Basic_binlog_ifile Class Reference

Base class of binlog input files. More...

#include <binlog_istream.h>

Inheritance diagram for Basic_binlog_ifile:

Public Member Functions
	Basic_binlog_ifile (Binlog_read_error *binlog_read_error)
	Basic_binlog_ifile (const Basic_binlog_ifile &)=delete
Basic_binlog_ifile &	operator= (const Basic_binlog_ifile &)=delete
	~Basic_binlog_ifile () override
bool	open (const char *file_name)
	Open a binlog file. More...
void	close ()
	Close the binlog file it is reading. More...
ssize_t	read (unsigned char *buffer, size_t length) override
	Read some bytes from the input stream. More...
bool	seek (my_off_t position) override
	Puts the read position to a given offset. More...
my_off_t	position () const
bool	is_open () const
const std::string &	file_name () const
my_off_t	length () override
	Get length of the binlog file. More...
Public Member Functions inherited from Basic_seekable_istream
	~Basic_seekable_istream () override=default
Public Member Functions inherited from Basic_istream
virtual	~Basic_istream ()=default

Protected Member Functions
virtual std::unique_ptr< Basic_seekable_istream >	open_file (const char *file_name)=0
	Open the system layer file. More...

Protected Attributes
Binlog_read_error *	m_error
	It is convenient for caller to share a Binlog_read_error object between streams. More...

Private Member Functions
bool	read_binlog_magic ()
	Read binlog magic from binlog file and check if it is valid binlog magic. More...

Private Attributes
my_off_t	m_position = 0
	The binlog's position where it is reading. More...
std::unique_ptr< Basic_seekable_istream >	m_istream
	It is the entry of the low level stream pipeline. More...
std::string	m_file_name
	Name of the file opened. More...

Detailed Description

Base class of binlog input files.

It is a logical binlog file which wraps and hides the detail of lower layer storage implementation. Binlog reader and other binlog code just uses this class to control real storage.

Constructor & Destructor Documentation

Basic_binlog_ifile() [1/2]

Basic_binlog_ifile::Basic_binlog_ifile

(

Binlog_read_error *

binlog_read_error

)

Parameters

[in]

binlog_read_error

Basic_binlog_ifile doesn't own an Binlog_read_error. So the caller should provide one to it. When error happens, the error type will be set into 'error'.

Basic_binlog_ifile() [2/2]

Basic_binlog_ifile::Basic_binlog_ifile ( const Basic_binlog_ifile &  )

delete

~Basic_binlog_ifile()

Basic_binlog_ifile::~Basic_binlog_ifile ( )

override

Member Function Documentation

close()

void Basic_binlog_ifile::close

(

)

Close the binlog file it is reading.

file_name()

const std::string & Basic_binlog_ifile::file_name ( ) const

inline

is_open()

bool Basic_binlog_ifile::is_open ( ) const

inline

length()

my_off_t Basic_binlog_ifile::length ( )

overridevirtual

Get length of the binlog file.

It is not os file length. The content maybe encrypted or compressed. It is the total length of BINLOG_MAGIC and all raw binlog events.

Implements Basic_seekable_istream.

open()

bool Basic_binlog_ifile::open

(

const char *

file_name

)

Open a binlog file.

Parameters

[in]

file_name

name of the binlog file which will be opened.

open_file()

virtual std::unique_ptr< Basic_seekable_istream > Basic_binlog_ifile::open_file ( const char *  file_name )

protectedpure virtual

Open the system layer file.

It is the entry of the stream pipeline. Implementation is delegated to sub-classes. Sub-classes opens system layer files in different way.

Parameters

[in]

file_name

name of the binlog file which will be opened.

Implemented in Binlog_ifile, and Relaylog_ifile.

operator=()

Basic_binlog_ifile & Basic_binlog_ifile::operator= ( const Basic_binlog_ifile &  )

delete

position()

my_off_t Basic_binlog_ifile::position ( ) const

inline

read()

ssize_t Basic_binlog_ifile::read ( unsigned char *  buffer, size_t  length  )

overridevirtual

Read some bytes from the input stream.

It should read exact 'length' bytes unless error happens or it reaches the end of the stream. It should block when reaching the end of a pipe that is not closed.

Parameters

[out]	buffer	Where data will be put in.
[in]	length	The number of bytes that you want to read. length should not be larger than max long.

Returns

Return values fall into three cases:

Return values

'length'	Read 'length' bytes successfully
>=0	Reach EOF, return the number of bytes actually read. It is between 0 and length-1.
-1	Error.

Implements Basic_istream.

read_binlog_magic()

bool Basic_binlog_ifile::read_binlog_magic ( )

private

Read binlog magic from binlog file and check if it is valid binlog magic.

This function also takes care of setting up any other stream layer (i.e. encryption) when needed.

Return values

false	The high level stream layer was recognized as a binary log.
true	Failure identifying the high level stream layer.

seek()

bool Basic_binlog_ifile::seek ( my_off_t  offset )

overridevirtual

Puts the read position to a given offset.

The offset counts from the beginning of the stream. In case an implementing class transforms the data in a way that does not preserve positions, the offset here will be relative to the bytes that are read out from the stream, not relative to the bytes in lower layer storage.

it is allowed for a subclass to return success even if the position is greater than the size of the file. Error may be returned by the next read for this case. Users should call length() if they need to check that the position is within bounds.

Parameters

[in]

offset

Where the read position will be.

Return values

false	Success
true	Error

Implements Basic_seekable_istream.

Member Data Documentation

m_error

Binlog_read_error* Basic_binlog_ifile::m_error

protected

It is convenient for caller to share a Binlog_read_error object between streams.

So Binlog_read_error pointer is defined here. It should be initialized in constructor by caller.

m_file_name

std::string Basic_binlog_ifile::m_file_name

private

Name of the file opened.

m_istream

std::unique_ptr<Basic_seekable_istream> Basic_binlog_ifile::m_istream

private

It is the entry of the low level stream pipeline.

m_position

my_off_t Basic_binlog_ifile::m_position = 0

private

The binlog's position where it is reading.

It is the position in logical binlog file, but not the position of system file.

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

• sql/binlog_istream.h
• sql/binlog_istream.cc