binary_log::transaction::compression::Decompressor Class Reference

Abstract base class for decompressors. More...

#include <decompressor.h>

Inheritance diagram for binary_log::transaction::compression::Decompressor:

Public Types
using	Char_t = unsigned char
using	Size_t = mysqlns::buffer::Buffer_view< Char_t >::Size_t
using	Managed_buffer_t = mysqlns::buffer::Managed_buffer< Char_t >
using	Grow_constraint_t = mysqlns::buffer::Grow_constraint

Public Member Functions
	Decompressor ()=default
	Decompressor (const Decompressor &)=delete
	Decompressor (const Decompressor &&)=delete
const Decompressor &	operator= (const Decompressor &)=delete
const Decompressor &	operator= (const Decompressor &&)=delete
virtual	~Decompressor ()=default
type	get_type_code () const
void	reset ()
	Reset the frame. More...
template<class Input_char_t >
void	feed (const Input_char_t *input_data, Size_t input_size)
	Submit data to decompress. More...
Decompress_status	decompress (Managed_buffer_t &out, Size_t output_size)
	Decompress an exact, given number of bytes. More...
std::pair< Decompress_status, Size_t >	decompress (Char_t *out, Size_t output_size)
	Decompress an exact, given number of bytes. More...
Grow_constraint_t	get_grow_constraint_hint () const
	Return a Grow_constraint that may be used with the Managed_buffer storing the output, in order to optimize memory usage for a particular compression algorithm. More...

Private Types
using	Grow_status_t = mysqlns::buffer::Grow_status

Private Member Functions
virtual type	do_get_type_code () const =0
	Implement get_type_code. More...
virtual void	do_reset ()=0
	Implement do_reset. More...
void	feed_char_t (const Char_t *input_data, Size_t input_size)
virtual void	do_feed (const Char_t *input_data, Size_t input_size)=0
	Implement feed. More...
virtual std::pair< Decompress_status, Size_t >	do_decompress (Char_t *out, Size_t output_size)=0
	Implement decompress. More...
virtual Grow_constraint_t	do_get_grow_constraint_hint () const
	Implement get_grow_constraint_hint. More...

Detailed Description

Abstract base class for decompressors.

Each subclass normally corresponds to a compression algorithm, and maintains the algorithm-specific state for it.

An instance of this class can be reused to decompress several different frames. Each frame input may be split into multiple pieces.

See also

Compressor.

To decompress one or more frames in one piece, use this API as follows:

1. Call feed to provide all input
2. Repeatedly call decompress, each time producing as much output as you need.

To decompress one or more frames in multiple pieces, use this API as follows:

1. Repeatedly call decompress, each time producing as much output as you need. Whenever it returns eof or truncated, call feed to provide more input, and try again.

This class uses a buffer::Managed_buffer to store output.

Member Typedef Documentation

Char_t

using binary_log::transaction::compression::Decompressor::Char_t = unsigned char

Grow_constraint_t

using binary_log::transaction::compression::Decompressor::Grow_constraint_t = mysqlns::buffer::Grow_constraint

Grow_status_t

using binary_log::transaction::compression::Decompressor::Grow_status_t = mysqlns::buffer::Grow_status

private

Managed_buffer_t

using binary_log::transaction::compression::Decompressor::Managed_buffer_t = mysqlns::buffer::Managed_buffer<Char_t>

Size_t

using binary_log::transaction::compression::Decompressor::Size_t = mysqlns::buffer::Buffer_view<Char_t>::Size_t

Constructor & Destructor Documentation

Decompressor() [1/3]

binary_log::transaction::compression::Decompressor::Decompressor ( )

default

Decompressor() [2/3]

binary_log::transaction::compression::Decompressor::Decompressor ( const Decompressor &  )

delete

Decompressor() [3/3]

binary_log::transaction::compression::Decompressor::Decompressor ( const Decompressor &&  )

delete

~Decompressor()

virtual binary_log::transaction::compression::Decompressor::~Decompressor ( )

virtualdefault

Member Function Documentation

decompress() [1/2]

std::pair< Decompress_status, Decompressor::Size_t > binary_log::transaction::compression::Decompressor::decompress	(	Char_t *	out,
		Size_t	output_size
	)

Decompress an exact, given number of bytes.

Parameters

out	The output buffer.
output_size	The number of bytes to decompress.

