Gcs_message_data Class Reference

This class serves as data container for information flowing in the GCS ecosystem. More...

#include <gcs_message.h>

Public Member Functions
	Gcs_message_data ()
	Gcs_message_data implementation. More...
	Gcs_message_data (const uint32_t header_capacity, const uint64_t payload_capacity)
	Constructor of Gcs_message_data which pre-allocates space to store the header and payload and should be used when creating messages to send information to remote peers. More...
	Gcs_message_data (const uint64_t data_len)
	Constructor of Gcs_message_data which pre-allocates space to store a message received from a remote peer. More...
virtual	~Gcs_message_data ()
bool	append_to_header (const uchar *to_append, uint32_t to_append_len)
	Appends data to the header of the message. More...
bool	append_to_payload (const uchar *to_append, uint64_t to_append_len)
	Appends data to the payload of the message. More...
void	release_ownership ()
	Release the buffer's ownership which means that this object will not be responsible for deallocating its internal buffer. More...
bool	encode (uchar **buffer, uint64_t *buffer_len) const
	Encodes the header and payload into an internal buffer. More...
bool	encode (uchar *buffer, uint64_t *buffer_len) const
	Encodes the header and payload into a buffer provided by the caller. More...
bool	decode (const uchar *data, uint64_t data_len)
	Decodes data received via GCS and that belongs to a message. More...
const uchar *	get_header () const
uint32_t	get_header_length () const
const uchar *	get_payload () const
uint64_t	get_payload_length () const
virtual uint64_t	get_encode_size () const
uint64_t	get_encode_payload_size () const
uint64_t	get_encode_header_size () const

Private Member Functions
bool	report_allocate_memory (size_t size)
	On memory allocation this function is called, so that memory consumption can be tracked. More...
void	report_deallocate_memory (size_t size)
	On memory free this function is called to reduce count of allocated memory. More...
	Gcs_message_data (Gcs_message_data const &)
Gcs_message_data &	operator= (Gcs_message_data const &)

Private Attributes
uchar *	m_header
uchar *	m_header_slider
uint32_t	m_header_len
uint32_t	m_header_capacity
uchar *	m_payload
uchar *	m_payload_slider
uint64_t	m_payload_len
uint64_t	m_payload_capacity
uchar *	m_buffer
uint64_t	m_buffer_len
bool	m_owner

Detailed Description

This class serves as data container for information flowing in the GCS ecosystem.

It has been isolated in order to be used in place where a full-blown Gcs_message does not make sense.

For a full usage example, check the Gcs_message documentation.

Constructor & Destructor Documentation

Gcs_message_data() [1/4]

Gcs_message_data::Gcs_message_data

(

)

Gcs_message_data implementation.

Gcs_message_data() [2/4]

Gcs_message_data::Gcs_message_data ( const uint32_t  header_capacity, const uint64_t  payload_capacity  )

explicit

Constructor of Gcs_message_data which pre-allocates space to store the header and payload and should be used when creating messages to send information to remote peers.

Parameters

header_capacity	Determines the header's size.
payload_capacity	Determines the payload's size.

Gcs_message_data() [3/4]

Gcs_message_data::Gcs_message_data ( const uint64_t  data_len )

explicit

Constructor of Gcs_message_data which pre-allocates space to store a message received from a remote peer.

Parameters

data_len

Data's length.

~Gcs_message_data()

Gcs_message_data::~Gcs_message_data ( )

virtual

Gcs_message_data() [4/4]

Gcs_message_data::Gcs_message_data ( Gcs_message_data const &  )

private

Member Function Documentation

append_to_header()

bool Gcs_message_data::append_to_header	(	const uchar *	to_append,
		uint32_t	to_append_len
	)

Appends data to the header of the message.

The data MUST have been previously encoded in little endian format.

If the data to be appended exceeds the pre-allocated buffer capacity an error is returned.

Parameters

[in]	to_append	the data to append
[in]	to_append_len	the length of the data to append

Returns

true on error, false otherwise.

append_to_payload()

bool Gcs_message_data::append_to_payload	(	const uchar *	to_append,
		uint64_t	to_append_len
	)

Appends data to the payload of the message.

The data MUST have been previously encoded in little endian format.

If the data to be appended exceeds the pre-allocated buffer capacity an error is returned.

