org.apache.hadoop.hdfs.protocol

Interface ClientDatanodeProtocol

All Known Implementing Classes:

ClientDatanodeProtocolTranslatorPB, DataNode

@InterfaceAudience.Private
@InterfaceStability.Evolving
public interface ClientDatanodeProtocol

An client-datanode protocol for block recovery

Field Summary

Fields

Modifier and Type	Field and Description
static long	versionID Until version 9, this class ClientDatanodeProtocol served as both the client interface to the DN AND the RPC protocol used to communicate with the NN.

Method Summary

Methods

Modifier and Type	Method and Description
void	deleteBlockPool(String bpid, boolean force) Delete the block pool directory.
BlockLocalPathInfo	getBlockLocalPathInfo(ExtendedBlock block, Token<BlockTokenIdentifier> token) Retrieves the path names of the block file and metadata file stored on the local file system.
HdfsBlocksMetadata	getHdfsBlocksMetadata(List<ExtendedBlock> blocks, List<Token<BlockTokenIdentifier>> tokens) Retrieves volume location information about a list of blocks on a datanode.
long	getReplicaVisibleLength(ExtendedBlock b) Return the visible length of a replica.
void	refreshNamenodes() Refresh the list of federated namenodes from updated configuration Adds new namenodes and stops the deleted namenodes.

Field Detail

versionID

static final long versionID

Until version 9, this class ClientDatanodeProtocol served as both the client interface to the DN AND the RPC protocol used to communicate with the NN. This class is used by both the DFSClient and the DN server side to insulate from the protocol serialization. If you are adding/changing DN's interface then you need to change both this class and ALSO related protocol buffer wire protocol definition in ClientDatanodeProtocol.proto. For more details on protocol buffer wire protocol, please see .../org/apache/hadoop/hdfs/protocolPB/overview.html The log of historical changes can be retrieved from the svn). 9: Added deleteBlockPool method 9 is the last version id when this class was used for protocols serialization. DO not update this version any further.

See Also:

Constant Field Values

Method Detail

getReplicaVisibleLength

long getReplicaVisibleLength(ExtendedBlock b)
                             throws IOException

Return the visible length of a replica.

Throws:

IOException

refreshNamenodes

void refreshNamenodes()
                      throws IOException

Refresh the list of federated namenodes from updated configuration Adds new namenodes and stops the deleted namenodes.

Throws:

IOException - on error

deleteBlockPool

void deleteBlockPool(String bpid,
                   boolean force)
                     throws IOException

Delete the block pool directory. If force is false it is deleted only if it is empty, otherwise it is deleted along with its contents.

Parameters:

bpid - Blockpool id to be deleted.

force - If false blockpool directory is deleted only if it is empty i.e. if it doesn't contain any block files, otherwise it is deleted along with its contents.

Throws:

IOException

getBlockLocalPathInfo

BlockLocalPathInfo getBlockLocalPathInfo(ExtendedBlock block,
                                       Token<BlockTokenIdentifier> token)
                                         throws IOException

Retrieves the path names of the block file and metadata file stored on the local file system. In order for this method to work, one of the following should be satisfied:

• The client user must be configured at the datanode to be able to use this method.
• When security is enabled, kerberos authentication must be used to connect to the datanode.

Parameters:

block - the specified block on the local datanode

token - the block access token.

Returns:

the BlockLocalPathInfo of a block

Throws:

IOException - on error

getHdfsBlocksMetadata

HdfsBlocksMetadata getHdfsBlocksMetadata(List<ExtendedBlock> blocks,
                                       List<Token<BlockTokenIdentifier>> tokens)
                                         throws IOException

Retrieves volume location information about a list of blocks on a datanode. This is in the form of an opaque VolumeId for each configured data directory, which is not guaranteed to be the same across DN restarts.

Parameters:

blocks - list of blocks on the local datanode

tokens - block access tokens corresponding to the requested blocks

Returns:

an HdfsBlocksMetadata that associates ExtendedBlocks with data directories

Throws:

IOException - if datanode is unreachable, or replica is not found on datanode