IsSingleInstance(MutexName : string; KeepMutex : boolean = true):boolean; 
const MUTEX_GLOBAL = 'Global\'; //Prefix to explicitly create the object in the global or session namespace. I.e. both client app (local user) and service (system account) 

var MutexHandel : THandle; 
    SecurityDesc: TSecurityDescriptor; 
    SecurityAttr: TSecurityAttributes; 
    ErrCode : integer; 
begin 
    // By default (lpMutexAttributes =nil) created mutexes are accessible only by 
    // the user running the process. We need our mutexes to be accessible to all 
    // users, so that the mutex detection can work across user sessions. 
    // I.e. both the current user account and the System (Service) account. 
    // To do this we use a security descriptor with a null DACL. 
    InitializeSecurityDescriptor(@SecurityDesc, SECURITY_DESCRIPTOR_REVISION); 
    SetSecurityDescriptorDacl(@SecurityDesc, True, nil, False); 
    SecurityAttr.nLength:=SizeOf(SecurityAttr); 
    SecurityAttr.lpSecurityDescriptor:=@SecurityDesc; 
    SecurityAttr.bInheritHandle:=False; 

    // The mutex is created in the global name space which makes it possible to 
    // access across user sessions. 
    MutexHandel := CreateMutex(@SecurityAttr, True, PChar(MUTEX_GLOBAL + MutexName)); 
    ErrCode := GetLastError; 

    // If the function fails, the return value is 0 
    // If the mutex is a named mutex and the object existed before this function 
    // call, the return value is a handle to the existing object, GetLastError 
    // returns ERROR_ALREADY_EXISTS. 
    if {(MutexHandel = 0) or }(ErrCode = ERROR_ALREADY_EXISTS) then 
    begin 
    result := false; 
    closeHandle(MutexHandel); 
    end 
    else 
    begin 
    // Mutex object has not yet been created, meaning that no previous 
    // instance has been created. 
    result := true; 

    if not KeepMutex then 
     CloseHandle(MutexHandel); 
    end; 

    // The Mutexhandle is not closed because we want it to exist during the 
    // lifetime of the application. The system closes the handle automatically 
    //when the process terminates. 
end;