C++ LogRecord::getTxID方法代码示例

/*
 * If no txnum is specified, run the undo phase of ARIES.
 * If a txnum is provided, abort that transaction.
 * Hint: the logic is very similar for these two tasks!
 */
void LogMgr::undo(vector <LogRecord*> log, int txnum)
{
  vector <int> loserTxID;
  priority_queue <int> ToUndo;
  int lsn, lastLsn, nextLsn, txID, pageID, offset, prevLsn, undoNextLsn;
  TxType tType;
  string beforeImage;

  // If a txnum is provided, abort that transaction.
  if ( txnum != NULL_TX )
    {
      lsn = se->nextLSN();
      lastLsn = getLastLSN(txnum);
      setLastLSN(txnum, lsn);
      logtail.push_back(new LogRecord(lsn, lastLsn, txnum, ABORT));
      log.push_back(new LogRecord(lsn, lastLsn, txnum, ABORT));
      tx_table[txnum].lastLSN = lsn;
      tx_table[txnum].status = U;
      loserTxID.push_back(txnum);
    }
  else
    {
      for (auto it = tx_table.begin(); it != tx_table.end(); it++)
        {
          if ( it->second.status != C )
            {
              loserTxID.push_back(it->first);
            }
        }
    }

  auto it = log.end();
  if ( log.size() > 0 )
    {
      it--;
    }
  else
    {
      return;
    }
      
  for ( int i = 0; i < loserTxID.size(); i++ )
    {
      ToUndo.push(tx_table[loserTxID[i]].lastLSN);
    }

  it = log.end();
  if ( log.size() > 0 )
    {
      it--;
    }
  else
    {
      return;
    }
  while ( it >= log.begin() && !(ToUndo.empty()) )
    {
      LogRecord *logPointer = *it;
      tType = logPointer->getType();
      lsn = logPointer->getLSN();
      if (lsn == ToUndo.top())
        {
          ToUndo.pop();
	  if ( tType == UPDATE )
	    {
	      UpdateLogRecord * updateLogPointer = dynamic_cast<UpdateLogRecord *>(logPointer);
	      txID = updateLogPointer->getTxID();
	      pageID = updateLogPointer->getPageID();
	      offset = updateLogPointer->getOffset();
	      beforeImage = updateLogPointer->getBeforeImage();
	      prevLsn = updateLogPointer->getprevLSN();
	      lastLsn = getLastLSN(txID);
	      nextLsn = se->nextLSN();
	      logtail.push_back(new CompensationLogRecord(nextLsn, lastLsn, txID, pageID, offset, beforeImage, prevLsn));
	      setLastLSN(txID, nextLsn);
	      tx_table[txID].status = U;
	      
	      if ( dirty_page_table.find(pageID) == dirty_page_table.end() )
		{
		  dirty_page_table[pageID] = nextLsn; 
		}
	      if( !(se->pageWrite(pageID, offset, beforeImage, nextLsn)) )
		{
		  return;
		}
	      if ( prevLsn == NULL_LSN )
		{
		  logtail.push_back( new LogRecord(se->nextLSN(), nextLsn, txID, END) );
		  tx_table.erase(txID);
		}
	      else
		{
		  ToUndo.push(prevLsn);
		}
	    }
//.........这里部分代码省略.........

/* 
 * Run the analysis phase of ARIES.
 */
void LogMgr::analyze(vector <LogRecord*> log)
{
  auto it = log.end();  
  TxType tType;
  int lsn, txID, pageID;
  bool foundCheckpoint = false;

  tx_table.clear();
  dirty_page_table.clear();

  if ( log.size() > 0 )
    {
      it--;
    }
  else
    {
      return;
    }

  while( it >= log.begin() )
    {
      LogRecord *logPointer = *it;
      tType = logPointer->getType();      
      if ( tType == END_CKPT )
        {
          ChkptLogRecord *chkptLogPointer = dynamic_cast<ChkptLogRecord *>(logPointer);
          tx_table = chkptLogPointer->getTxTable();
          dirty_page_table = chkptLogPointer->getDirtyPageTable();
          foundCheckpoint = true;
          break;
        }
      it--;
    }

  if ( !foundCheckpoint )
    {
      it = log.begin();
    }

  while( it != log.end() )
    {
      LogRecord *logPointer = *it;
      tType = logPointer->getType();
      txID = logPointer->getTxID();
      lsn = logPointer->getLSN();
      tx_table[txID].lastLSN = lsn;