Parameters

[in]	to_append	the data to append
[in]	to_append_len	the length of the data to append

Returns

true on error, false otherwise.

decode()

bool Gcs_message_data::decode	(	const uchar *	data,
		uint64_t	data_len
	)

Decodes data received via GCS and that belongs to a message.

After decoding, all the fields will be filled. The data MUST be in little endian format.

If the buffer is not large enough to store the encoded data or is a NULL pointer, an error is returned.

Parameters

[in]	data	Data received via network
[in]	data_len	Data length received via network

Returns

true on error, false otherwise.

encode() [1/2]

bool Gcs_message_data::encode	(	uchar **	buffer,
		uint64_t *	buffer_len
	)		const

Encodes the header and payload into an internal buffer.

If NULL pointer is provided or the data was not already appended to the buffer, an error is returned.

The meta data is formatted in little endian format, and is structured on the wire as depicted below:

---

| header len | payload len | header | payload |

Parameters

[in,out]	buffer	Variable that will hold a pointer to the buffer
[in,out]	buffer_len	Variable that will hold the buffer's size.

Returns

true on error, false otherwise.

encode() [2/2]

bool Gcs_message_data::encode	(	uchar *	buffer,
		uint64_t *	buffer_len
	)		const

Encodes the header and payload into a buffer provided by the caller.

If the buffer is not large enough to store the encoded data or is a NULL pointer, an error is returned.

Parameters

[in,out]	buffer	Buffer to store the encoded data in the message.
[in,out]	buffer_len	The length of the buffer where the data is to be stored. It contains the length of the data dumped into the buffer once the function succeeds.

Returns

true on error, false otherwise.

get_encode_header_size()

uint64_t Gcs_message_data::get_encode_header_size

(

)

const

Returns

the size of the encoded header when put on the wire.

get_encode_payload_size()

uint64_t Gcs_message_data::get_encode_payload_size

(

)

const

Returns

the size of the encoded payload when put on the wire.

get_encode_size()

uint64_t Gcs_message_data::get_encode_size ( ) const

virtual

Returns

the size of the encoded data when put on the wire.

get_header()

const uchar * Gcs_message_data::get_header

(

)

const

Returns

the message header in little endian format

get_header_length()

uint32_t Gcs_message_data::get_header_length

(

)

const

Returns

the message header length

get_payload()

const uchar * Gcs_message_data::get_payload

(

)

const

Returns

the message payload in little endian format

get_payload_length()

uint64_t Gcs_message_data::get_payload_length

(

)

const

Returns

the message payload_length

operator=()

Gcs_message_data & Gcs_message_data::operator= ( Gcs_message_data const &  )

private

release_ownership()

void Gcs_message_data::release_ownership

(

)

Release the buffer's ownership which means that this object will not be responsible for deallocating its internal buffer.

The caller should do so.

This method should be used along with the following method: encode(**buffer, *buffer_len).

report_allocate_memory()

bool Gcs_message_data::report_allocate_memory ( size_t  size )

private

On memory allocation this function is called, so that memory consumption can be tracked.

Parameters

[in]

size

memory size to be allocated

Returns

true on error, false otherwise.

report_deallocate_memory()

void Gcs_message_data::report_deallocate_memory ( size_t  size )

private

On memory free this function is called to reduce count of allocated memory.

Parameters

[in]

size

memory size to be allocated

Member Data Documentation

m_buffer

uchar* Gcs_message_data::m_buffer

private

m_buffer_len

uint64_t Gcs_message_data::m_buffer_len

private

m_header

uchar* Gcs_message_data::m_header

private

m_header_capacity

uint32_t Gcs_message_data::m_header_capacity

private

m_header_len

uint32_t Gcs_message_data::m_header_len

private

m_header_slider

uchar* Gcs_message_data::m_header_slider

private

m_owner

bool Gcs_message_data::m_owner

private

m_payload

uchar* Gcs_message_data::m_payload

private

m_payload_capacity

uint64_t Gcs_message_data::m_payload_capacity

private

m_payload_len

uint64_t Gcs_message_data::m_payload_len

private

m_payload_slider

uchar* Gcs_message_data::m_payload_slider

private

---

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

• plugin/group_replication/libmysqlgcs/include/mysql/gcs/gcs_message.h
• plugin/group_replication/libmysqlgcs/src/interface/gcs_message.cc