org.apache.hadoop.fs

Class BlockLocation

java.lang.Object

org.apache.hadoop.fs.BlockLocation

All Implemented Interfaces:

Serializable

@InterfaceAudience.Public
 @InterfaceStability.Stable
public class BlockLocation
extends Object
implements Serializable

Represents the network location of a block, information about the hosts that contain block replicas, and other block metadata (E.g. the file offset associated with the block, length, whether it is corrupt, etc). For a single BlockLocation, it will have different meanings for replicated and erasure coded files. If the file is 3-replicated, offset and length of a BlockLocation represent the absolute value in the file and the hosts are the 3 datanodes that holding the replicas. Here is an example:

 BlockLocation(offset: 0, length: BLOCK_SIZE,
   hosts: {"host1:9866", "host2:9866, host3:9866"})
 

And if the file is erasure-coded, each BlockLocation represents a logical block groups. Value offset is the offset of a block group in the file and value length is the total length of a block group. Hosts of a BlockLocation are the datanodes that holding all the data blocks and parity blocks of a block group. Suppose we have a RS_3_2 coded file (3 data units and 2 parity units). A BlockLocation example will be like:

 BlockLocation(offset: 0, length: 3 * BLOCK_SIZE, hosts: {"host1:9866",
   "host2:9866","host3:9866","host4:9866","host5:9866"})
 

Please refer to FileSystem.getFileBlockLocations(FileStatus, long, long) or FileContext.getFileBlockLocations(Path, long, long) for more examples.

See Also:

Serialized Form

Constructor Summary

Constructors

Constructor and Description
BlockLocation() Default Constructor
BlockLocation(BlockLocation that) Copy constructor
BlockLocation(String[] names, String[] hosts, long offset, long length) Constructor with host, name, offset and length
BlockLocation(String[] names, String[] hosts, long offset, long length, boolean corrupt) Constructor with host, name, offset, length and corrupt flag
BlockLocation(String[] names, String[] hosts, String[] topologyPaths, long offset, long length) Constructor with host, name, network topology, offset and length
BlockLocation(String[] names, String[] hosts, String[] topologyPaths, long offset, long length, boolean corrupt) Constructor with host, name, network topology, offset, length and corrupt flag
BlockLocation(String[] names, String[] hosts, String[] cachedHosts, String[] topologyPaths, long offset, long length, boolean corrupt)
BlockLocation(String[] names, String[] hosts, String[] cachedHosts, String[] topologyPaths, String[] storageIds, StorageType[] storageTypes, long offset, long length, boolean corrupt)

Method Summary

Modifier and Type	Method and Description
String[]	getCachedHosts() Get the list of hosts (hostname) hosting a cached replica of the block
String[]	getHosts() Get the list of hosts (hostname) hosting this block
long	getLength() Get the length of the block
String[]	getNames() Get the list of names (IP:xferPort) hosting this block
long	getOffset() Get the start offset of file associated with this block
String[]	getStorageIds() Get the storageID of each replica of the block.
StorageType[]	getStorageTypes() Get the storage type of each replica of the block.
String[]	getTopologyPaths() Get the list of network topology paths for each of the hosts.
boolean	isCorrupt() Get the corrupt flag.
boolean	isStriped() Return true if the block is striped (erasure coded).
void	setCachedHosts(String[] cachedHosts) Set the hosts hosting a cached replica of this block
void	setCorrupt(boolean corrupt) Set the corrupt flag.
void	setHosts(String[] hosts) Set the hosts hosting this block
void	setLength(long length) Set the length of block
void	setNames(String[] names) Set the names (host:port) hosting this block
void	setOffset(long offset) Set the start offset of file associated with this block
void	setStorageIds(String[] storageIds)
void	setStorageTypes(StorageType[] storageTypes)
void	setTopologyPaths(String[] topologyPaths) Set the network topology paths of the hosts
String	toString()

Methods inherited from class java.lang.Object

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

Constructor Detail

BlockLocation

public BlockLocation()

Default Constructor

BlockLocation

public BlockLocation(BlockLocation that)

Copy constructor

BlockLocation

public BlockLocation(String[] names,
                     String[] hosts,
                     long offset,
                     long length)

Constructor with host, name, offset and length

BlockLocation

public BlockLocation(String[] names,
                     String[] hosts,
                     long offset,
                     long length,
                     boolean corrupt)

Constructor with host, name, offset, length and corrupt flag

BlockLocation

public BlockLocation(String[] names,
                     String[] hosts,
                     String[] topologyPaths,
                     long offset,
                     long length)

Constructor with host, name, network topology, offset and length

BlockLocation

public BlockLocation(String[] names,
                     String[] hosts,
                     String[] topologyPaths,
                     long offset,
                     long length,
                     boolean corrupt)

Constructor with host, name, network topology, offset, length and corrupt flag

BlockLocation

public BlockLocation(String[] names,
                     String[] hosts,
                     String[] cachedHosts,
                     String[] topologyPaths,
                     long offset,
                     long length,
                     boolean corrupt)

BlockLocation

public BlockLocation(String[] names,
                     String[] hosts,
                     String[] cachedHosts,
                     String[] topologyPaths,
                     String[] storageIds,
                     StorageType[] storageTypes,
                     long offset,
                     long length,
                     boolean corrupt)

Method Detail

getHosts

public String[] getHosts()
                  throws IOException

Get the list of hosts (hostname) hosting this block

Throws:

IOException

getCachedHosts

public String[] getCachedHosts()

Get the list of hosts (hostname) hosting a cached replica of the block

getNames

public String[] getNames()
                  throws IOException

Get the list of names (IP:xferPort) hosting this block

Throws:

IOException

getTopologyPaths

public String[] getTopologyPaths()
                          throws IOException

Get the list of network topology paths for each of the hosts. The last component of the path is the "name" (IP:xferPort).

Throws:

IOException

getStorageIds

public String[] getStorageIds()

Get the storageID of each replica of the block.

getStorageTypes

public StorageType[] getStorageTypes()

Get the storage type of each replica of the block.

getOffset

public long getOffset()

Get the start offset of file associated with this block

getLength

public long getLength()

Get the length of the block

isCorrupt

public boolean isCorrupt()

Get the corrupt flag.

isStriped

public boolean isStriped()

Return true if the block is striped (erasure coded).

setOffset

public void setOffset(long offset)

Set the start offset of file associated with this block

setLength

public void setLength(long length)

Set the length of block

setCorrupt

public void setCorrupt(boolean corrupt)

Set the corrupt flag.

setHosts

public void setHosts(String[] hosts)
              throws IOException

Set the hosts hosting this block

Throws:

IOException

setCachedHosts

public void setCachedHosts(String[] cachedHosts)

Set the hosts hosting a cached replica of this block

setNames

public void setNames(String[] names)
              throws IOException

Set the names (host:port) hosting this block

Throws:

IOException

setTopologyPaths

public void setTopologyPaths(String[] topologyPaths)
                      throws IOException

Set the network topology paths of the hosts

Throws:

IOException

setStorageIds

public void setStorageIds(String[] storageIds)

setStorageTypes

public void setStorageTypes(StorageType[] storageTypes)

toString

public String toString()

Overrides:

toString in class Object