Read view lists the trx ids of those transactions for which a consistent read should not see the modifications to the database. More...

#include <read0types.h>

Classes
class	ids_t
	This is similar to a std::vector but it is not a drop in replacement. More...

Public Member Functions
	ReadView ()
	ReadView constructor. More...

	~ReadView ()
	ReadView destructor. More...

bool	changes_visible (trx_id_t id, const table_name_t &name) const
	Check whether the changes by id are visible. More...

bool	sees (trx_id_t id) const

void	close ()
	Mark the view as closed. More...

bool	is_closed () const

void	print_limits (FILE *file) const
	Write the limits to the file. More...

void	reduce_low_limit (trx_id_t trx_no)
	Check and reduce low limit number for read view. More...

trx_id_t	low_limit_no () const

trx_id_t	low_limit_id () const

bool	empty () const

trx_id_t	view_low_limit_no () const

bool	le (const ReadView *rhs) const

Static Public Member Functions
static void	check_trx_id_sanity (trx_id_t id, const table_name_t &name)
	Check whether transaction id is valid. More...

Private Member Functions
void	copy_trx_ids (const trx_ids_t &trx_ids)
	Copy the transaction ids from the source vector. More...

void	prepare (trx_id_t id)
	Opens a read view where exactly the transactions serialized before this point in time are seen in the view. More...

void	copy_prepare (const ReadView &other)
	Copy state from another view. More...

void	copy_complete ()
	Complete the copy, insert the creator transaction id into the m_trx_ids too and adjust the m_up_limit_id *, if required. More...

void	creator_trx_id (trx_id_t id)
	Set the creator transaction id, existing id must be 0. More...

	ReadView (const ReadView &)

ReadView &	operator= (const ReadView &)

typedef	UT_LIST_NODE_T (ReadView) node_t

Private Attributes
trx_id_t	m_low_limit_id
	The read should not see any transaction with trx id >= this value. More...

trx_id_t	m_up_limit_id
	The read should see all trx ids which are strictly smaller (<) than this value. More...

trx_id_t	m_creator_trx_id
	trx id of creating transaction, set to TRX_ID_MAX for free views. More...

ids_t	m_ids
	Set of RW transactions that was active when this snapshot was taken. More...

trx_id_t	m_low_limit_no
	The view does not need to see the undo logs for transactions whose transaction number is strictly smaller (<) than this value: they can be removed in purge if not needed by other views. More...

trx_id_t	m_view_low_limit_no
	The low limit number up to which read views don't need to access undo log records for MVCC. More...

bool	m_closed
	AC-NL-RO transaction view that has been "closed". More...

byte	pad1 [64 - sizeof(node_t)]
	List of read views in trx_sys. More...

node_t	m_view_list

Friends
class	MVCC

Detailed Description

Read view lists the trx ids of those transactions for which a consistent read should not see the modifications to the database.

Constructor & Destructor Documentation

◆ ReadView() [1/2]

ReadView::ReadView ( )

ReadView constructor.

◆ ~ReadView()

ReadView::~ReadView ( )

ReadView destructor.

◆ ReadView() [2/2]

ReadView::ReadView ( const ReadView & )

private

Member Function Documentation

◆ changes_visible()

bool ReadView::changes_visible	(	trx_id_t	id,
		const table_name_t &	name
	)		const

inline

Check whether the changes by id are visible.

Parameters

[in]	id	transaction id to check against the view
[in]	name	table name

Returns: whether the view sees the modifications of id.

◆ check_trx_id_sanity()

void ReadView::check_trx_id_sanity	(	trx_id_t	id,
		const table_name_t &	name
	)

static

Check whether transaction id is valid.

Parameters

[in]	id	transaction id to check
[in]	name	table name

◆ close()

void ReadView::close ( void )

inline

Mark the view as closed.

◆ copy_complete()

void ReadView::copy_complete ( )

inlineprivate

Complete the copy, insert the creator transaction id into the m_trx_ids too and adjust the m_up_limit_id *, if required.

Complete the copy, insert the creator transaction id into the m_ids too and adjust the m_up_limit_id, if required.

◆ copy_prepare()

void ReadView::copy_prepare ( const ReadView & other )

inlineprivate

Copy state from another view.

Must call copy_complete() to finish.

Parameters

other view to copy from

◆ copy_trx_ids()

void ReadView::copy_trx_ids ( const trx_ids_t & trx_ids )

inlineprivate

Copy the transaction ids from the source vector.

◆ creator_trx_id()

void ReadView::creator_trx_id ( trx_id_t id )

inlineprivate

Set the creator transaction id, existing id must be 0.

