binlog::Decompressing_event_object_istream Class Reference

Stream class that yields Log_event objects from a source. More...

#include <decompressing_event_object_istream.h>

Public Types
using	Buffer_stream_t = binary_log::transaction::compression::Payload_event_buffer_istream
using	Buffer_view_t = Buffer_stream_t::Buffer_view_t
using	Buffer_ptr_t = Buffer_stream_t::Buffer_ptr_t
using	Event_ptr_t = std::shared_ptr< Log_event >
using	Tple_ptr_t = std::shared_ptr< const Transaction_payload_log_event >
using	Fde_ref_t = const Format_description_event &
using	Status_t = binary_log::transaction::compression::Decompress_status
using	Grow_calculator_t = Buffer_stream_t::Grow_calculator_t

Public Member Functions
	Decompressing_event_object_istream (IBasic_binlog_file_reader &reader)
	Construct stream over a file, decompressing payload events. More...
	Decompressing_event_object_istream (const Tple_ptr_t &transaction_payload_log_event, Fde_ref_t format_description_event)
	Construct stream over a Transaction_payload_log_event. More...
	Decompressing_event_object_istream (const Transaction_payload_log_event &transaction_payload_log_event, Fde_ref_t format_description_event)
	Construct stream over a Transaction_payload_log_event. More...
	~Decompressing_event_object_istream ()
	Decompressing_event_object_istream (Decompressing_event_object_istream &)=delete
	Decompressing_event_object_istream (Decompressing_event_object_istream &&)=delete
Decompressing_event_object_istream &	operator= (Decompressing_event_object_istream &)=delete
Decompressing_event_object_istream &	operator= (Decompressing_event_object_istream &&)=delete
void	set_verify_checksum (bool verify_checksum=true)
	Specify whether checksums shall be verified or not. More...
Decompressing_event_object_istream &	operator>> (Event_ptr_t &out)
	Read an event from the stream. More...
	operator bool () const
	Indicate if EOF or error has not happened. More...
bool	operator! () const
	Indicate if EOF or error has happened. More...
bool	has_error () const
	Return true if an error has happened. More...
std::string	get_error_str () const
	Return a message describing the last error. More...
Status_t	get_status () const
	Return the status. More...
const Grow_calculator_t &	get_grow_calculator () const
	Return const reference to Grow_calculator to the internal event buffer. More...
void	set_grow_calculator (const Grow_calculator_t &grow_calculator)
	Set the Grow_calculator for the internal event buffer. More...

Private Types
enum class	Read_status { success , eof , error }
	Status from read_from_payload_stream. More...

Private Member Functions
raii::Targeted_stringstream	error_stream (Status_t status)
	Report an error. More...
void	begin_payload_event (const Transaction_payload_log_event &tple)
	Prepare to unfold a given Transaction_payload_log_event by setting state variables and creating the Payload_event_buffer_istream object. More...
void	begin_payload_event (const Tple_ptr_t &tple)
	Prepare to unfold a given Transaction_payload_log_event by setting state variables and creating the Payload_event_buffer_istream object. More...
template<class Event_ref_or_ptr >
void	do_begin_payload_event (const Transaction_payload_log_event &tple, const Event_ref_or_ptr &ownership_tple)
	Worker function implementing both forms of begin_payload_event. More...
bool	decode_from_buffer (Buffer_view_t &buffer, Event_ptr_t &out)
	Worker that deserializes an event from the buffer. More...
Read_status	read_from_payload_stream (Event_ptr_t &out)
	Read and decode next event from the Payload_log_event stream. More...
bool	read_from_binlog_stream (Event_ptr_t &out)
	Read and decode the next event from the binlog stream. More...

