一个Windows C++ 读写锁的实现

#ifndef __RW_LOCK_H__
#define __RW_LOCK_H__

#include 

/*************************************************************************
*** file: RWLock.h
***	Reference:
***		http://bbs.csdn.net/topics/390331427?page=1
*************************************************************************/

class CRWLock
{
public:
	CRWLock(): m_readCount(0), m_writeCount(0) {	::InitializeCriticalSection(&mtx); }
	~CRWLock() { ::DeleteCriticalSection(&mtx); }
	
	void ReadLock()
	{
		while(true)
		{
			if(!m_writeCount)
			{
				::InterlockedIncrement((volatile long*)&m_readCount);
				if(m_writeCount)
				{
					// 有读写冲突，让位于写
					::InterlockedDecrement((volatile long*)&m_readCount);
					continue;
				}
				//获得读锁
				break;
			}

			::Sleep(0);
		}
	}	
	void ReadUnlock() { ::InterlockedDecrement((volatile long*)&m_readCount); }
	
	void WriteLock()
	{
		::InterlockedIncrement((volatile long*)&m_writeCount);
		::EnterCriticalSection(&mtx);
		// 等待已经在读的线程结束读操作
		while(true)
		{
			if(!m_readCount)
				break;

			::Sleep(0);
		}
	}	
	void WriteUnlock()
	{
		::LeaveCriticalSection(&mtx);
		::InterlockedDecrement((volatile long*)&m_writeCount);
	}
private:
	CRWLock(const CRWLock &);
	CRWLock & operator = (const CRWLock &);
	CRITICAL_SECTION mtx;
	int m_readCount;
	int m_writeCount;
};

#endif // !__RW_LOCK_H__