◆ empty()

bool ReadView::empty ( ) const

inline

Returns: true if there are no transaction ids in the snapshot

◆ is_closed()

bool ReadView::is_closed ( ) const

inline

Returns: true if the view is closed

◆ le()

bool ReadView::le ( const ReadView * rhs ) const

inline

Parameters

rhs	view to compare with

Returns: truen if this view is less than or equal rhs

◆ low_limit_id()

trx_id_t ReadView::low_limit_id ( ) const

inline

Returns: the low limit id

◆ low_limit_no()

trx_id_t ReadView::low_limit_no ( ) const

inline

Returns: the low limit no

◆ operator=()

ReadView & ReadView::operator= ( const ReadView & )

private

◆ prepare()

void ReadView::prepare ( trx_id_t id )

inlineprivate

Opens a read view where exactly the transactions serialized before this point in time are seen in the view.

Parameters

id	Creator transaction id

◆ print_limits()

void ReadView::print_limits ( FILE * file ) const

inline

Write the limits to the file.

Parameters

file	file to write to

◆ reduce_low_limit()

void ReadView::reduce_low_limit ( trx_id_t trx_no )

inline

Check and reduce low limit number for read view.

Used to block purge till GTID is persisted on disk table.

Parameters

[in] trx_no transaction number to check with

◆ sees()

bool ReadView::sees ( trx_id_t id ) const

inline

Parameters

id	transaction to check

Returns: true if view sees transaction id

◆ UT_LIST_NODE_T()

typedef ReadView::UT_LIST_NODE_T ( ReadView )

private

◆ view_low_limit_no()

trx_id_t ReadView::view_low_limit_no ( ) const

inline

Returns: the view low limit number

Friends And Related Function Documentation

◆ MVCC

friend class MVCC

friend

Member Data Documentation

◆ m_closed

bool ReadView::m_closed

private

AC-NL-RO transaction view that has been "closed".

◆ m_creator_trx_id

trx_id_t ReadView::m_creator_trx_id

private

trx id of creating transaction, set to TRX_ID_MAX for free views.

◆ m_ids

ids_t ReadView::m_ids

private

Set of RW transactions that was active when this snapshot was taken.

◆ m_low_limit_id

trx_id_t ReadView::m_low_limit_id

private

The read should not see any transaction with trx id >= this value.

In other words, this is the "high water mark".

◆ m_low_limit_no

trx_id_t ReadView::m_low_limit_no

private

The view does not need to see the undo logs for transactions whose transaction number is strictly smaller (<) than this value: they can be removed in purge if not needed by other views.

◆ m_up_limit_id

trx_id_t ReadView::m_up_limit_id

private

The read should see all trx ids which are strictly smaller (<) than this value.

In other words, this is the low water mark".

◆ m_view_list

node_t ReadView::m_view_list

private

◆ m_view_low_limit_no

trx_id_t ReadView::m_view_low_limit_no

private

The low limit number up to which read views don't need to access undo log records for MVCC.

This could be higher than m_low_limit_no if purge is blocked for GTID persistence. Currently used for debug variable INNODB_PURGE_VIEW_TRX_ID_AGE.

◆ pad1

byte ReadView::pad1[64 - sizeof(node_t)]

private

List of read views in trx_sys.

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

storage/innobase/include/read0types.h
storage/innobase/read/read0read.cc
storage/innobase/trx/trx0sys.cc

Classes

Public Member Functions

Static Public Member Functions

Private Member Functions

Private Attributes

Friends

Detailed Description

Constructor & Destructor Documentation

◆ ReadView() [1/2]

◆ ~ReadView()

◆ ReadView() [2/2]

Member Function Documentation

◆ changes_visible()

◆ check_trx_id_sanity()

◆ close()

◆ copy_complete()

◆ copy_prepare()

◆ copy_trx_ids()

◆ creator_trx_id()

◆ empty()

◆ is_closed()

◆ le()

◆ low_limit_id()

◆ low_limit_no()

◆ operator=()

◆ prepare()

◆ print_limits()

◆ reduce_low_limit()

◆ sees()

◆ UT_LIST_NODE_T()

◆ view_low_limit_no()

Friends And Related Function Documentation

◆ MVCC

Member Data Documentation

◆ m_closed

◆ m_creator_trx_id

◆ m_ids

◆ m_low_limit_id

◆ m_low_limit_no

◆ m_up_limit_id

◆ m_view_list

◆ m_view_low_limit_no

◆ pad1