org.apache.zookeeper.server.persistence

Class FileSnap

java.lang.Object

org.apache.zookeeper.server.persistence.FileSnap

All Implemented Interfaces:

SnapShot

public class FileSnap
extends Object
implements SnapShot

This class implements the snapshot interface. it is responsible for storing, serializing and deserializing the right snapshot. and provides access to the snapshots.

Field Summary

Fields

Modifier and Type	Field and Description
static int	SNAP_MAGIC
static String	SNAPSHOT_FILE_PREFIX

Constructor Summary

Constructors

Constructor and Description
FileSnap(File snapDir)

Method Summary

Modifier and Type	Method and Description
void	close() synchronized close just so that if serialize is in place the close operation will block and will wait till serialize is done and will set the close flag
long	deserialize(DataTree dt, Map<Long,Integer> sessions) deserialize a data tree from the most recent snapshot
void	deserialize(DataTree dt, Map<Long,Integer> sessions, InputArchive ia) deserialize the datatree from an inputarchive
File	findMostRecentSnapshot() find the most recent snapshot in the database.
List<File>	findNRecentSnapshots(int n) find the last n snapshots.
protected List<File>	findNValidSnapshots(int n) find the last (maybe) valid n snapshots.
SnapshotInfo	getLastSnapshotInfo() get information of the last saved/restored snapshot
void	serialize(DataTree dt, Map<Long,Integer> sessions, File snapShot, boolean fsync) serialize the datatree and session into the file snapshot
protected void	serialize(DataTree dt, Map<Long,Integer> sessions, OutputArchive oa, FileHeader header) serialize the datatree and sessions

Methods inherited from class java.lang.Object

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

Field Detail

SNAP_MAGIC

public static final int SNAP_MAGIC

SNAPSHOT_FILE_PREFIX

public static final String SNAPSHOT_FILE_PREFIX

See Also:

Constant Field Values

Constructor Detail

FileSnap

public FileSnap(File snapDir)

Method Detail

getLastSnapshotInfo

public SnapshotInfo getLastSnapshotInfo()

get information of the last saved/restored snapshot

Specified by:

getLastSnapshotInfo in interface SnapShot

Returns:

info of last snapshot

deserialize

public long deserialize(DataTree dt,
                        Map<Long,Integer> sessions)
                 throws IOException

deserialize a data tree from the most recent snapshot

Specified by:

deserialize in interface SnapShot

Parameters:

dt - the datatree to be deserialized into

sessions - the sessions to be deserialized into

Returns:

the zxid of the snapshot

Throws:

IOException

deserialize

public void deserialize(DataTree dt,
                        Map<Long,Integer> sessions,
                        InputArchive ia)
                 throws IOException

deserialize the datatree from an inputarchive

Parameters:

dt - the datatree to be serialized into

sessions - the sessions to be filled up

ia - the input archive to restore from

Throws:

IOException

findMostRecentSnapshot

public File findMostRecentSnapshot()
                            throws IOException

find the most recent snapshot in the database.

Specified by:

findMostRecentSnapshot in interface SnapShot

Returns:

the file containing the most recent snapshot

Throws:

IOException

findNValidSnapshots

protected List<File> findNValidSnapshots(int n)
                                  throws IOException

find the last (maybe) valid n snapshots. this does some minor checks on the validity of the snapshots. It just checks for / at the end of the snapshot. This does not mean that the snapshot is truly valid but is valid with a high probability. also, the most recent will be first on the list.

Parameters:

n - the number of most recent snapshots

Returns:

the last n snapshots (the number might be less than n in case enough snapshots are not available).

Throws:

IOException

findNRecentSnapshots

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

find the last n snapshots. this does not have any checks if the snapshot might be valid or not

Parameters:

n - the number of most recent snapshots

Returns:

the last n snapshots

Throws:

IOException

serialize

protected void serialize(DataTree dt,
                         Map<Long,Integer> sessions,
                         OutputArchive oa,
                         FileHeader header)
                  throws IOException

serialize the datatree and sessions

Parameters:

dt - the datatree to be serialized

sessions - the sessions to be serialized

oa - the output archive to serialize into

header - the header of this snapshot

Throws:

IOException

serialize

public void serialize(DataTree dt,
                      Map<Long,Integer> sessions,
                      File snapShot,
                      boolean fsync)
               throws IOException

serialize the datatree and session into the file snapshot

Specified by:

serialize in interface SnapShot

Parameters:

dt - the datatree to be serialized

sessions - the sessions to be serialized

snapShot - the file to store snapshot into

fsync - sync the file immediately after write

Throws:

IOException

close

public void close()
           throws IOException

synchronized close just so that if serialize is in place the close operation will block and will wait till serialize is done and will set the close flag

Specified by:

close in interface SnapShot

Throws:

IOException