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

#include <BlockCompressionCodecZlib.h>

Inheritance diagram for Hypertable::BlockCompressionCodecZlib:

Collaboration diagram for Hypertable::BlockCompressionCodecZlib:

Public Member Functions
	BlockCompressionCodecZlib (const Args &args)

virtual	~BlockCompressionCodecZlib ()

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

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

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

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

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

Private Attributes
z_stream	m_stream_inflate
	Inflate state. More...

bool	m_inflate_initialized
	Flag indicating that inflate state has been initialized. More...

z_stream	m_stream_deflate
	Deflate state. More...

bool	m_deflate_initialized
	Flag indicating that deflate state has been initialized. More...

int	m_level
	Compression level. 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 ZLIB algorithm.

This class provides a way to compress and decompress blocks of data using the libz compression algorithm, a general purpose, dictionary-based compression algorithm that provides a good compression ratio at the expense of speed.

Definition at line 46 of file BlockCompressionCodecZlib.h.

Constructor & Destructor Documentation

BlockCompressionCodecZlib::BlockCompressionCodecZlib ( const Args & args )

Definition at line 33 of file BlockCompressionCodecZlib.cc.

BlockCompressionCodecZlib::~BlockCompressionCodecZlib ( )

virtual

Definition at line 40 of file BlockCompressionCodecZlib.cc.

Member Function Documentation

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

virtual

Compresses a buffer using the ZLIB algorithm.

This method first checks m_deflate_initialized. If is false it initializes m_stream_deflate and sets m_deflate_initialized to true. It then 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

input	Input buffer
output	Output buffer
header	Block header populated by function
reserve	Additional space to reserve at end of `output` buffer

Implements Hypertable::BlockCompressionCodec.

Definition at line 73 of file BlockCompressionCodecZlib.cc.

virtual int Hypertable::BlockCompressionCodecZlib::get_type ( )

inlinevirtual

Returns enum value representing compression type ZLIB.

Returns the enum value ZLIB

See also: BlockCompressionCodec::ZLIB

Returns: Compression type (ZLIB)

Implements Hypertable::BlockCompressionCodec.

Definition at line 111 of file BlockCompressionCodecZlib.h.

void BlockCompressionCodecZlib::inflate	(	const DynamicBuffer &	input,
		DynamicBuffer &	output,
		BlockHeader &	header
	)

virtual

Decompresses a buffer compressed with the ZLIB algorithm.

This method first checks m_inflate_initialized. If is false it initializes m_stream_inflate and sets m_inflate_initialized to true. It then decompresses the input buffer and fills in header.