Package org.apache.hadoop.hdfs.server.namenode.snapshot

Class Snapshot

java.lang.Object

org.apache.hadoop.hdfs.server.namenode.snapshot.Snapshot

All Implemented Interfaces:

Comparable<byte[]>

@Private
public class Snapshot
extends Object
implements Comparable<byte[]>

Snapshot of a sub-tree in the namesystem.

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static class	Snapshot.Root	The root directory of the snapshot.

Field Summary

Fields

Modifier and Type	Field	Description
static final int	CURRENT_STATE_ID	This id is used to indicate the current state (vs. snapshots)
static final Comparator<Snapshot>	ID_COMPARATOR	Compare snapshot with IDs, where null indicates the current status thus is greater than any non-null snapshot.
static final Comparator<Integer>	ID_INTEGER_COMPARATOR	Compare snapshot with IDs, where null indicates the current status thus is greater than any non-null ID.
static final int	NO_SNAPSHOT_ID

Method Summary

Modifier and Type	Method	Description
int	compareTo(byte[] bytes)
boolean	equals(Object that)
static int	findLatestSnapshot(INode inode, int anchor)	Find the latest snapshot that 1) covers the given inode (which means the snapshot was either taken on the inode or taken on an ancestor of the inode), and 2) was taken before the given snapshot (if the given snapshot is not null).
static String	generateDefaultSnapshotName()
static String	generateDeletedSnapshotName(Snapshot s)
int	getId()
Snapshot.Root	getRoot()
static int	getSnapshotId(Snapshot s)
static String	getSnapshotPath(String snapshottableDir, String snapshotRelativePath)
static String	getSnapshotString(int snapshot)
int	hashCode()
String	toString()

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Field Details

CURRENT_STATE_ID

public static final int CURRENT_STATE_ID

This id is used to indicate the current state (vs. snapshots)

See Also:

• Constant Field Values

NO_SNAPSHOT_ID

public static final int NO_SNAPSHOT_ID

See Also:

• Constant Field Values

ID_COMPARATOR

public static final Comparator<Snapshot> ID_COMPARATOR

Compare snapshot with IDs, where null indicates the current status thus is greater than any non-null snapshot.

ID_INTEGER_COMPARATOR

public static final Comparator<Integer> ID_INTEGER_COMPARATOR

Compare snapshot with IDs, where null indicates the current status thus is greater than any non-null ID.

Method Details

generateDefaultSnapshotName

public static String generateDefaultSnapshotName()

generateDeletedSnapshotName

public static String generateDeletedSnapshotName(Snapshot s)

getSnapshotPath

public static String getSnapshotPath(String snapshottableDir,
 String snapshotRelativePath)

getSnapshotId

public static int getSnapshotId(Snapshot s)

getSnapshotString

public static String getSnapshotString(int snapshot)

findLatestSnapshot

public static int findLatestSnapshot(INode inode,
 int anchor)

Find the latest snapshot that 1) covers the given inode (which means the snapshot was either taken on the inode or taken on an ancestor of the inode), and 2) was taken before the given snapshot (if the given snapshot is not null).

Parameters:

inode - the given inode that the returned snapshot needs to cover

anchor - the returned snapshot should be taken before this given id.

Returns:

id of the latest snapshot that covers the given inode and was taken before the the given snapshot (if it is not null).

getId

public int getId()

getRoot

public Snapshot.Root getRoot()

Returns:

the root directory of the snapshot.

compareTo

public int compareTo(byte[] bytes)

Specified by:

compareTo in interface Comparable<byte[]>

equals

public boolean equals(Object that)

Overrides:

equals in class Object

hashCode

public int hashCode()

Overrides:

hashCode in class Object

toString

public String toString()

Overrides:

toString in class Object