Compression Struct Reference

Compression algorithm. More...

#include <file.h>

Classes
struct	meta_t
	Compressed page meta-data. More...

Public Types
enum	Type : uint8_t { NONE = 0 , ZLIB = 1 , LZ4 = 2 }
	Algorithm types supported. More...

Public Member Functions
	Compression ()
	Default constructor. More...
	Compression (Type type)
	Specific constructor. More...
std::string	to_string () const

Static Public Member Functions
static bool	is_compressed_page (const byte *page)
	Check the page header type field. More...
static bool	is_compressed_encrypted_page (const byte *page)
	Check the page header type field. More...
static bool	is_valid_page_version (uint8_t version)
	Check if the version on page is valid. More...
static dberr_t	check (const char *algorithm, Compression *compression)
	Check whether the compression algorithm is supported. More...
static dberr_t	validate (const char *algorithm)
	Validate the algorithm string. More...
static bool	validate (const Type type)
	Validate the algorithm string. More...
static const char *	to_string (Type type)
	Convert to a "string". More...
static std::string	to_string (const meta_t &meta)
	Convert the meta data to a std::string. More...
static void	deserialize_header (const byte *page, meta_t *control)
	Deserizlise the page header compression meta-data. More...
static bool	is_none (const char *algorithm)
	Check if the string is "empty" or "none". More...
static dberr_t	deserialize (bool dblwr_read, byte *src, byte *dst, ulint dst_len)
	Decompress the page data contents. More...

Public Attributes
Type	m_type
	Compression type. More...

Static Public Attributes
static constexpr uint8_t	FIL_PAGE_VERSION_1 = 1
	Version of compressed page. More...
static constexpr uint8_t	FIL_PAGE_VERSION_2 = 2

Detailed Description

Compression algorithm.

Member Enumeration Documentation

Type

enum Compression::Type : uint8_t

Algorithm types supported.

Enumerator
NONE	No compression.
ZLIB	Use ZLib.
LZ4	Use LZ4 faster variant, usually lower compression.

Constructor & Destructor Documentation

Compression() [1/2]

Compression::Compression ( )

inline

Default constructor.

Compression() [2/2]

Compression::Compression ( Type  type )

inlineexplicit

Specific constructor.

Parameters

[in]

type

Algorithm type

Member Function Documentation

check()

dberr_t Compression::check ( const char *  algorithm, Compression *  compression  )

static

Check whether the compression algorithm is supported.

Parameters

[in]	algorithm	Compression algorithm to check
[out]	compression	The type that algorithm maps to

Returns

DB_SUCCESS or error code

deserialize()

dberr_t Compression::deserialize ( bool  dblwr_read, byte *  src, byte *  dst, ulint  dst_len  )

static

Decompress the page data contents.

Page type must be FIL_PAGE_COMPRESSED, if not then the source contents are left unchanged and DB_SUCCESS is returned.

Parameters

[in]	dblwr_read	true if double write recovery in progress
[in,out]	src	Data read from disk, decompressed data will be copied to this page
[in,out]	dst	Scratch area to use for decompression or nullptr.
[in]	dst_len	If dst is valid, size of the scratch area in bytes.

Returns

DB_SUCCESS or error code

deserialize_header()

void Compression::deserialize_header ( const byte *  page, Compression::meta_t *  control  )

static

Deserizlise the page header compression meta-data.

Parameters

[in]	page	Pointer to the page header
[out]	control	Deserialised data

is_compressed_encrypted_page()

bool Compression::is_compressed_encrypted_page ( const byte *  page )

static

Check the page header type field.

Parameters

[in]

page

Page contents

Returns

true if it is a compressed and encrypted page

is_compressed_page()

bool Compression::is_compressed_page ( const byte *  page )

static

Check the page header type field.

Parameters

[in]

page

Page contents

Returns

true if it is a compressed page

true if it is a compressed page

is_none()

bool Compression::is_none ( const char *  algorithm )

static

Check if the string is "empty" or "none".

Parameters

[in]

algorithm

Compression algorithm to check

Returns

true if no algorithm requested

is_valid_page_version()

bool Compression::is_valid_page_version ( uint8_t  version )

static

Check if the version on page is valid.

Parameters

[in]

version

version

Returns

true if version is valid

to_string() [1/3]

std::string Compression::to_string ( ) const

inline

Returns

string representation.

to_string() [2/3]

std::string Compression::to_string ( const meta_t &  meta )

static

Convert the meta data to a std::string.

Parameters

[in]

meta

Page Meta data

Returns

the string representation

to_string() [3/3]

const char * Compression::to_string ( Type  type )

static

Convert to a "string".

Parameters

[in]

type

The compression type

Returns

the string representation

validate() [1/2]

dberr_t Compression::validate ( const char *  algorithm )

static

Validate the algorithm string.

Parameters

[in]

algorithm

Compression algorithm to check

Returns

DB_SUCCESS or error code

validate() [2/2]

bool Compression::validate ( const Type  type )

static

Validate the algorithm string.

Parameters

[in]

type

compression type

Returns

true if type is valid, else false

Member Data Documentation

FIL_PAGE_VERSION_1

constexpr uint8_t Compression::FIL_PAGE_VERSION_1 = 1

staticconstexpr

Version of compressed page.

FIL_PAGE_VERSION_2

constexpr uint8_t Compression::FIL_PAGE_VERSION_2 = 2

staticconstexpr

m_type

Type Compression::m_type

Compression type.

---

The documentation for this struct was generated from the following files:

• storage/innobase/os/file.h
• storage/innobase/handler/ha_innodb.cc
• storage/innobase/os/file.cc