Private Attributes
IBasic_binlog_file_reader *	m_binlog_reader {nullptr}
	Stream of events to read from. More...
bool	m_verify_checksum {false}
	Whether we should verify checksum. Unused! More...
std::string	m_error_str
	Error from last operation. More...
bool	m_end {false}
	True if we have reached EOF, false otherwise. More...
Status_t	m_status {Status_t::success}
	Status. More...
my_off_t	m_event_position {0}
	Position of last event. More...
bool	m_outstanding_error {false}
	True if a read has failed but neither get_error_str nor has_error has been called. More...
Grow_calculator_t	m_grow_calculator
	Policy for growing buffers in the decompressing stream. More...
std::unique_ptr< Buffer_stream_t >	m_buffer_istream {nullptr}
	The decompression stream; non-null while we are positioned in a TPLE. More...
my_off_t	m_transaction_payload_event_offset {0}
	end_log_pos for the currently processed TPLE, if any More...
int	m_embedded_event_number {0}
	0 when not processing a TPLE; N>0 when positioned before the Nth embedded event of a TPLE. More...
std::function< Fde_ref_t()>	m_get_format_description_event
	Return the current FDE. More...

Detailed Description

Stream class that yields Log_event objects from a source.

The source can be a Transaction_payload_log_event, in which case it will produce the contained events. Or it can be a file, in which case it will yield all events in the file, and if there is a Transaction_payload_log_event, it will yield first that and then all the contained events.

The recommended use pattern is:

while (stream >> event) {
  // handle event
}
if (stream.has_error()) {
  // handle error
}

This class actually enforces that you call has_error after the loop; failure to do so will result in an assertion in debug mode. In the unlikely case that your code doesn't need to check for errors, you can get rid of the assert by calling has_error() and discarding the return value.

Member Typedef Documentation

Buffer_ptr_t

using binlog::Decompressing_event_object_istream::Buffer_ptr_t = Buffer_stream_t::Buffer_ptr_t

Buffer_stream_t

using binlog::Decompressing_event_object_istream::Buffer_stream_t = binary_log::transaction::compression::Payload_event_buffer_istream

Buffer_view_t

using binlog::Decompressing_event_object_istream::Buffer_view_t = Buffer_stream_t::Buffer_view_t

Event_ptr_t

using binlog::Decompressing_event_object_istream::Event_ptr_t = std::shared_ptr<Log_event>

Fde_ref_t

using binlog::Decompressing_event_object_istream::Fde_ref_t = const Format_description_event &

Grow_calculator_t

using binlog::Decompressing_event_object_istream::Grow_calculator_t = Buffer_stream_t::Grow_calculator_t

Status_t

using binlog::Decompressing_event_object_istream::Status_t = binary_log::transaction::compression::Decompress_status

Tple_ptr_t

using binlog::Decompressing_event_object_istream::Tple_ptr_t = std::shared_ptr<const Transaction_payload_log_event>

Member Enumeration Documentation

Read_status

enum class binlog::Decompressing_event_object_istream::Read_status

strongprivate

Status from read_from_payload_stream.

Enumerator
success
eof
error

Constructor & Destructor Documentation

Decompressing_event_object_istream() [1/5]

binlog::Decompressing_event_object_istream::Decompressing_event_object_istream ( IBasic_binlog_file_reader &  reader )

explicit

Construct stream over a file, decompressing payload events.

This will produce all events in the file, and in addition, each Transaction_payload_log_event is followed by the contained events.

Parameters

reader

The source file to read from.

Decompressing_event_object_istream() [2/5]

binlog::Decompressing_event_object_istream::Decompressing_event_object_istream	(	const Tple_ptr_t &	transaction_payload_log_event,
		Fde_ref_t	format_description_event
	)

Construct stream over a Transaction_payload_log_event.

This will produce all events contained in the event, but not the event itself.

This Decompressing_event_object_istream will, during its entire life time, hold shared ownership of the Transaction_payload_log_event.

Parameters

transaction_payload_log_event	The source file to read from.
format_description_event	The FD event used to parse events.

Decompressing_event_object_istream() [3/5]

binlog::Decompressing_event_object_istream::Decompressing_event_object_istream	(	const Transaction_payload_log_event &	transaction_payload_log_event,
		Fde_ref_t	format_description_event
	)

Construct stream over a Transaction_payload_log_event.

