org.apache.hadoop.hbase.io.hfile
Interface HFileDataBlockEncoder

All Known Implementing Classes:

HFileDataBlockEncoderImpl, NoOpDataBlockEncoder

@InterfaceAudience.Private
public interface HFileDataBlockEncoder

Controls what kind of data block encoding is used. If data block encoding is not set or the given block is not a data block (encoded or not), methods should just return the unmodified block.

Field Summary

static byte[]

DATA_BLOCK_ENCODING Type of encoding used for data blocks in HFile.

Method Summary

void	beforeWriteToDisk(ByteBuffer in, HFileBlockEncodingContext encodingResult, BlockType blockType) Should be called before an encoded or unencoded data block is written to disk.
DataBlockEncoding	getDataBlockEncoding()
HFileBlockDecodingContext	newDataBlockDecodingContext(HFileContext fileContext) create a encoder specific decoding context for reading.
HFileBlockEncodingContext	newDataBlockEncodingContext(byte[] headerBytes, HFileContext fileContext) Create an encoder specific encoding context object for writing.
void	saveMetadata(HFile.Writer writer) Save metadata in HFile which will be written to disk
boolean	useEncodedScanner() Decides whether we should use a scanner over encoded blocks.

Field Detail

DATA_BLOCK_ENCODING

static final byte[] DATA_BLOCK_ENCODING

Type of encoding used for data blocks in HFile. Stored in file info.

Method Detail

beforeWriteToDisk

void beforeWriteToDisk(ByteBuffer in,
                       HFileBlockEncodingContext encodingResult,
                       BlockType blockType)
                       throws IOException

Should be called before an encoded or unencoded data block is written to disk.

Parameters:

in - KeyValues next to each other

encodingResult - the encoded result

blockType - block type

Throws:

IOException

useEncodedScanner

boolean useEncodedScanner()

Decides whether we should use a scanner over encoded blocks.

Returns:

Whether to use encoded scanner.

saveMetadata

void saveMetadata(HFile.Writer writer)
                  throws IOException

Save metadata in HFile which will be written to disk

Parameters:

writer - writer for a given HFile

Throws:

IOException - on disk problems

getDataBlockEncoding

DataBlockEncoding getDataBlockEncoding()

Returns:

the data block encoding

newDataBlockEncodingContext

HFileBlockEncodingContext newDataBlockEncodingContext(byte[] headerBytes,
                                                      HFileContext fileContext)

Create an encoder specific encoding context object for writing. And the encoding context should also perform compression if compressionAlgorithm is valid.

Parameters:

headerBytes - header bytes

fileContext - HFile meta data

Returns:

a new HFileBlockEncodingContext object

newDataBlockDecodingContext

HFileBlockDecodingContext newDataBlockDecodingContext(HFileContext fileContext)

create a encoder specific decoding context for reading. And the decoding context should also do decompression if compressionAlgorithm is valid.

Parameters:

fileContext - - HFile meta data

Returns:

a new HFileBlockDecodingContext object