Represents the Binlog Group Commit Ticket - BGC Ticket. More...

#include <bgc_ticket.h>

Public Types
using	ValueType = std::uint64_t

Public Member Functions
	BgcTicket (const ValueType &ticket=first_ticket_value)
	Constructor. More...

ValueType	get_value () const
	Obtain ticket value (1st bit cleared out) More...

const ValueType &	get () const
	Obtain ticket, may be in use or not (cannot be easily compared) More...

void	set_in_use ()
	sets synchronization bit to 1, only 1 thread can operate on this ticket More...

void	set_used ()
	sets synchronization bit to 0, other thread may "lock" this ticket for writing More...

bool	is_in_use () const
	checks whether this ticket is "locked" for writing More...

BgcTicket	next () const
	Returns incremented ticket, this remain unchanged. More...

void	set_next ()
	Increments this ticket value. More...

bool	is_set () const
	Checks whether the ticket value differs from kTicketUnset. More...

Static Public Attributes
static constexpr BgcTicket::ValueType	kTicketUnset = 0
	Default value of ticket, which means it is not being used. More...

static constexpr ValueType	set_bit = 1ULL << 63
	64-bit mask with all 0s except for the most significant bit, to extract synchronization bit More...

static constexpr ValueType	clear_bit = set_bit - 1
	64-bit mask with all 0s except for the most significant bit, to clear out synchronization bit - get ticket value More...

static constexpr ValueType	max_ticket_value
	Maximum allowed value for a ticket, after which will wrap around to first_ticket_value. More...

static constexpr ValueType	first_ticket_value = 1
	Minimum allowed value for a ticket. More...

Protected Attributes
ValueType	m_ticket
	1 bit for synchronization, 63 bits - ticket value More...

Friends
class	AtomicBgcTicket

bool	operator< (const BgcTicket &lhs, const BgcTicket &rhs)
	"Less than" operator More...

bool	operator> (const BgcTicket &lhs, const BgcTicket &rhs)
	"Greater than" operator More...

bool	operator>= (const BgcTicket &lhs, const BgcTicket &rhs)
	Comparison operator (>=) More...

bool	operator== (const BgcTicket &lhs, const BgcTicket &rhs)
	Comparison operator. More...

bool	operator!= (const BgcTicket &lhs, const BgcTicket &rhs)
	Comparison operator. More...

std::ostream &	operator<< (std::ostream &os, const BgcTicket &arg)
	Stream operator impl for BgcTicket class. More...

Detailed Description

Represents the Binlog Group Commit Ticket - BGC Ticket.

Context: BGC ticket is granted to sessions with the same View, which may be changed with the View Change Event (server connecting to / disconnecting from group). When View Change Event is generated, it is granted a separate ticket value (value+1). All sessions that should be executed after View Change Event are assigned with a ticket value + 2. Implementation: Ticket is composed of 1 synchronization bit, used for critical section implementation and 63 bits that represent a ticket value. This class contains operation common for BGC tickets, such as: value extraction, changing synchronization bit between 0 and 1, ticket comparison, formatting, incrementation, internal constants. After reachning the maximum value for a ticket, ticket value is wrapped up to the first valid ticket value.

See also: Bgc_ticket_manager

Member Typedef Documentation

◆ ValueType

using binlog::BgcTicket::ValueType = std::uint64_t

Constructor & Destructor Documentation

◆ BgcTicket()

binlog::BgcTicket::BgcTicket ( const ValueType & ticket = first_ticket_value )

explicit

Constructor.

Parameters

[in] ticket Pattern to copy from

Member Function Documentation

◆ get()

const ValueType & binlog::BgcTicket::get ( ) const

inline

Obtain ticket, may be in use or not (cannot be easily compared)

Cannot be easily compared, use comparison operator from BgcTicket instead

Returns: Internal value of the ticket (value+sync bit)

◆ get_value()

BgcTicket::ValueType binlog::BgcTicket::get_value ( ) const

Obtain ticket value (1st bit cleared out)

Returns: Ticket value

◆ is_in_use()

bool binlog::BgcTicket::is_in_use ( ) const

checks whether this ticket is "locked" for writing

Return values

true	Ticket is in use
false	Ticket is not in use

◆ is_set()

bool binlog::BgcTicket::is_set ( ) const

Checks whether the ticket value differs from kTicketUnset.

Return values

true	Ticket value is set
false	Ticket value is unset

◆ next()

BgcTicket binlog::BgcTicket::next ( ) const

Returns incremented ticket, this remain unchanged.

Returns: Incremented ticket

◆ set_in_use()

void binlog::BgcTicket::set_in_use ( )

sets synchronization bit to 1, only 1 thread can operate on this ticket

◆ set_next()

void binlog::BgcTicket::set_next ( )

Increments this ticket value.