      if ( txID == NULL_TX )
	{
	  it++;
	  continue;
	}

      if ( tType ==  UPDATE)
          {
            UpdateLogRecord * updateLogPointer = dynamic_cast<UpdateLogRecord *>(logPointer);
            tx_table[txID].status = U;
            pageID = updateLogPointer->getPageID();
            if ( dirty_page_table.find(pageID) == dirty_page_table.end() )
              {
                // not found                                                                           
                dirty_page_table[pageID] = lsn; 
              }
          }
      else if( tType ==  COMMIT)
          {
            tx_table[txID].status = C;
          }
      else if( tType ==  CLR)
          {
            CompensationLogRecord * compensationLogPointer = dynamic_cast<CompensationLogRecord *>(logPointer);
            tx_table[txID].status = U;
            pageID = compensationLogPointer->getPageID();
            if ( dirty_page_table.find(pageID) == dirty_page_table.end() )
              {
                // not found
                dirty_page_table[pageID] = lsn;
              }
          }
      else if( tType ==  END)
          {
            tx_table.erase(txID);
          }
      it++;
    }
}

/*
* If no txnum is specified, run the undo phase of ARIES.
* If a txnum is provided, abort that transaction.
* Hint: the logic is very similar for these two tasks!
*/
void LogMgr::undo(vector <LogRecord*> log, int txnum) 
{ 
	set<int> ToUndo;
	if (txnum == NULL_TX)
	{
		for (auto txn : tx_table)
		{
			if (txn.second.status == U && txn.second.lastLSN != -1)
				ToUndo.insert(txn.second.lastLSN);
		}
	}
	else
	{
		ToUndo.insert(tx_table[txnum].lastLSN);
	}

	while (!ToUndo.empty())
	{
		int L = *(ToUndo.rbegin());

		LogRecord *record = nullptr;
		for (auto rec : log)
		{
			if (rec->getLSN() == L)
			{
				record = rec;
				break;
			}
		}
		if (!record)
		{
			return;
		}

		// If it is an update, write a CLR and undo the action
		// And add the prevLSN to the set toUndo
		if (record->getType() == UPDATE)
		{
			UpdateLogRecord *upRecord = (UpdateLogRecord*)record;
			int pageLSN = se->getLSN(upRecord->getPageID());

			int next = se->nextLSN();

			logtail.push_back(new CompensationLogRecord(
				next, 
				getLastLSN(upRecord->getTxID()), 
				upRecord->getTxID(), 
				upRecord->getPageID(), 
				upRecord->getOffset(),
				upRecord->getBeforeImage(),
				record->getprevLSN()));
			tx_table[upRecord->getTxID()].lastLSN = next;

			// Undo the action
			if (dirty_page_table.find(upRecord->getPageID()) != dirty_page_table.end() 
				&& pageLSN < record->getLSN() 
				&& dirty_page_table.find(upRecord->getPageID())->second <= record->getLSN()) 
			{
				bool unwritten = se->pageWrite(upRecord->getPageID(), upRecord->getOffset(), upRecord->getBeforeImage(), upRecord->getLSN());
				
				// Return false if Storage Engine got stuck
				if (!unwritten)
					return;
			}

			if (record->getprevLSN() != NULL_LSN)
				ToUndo.insert(record->getprevLSN());
			else
			{
				int next2 = se->nextLSN();
				logtail.push_back(new LogRecord(next2, next, record->getTxID(), END)); 
				tx_table.erase(record->getTxID());
			}

		}

		if (record->getType() == ABORT) {
			ToUndo.insert(record->getprevLSN());
		}

		// If it is a CLR
		if (record->getType() == CLR)
		{
			// If the undoNextLSN value is null, write an end record 
			if (((CompensationLogRecord*)record)->getUndoNextLSN() == NULL_LSN)
			{
				int next2 = se->nextLSN();
				logtail.push_back(new LogRecord(next2, record->getLSN(), record->getTxID(), END)); 
				tx_table.erase(record->getTxID());
			}
			else
				ToUndo.insert(((CompensationLogRecord*)record)->getUndoNextLSN()); 
		}

		ToUndo.erase(L);
//.........这里部分代码省略.........