org.apache.hadoop.hdfs.server.namenode

Class FSImageSerialization

java.lang.Object

org.apache.hadoop.hdfs.server.namenode.FSImageSerialization

@InterfaceAudience.Private
@InterfaceStability.Evolving
public class FSImageSerialization
extends Object

Static utility functions for serializing various pieces of data in the correct format for the FSImage file. Some members are currently public for the benefit of the Offline Image Viewer which is located outside of this package. These members should be made package-protected when the OIV is refactored.

Method Summary

Methods

Modifier and Type	Method and Description
static byte[]	readBytes(DataInput in)
static Block[]	readCompactBlockArray(DataInput in, int logVersion)
static byte[]	readLocalName(DataInput in)
static byte[][]	readPathComponents(DataInput in) Reading the path from the image and converting it to byte[][] directly this saves us an array copy and conversions to and from String
static String	readString(DataInput in)
static void	saveINode2Image(INode node, DataOutput out, boolean writeUnderConstruction, SnapshotFSImageFormat.ReferenceMap referenceMap) Save one inode's attributes to the image.
static void	writeBytes(byte[] data, DataOutput out)
static void	writeCompactBlockArray(Block[] blocks, DataOutputStream out) Write an array of blocks as compactly as possible.
static void	writeINodeDirectory(INodeDirectory node, DataOutput out) Serialize a INodeDirectory
static void	writeINodeDirectoryAttributes(INodeDirectoryAttributes a, DataOutput out) Serialize a INodeDirectory
static void	writeINodeFile(INodeFile file, DataOutput out, boolean writeUnderConstruction) Serialize a INodeFile node
static void	writeINodeFileAttributes(INodeFileAttributes file, DataOutput out) Serialize an INodeFileAttributes.
static void	writeString(String str, DataOutput out)

Methods inherited from class java.lang.Object

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

Method Detail

writeINodeFile

public static void writeINodeFile(INodeFile file,
                  DataOutput out,
                  boolean writeUnderConstruction)
                           throws IOException

Serialize a INodeFile node

Parameters:

node - The node to write

out - The DataOutputStream where the fields are written

writeBlock - Whether to write block information

Throws:

IOException

writeINodeFileAttributes

public static void writeINodeFileAttributes(INodeFileAttributes file,
                            DataOutput out)
                                     throws IOException

Serialize an INodeFileAttributes.

Throws:

IOException

writeINodeDirectory

public static void writeINodeDirectory(INodeDirectory node,
                       DataOutput out)
                                throws IOException

Serialize a INodeDirectory

Parameters:

node - The node to write

out - The DataOutput where the fields are written

Throws:

IOException

writeINodeDirectoryAttributes

public static void writeINodeDirectoryAttributes(INodeDirectoryAttributes a,
                                 DataOutput out)
                                          throws IOException

Serialize a INodeDirectory

Parameters:

a - The node to write

out - The DataOutput where the fields are written

Throws:

IOException

saveINode2Image

public static void saveINode2Image(INode node,
                   DataOutput out,
                   boolean writeUnderConstruction,
                   SnapshotFSImageFormat.ReferenceMap referenceMap)
                            throws IOException

Save one inode's attributes to the image.

Throws:

IOException

readString

public static String readString(DataInput in)
                         throws IOException

Throws:

IOException

writeString

public static void writeString(String str,
               DataOutput out)
                        throws IOException

Throws:

IOException

readBytes

public static byte[] readBytes(DataInput in)
                        throws IOException

Throws:

IOException

readPathComponents

public static byte[][] readPathComponents(DataInput in)
                                   throws IOException

Reading the path from the image and converting it to byte[][] directly this saves us an array copy and conversions to and from String

Parameters:

in -

Returns:

the array each element of which is a byte[] representation of a path component

Throws:

IOException

readLocalName

public static byte[] readLocalName(DataInput in)
                            throws IOException

Throws:

IOException

writeBytes

public static void writeBytes(byte[] data,
              DataOutput out)
                       throws IOException

Throws:

IOException

writeCompactBlockArray

public static void writeCompactBlockArray(Block[] blocks,
                          DataOutputStream out)
                                   throws IOException

Write an array of blocks as compactly as possible. This uses delta-encoding for the generation stamp and size, following the principle that genstamp increases relatively slowly, and size is equal for all but the last block of a file.

Throws:

IOException

readCompactBlockArray

public static Block[] readCompactBlockArray(DataInput in,
                            int logVersion)
                                     throws IOException

Throws:

IOException