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

Class FsVolumeSpi.ScanInfo

java.lang.Object

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

All Implemented Interfaces:

Comparable<FsVolumeSpi.ScanInfo>

Enclosing interface:

FsVolumeSpi

public static class FsVolumeSpi.ScanInfo
extends Object
implements Comparable<FsVolumeSpi.ScanInfo>

Tracks the files and other information related to a block on the disk Missing file is indicated by setting the corresponding member to null. Because millions of these structures may be created, we try to save memory here. So instead of storing full paths, we store path suffixes. The block file, if it exists, will have a path like this: / So we don't need to store the volume path, since we already know what the volume is. The metadata file, if it exists, will have a path like this: /_.meta So if we have a block file, there isn't any need to store the block path again. The accessor functions take care of these manipulations.

Constructor Summary

Constructors

Constructor and Description
ScanInfo(long blockId, File blockFile, File metaFile, FsVolumeSpi vol) Create a ScanInfo object for a block.
ScanInfo(long blockId, FsVolumeSpi vol, FileRegion fileRegion, long length) Create a ScanInfo object for a block.

Method Summary

Modifier and Type	Method and Description
int	compareTo(FsVolumeSpi.ScanInfo b)
boolean	equals(Object o)
File	getBlockFile() Returns the block data file.
long	getBlockId() Returns the block ID.
long	getBlockLength() Return the length of the data block.
FileRegion	getFileRegion()
long	getGenStamp()
File	getMetaFile() Returns the block meta data file or null if there isn't one.
FsVolumeSpi	getVolume() Returns the volume that contains the block that this object describes.
int	hashCode()

Methods inherited from class java.lang.Object

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

Constructor Detail

ScanInfo

public ScanInfo(long blockId,
                File blockFile,
                File metaFile,
                FsVolumeSpi vol)

Create a ScanInfo object for a block. This constructor will examine the block data and meta-data files.

Parameters:

blockId - the block ID

blockFile - the path to the block data file

metaFile - the path to the block meta-data file

vol - the volume that contains the block

ScanInfo

public ScanInfo(long blockId,
                FsVolumeSpi vol,
                FileRegion fileRegion,
                long length)

Create a ScanInfo object for a block. This constructor will examine the block data and meta-data files.

Parameters:

blockId - the block ID

vol - the volume that contains the block

fileRegion - the file region (for provided blocks)

length - the length of the block data

Method Detail

getBlockFile

public File getBlockFile()

Returns the block data file.

Returns:

the block data file

getBlockLength

public long getBlockLength()

Return the length of the data block. The length returned is the length cached when this object was created.

Returns:

the length of the data block

getMetaFile

public File getMetaFile()

Returns the block meta data file or null if there isn't one.

Returns:

the block meta data file

getBlockId

public long getBlockId()

Returns the block ID.

Returns:

the block ID

getVolume

public FsVolumeSpi getVolume()

Returns the volume that contains the block that this object describes.

Returns:

the volume

compareTo

public int compareTo(FsVolumeSpi.ScanInfo b)

Specified by:

compareTo in interface Comparable<FsVolumeSpi.ScanInfo>

equals

public boolean equals(Object o)

Overrides:

equals in class Object

hashCode

public int hashCode()

Overrides:

hashCode in class Object

getGenStamp

public long getGenStamp()

getFileRegion

public FileRegion getFileRegion()