simpledb.tx.recovery
Class StartRecord

java.lang.Object
  simpledb.tx.recovery.StartRecord

All Implemented Interfaces:

LogRecord

 class StartRecord
extends java.lang.Object
implements LogRecord

Field Summary

Fields inherited from interface simpledb.tx.recovery.LogRecord

CHECKPOINT, COMMIT, logMgr, ROLLBACK, SETINT, SETSTRING, START

Constructor Summary

StartRecord(BasicLogRecord rec)
Creates a log record by reading one other value from the log.

StartRecord(int txnum)
Creates a new start log record for the specified transaction.

Method Summary

int	op() Returns the log record's type.
java.lang.String	toString()
int	txNumber() Returns the transaction id stored with the log record.
void	undo(int txnum) Does nothing, because a start record contains no undo information.
int	writeToLog() Writes a start record to the log.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Constructor Detail

StartRecord

public StartRecord(int txnum)

Creates a new start log record for the specified transaction.

Parameters:

txnum - the ID of the specified transaction

StartRecord

public StartRecord(BasicLogRecord rec)

Creates a log record by reading one other value from the log.

Parameters:

rec - the basic log record

Method Detail

writeToLog

public int writeToLog()

Writes a start record to the log. This log record contains the START operator, followed by the transaction id.

Specified by:

writeToLog in interface LogRecord

Returns:

the LSN of the last log value

op

public int op()

Description copied from interface: LogRecord

Returns the log record's type.

Specified by:

op in interface LogRecord

Returns:

the log record's type

txNumber

public int txNumber()

Description copied from interface: LogRecord

Returns the transaction id stored with the log record.

Specified by:

txNumber in interface LogRecord

Returns:

the log record's transaction id

undo

public void undo(int txnum)

Does nothing, because a start record contains no undo information.

Specified by:

undo in interface LogRecord

Parameters:

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

toString

public java.lang.String toString()

Overrides:

toString in class java.lang.Object