my_compress.cc File Reference

#include "my_compress.h"
#include <assert.h>
#include <sys/types.h>
#include <zconf.h>
#include <zlib.h>
#include <zstd.h>
#include <cstddef>
#include <cstring>
#include <utility>
#include "my_dbug.h"
#include "my_inttypes.h"
#include "my_sys.h"
#include "mysql/service_mysql_alloc.h"
#include "mysys/mysys_priv.h"

Functions
void	mysql_compress_context_init (mysql_compress_context *cmp_ctx, enum enum_compression_algorithm algorithm, unsigned int compression_level)
	Initialize a compress context object to be associated with a NET object. More...
void	mysql_compress_context_deinit (mysql_compress_context *mysql_compress_ctx)
	Deinitialize the compression context allocated. More...
uchar *	zstd_compress_alloc (mysql_zstd_compress_context *comp_ctx, const uchar *packet, size_t *len, size_t *complen)
	Allocate zstd compression contexts if necessary and compress using zstd the buffer. More...
static bool	zstd_uncompress (mysql_zstd_compress_context *comp_ctx, uchar *packet, size_t len, size_t *complen)
	Uncompress a zstd compressed data. More...
static uchar *	zlib_compress_alloc (mysql_zlib_compress_context *comp_ctx, const uchar *packet, size_t *len, size_t *complen)
	Allocate zlib compression contexts if necessary and compress using zlib the buffer. More...
static bool	zlib_uncompress (uchar *packet, size_t len, size_t *complen)
	Uncompress a zlib compressed data. More...
bool	my_compress (mysql_compress_context *comp_ctx, uchar *packet, size_t *len, size_t *complen)
	This replaces the packet with a compressed packet. More...
uchar *	my_compress_alloc (mysql_compress_context *comp_ctx, const uchar *packet, size_t *len, size_t *complen)
bool	my_uncompress (mysql_compress_context *comp_ctx, uchar *packet, size_t len, size_t *complen)
	Uncompress packet. More...
unsigned int	mysql_default_compression_level (enum enum_compression_algorithm algorithm)
	Get default compression level corresponding to a given compression method. More...

Function Documentation

mysql_compress_context_deinit()

void mysql_compress_context_deinit

(

mysql_compress_context *

mysql_compress_ctx

)

Deinitialize the compression context allocated.

Parameters

mysql_compress_ctx

Pointer to Compression context.

mysql_compress_context_init()

void mysql_compress_context_init	(	mysql_compress_context *	cmp_ctx,
		enum enum_compression_algorithm	algorithm,
		unsigned int	compression_level
	)

Initialize a compress context object to be associated with a NET object.

Parameters

cmp_ctx	Pointer to compression context.
algorithm	Compression algorithm.
compression_level	Compression level corresponding to the compression algorithm.

mysql_default_compression_level()

unsigned int mysql_default_compression_level

(

enum enum_compression_algorithm

algorithm

)

Get default compression level corresponding to a given compression method.

Parameters

algorithm

Compression Method. Possible values are zlib or zstd.

Returns

an unsigned int representing default compression level. 6 is the default compression level for zlib and 3 is the default compression level for zstd.

zlib_compress_alloc()

static uchar * zlib_compress_alloc ( mysql_zlib_compress_context *  comp_ctx, const uchar *  packet, size_t *  len, size_t *  complen  )

static

Allocate zlib compression contexts if necessary and compress using zlib the buffer.

Parameters

	comp_ctx	Compression context info relating to zlib.
	packet	Data to compress. This is is replaced with the compressed data.
	len	Length of data to compress at 'packet'
[out]	complen	0 if packet was not compressed

Returns

nullptr if error (len is not changed) else pointer to buffer. size of compressed packet).

zlib_uncompress()

static bool zlib_uncompress ( uchar *  packet, size_t  len, size_t *  complen  )

static

Uncompress a zlib compressed data.

Parameters

	packet	Packet which zstd compressed data.
	len	Length of zstd compressed packet.
[out]	complen	Length of uncompressed packet.

Returns

true on error else false.

zstd_compress_alloc()

uchar * zstd_compress_alloc	(	mysql_zstd_compress_context *	comp_ctx,
		const uchar *	packet,
		size_t *	len,
		size_t *	complen
	)

Allocate zstd compression contexts if necessary and compress using zstd the buffer.

Parameters

comp_ctx	Compression context info relating to zstd.
packet	Data to compress. This is is replaced with the compressed data.
len	Length of data to compress at 'packet'
complen	out: 0 if packet was not compressed

Returns

nullptr if error (len is not changed) else pointer to buffer. size of compressed packet).

zstd_uncompress()

static bool zstd_uncompress ( mysql_zstd_compress_context *  comp_ctx, uchar *  packet, size_t  len, size_t *  complen  )

static

Uncompress a zstd compressed data.

Parameters

	comp_ctx	Pointer to compression context.
	packet	Packet with zstd compressed data.
	len	Length of zstd compressed packet.
[out]	complen	Length of uncompressed packet.

Returns

true on error else false.