This will produce all events contained in the event, but not the event itself.

This Decompressing_event_object_istream will, during its entire life time, hold a pointer to the Transaction_payload_log_event, and the caller must ensure that the event outlives the stream.

Parameters

transaction_payload_log_event	The source file to read from.
format_description_event	The FD event used to parse events.

~Decompressing_event_object_istream()

binlog::Decompressing_event_object_istream::~Decompressing_event_object_istream

(

)

Decompressing_event_object_istream() [4/5]

binlog::Decompressing_event_object_istream::Decompressing_event_object_istream ( Decompressing_event_object_istream &  )

delete

Decompressing_event_object_istream() [5/5]

binlog::Decompressing_event_object_istream::Decompressing_event_object_istream ( Decompressing_event_object_istream &&  )

delete

Member Function Documentation

begin_payload_event() [1/2]

void binlog::Decompressing_event_object_istream::begin_payload_event ( const Tple_ptr_t &  tple )

inlineprivate

Prepare to unfold a given Transaction_payload_log_event by setting state variables and creating the Payload_event_buffer_istream object.

This object will hold shared ownership of the event.

Parameters

tple	Event to unfold

begin_payload_event() [2/2]

void binlog::Decompressing_event_object_istream::begin_payload_event ( const Transaction_payload_log_event &  tple )

inlineprivate

Prepare to unfold a given Transaction_payload_log_event by setting state variables and creating the Payload_event_buffer_istream object.

This object will not hold ownership of the event. The caller must ensure that the event outlives the stream.

Parameters

tple	Event to unfold

decode_from_buffer()

bool binlog::Decompressing_event_object_istream::decode_from_buffer ( Buffer_view_t &  buffer, Event_ptr_t &  out  )

private

Worker that deserializes an event from the buffer.

Parameters

[in]	buffer	Input byte buffer.
[out]	out	Pointer to output event.

Return values

false	success
true	error

do_begin_payload_event()

template<class Event_ref_or_ptr >

void binlog::Decompressing_event_object_istream::do_begin_payload_event ( const Transaction_payload_log_event &  tple, const Event_ref_or_ptr &  ownership_tple  )

inlineprivate

Worker function implementing both forms of begin_payload_event.

Template Parameters

Event_ref_or_ptr

Either reference-to-event or shared-pointer-to-event.

Parameters

tple	Event to unfold.
ownership_tple	Ownership handle for the event. This can be a shared_ptr if this object should hold shared ownership, or a reference otherwise.

error_stream()

raii::Targeted_stringstream binlog::Decompressing_event_object_istream::error_stream ( Status_t  status )

private

Report an error.

This sets the status as specified, and returns a stringstream to which the caller shall write a message.

Parameters

status

The status

Returns

Targeted_stringstream object; the error for this stream will be set to the given status.

get_error_str()

std::string binlog::Decompressing_event_object_istream::get_error_str

(

)

const

Return a message describing the last error.

Return values

""	No error
string	Error

get_grow_calculator()

const Decompressing_event_object_istream::Grow_calculator_t & binlog::Decompressing_event_object_istream::get_grow_calculator

(

)

const

Return const reference to Grow_calculator to the internal event buffer.

get_status()

Decompressing_event_object_istream::Status_t binlog::Decompressing_event_object_istream::get_status

(

)

const

Return the status.

has_error()

bool binlog::Decompressing_event_object_istream::has_error

(

)

const

Return true if an error has happened.

operator bool()

binlog::Decompressing_event_object_istream::operator bool ( ) const

explicit

Indicate if EOF or error has not happened.

Return values

true	last read was successful (or there was no last read).
false	last read resulted in end-of-stream or error.

operator!()

bool binlog::Decompressing_event_object_istream::operator!

(

)

const

Indicate if EOF or error has happened.

This is the negation of operator bool.

