void BufferManager::deleteRecord(const std::string& fileName, int blockOffset, int start)//给recordManager
{
int n = fileName.find(".table",0);
std::string tableName = fileName.substr(0, n);
Table* tablePtr = Cat.getTablePtr(tableName);
std::string ss = "";
for (int i = 0; i < tablePtr->recordSize; i++)
ss += '\0';
std::list<Block*>::iterator it = readFileBlock(fileName, blockOffset);
if (start + tablePtr->recordSize>BLOCK_SIZE)
{
int length1 = BLOCK_SIZE - start;
int length2 = tablePtr->recordSize - length1;
(*it)->changeContent(start,ss.substr(0,length1));
it = readFileBlock(fileName, blockOffset+1);
(*it)->changeContent(0,ss.substr(0,length2));
}
else
(*it)->changeContent(start, ss);
int recordOffset = (blockOffset*BLOCK_SIZE + start) / tablePtr->recordSize;
tablePtr->emptyRecordOffset.push_back(recordOffset);
}
void BufferManager::readFile(const std::string& fileName)
{
int blockNum; int n;
if ((n = fileName.find(".table", 0)) != std::string::npos)
{
Table* tablePtr = Cat.getTablePtr(fileName.substr(0,n));
blockNum = tablePtr->blockNum;
}
if ((n = fileName.find(".index", 0)) != std::string::npos)
{
Index* indexPtr = Cat.getIndexPtr(fileName.substr(0, n));
blockNum = indexPtr->blockNum;
}
std::list<Block*>::iterator it;
for (int i = 0; i < blockNum; i++)
it = readFileBlock(fileName, i);
}
std::string BufferManager::getRecord(const std::string& fileName, int blockOffset, int start)
{
int n = fileName.find(".table",0);
Table* tablePtr = Cat.getTablePtr(fileName.substr(0, n));
std::list<Block*>::iterator it = readFileBlock(fileName, blockOffset);
std::string record = "";
if (start + tablePtr->recordSize > BLOCK_SIZE)
{
int length1 = BLOCK_SIZE - start;
int length2 = tablePtr->recordSize - length1;
for (int i = 0; i < length1; i++)
record += (*it)->content[start + i];
it = readFileBlock(fileName, blockOffset+1);
for (int i = 0; i < length2; i++)
record += (*it)->content[i];
}
else
for (int i = 0; i < tablePtr->recordSize; i++)
record += (*it)->content[i+start];
return record;
}
int BufferManager::insertRecord(const std::string& fileName, const std::string& content)
{
int n = fileName.find(".table", 0);
std::string tableName = fileName.substr(0, fileName.size()-6);
Table* tablePtr = Cat.getTablePtr(tableName);
std::list<Block*>::iterator it;
if (tablePtr->emptyRecordOffset.empty() == 1)//没有空位
{
it = addBlockInFile(fileName);
(*it)->blockOffset = tablePtr->blockNum;
(*it)->fileName = fileName;
(*it)->isDirty = 1;
tablePtr->blockNum++;
(*it)->changeContent(0, content);
int recordOffset = ((tablePtr->blockNum - 1)*BLOCK_SIZE )/ tablePtr->recordSize;
int num;
if (BLOCK_SIZE % tablePtr->recordSize == 0)
num = BLOCK_SIZE / tablePtr->recordSize;
else
num = BLOCK_SIZE / tablePtr->recordSize + 1;
for (int i = 1; i < num; i++)
tablePtr->emptyRecordOffset.push_back(recordOffset + i);
return (*it)->blockOffset << 16;
}
else//有空位
{
int recordOffset = *((tablePtr->emptyRecordOffset).begin());
(tablePtr->emptyRecordOffset).erase((tablePtr->emptyRecordOffset).begin());
int blockOffset = (recordOffset*tablePtr->recordSize) / BLOCK_SIZE;
int start = (recordOffset*tablePtr->recordSize) % BLOCK_SIZE;
it = readFileBlock(fileName, blockOffset);
if (start + tablePtr->recordSize > BLOCK_SIZE)//记录跨block
{
int length1 = BLOCK_SIZE - start;
int length2 = tablePtr->recordSize - length1;
(*it)->changeContent(start, content.substr(0, length1));
if (blockOffset + 1 == tablePtr->blockNum)//所跨block的下一个需要生成
{
it = addBlockInFile(fileName);
(*it)->blockOffset = tablePtr->blockNum;
(*it)->fileName = fileName;
(*it)->isDirty = 1;
tablePtr->blockNum++;
(*it)->changeContent(0, content.substr(length1, length2));
int i = recordOffset+1;
int size = length2;
while (size < BLOCK_SIZE)
{
tablePtr->emptyRecordOffset.push_back(i);
size += tablePtr->recordSize;
i++;
}
}
else//所跨block的下一个不需要生成
{
it = readFileBlock(fileName,blockOffset+1);
(*it)->changeContent(0, content.substr(length1, length2));
}
}
else//记录不跨block
(*it)->changeContent(start, content);
return (blockOffset << 16) | start;
}
}