◆ set_used()

void binlog::BgcTicket::set_used ( )

sets synchronization bit to 0, other thread may "lock" this ticket for writing

Friends And Related Function Documentation

◆ AtomicBgcTicket

friend class AtomicBgcTicket

friend

◆ operator!=

bool operator!=	(	const BgcTicket &	lhs,
		const BgcTicket &	rhs
	)

friend

Comparison operator.

Comparison without (!) first bit

Parameters

[in]	lhs	Left hand side BgcTicket argument (const ref)
[in]	rhs	Right hand side BgcTicket argument (const ref)

Return values

true	lhs != rhs
false	rhs == lhs

◆ operator<

bool operator<	(	const BgcTicket &	lhs,
		const BgcTicket &	rhs
	)

friend

"Less than" operator

Parameters

[in]	lhs	Left hand side BgcTicket argument (const ref)
[in]	rhs	Right hand side BgcTicket argument (const ref)

◆ operator<<

std::ostream & operator<<	(	std::ostream &	os,
		const BgcTicket &	arg
	)

friend

Stream operator impl for BgcTicket class.

Parameters

[in]	os	Reference to stream obj
[in]	arg	Constant reference to BgcTicket object

Returns: Reference to changed stream obj

◆ operator==

bool operator==	(	const BgcTicket &	lhs,
		const BgcTicket &	rhs
	)

friend

Comparison operator.

Comparison without (!) first bit, meaning that if some thread locked on lhs or rhs, tickets can still be equal

Parameters

[in]	lhs	Left hand side BgcTicket argument (const ref)
[in]	rhs	Right hand side BgcTicket argument (const ref)

Return values

true	lhs == rhs
false	rhs != lhs

◆ operator>

bool operator>	(	const BgcTicket &	lhs,
		const BgcTicket &	rhs
	)

friend

"Greater than" operator

Parameters

[in]	lhs	Left hand side BgcTicket argument (const ref)
[in]	rhs	Right hand side BgcTicket argument (const ref)

Return values

true	lhs > rhs
false	rhs <= lhs

◆ operator>=

bool operator>=	(	const BgcTicket &	lhs,
		const BgcTicket &	rhs
	)

friend

Comparison operator (>=)

Parameters

[in]	lhs	Left hand side BgcTicket argument (const ref)
[in]	rhs	Right hand side BgcTicket argument (const ref)

Return values

true	lhs >= rhs
false	!(rhs >= lhs)

Member Data Documentation

◆ clear_bit

constexpr ValueType binlog::BgcTicket::clear_bit = set_bit - 1

staticconstexpr

64-bit mask with all 0s except for the most significant bit, to clear out synchronization bit - get ticket value

◆ first_ticket_value

constexpr ValueType binlog::BgcTicket::first_ticket_value = 1

staticconstexpr

Minimum allowed value for a ticket.

◆ kTicketUnset

constexpr BgcTicket::ValueType binlog::BgcTicket::kTicketUnset = 0

staticconstexpr

Default value of ticket, which means it is not being used.

◆ m_ticket

ValueType binlog::BgcTicket::m_ticket

protected

1 bit for synchronization, 63 bits - ticket value

◆ max_ticket_value

constexpr ValueType binlog::BgcTicket::max_ticket_value

staticconstexpr

Initial value:

=

std::numeric_limits<ValueType>::max() & clear_bit

binlog::BgcTicket::clear_bit

static constexpr ValueType clear_bit

64-bit mask with all 0s except for the most significant bit, to clear out synchronization bit - get t...

Definition: bgc_ticket.h:147

Maximum allowed value for a ticket, after which will wrap around to first_ticket_value.

◆ set_bit

constexpr ValueType binlog::BgcTicket::set_bit = 1ULL << 63

staticconstexpr

64-bit mask with all 0s except for the most significant bit, to extract synchronization bit

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

sql/binlog/group_commit/bgc_ticket.h
sql/binlog/group_commit/bgc_ticket.cc

Public Types

Public Member Functions

Static Public Attributes

Protected Attributes

Friends

Detailed Description

Member Typedef Documentation

◆ ValueType

Constructor & Destructor Documentation

◆ BgcTicket()

Member Function Documentation

◆ get()

◆ get_value()

◆ is_in_use()

◆ is_set()

◆ next()

◆ set_in_use()

◆ set_next()

◆ set_used()

Friends And Related Function Documentation

◆ AtomicBgcTicket

◆ operator!=

◆ operator<

◆ operator<<

◆ operator==

◆ operator>

◆ operator>=

Member Data Documentation

◆ clear_bit

◆ first_ticket_value

◆ kTicketUnset

◆ m_ticket

◆ max_ticket_value

◆ set_bit