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

Class SnapshotManager

java.lang.Object

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

All Implemented Interfaces:

SnapshotStats

public class SnapshotManager
extends Object
implements SnapshotStats

Manage snapshottable directories and their snapshots. This class includes operations that create, access, modify snapshots and/or snapshot-related data. In general, the locking structure of snapshot operations is:
1. Lock the FSNamesystem lock in FSNamesystem before calling into SnapshotManager methods.
2. Lock the FSDirectory lock for the SnapshotManager methods if necessary.

Constructor Summary

Constructors

Constructor and Description
SnapshotManager(FSDirectory fsdir)

Method Summary

Methods

Modifier and Type	Method and Description
void	addSnapshottable(org.apache.hadoop.hdfs.server.namenode.snapshot.INodeDirectorySnapshottable dir) Add the given snapshottable directory to snapshottables.
void	clearSnapshottableDirs()
String	createSnapshot(String path, String snapshotName) Create a snapshot of the given path.
void	deleteSnapshot(String path, String snapshotName, INode.BlocksMapUpdateInfo collectedBlocks, List<org.apache.hadoop.hdfs.server.namenode.INode> removedINodes) Delete a snapshot for a snapshottable directory
INodeDirectorySnapshottable.SnapshotDiffInfo	diff(String path, String from, String to) Compute the difference between two snapshots of a directory, or between a snapshot of the directory and its current tree.
int	getMaxSnapshotID() Returns the maximum allowable snapshot ID based on the bit width of the snapshot ID.
int	getNumSnapshots()
int	getNumSnapshottableDirs()
SnapshottableDirectoryStatus[]	getSnapshottableDirListing(String userName) List all the snapshottable directories that are owned by the current user.
org.apache.hadoop.hdfs.server.namenode.snapshot.INodeDirectorySnapshottable	getSnapshottableRoot(String path) Find the source root directory where the snapshot will be taken for a given path.
Map<Integer,org.apache.hadoop.hdfs.server.namenode.snapshot.Snapshot>	read(DataInput in, FSImageFormat.Loader loader) Read values of snapshotCounter, numSnapshots, and all snapshots from the DataInput
void	removeSnapshottable(List<org.apache.hadoop.hdfs.server.namenode.snapshot.INodeDirectorySnapshottable> toRemove) Remove snapshottable directories from snapshottables
void	renameSnapshot(String path, String oldSnapshotName, String newSnapshotName) Rename the given snapshot
void	resetSnapshottable(String path) Set the given snapshottable directory to non-snapshottable.
void	setSnapshottable(String path, boolean checkNestedSnapshottable) Set the given directory as a snapshottable directory.

Methods inherited from class java.lang.Object

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

Constructor Detail

SnapshotManager

public SnapshotManager(FSDirectory fsdir)

Method Detail

setSnapshottable

public void setSnapshottable(String path,
                    boolean checkNestedSnapshottable)
                      throws IOException

Set the given directory as a snapshottable directory. If the path is already a snapshottable directory, update the quota.

Throws:

IOException

addSnapshottable

public void addSnapshottable(org.apache.hadoop.hdfs.server.namenode.snapshot.INodeDirectorySnapshottable dir)

Add the given snapshottable directory to snapshottables.

removeSnapshottable

public void removeSnapshottable(List<org.apache.hadoop.hdfs.server.namenode.snapshot.INodeDirectorySnapshottable> toRemove)

Remove snapshottable directories from snapshottables

resetSnapshottable

public void resetSnapshottable(String path)
                        throws IOException

Set the given snapshottable directory to non-snapshottable.

Throws:

SnapshotException - if there are snapshots in the directory.

IOException

getSnapshottableRoot

public org.apache.hadoop.hdfs.server.namenode.snapshot.INodeDirectorySnapshottable getSnapshottableRoot(String path)
                                                                                                 throws IOException

Find the source root directory where the snapshot will be taken for a given path.

Parameters:

path - The directory path where the snapshot will be taken.

Returns:

Snapshottable directory.

Throws:

IOException - Throw IOException when the given path does not lead to an existing snapshottable directory.

createSnapshot

public String createSnapshot(String path,
                    String snapshotName)
                      throws IOException

Create a snapshot of the given path. It is assumed that the caller will perform synchronization.

Parameters:

path - The directory path where the snapshot will be taken.

snapshotName - The name of the snapshot.

Throws:

IOException - Throw IOException when 1) the given path does not lead to an existing snapshottable directory, and/or 2) there exists a snapshot with the given name for the directory, and/or 3) snapshot number exceeds quota

deleteSnapshot

public void deleteSnapshot(String path,
                  String snapshotName,
                  INode.BlocksMapUpdateInfo collectedBlocks,
                  List<org.apache.hadoop.hdfs.server.namenode.INode> removedINodes)
                    throws IOException

Delete a snapshot for a snapshottable directory

Parameters:

path - Path to the directory where the snapshot was taken

snapshotName - Name of the snapshot to be deleted

collectedBlocks - Used to collect information to update blocksMap

Throws:

IOException

renameSnapshot

public void renameSnapshot(String path,
                  String oldSnapshotName,
                  String newSnapshotName)
                    throws IOException

Rename the given snapshot

Parameters:

path - The directory path where the snapshot was taken

oldSnapshotName - Old name of the snapshot

newSnapshotName - New name of the snapshot

Throws:

IOException - Throw IOException when 1) the given path does not lead to an existing snapshottable directory, and/or 2) the snapshot with the old name does not exist for the directory, and/or 3) there exists a snapshot with the new name for the directory

getNumSnapshottableDirs

public int getNumSnapshottableDirs()

Specified by:

getNumSnapshottableDirs in interface SnapshotStats

Returns:

The number of snapshottale directories in the system

getNumSnapshots

public int getNumSnapshots()

Specified by:

getNumSnapshots in interface SnapshotStats

Returns:

The number of directories that have been snapshotted

read

public Map<Integer,org.apache.hadoop.hdfs.server.namenode.snapshot.Snapshot> read(DataInput in,
                                                                         FSImageFormat.Loader loader)
                                                                           throws IOException

Read values of snapshotCounter, numSnapshots, and all snapshots from the DataInput

Throws:

IOException

getSnapshottableDirListing

public SnapshottableDirectoryStatus[] getSnapshottableDirListing(String userName)

List all the snapshottable directories that are owned by the current user.

Parameters:

userName - Current user name.

Returns:

Snapshottable directories that are owned by the current user, represented as an array of SnapshottableDirectoryStatus. If userName is null, return all the snapshottable dirs.

diff

public INodeDirectorySnapshottable.SnapshotDiffInfo diff(String path,
                                                String from,
                                                String to)
                                                  throws IOException

Compute the difference between two snapshots of a directory, or between a snapshot of the directory and its current tree.

Throws:

IOException

clearSnapshottableDirs

public void clearSnapshottableDirs()

getMaxSnapshotID

public int getMaxSnapshotID()

Returns the maximum allowable snapshot ID based on the bit width of the snapshot ID.

Returns:

maximum allowable snapshot ID.