Block compressor that uses the LZO algorithm. More...

#include <BlockCompressionCodecLzo.h>

Inheritance diagram for Hypertable::BlockCompressionCodecLzo:

Collaboration diagram for Hypertable::BlockCompressionCodecLzo:

Public Member Functions
	BlockCompressionCodecLzo (const Args &args)
	Constructor. More...

virtual	~BlockCompressionCodecLzo ()
	Destructor. More...

virtual void	deflate (const DynamicBuffer &input, DynamicBuffer &output, BlockHeader &header, size_t reserve=0)
	Compresses a buffer using the LZO algorithm. More...

virtual void	inflate (const DynamicBuffer &input, DynamicBuffer &output, BlockHeader &header)
	Decompresses a buffer compressed with the LZO algorithm. More...

virtual int	get_type ()
	Returns enum value representing compression type LZO. More...

Public Member Functions inherited from Hypertable::BlockCompressionCodec
virtual	~BlockCompressionCodec ()
	Destructor. More...

virtual void	set_args (const Args &args)
	Sets arguments to control compression behavior. More...

Private Attributes
std::unique_ptr< uint8_t[]>	m_workmem
	Working memory buffer used by deflate() and inflate() More...

Additional Inherited Members
Public Types inherited from Hypertable::BlockCompressionCodec
enum	Type { UNKNOWN =-1, NONE =0, BMZ =1, ZLIB =2, LZO =3, QUICKLZ =4, SNAPPY =5, COMPRESSION_TYPE_LIMIT =6 }
	Enumeration for compression type. More...

typedef std::vector< String >	Args
	Compression codec argument vector. More...

Static Public Member Functions inherited from Hypertable::BlockCompressionCodec
static const char *	get_compressor_name (uint16_t algo)
	Returns string mnemonic for compression type. More...

Detailed Description

Block compressor that uses the LZO algorithm.

This class provides a way to compress and decompress blocks of data using the Lempel–Ziv–Oberhumer (lzo) algorithm, a general purpose, dictionary-based compression algorithm that focuses on decompression speed.

Definition at line 44 of file BlockCompressionCodecLzo.h.

Constructor & Destructor Documentation

BlockCompressionCodecLzo::BlockCompressionCodecLzo ( const Args & args )

Constructor.

Calls lzo_init(), allocates and initializes m_workmem, and passes args to the default implementation of set_args() since it does not support any arguments.

Parameters

args	Arguments to control compression behavior (unused)

Exceptions

Exception Code set to Error::BLOCK_COMPRESSOR_INVALID_ARG

Definition at line 45 of file BlockCompressionCodecLzo.cc.

BlockCompressionCodecLzo::~BlockCompressionCodecLzo ( )

virtual

Destructor.

Definition at line 55 of file BlockCompressionCodecLzo.cc.

Member Function Documentation

void BlockCompressionCodecLzo::deflate	(	const DynamicBuffer &	input,
		DynamicBuffer &	output,
		BlockHeader &	header,
		size_t	reserve = `0`
	)

virtual

Compresses a buffer using the LZO algorithm.

This method reserves enough space in output to hold the serialized header followed by the compressed input followed by reserve bytes. If the resulting compressed buffer is larger than the input buffer, then the input buffer is copied directly to the output buffer and the compression type is set to BlockCompressionCodec::NONE. Before serailizing header, the data_length, data_zlength, data_checksum, and compression_type fields are set appropriately. The output buffer is formatted as follows:

header

compressed data

reserve

Parameters