log_reader(const char * filename);

~log_reader();

void close() ;

transaction_id_t seek_transaction(transaction_id_t lsn) ;

Reads the log file until finding the first LSN which is equal to or greater than the LSN passed. Returns the transaction_id which if found. Returns no_transaction if the EOF is reached prior to finding an eligible transaction. throws if an error is encountered with the content of the log file.

transaction_id_t next_transaction() ;

Reads the next transaction from the log file. Returns the transaction_id which is found. Returns no_transaction if the EOF is reached. throws if an error is encountered with the content of the log file.

std::pair< log_header *, std::vector< char > * > get_transaction() ;

Returns the header and data buffer of the last transacton read from disk via a call to seekTransacton() or nextTransaction(). The returned pointers are only valid until the next call to either of those methods.

transaction_id_t read_next_txn() ;

Read the next transaction from the file into _buffer. Confirm its checkpoints, and return the header of that transaction