simpledb.tx.recovery
Interface LogRecord

public interface LogRecord

The interface implemented by each type of log record.

Author:

Edward Sciore

Field Summary

static int	CHECKPOINT The six different types of log record
static int	COMMIT The six different types of log record
static LogMgr	logMgr
static int	ROLLBACK The six different types of log record
static int	SETINT The six different types of log record
static int	SETSTRING The six different types of log record
static int	START The six different types of log record

Method Summary

int	op() Returns the log record's type.
int	txNumber() Returns the transaction id stored with the log record.
void	undo(int txnum) Undoes the operation encoded by this log record.
int	writeToLog() Writes the record to the log and returns its LSN.

Field Detail

CHECKPOINT

static final int CHECKPOINT

The six different types of log record

See Also:

Constant Field Values

START

static final int START

The six different types of log record

See Also:

Constant Field Values

COMMIT

static final int COMMIT

The six different types of log record

See Also:

Constant Field Values

ROLLBACK

static final int ROLLBACK

The six different types of log record

See Also:

Constant Field Values

SETINT

static final int SETINT

The six different types of log record

See Also:

Constant Field Values

SETSTRING

static final int SETSTRING

The six different types of log record

See Also:

Constant Field Values

logMgr

static final LogMgr logMgr

Method Detail

writeToLog

int writeToLog()

Writes the record to the log and returns its LSN.

Returns:

the LSN of the record in the log

op

int op()

Returns the log record's type.

Returns:

the log record's type

txNumber

int txNumber()

Returns the transaction id stored with the log record.

Returns:

the log record's transaction id

undo

void undo(int txnum)

Undoes the operation encoded by this log record. The only log record types for which this method does anything interesting are SETINT and SETSTRING.

Parameters:

txnum - the id of the transaction that is performing the undo.