BaseClasses学习(-)CAMEvent

CAMEvent是Baseclasses提供的对windows自带的event的一种包装.

实现如下:

// wrapper for event objects
class CAMEvent
{

    // make copy constructor and assignment operator inaccessible

    CAMEvent(const CAMEvent &refEvent);
    CAMEvent &operator=(const CAMEvent &refEvent);

protected:
    HANDLE m_hEvent;
public:
    CAMEvent(BOOL fManualReset = FALSE, __inout_opt HRESULT *phr = NULL);
    CAMEvent(__inout_opt HRESULT *phr);
    ~CAMEvent();

    // Cast to HANDLE - we don't support this as an lvalue
    operator HANDLE () const { return m_hEvent; };

    void Set() {EXECUTE_ASSERT(SetEvent(m_hEvent));};
    BOOL Wait(DWORD dwTimeout = INFINITE) {
	return (WaitForSingleObject(m_hEvent, dwTimeout) == WAIT_OBJECT_0);
    };
    void Reset() { ResetEvent(m_hEvent); };
    BOOL Check() { return Wait(0); };
};

创建时一般采用CAMEvent Test(TRUE)的方式创建,如果参数为TRUE则m_hEvent是一个手动重置事件,如果参数为FALSE或者默认则m_hEvent是一个自动重置事件,一般会采用手动重置事件.

(1)手动事件是需要手动reset的,自动的是在被wait以后自动 reset.

(2)手动实践一旦被signal,所有等待的线程全部工作,自动的只有一个工作.除非再次signal

其中Check()函数检查事件是否被set,如果是signal状态返回TRUE,否则返回FALSE.