C++简洁实现线程安全单例类

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关于单例模式这里不再多说了，网上很多例子。这里实现一个很通用的，线程安全的单例类，具体应用场景如：线程池的任务队列，epoll事件框架类等。

#define DISABLE_COPY_AND_ASSIGN(T) \          T(const T &); \          T& operator=(const T &)  struct Recursive {};class Mutex {  public:      Mutex() {          pthread_mutex_init(&_mutex, NULL);      }      explicit Mutex(Recursive) {        pthread_mutexattr_t attr;        pthread_mutexattr_init(&attr);        pthread_mutexattr_settype(&attr, PTHREAD_MUTEX_RECURSIVE_NP);        pthread_mutex_init(&_mutex, &attr);        pthread_mutexattr_destroy(&attr);    }    ~Mutex() {          pthread_mutex_destroy(&_mutex);      }            int lock() {          return pthread_mutex_lock(&_mutex);      }            int trylock() {          return pthread_mutex_trylock(&_mutex);      }            int unlock() {          return pthread_mutex_unlock(&_mutex);      }        private:      pthread_mutex_t _mutex;      // RAII class should not be able to be copied    DISABLE_COPY_AND_ASSIGN(Mutex); };    template <class T>  class AutoLock {  public:      explicit AutoLock(T* t) : _t(t) {          _t.lock();      }      ~AutoLock() {          _t.unlock();      }  private:      T* _t;      // RAII class should not be able to be copied    DISABLE_COPY_AND_ASSIGN(AutoLock);  };  class Queue {  public:      static Queue& instance() ｛      static Queue instance; // it's only construct once when using Queue::instance()      return instance;      }      Request* fetch() {      AutoLock<Mutex> autolock(&_lock);      //TODO      }      void add(Item* ite_) {      AutoLock<Mutex> autolock(&_lock);      //TODO      }  private:      Queue();      ~Queue();      Mutex _lock;        DISABLE_COPY_AND_ASSIGN(Queue);  };    // using method  void foo (void)   {      Queue::instance().fetch();          ... ...      Queue::instance().add(...);  }

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