org.apache.zookeeper.server.persistence
Class FileTxnSnapLog

java.lang.Object
  org.apache.zookeeper.server.persistence.FileTxnSnapLog

public class FileTxnSnapLog
extends Object

This is a helper class above the implementations of txnlog and snapshot classes

Nested Class Summary

static interface

FileTxnSnapLog.PlayBackListener This listener helps the external apis calling restore to gather information while the data is being restored.

Field Summary

static String	version
static int	VERSION

Constructor Summary

FileTxnSnapLog(File dataDir, File snapDir)
the constructor which takes the datadir and snapdir.

Method Summary

void	append(Request si) append the request to the transaction logs
void	commit() commit the transaction of logs
File	findMostRecentSnapshot() the most recent snapshot in the snapshot directory
List<File>	findNRecentSnapshots(int n) the n most recent snapshots
File	getDataDir() get the datadir used by this filetxn snap log
long	getLastLoggedZxid() the last logged zxid on the transaction logs
File	getSnapDir() get the snap dir used by this filetxn snap log
File[]	getSnapshotLogs(long zxid) get the snapshot logs that are greater than the given zxid
long	restore(DataTree dt, Map<Long,Integer> sessions, FileTxnSnapLog.PlayBackListener listener) this function restors the server database after reading from the snapshots and transaction logs
void	rollLog() roll the transaction logs
void	save(DataTree dataTree, ConcurrentHashMap<Long,Integer> sessionsWithTimeouts) save the datatree and the sessions into a snapshot
boolean	truncateLog(long zxid) truncate the transaction logs the zxid specified

Methods inherited from class java.lang.Object

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

Field Detail

VERSION

public static final int VERSION

See Also:

Constant Field Values

version

public static final String version

See Also:

Constant Field Values

Constructor Detail

FileTxnSnapLog

public FileTxnSnapLog(File dataDir,
                      File snapDir)
               throws IOException

the constructor which takes the datadir and snapdir.

Parameters:

dataDir - the trasaction directory

snapDir - the snapshot directory

Throws:

IOException

Method Detail

getDataDir

public File getDataDir()

get the datadir used by this filetxn snap log

Returns:

the data dir

getSnapDir

public File getSnapDir()

get the snap dir used by this filetxn snap log

Returns:

the snap dir

restore

public long restore(DataTree dt,
                    Map<Long,Integer> sessions,
                    FileTxnSnapLog.PlayBackListener listener)
             throws IOException

this function restors the server database after reading from the snapshots and transaction logs

Parameters:

dt - the datatree to be restored

sessions - the sessions to be restored

listener - the playback listener to run on the database restoration

Returns:

the highest zxid restored

Throws:

IOException

getLastLoggedZxid

public long getLastLoggedZxid()

the last logged zxid on the transaction logs

Returns:

the last logged zxid

save

public void save(DataTree dataTree,
                 ConcurrentHashMap<Long,Integer> sessionsWithTimeouts)
          throws IOException

save the datatree and the sessions into a snapshot

Parameters:

dataTree - the datatree to be serialized onto disk

sessionsWithTimeouts - the sesssion timeouts to be serialized onto disk

Throws:

IOException

truncateLog

public boolean truncateLog(long zxid)
                    throws IOException

truncate the transaction logs the zxid specified

Parameters:

zxid - the zxid to truncate the logs to

Returns:

true if able to truncate the log, false if not

Throws:

IOException

findMostRecentSnapshot

public File findMostRecentSnapshot()
                            throws IOException

the most recent snapshot in the snapshot directory

Returns:

the file that contains the most recent snapshot

Throws:

IOException

findNRecentSnapshots

public List<File> findNRecentSnapshots(int n)
                                throws IOException

the n most recent snapshots

Parameters:

n - the number of recent snapshots

Returns:

the list of n most recent snapshots, with the most recent in front

Throws:

IOException

getSnapshotLogs

public File[] getSnapshotLogs(long zxid)

get the snapshot logs that are greater than the given zxid

Parameters:

zxid - the zxid that contains logs greater than zxid

Returns:

append

public void append(Request si)
            throws IOException

append the request to the transaction logs

Parameters:

si - the request to be appended

Throws:

IOException

commit

public void commit()
            throws IOException

commit the transaction of logs

Throws:

IOException

rollLog

public void rollLog()
             throws IOException

roll the transaction logs

Throws:

IOException