Package 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:

java.lang.Comparable<FsVolumeSpi.ScanInfo>

Enclosing interface:

FsVolumeSpi

public static class FsVolumeSpi.ScanInfo
extends java.lang.Object
implements java.lang.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: <volume_base_path>/<block_path> 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: <volume_base_path>/<block_path>_<genstamp>.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	Description
ScanInfo(long blockId, java.io.File basePath, java.lang.String blockFile, java.lang.String 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	Description
int	compareTo(FsVolumeSpi.ScanInfo b)
boolean	equals(java.lang.Object o)
java.io.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()
java.io.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,
                java.io.File basePath,
                java.lang.String blockFile,
                java.lang.String 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

basePath - The full path to the directory the block is stored in

blockFile - The block filename, with no path

metaFile - The meta filename, with no path. If blockFile is not null then the metaFile and blockFile should have the same prefix, with the meta file having a suffix like "_1234.meta". To save memory, if the blockFile is present we store only the meta file suffix in the object

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 java.io.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 java.io.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 java.lang.Comparable<FsVolumeSpi.ScanInfo>

equals

public boolean equals(java.lang.Object o)

Overrides:

equals in class java.lang.Object

hashCode

public int hashCode()

Overrides:

hashCode in class java.lang.Object

getGenStamp

public long getGenStamp()

getFileRegion

public FileRegion getFileRegion()