四、程序运行
程序数据输入如下：
数据库读写锁的实现（C++）(二)
for (set::iterator it_index = obj->shareList.begin();
it_index != obj->shareList.end(); it_index++)
{
sTemp += " " + *it_index;
}
obj->waitingTransList.push(trId->tranId);
result += "Waiting for lock (S-lock held by:" + sTemp + "\n";
}
else if (shareNum == 1)
{
//update
if (*(obj->shareList.begin()) == trId->tranId)
{
obj->curXLockTrans = trId->tranId;
obj->shareList.clear();
result += "Upgrade to XLock granted\n";
}
else
{
obj->waitingTransList.push(trId->tranId);
result += "Waiting for lock (S-lock held by:" + *(obj->shareList.begin()) + ")\n";
}
}
else if (shareNum == 0)
{
obj->curXLockTrans = trId->tranId;
trId->curLockObjList.insert(obj);
result += "XLock granted\n";
}
}
else//当前存在写操作
{
obj->waitingTransList.push(trId->tranId);
result += "Waiting for lock (X-lock held by: "+ obj->curXLockTrans +")\n";
}
}
}
void LMer::diviTransID(transId* trId, object* pObj, string& result)
{
if(pObj->curXLockTrans != "")
{
//对写操作解绑
if (pObj->curXLockTrans == trId->tranId)
{
pObj->curXLockTrans = "";
trId->curLockObjList.erase(pObj);
result += "Lock released\n\t\t\t";
}
else
{
result += "I can not find the transaction.\n\t\t\t";
}
}//对共享读集合解绑
else
{
set::iterator shareIndex = pObj->shareList.find(trId->tranId);
if (shareIndex != pObj->shareList.end())
{
pObj->shareList.erase(shareIndex);
trId->curLockObjList.erase(pObj);
result += "Lock released\n\t\t\t";
}
else
{
result += "I can not find the transaction.\n\t\t\t";
}
}
//查看写等待队列
if (pObj->waitingTransList.size() != 0)
{
pObj->curXLockTrans = pObj->waitingTransList.front();
pObj->waitingTransList.pop();
result += "X-Lock on "+ pObj->objectName +" granted to "+ pObj->curXLockTrans +"\n";
}//查看共享队列
else if (pObj->shareList.size() != 0)
{
string temp = "";
for(set::iterator it_index = pObj->shareList.begin();
it_index != pObj->shareList.end(); it_index++)
{
temp += " " + *it_index;
}
result += "S-Lock on "+ pObj->objectName +" granted to "+ temp +"\n";
}
}
运行后得到结果如下：