org.h2.log
Class LogSystem

java.lang.Object
  org.h2.log.LogSystem

public class LogSystem
extends java.lang.Object

The transaction log system is responsible for the write ahead log mechanism used in this database. A number of LogFile objects are used (one for each file).

Field Summary

static int

LOG_WRITTEN This special log position means that the log entry has been written.

Constructor Summary

LogSystem(Database database, java.lang.String fileNamePrefix, boolean readOnly, java.lang.String accessMode, PageStore pageStore)
Create new transaction log object.

Method Summary

void	add(Session session, DiskFile file, Record record) Add an log entry to the last transaction log file.
void	addTruncate(Session session, DiskFile file, int storageId, int recordId, int blockCount) Add a truncate entry.
void	checkpoint() Flush all data to the transaction log files as well as to the data files and and switch log files.
void	close(boolean checkpoint) Close all log files.
void	commit(Session session) Commit the current transaction of the given session.
boolean	containsInDoubtTransactions() Check if there are any in-doubt transactions.
void	flush() Flush all pending changes to the transaction log files.
ObjectArray<LogFile>	getActiveLogFiles() Get all active log files.
boolean	getFlushOnEachCommit() Check if flush-on-each-commit is enabled.
ObjectArray<InDoubtTransaction>	getInDoubtTransactions() Get the list of in-doubt transactions.
java.lang.String	getWritePos() Get the write position.
void	invalidateIndexSummary() Write a log entry meaning the index summary is invalid.
void	open() Open all existing transaction log files and create a new one if required.
void	prepareCommit(Session session, java.lang.String transaction) Prepare a transaction.
boolean	recover() Roll back any uncommitted transactions if required, and apply committed changed to the data files.
void	setDisabled(boolean disabled) Enable or disable the transaction log
void	setFlushOnEachCommit(boolean b) Enable or disable-flush-on-each-commit.
void	setMaxLogSize(long maxSize) Set the maximum log file size in megabytes.
void	setReadOnly(boolean readOnly) Set the read only flag for this log system.
void	sync() Flush the transaction log file and sync the data to disk.
void	updateKeepFiles(int incrementDecrement) Increment or decrement the flag to keep (not delete) old log files.

Methods inherited from class java.lang.Object

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

Field Detail

LOG_WRITTEN

public static final int LOG_WRITTEN

This special log position means that the log entry has been written.

See Also:

Constant Field Values

Constructor Detail

LogSystem

public LogSystem(Database database,
                 java.lang.String fileNamePrefix,
                 boolean readOnly,
                 java.lang.String accessMode,
                 PageStore pageStore)

Create new transaction log object. This will not open or create files yet.

Parameters:

database - the database

fileNamePrefix - the name of the database file

readOnly - if the log should be opened in read-only mode

accessMode - the file access mode (r, rw, rws, rwd)

pageStore - the page store

Method Detail

setMaxLogSize

public void setMaxLogSize(long maxSize)

Set the maximum log file size in megabytes.

Parameters:

maxSize - the new maximum log file size

containsInDoubtTransactions

public boolean containsInDoubtTransactions()

Check if there are any in-doubt transactions.

Returns:

true if there are

close

public void close(boolean checkpoint)
           throws java.sql.SQLException

Close all log files.

Parameters:

checkpoint - if a checkpoint should be written

Throws:

java.sql.SQLException

recover

public boolean recover()
                throws java.sql.SQLException

Roll back any uncommitted transactions if required, and apply committed changed to the data files.

Returns:

if recovery was needed

Throws:

java.sql.SQLException

open

public void open()
          throws java.sql.SQLException

Open all existing transaction log files and create a new one if required.

Throws:

java.sql.SQLException

getInDoubtTransactions

public ObjectArray<InDoubtTransaction> getInDoubtTransactions()

Get the list of in-doubt transactions.

Returns:

the list

prepareCommit

public void prepareCommit(Session session,
                          java.lang.String transaction)
                   throws java.sql.SQLException

Prepare a transaction.

Parameters:

session - the session

transaction - the name of the transaction

Throws:

java.sql.SQLException

commit

public void commit(Session session)
            throws java.sql.SQLException

Commit the current transaction of the given session.

Parameters:

session - the session

Throws:

java.sql.SQLException

flush

public void flush()
           throws java.sql.SQLException

Flush all pending changes to the transaction log files.

Throws:

java.sql.SQLException

addTruncate

public void addTruncate(Session session,
                        DiskFile file,
                        int storageId,
                        int recordId,
                        int blockCount)
                 throws java.sql.SQLException

Add a truncate entry.

Parameters:

session - the session

file - the disk file

storageId - the storage id

recordId - the id of the first record

blockCount - the number of blocks

Throws:

java.sql.SQLException

add

public void add(Session session,
                DiskFile file,
                Record record)
         throws java.sql.SQLException

Add an log entry to the last transaction log file.

Parameters:

session - the session

file - the file

record - the record to log

Throws:

java.sql.SQLException

checkpoint

public void checkpoint()
                throws java.sql.SQLException

Flush all data to the transaction log files as well as to the data files and and switch log files.

Throws:

java.sql.SQLException

getActiveLogFiles

public ObjectArray<LogFile> getActiveLogFiles()

Get all active log files.

Returns:

the list of log files

setFlushOnEachCommit

public void setFlushOnEachCommit(boolean b)

Enable or disable-flush-on-each-commit.

Parameters:

b - the new value

getFlushOnEachCommit

public boolean getFlushOnEachCommit()

Check if flush-on-each-commit is enabled.

Returns:

true if it is

sync

public void sync()
          throws java.sql.SQLException

Flush the transaction log file and sync the data to disk.

Throws:

java.sql.SQLException

setDisabled

public void setDisabled(boolean disabled)

Enable or disable the transaction log

Parameters:

disabled - true if the log should be switched off

setReadOnly

public void setReadOnly(boolean readOnly)

Set the read only flag for this log system.

Parameters:

readOnly - the new value

invalidateIndexSummary

public void invalidateIndexSummary()
                            throws java.sql.SQLException

Write a log entry meaning the index summary is invalid.

Throws:

java.sql.SQLException

updateKeepFiles

public void updateKeepFiles(int incrementDecrement)

Increment or decrement the flag to keep (not delete) old log files.

Parameters:

incrementDecrement - (1 to increment, -1 to decrement)

getWritePos

public java.lang.String getWritePos()

Get the write position.

Returns:

the write position