QMutex SingleTon::mutex; QAtomicPointer<SingleTon> SingleTon::instance = 0; 双重锁检测在C++中是安全的,另外提供了读写锁,在修改单例数据的函数中使用写锁(QWriteLocker locker(&internalMutex););在读取单例数据的函数中使用读锁(QReadLocker locker(&internalMutex);)。 之前没考虑到乱序执行问题,并且此前...
Singleton*Singleton::m_pInstance=NULL; 17 18 /** 19 * @fn creatInstance 20 * @brief Create a Singleton instance. 21 * @return A pointer to Singleton Instance, or NULL if failed. 22 * @author wei.chen (2010-7-19) 23 */ 24 Singleton*Singleton::creatInstance() 25 { 26 std::cout...
// AtExit should only ever be register after the singleton instance was // created. We should only ever get here with a valid instance_ pointer. Traits::Delete(reinterpret_cast<Type*>(subtle::NoBarrier_Load(&instance_))); instance_ = 0; } staticsubtle::AtomicWord instance_; }; template...
Thread 1 调用getInstance() 方法,并且判断instance是null,然後进入if模块, 在实例化instance之前, Thread 2抢占了Thread 1的cpu Thread 2 调用getInstance() 方法,并且判断instance是null,然後进入if模块, Thread 2 实例化instance 完成,返回 Thread 1 再次实例化instance 这个单态已经不在是单态 二,为了解决刚才的...
I prefer to use a static method, Instance, that returns a pointer to a static instance of the class. Here’s an example:/* --- MyClass.h --- */ #ifndef MY_SINGLETON #define MY_SINGLETON class MyClass { private: // member data int m_iNum; //constructor is private MyClass(){} ...
return *instance;} private:SingleTon();//禁⽌构造函数。SingleTon(const SingleTon &);//禁⽌拷贝构造函数。SingleTon & operator=(const SingleTon &);//禁⽌赋值拷贝函数。QReadWriteLock internalMutex;//函数使⽤的读写锁。static QMutex mutex;//实例互斥锁。static QAtomicPointer<SingleTon> ...
问尝试使用Singleton访问变量时的NPEEN假如后端有一个系统访问方式是通过IP加端口的形式访问的，如：10.1...
在Singleton类的内部,直接声明并@Ref那个字段,如果在Singleton类的外部,则拿到这个容器,并调用instance获取就行了,用容器获取instance其实是非常少用的,因为大部分逻辑都活跃在这些Singleton之间,所以最后是很好的达到了简化代码的效果,当然我们这里举例的只是特别特别轻量并且特殊的例子,如果你觉得不够用,我推荐你可以试一...
However, if you return a pointer, clients could potentially delete the object. You should therefore prefer returning a reference. The general form of a singleton in C++ can therefore be given as follows (Alexandrescu, 2001): class Singleton { public: static Singleton &GetInstance(); private: ...
sealed class Singleton { private Singleton() { } public static readonly Singleton TheInstance = new Singleton(); } ASingleton classes are even easier in C# than they are in C++ because the .NET Framework has the notion of singletons built in. Here's the C# Singleton pa...