code: @Override
  	public void onTxRollback(Transaction tx) {
  		if (!tx.isReadOnly() && enableLogging) {
  			rollback(tx);
  			LogSeqNum lsn = new RollbackRecord(txNum).writeToLog();
  			VanillaDb.logMgr().flush(lsn);
  		}
  	}
docs: Does the roll back process, writes a rollback record to the log, and
  flushes the log record to disk.