Returns

a pair where the first component is a Decompress_status value and the second component is the number of bytes that were successfully stored in out. The Decompress_status has the same possible values as for decompress(Managed_buffer_t, output_size), except it cannot take the value exceeds_max_capacity. The size will be equal to output_size if the status is success; strictly between 0 and output_size if the status is truncated; and 0 for the other cases.

decompress() [2/2]

Decompress_status binary_log::transaction::compression::Decompressor::decompress	(	Managed_buffer_t &	out,
		Size_t	output_size
	)

Decompress an exact, given number of bytes.

Parameters

out	The output buffer. This function first grows the write part of out to at least output_size bytes, then decompresses into the write part, and then moves the decompressed bytes from the beginning of the write part to the end of the read part.
output_size	Number of bytes to decompress.

Return values

success	Decompression succeeded. The requested bytes are available in out.
eof	There were no more bytes to decompress. The out buffer has not been changed and the frame has not been reset.
truncated	All input was consumed, but produced less output than requested. The out buffer has been changed and the frame has not been reset. The caller may resume decompression after calling feed.
corrupted	The compression library detected that the data was corrupted. The frame has been reset.
out_of_memory	The operation failed due to an out of memory error. The frame has been reset.
exceeds_max_capacity	The requested size exceeds the maximium capacity configured for the Managed_buffer. The out buffer has not been changed and the frame has not been reset. The caller may resume decompression after increasing the capacity, or resetting the buffer (perhaps after moving the data elsewhere), or using a different output buffer, or similar.

do_decompress()

virtual std::pair< Decompress_status, Size_t > binary_log::transaction::compression::Decompressor::do_decompress ( Char_t *  out, Size_t  output_size  )

privatepure virtual

Implement decompress.

This differs from decompress in that it does not have to reset the frame when returning out_of_memory or corrupted; the caller does that.

Implemented in binary_log::transaction::compression::None_dec, and binary_log::transaction::compression::Zstd_dec.

do_feed()

virtual void binary_log::transaction::compression::Decompressor::do_feed ( const Char_t *  input_data, Size_t  input_size  )

privatepure virtual

Implement feed.

Implemented in binary_log::transaction::compression::None_dec, and binary_log::transaction::compression::Zstd_dec.

do_get_grow_constraint_hint()

Decompressor::Grow_constraint_t binary_log::transaction::compression::Decompressor::do_get_grow_constraint_hint ( ) const

privatevirtual

Implement get_grow_constraint_hint.

In this base class, the function returns a default-constructed Grow_constraint, i.e., one which does not limit the Grow_calculator.

Reimplemented in binary_log::transaction::compression::Zstd_dec.

do_get_type_code()

virtual type binary_log::transaction::compression::Decompressor::do_get_type_code ( ) const

privatepure virtual

Implement get_type_code.

Implemented in binary_log::transaction::compression::None_dec, and binary_log::transaction::compression::Zstd_dec.

do_reset()

virtual void binary_log::transaction::compression::Decompressor::do_reset ( )

privatepure virtual

Implement do_reset.

Implemented in binary_log::transaction::compression::None_dec, and binary_log::transaction::compression::Zstd_dec.

feed()

template<class Input_char_t >

void binary_log::transaction::compression::Decompressor::feed ( const Input_char_t *  input_data, Size_t  input_size  )

inline

Submit data to decompress.

Parameters

input_data	The buffer of input data that this decompressor will read.
input_size	The size of the input buffer.

feed_char_t()

void binary_log::transaction::compression::Decompressor::feed_char_t ( const Char_t *  input_data, Size_t  input_size  )

private

get_grow_constraint_hint()

Decompressor::Grow_constraint_t binary_log::transaction::compression::Decompressor::get_grow_constraint_hint

(

)

const

Return a Grow_constraint that may be used with the Managed_buffer storing the output, in order to optimize memory usage for a particular compression algorithm.

get_type_code()

type binary_log::transaction::compression::Decompressor::get_type_code

(

)

const

Returns

the compression type.

operator=() [1/2]

const Decompressor & binary_log::transaction::compression::Decompressor::operator= ( const Decompressor &&  )

delete

operator=() [2/2]

const Decompressor & binary_log::transaction::compression::Decompressor::operator= ( const Decompressor &  )

delete

reset()

void binary_log::transaction::compression::Decompressor::reset

(

)

Reset the frame.

This cancels the current frame and starts a new one.

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

• libbinlogevents/include/compression/decompressor.h
• libbinlogevents/src/compression/decompressor.cpp