Return values

false	last read was successful, or there was no last read.
true	last read resulted in end-of-stream or error.

operator=() [1/2]

Decompressing_event_object_istream & binlog::Decompressing_event_object_istream::operator= ( Decompressing_event_object_istream &&  )

delete

operator=() [2/2]

Decompressing_event_object_istream & binlog::Decompressing_event_object_istream::operator= ( Decompressing_event_object_istream &  )

delete

operator>>()

Decompressing_event_object_istream & binlog::Decompressing_event_object_istream::operator>>

(

Event_ptr_t &

out

)

Read an event from the stream.

Parameters

out	Shared pointer to the produced event. If this is a Transaction_payload_log_event, the stream will keep a shared pointer to it, until it has produced all the contained events.

Returns

This object.

read_from_binlog_stream()

bool binlog::Decompressing_event_object_istream::read_from_binlog_stream ( Event_ptr_t &  out )

private

Read and decode the next event from the binlog stream.

Parameters

[out]

out

Pointer to the output event.

Return values

false	The event was successfully read and decoded.
true	Error or EOF occurred. In case of error, get_error_str will contain the reason.

read_from_payload_stream()

Decompressing_event_object_istream::Read_status binlog::Decompressing_event_object_istream::read_from_payload_stream ( Event_ptr_t &  out )

private

Read and decode next event from the Payload_log_event stream.

Parameters

[out]

out

Pointer to output event.

Return values

success	The event was successfully read and decoded
error	An error occurred. get_error_str will contain the reason.
eof	Nothing was read because the read position was at the end of the event.

set_grow_calculator()

void binlog::Decompressing_event_object_istream::set_grow_calculator

(

const Grow_calculator_t &

grow_calculator

)

Set the Grow_calculator for the internal event buffer.

set_verify_checksum()

void binlog::Decompressing_event_object_istream::set_verify_checksum

(

bool

verify_checksum = true

)

Specify whether checksums shall be verified or not.

Parameters

verify_checksum

If true, verify checksums; otherwise don't.

Member Data Documentation

m_binlog_reader

IBasic_binlog_file_reader* binlog::Decompressing_event_object_istream::m_binlog_reader {nullptr}

private

Stream of events to read from.

m_buffer_istream

std::unique_ptr<Buffer_stream_t> binlog::Decompressing_event_object_istream::m_buffer_istream {nullptr}

private

The decompression stream; non-null while we are positioned in a TPLE.

m_embedded_event_number

int binlog::Decompressing_event_object_istream::m_embedded_event_number {0}

private

0 when not processing a TPLE; N>0 when positioned before the Nth embedded event of a TPLE.

m_end

bool binlog::Decompressing_event_object_istream::m_end {false}

private

True if we have reached EOF, false otherwise.

m_error_str

std::string binlog::Decompressing_event_object_istream::m_error_str

private

Error from last operation.

m_event_position

my_off_t binlog::Decompressing_event_object_istream::m_event_position {0}

private

Position of last event.

m_get_format_description_event

std::function<Fde_ref_t()> binlog::Decompressing_event_object_istream::m_get_format_description_event

private

Return the current FDE.

m_grow_calculator

Grow_calculator_t binlog::Decompressing_event_object_istream::m_grow_calculator

private

Policy for growing buffers in the decompressing stream.

m_outstanding_error

bool binlog::Decompressing_event_object_istream::m_outstanding_error {false}

mutableprivate

True if a read has failed but neither get_error_str nor has_error has been called.

m_status

Status_t binlog::Decompressing_event_object_istream::m_status {Status_t::success}

private

Status.

m_transaction_payload_event_offset

my_off_t binlog::Decompressing_event_object_istream::m_transaction_payload_event_offset {0}

private

end_log_pos for the currently processed TPLE, if any

m_verify_checksum

bool binlog::Decompressing_event_object_istream::m_verify_checksum {false}

private

Whether we should verify checksum. Unused!

---

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

• sql/binlog/decompressing_event_object_istream.h
• sql/binlog/decompressing_event_object_istream.cc