Package org.apache.hadoop.hdfs.server.datanode

Class DatanodeUtil

java.lang.Object

org.apache.hadoop.hdfs.server.datanode.DatanodeUtil

@Private
public class DatanodeUtil
extends Object

Provide utility methods for Datanode.

Field Summary

Fields

Modifier and Type	Field	Description
static final String	DISK_ERROR
static final String	UNLINK_BLOCK_SUFFIX

Constructor Summary

Constructors

Constructor	Description
DatanodeUtil()

Method Summary

Modifier and Type	Method	Description
static File	createFileWithExistsCheck(FsVolumeSpi volume, org.apache.hadoop.hdfs.protocol.Block b, File f, FileIoProvider fileIoProvider)	Create a new file.
static boolean	dirNoFilesRecursive(FsVolumeSpi volume, File dir, FileIoProvider fileIoProvider)	Checks whether there are any files anywhere in the directory tree rooted at dir (directories don't count as files). dir must exist
static List<String>	getAllSubDirNameForDataSetLock()
static FileInputStream	getMetaDataInputStream(org.apache.hadoop.hdfs.protocol.ExtendedBlock b, FsDatasetSpi<?> data)
static String	getMetaName(String blockName, long generationStamp)
static File	getUnlinkTmpFile(File f)
static File	idToBlockDir(File root, long blockId)	Get the directory where a finalized block with this ID should be stored.
static String	idToBlockDirSuffix(long blockId)	Take an example.

Methods inherited from class java.lang.Object

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

Field Details

UNLINK_BLOCK_SUFFIX

public static final String UNLINK_BLOCK_SUFFIX

See Also:

• Constant Field Values

DISK_ERROR

public static final String DISK_ERROR

See Also:

• Constant Field Values

Constructor Details

DatanodeUtil

public DatanodeUtil()

Method Details

createFileWithExistsCheck

public static File createFileWithExistsCheck(FsVolumeSpi volume,
 org.apache.hadoop.hdfs.protocol.Block b,
 File f,
 FileIoProvider fileIoProvider)
                                      throws IOException

Create a new file.

Throws:

IOException - if the file already exists or if the file cannot be created.

getMetaName

public static String getMetaName(String blockName,
 long generationStamp)

Returns:

the meta name given the block name and generation stamp.

getUnlinkTmpFile

public static File getUnlinkTmpFile(File f)

Returns:

the unlink file.

dirNoFilesRecursive

public static boolean dirNoFilesRecursive(FsVolumeSpi volume,
 File dir,
 FileIoProvider fileIoProvider)
                                   throws IOException

Checks whether there are any files anywhere in the directory tree rooted at dir (directories don't count as files). dir must exist

Returns:

true if there are no files

Throws:

IOException - if unable to list subdirectories

idToBlockDirSuffix

public static String idToBlockDirSuffix(long blockId)

Take an example. We hava a block with blockid mapping to: "/data1/hadoop/hdfs/datanode/current/BP-xxxx/current/finalized/subdir0/subdir1" We return "subdir0/subdir0".

Parameters:

blockId - the block id.

Returns:

two-level subdir string where block will be stored.

idToBlockDir

public static File idToBlockDir(File root,
 long blockId)

Get the directory where a finalized block with this ID should be stored. Do not attempt to create the directory.

Parameters:

root - the root directory where finalized blocks are stored

blockId -

Returns:

getAllSubDirNameForDataSetLock

public static List<String> getAllSubDirNameForDataSetLock()

getMetaDataInputStream

public static FileInputStream getMetaDataInputStream(org.apache.hadoop.hdfs.protocol.ExtendedBlock b,
 FsDatasetSpi<?> data)
                                              throws IOException

Returns:

the FileInputStream for the meta data of the given block.

Throws:

FileNotFoundException - if the file not found.

ClassCastException - if the underlying input stream is not a FileInputStream.

IOException