mysql::binlog::event::Log_event_header Class Reference

The Common-Header always has the same form and length within one version of MySQL. More...

#include <binlog_event.h>

Public Types
typedef unsigned char	Byte
	The following type definition is to be used whenever data is placed and manipulated in a common buffer. More...

Public Member Functions
	Log_event_header (Log_event_type type_code_arg=ENUM_END_EVENT)
	Log_event_header (Event_reader &reader)
	Log_event_header constructor. More...
bool	get_is_valid ()
	The get_is_valid function is related to event specific sanity checks to determine that the object was initialized without errors. More...
void	set_is_valid (bool is_valid)
	Set if the event object shall be considered valid or not. More...
const Event_decoding_error &	get_decoding_error () const
	Accessor for decoding error. More...
void	set_decoding_error (const Event_decoding_error &decoding_error)
	Sets specific decoding error. More...

Public Attributes
struct timeval	when
Log_event_type	type_code
	Event type extracted from the header. More...
unsigned int	unmasked_server_id
size_t	data_written
unsigned long long	log_pos
uint16_t	flags

Private Attributes
bool	m_is_valid
Event_decoding_error	m_decoding_error = Event_decoding_error::ok
	Holds information about specific decoding error. More...

Detailed Description

The Common-Header always has the same form and length within one version of MySQL.

Each event type specifies a format and length of the Post-Header. The length of the Common-Header is the same for all events of the same type.

The binary format of Common-Header is as follows:

Common-Header

Name	Format	Description
when	4 byte unsigned integer, represented by type struct timeval	The time when the query started, in seconds since 1970.
type_code	1 byte enumeration	See enum Log_event_type.
unmasked_server_id	4 byte unsigned integer	Server ID of the server that created the event.
data_written	4 byte unsigned integer	The total size of this event, in bytes. In other words, this is the sum of the sizes of Common-Header, Post-Header, and Body.
log_pos	4 byte unsigned integer	The position of the next event in the master binary log, in bytes from the beginning of the file. In a binlog that is not a relay log, this is just the position of the next event, in bytes from the beginning of the file. In a relay log, this is the position of the next event in the master's binlog.
flags	2 byte bitfield	16 or less flags depending on the version of the binary log.

Summing up the numbers above, we see that the total size of the common header is 19 bytes.

Member Typedef Documentation

Byte

typedef unsigned char mysql::binlog::event::Log_event_header::Byte

The following type definition is to be used whenever data is placed and manipulated in a common buffer.

Use this typedef for buffers that contain data containing binary and character data.

Constructor & Destructor Documentation

Log_event_header() [1/2]

mysql::binlog::event::Log_event_header::Log_event_header ( Log_event_type  type_code_arg = ENUM_END_EVENT )

inlineexplicit

Log_event_header() [2/2]

mysql::binlog::event::Log_event_header::Log_event_header

(

Event_reader &

reader

)

Log_event_header constructor.

Parameters

reader

the Event_reader containing the serialized event (including header, event data and optional checksum information).

The first 19 bytes in the header is as follows:
  +============================================+
  | member_variable               offset : len |
  +============================================+
  | when.tv_sec                        0 : 4   |
  +--------------------------------------------+
  | type_code       EVENT_TYPE_OFFSET(4) : 1   |
  +--------------------------------------------+
  | server_id       SERVER_ID_OFFSET(5)  : 4   |
  +--------------------------------------------+
  | data_written    EVENT_LEN_OFFSET(9)  : 4   |
  +--------------------------------------------+
  | log_pos           LOG_POS_OFFSET(13) : 4   |
  +--------------------------------------------+
  | flags               FLAGS_OFFSET(17) : 2   |
  +--------------------------------------------+
  | extra_headers                     19 : x-19|
  +============================================+

Member Function Documentation

get_decoding_error()

const Event_decoding_error & mysql::binlog::event::Log_event_header::get_decoding_error

(

)

const

Accessor for decoding error.

Returns

Error that occurred during decoding

get_is_valid()

bool mysql::binlog::event::Log_event_header::get_is_valid ( )

inline

The get_is_valid function is related to event specific sanity checks to determine that the object was initialized without errors.

Note that a given event object may be valid at some point (ancestor event type initialization was fine) but be turned invalid in a later stage.

Returns

True if the event object is valid, false otherwise.

set_decoding_error()

void mysql::binlog::event::Log_event_header::set_decoding_error

(

const Event_decoding_error &

decoding_error

)

Sets specific decoding error.

Parameters

decoding_error

Decoding error to be set

set_is_valid()

void mysql::binlog::event::Log_event_header::set_is_valid ( bool  is_valid )

inline

Set if the event object shall be considered valid or not.

Parameters

is_valid

if the event object shall be considered valid.

Member Data Documentation

data_written

size_t mysql::binlog::event::Log_event_header::data_written

flags

uint16_t mysql::binlog::event::Log_event_header::flags

log_pos

unsigned long long mysql::binlog::event::Log_event_header::log_pos

m_decoding_error

Event_decoding_error mysql::binlog::event::Log_event_header::m_decoding_error = Event_decoding_error::ok

private

Holds information about specific decoding error.

m_is_valid

bool mysql::binlog::event::Log_event_header::m_is_valid

private

type_code

Log_event_type mysql::binlog::event::Log_event_header::type_code

Event type extracted from the header.

In the server, it is decoded by read_log_event(), but adding here for complete decoding.

unmasked_server_id

unsigned int mysql::binlog::event::Log_event_header::unmasked_server_id

when

struct timeval mysql::binlog::event::Log_event_header::when

---

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

• libs/mysql/binlog/event/binlog_event.h
• libs/mysql/binlog/event/binlog_event.cpp