//NOTICE:this can only be done by one thread
//write out all the elements to hard disk.
bool LRUCache::flush()
{
#ifdef DEBUG_VSTREE
cout<<"to flush in LRUCache"<<endl;
#endif
FILE* filePtr = fopen(this->dataFilePath.c_str(), "r+b");
if (filePtr == NULL)
{
cerr << "error, can't open file. @LRUCache::flush" << endl;
return false;
}
int startIndex = LRUCache::DEFAULT_NUM;
int endIndex = startIndex + this->size;
size_t vNodeSize = VNode::VNODE_SIZE;
//size_t vNodeSize = sizeof(VNode);
//NOTICE:values are continuous
for (int i = startIndex; i < endIndex; ++i)
{
VNode* nodePtr = this->values[i];
int line = this->keys[i];
//cout<<"file line to write "<<line<<endl;
#ifdef DEBUG
if (nodePtr->getFileLine() != line)
{
cout << "line error at !!!" << line << " " << nodePtr->getFileLine() << endl;
}
#endif
if (nodePtr == NULL)
{
cerr << "error, VNode do not exist. @LRUCache::flush" << endl;
return false;
}
if(!nodePtr->isDirty())
{
continue;
}
int flag = 0;
long long seekPos = (long long)line * vNodeSize;
flag = fseek(filePtr, seekPos, SEEK_SET);
if (flag != 0)
{
cerr << "error, can't seek to the fileLine. @LRUCache::flush" << endl;
return false;
}
//fwrite((char *)nodePtr, vNodeSize, 1, filePtr);
nodePtr->writeNode(filePtr);
}
fclose(filePtr);
return true;
}
//just write the values[_pos] to the hard disk, the VNode in memory will not be free.
bool
LRUCache::writeOut(int _pos, int _fileLine)
{
VNode* nodePtr = this->values[_pos];
FILE* filePtr = fopen(this->dataFilePath.c_str(), "r+b");
if (nodePtr == NULL)
{
cerr << "error, VNode do not exist. @LRUCache::writeOut" << endl;
return false;
}
if (filePtr == NULL)
{
cerr << "error, can't open file. @LRUCache::writeOut" << endl;
return false;
}
if (nodePtr->getFileLine() != _fileLine)
{
cerr << "error, fileLine " << _fileLine <<" "<< nodePtr->getFileLine() << " wrong. @LRUCache::writeOut" << endl;
}
if(!nodePtr->isDirty())
{
//cout<<"the node not dirty!"<<endl;
fclose(filePtr);
return true;
}
else //is modified
{
nodePtr->setDirty(false);
}
int line = _fileLine == -1 ? nodePtr->getFileLine() : _fileLine;
size_t vNodeSize = VNode::VNODE_SIZE;
//size_t vNodeSize = sizeof(VNode);
int flag = 0;
long long seekPos = (long long)line * vNodeSize;
flag = fseek(filePtr, seekPos, SEEK_SET);
if (flag != 0)
{
cerr << "error, can't seek to the fileLine. @LRUCache::writeOut" << endl;
return false;
}
//fwrite((char *)nodePtr, vNodeSize, 1, filePtr);
nodePtr->writeNode(filePtr);
fclose(filePtr);
return true;
}
