org.apache.hadoop.hdfs.server.datanode.fsdataset

Interface FsVolumeSpi

public interface FsVolumeSpi

This is an interface for the underlying volume.

Nested Class Summary

Nested Classes

Modifier and Type	Interface and Description
static interface	FsVolumeSpi.BlockIterator BlockIterator will return ExtendedBlock entries from a block pool in this volume.

Method Summary

Methods

Modifier and Type	Method and Description
long	getAvailable()
String	getBasePath()
String[]	getBlockPoolList()
org.apache.hadoop.hdfs.server.datanode.fsdataset.FsDatasetSpi	getDataset() Get the FSDatasetSpi which this volume is a part of.
File	getFinalizedDir(String bpid)
String	getPath(String bpid)
String	getStorageID()
org.apache.hadoop.fs.StorageType	getStorageType()
boolean	isTransientStorage() Returns true if the volume is NOT backed by persistent storage.
FsVolumeSpi.BlockIterator	loadBlockIterator(String bpid, String name) Load a saved block iterator.
byte[]	loadLastPartialChunkChecksum(File blockFile, File metaFile) Load last partial chunk checksum from checksum file.
FsVolumeSpi.BlockIterator	newBlockIterator(String bpid, String name) Create a new block iterator.
FsVolumeReference	obtainReference() Obtain a reference object that had increased 1 reference count of the volume.
void	releaseLockedMemory(long bytesToRelease) Release reserved memory for an RBW block written to transient storage i.e.
void	releaseReservedSpace(long bytesToRelease) Release disk space previously reserved for block opened for write.
void	reserveSpaceForReplica(long bytesToReserve) Reserve disk space for a block (RBW or Re-replicating) so a writer does not run out of space before the block is full.

Method Detail

obtainReference

FsVolumeReference obtainReference()
                                  throws ClosedChannelException

Obtain a reference object that had increased 1 reference count of the volume. It is caller's responsibility to close FsVolumeReference to decrease the reference count on the volume.

Throws:

ClosedChannelException

getStorageID

String getStorageID()

Returns:

the StorageUuid of the volume

getBlockPoolList

String[] getBlockPoolList()

Returns:

a list of block pools.

getAvailable

long getAvailable()
                  throws IOException

Returns:

the available storage space in bytes.

Throws:

IOException

getBasePath

String getBasePath()

Returns:

the base path to the volume

getPath

String getPath(String bpid)
               throws IOException

Returns:

the path to the volume

Throws:

IOException

getFinalizedDir

File getFinalizedDir(String bpid)
                     throws IOException

Returns:

the directory for the finalized blocks in the block pool.

Throws:

IOException

getStorageType

org.apache.hadoop.fs.StorageType getStorageType()

isTransientStorage

boolean isTransientStorage()

Returns true if the volume is NOT backed by persistent storage.

reserveSpaceForReplica

void reserveSpaceForReplica(long bytesToReserve)

Reserve disk space for a block (RBW or Re-replicating) so a writer does not run out of space before the block is full.

releaseReservedSpace

void releaseReservedSpace(long bytesToRelease)

Release disk space previously reserved for block opened for write.

releaseLockedMemory

void releaseLockedMemory(long bytesToRelease)

Release reserved memory for an RBW block written to transient storage i.e. RAM. bytesToRelease will be rounded down to the OS page size since locked memory reservation must always be a multiple of the page size.

newBlockIterator

FsVolumeSpi.BlockIterator newBlockIterator(String bpid,
                                         String name)

Create a new block iterator. It will start at the beginning of the block set.

Parameters:

bpid - The block pool id to iterate over.

name - The name of the block iterator to create.

Returns:

The new block iterator.

loadBlockIterator

FsVolumeSpi.BlockIterator loadBlockIterator(String bpid,
                                          String name)
                                            throws IOException

Load a saved block iterator.

Parameters:

bpid - The block pool id to iterate over.

name - The name of the block iterator to load.

Returns:

The saved block iterator.

Throws:

IOException - If there was an IO error loading the saved block iterator.

getDataset

org.apache.hadoop.hdfs.server.datanode.fsdataset.FsDatasetSpi getDataset()

Get the FSDatasetSpi which this volume is a part of.

loadLastPartialChunkChecksum

byte[] loadLastPartialChunkChecksum(File blockFile,
                                  File metaFile)
                                    throws IOException

Load last partial chunk checksum from checksum file. Need to be called with FsDataset lock acquired.

Parameters:

blockFile -

metaFile -

Returns:

the last partial checksum

Throws:

IOException