读写锁的实现

呆人 — Tue, 07 Dec 2010 03:33:00 GMT

#include"stdafx.h"
#include<windows.h>
/*对于一块临界区
**可以同时读
**当要写时，等待所有的读者离开，后来的读者不允许进入
**因为在同一个进程中
**所以使用临界区，而不是使用互斥对象，因为这样比较节省资源
*/
class __declspec(novtable) auto_RWLock
{
public:
    auto_RWLock(void);
    ~auto_RWLock(void);

    void LockForRead(void);
    void UnLockForRead(void);

    void LockForWrite(void);
    void UnLockForWrite(void);

private:
    long readerCount;
    CRITICAL_SECTION critical_section;
    CRITICAL_SECTION reader_all_leave;
};

#include"stdafx.h"
#include"auto_RWLock.h"

auto_RWLock::auto_RWLock(void):readerCount(0)
{
    InitializeCriticalSection(&critical_section);
    InitializeCriticalSection(&reader_all_leave);
}
auto_RWLock::~auto_RWLock(void)
{
    DeleteCriticalSection(&critical_section);
    DeleteCriticalSection(&reader_all_leave);
}

void auto_RWLock::LockForRead(void)
{
    EnterCriticalSection(&critical_section);

    if(InterlockedIncrement(&readerCount) ==1)
        EnterCriticalSection(&reader_all_leave);

    LeaveCriticalSection(&critical_section);
}

void auto_RWLock::UnLockForRead(void)
{
    if(InterlockedDecrement(&readerCount)==0)
        LeaveCriticalSection(&reader_all_leave);
}

void auto_RWLock::LockForWrite(void)
{
    EnterCriticalSection(&critical_section);
    EnterCriticalSection(&reader_all_leave);
}

void auto_RWLock::UnLockForWrite(void)
{
    LeaveCriticalSection(&critical_section);
    LeaveCriticalSection(&reader_all_leave);
}

呆人 2010-12-07 11:33 发表评论

C++博客-xyjzsh-随笔分类-多线程

读写锁的实现