Parallel reader context. More...

#include <row0pread.h>

Classes
struct	Iter
	Boundary of the range to scan. More...

Public Member Functions
	Scan_ctx (Parallel_reader reader, size_t id, trx_t trx, const Parallel_reader::Config &config, F &&f)
	Constructor. More...

	~Scan_ctx ()=default
	Destructor. More...

Private Types
using	Savepoint = std::pair< ulint, buf_block_t * >
	mtr_t savepoint. More...

using	Savepoints = std::vector< Savepoint, ut::allocator< Savepoint > >
	For releasing the S latches after processing the blocks. More...

using	Range = std::pair< std::shared_ptr< Iter >, std::shared_ptr< Iter > >
	The first cursor should read up to the second cursor [f, s). More...

using	Ranges = std::vector< Range, ut::allocator< Range > >

using	Config = Parallel_reader::Config

Private Member Functions
size_t	id () const

void	set_error_state (dberr_t err)
	Set the error state. More...

bool	is_error_set () const

buf_block_t *	block_get_s_latched (const page_id_t &page_id, mtr_t *mtr, size_t line) const
	Fetch a block from the buffer pool and acquire an S latch on it. More...

dberr_t	partition (const Scan_range &scan_range, Ranges &ranges, size_t split_level)
	Partition the B+Tree for parallel read. More...

page_no_t	search (const buf_block_t block, const dtuple_t key) const
	Find the page number of the node that contains the search key. More...

page_cur_t	start_range (page_no_t page_no, mtr_t mtr, const dtuple_t key, Savepoints &savepoints) const
	Traverse from given sub-tree page number to start of the scan range from the given page number. More...

void	create_range (Ranges &ranges, page_cur_t &leaf_page_cursor, mtr_t *mtr) const
	Create and add the range to the scan ranges. More...

dberr_t	create_ranges (const Scan_range &scan_range, page_no_t page_no, size_t depth, const size_t split_level, Ranges &ranges, mtr_t *mtr)
	Find the subtrees to scan in a block. More...

void	copy_row (const rec_t rec, Iter iter) const
	Build a dtuple_t from rec_t. More...

std::shared_ptr< Iter >	create_persistent_cursor (const page_cur_t &page_cursor, mtr_t *mtr) const
	Create the persistent cursor that will be used to traverse the partition and position on the the start row. More...

bool	check_visibility (const rec_t &rec, ulint &offsets, mem_heap_t &heap, mtr_t mtr)
	Build an old version of the row if required. More...

dberr_t	create_context (const Range &range, bool split)
	Create an execution context for a range and add it to the Parallel_reader's run queue. More...

dberr_t	create_contexts (const Ranges &ranges)
	Create the execution contexts based on the ranges. More...

size_t	max_threads () const

void	release_threads (size_t unused_threads)
	Release unused threads back to the pool. More...

void	index_s_lock ()
	S lock the index. More...

void	index_s_unlock ()
	S unlock the index. More...

bool	index_s_own () const

	Scan_ctx (Scan_ctx &&)=delete

	Scan_ctx (const Scan_ctx &)=delete

Scan_ctx &	operator= (Scan_ctx &&)=delete

Scan_ctx &	operator= (const Scan_ctx &)=delete

Private Attributes
size_t	m_id {std::numeric_limits<size_t>::max()}
	Context ID. More...

Config	m_config
	Parallel scan configuration. More...

const trx_t *	m_trx {}
	Covering transaction. More...

F	m_f
	Callback function. More...

size_t	m_depth {}
	Depth of the Btree. More...

Parallel_reader *	m_reader {}
	The parallel reader. More...

std::atomic< dberr_t >	m_err {DB_SUCCESS}
	Error during parallel read. More...

std::atomic_size_t	m_s_locks {}
	Number of threads that have S locked the index. More...

Friends
class	Parallel_reader

Detailed Description

Parallel reader context.

Member Typedef Documentation

◆ Config

using Parallel_reader::Scan_ctx::Config = Parallel_reader::Config

private

◆ Range

using Parallel_reader::Scan_ctx::Range = std::pair<std::shared_ptr<Iter>, std::shared_ptr<Iter> >

private

The first cursor should read up to the second cursor [f, s).

◆ Ranges

using Parallel_reader::Scan_ctx::Ranges = std::vector<Range, ut::allocator<Range> >

private

◆ Savepoint

using Parallel_reader::Scan_ctx::Savepoint = std::pair<ulint, buf_block_t *>

private

mtr_t savepoint.

◆ Savepoints

using Parallel_reader::Scan_ctx::Savepoints = std::vector<Savepoint, ut::allocator<Savepoint> >

private

For releasing the S latches after processing the blocks.

Constructor & Destructor Documentation

◆ Scan_ctx() [1/3]

Parallel_reader::Scan_ctx::Scan_ctx	(	Parallel_reader *	reader,
		size_t	id,
		trx_t *	trx,
		const Parallel_reader::Config &	config,
		F &&	f
	)

Constructor.

Parameters

[in]	reader	Parallel reader that owns this context.
[in]	id	ID of this scan context.
[in]	trx	Transaction covering the scan.
[in]	config	Range scan config.
[in]	f	Callback function.

◆ ~Scan_ctx()

Parallel_reader::Scan_ctx::~Scan_ctx ( )

default

Destructor.

◆ Scan_ctx() [2/3]

Parallel_reader::Scan_ctx::Scan_ctx ( Scan_ctx && )

privatedelete

◆ Scan_ctx() [3/3]

Parallel_reader::Scan_ctx::Scan_ctx ( const Scan_ctx & )

privatedelete

Member Function Documentation

◆ block_get_s_latched()

buf_block_t * Parallel_reader::Scan_ctx::block_get_s_latched	(	const page_id_t &	page_id,
		mtr_t *	mtr,
		size_t	line
	)		const

private

Fetch a block from the buffer pool and acquire an S latch on it.

Parameters

[in]	page_id	Page ID.
[in,out]	mtr	Mini-transaction covering the fetch.
[in]	line	Line from where called.

Returns: the block fetched from the buffer pool.

◆ check_visibility()

bool Parallel_reader::Scan_ctx::check_visibility	(	const rec_t *&	rec,
		ulint *&	offsets,
		mem_heap_t *&	heap,
		mtr_t *	mtr
	)

private

Build an old version of the row if required.

Parameters

[in,out]	rec	Current row read from the index. This can be modified by this method if an older version needs to be built.
[in,out]	offsets	Same as above but pertains to the rec offsets
[in,out]	heap	Heap to use if a previous version needs to be built from the undo log.
[in,out]	mtr	Mini-transaction covering the read.

Returns: true if row is visible to the transaction.

◆ copy_row()

void Parallel_reader::Scan_ctx::copy_row	(	const rec_t *	rec,
		Iter *	iter
	)		const

private

Build a dtuple_t from rec_t.

Parameters

[in]	rec	Build the dtuple from this record.
[in,out]	iter	Build in this iterator.

◆ create_context()

dberr_t Parallel_reader::Scan_ctx::create_context	(	const Range &	range,
		bool	split
	)

private

Create an execution context for a range and add it to the Parallel_reader's run queue.

Parameters

[in]	range	Range for which to create the context.
[in]	split	true if the sub-tree should be split further.

Returns: DB_SUCCESS or error code.

◆ create_contexts()

dberr_t Parallel_reader::Scan_ctx::create_contexts ( const Ranges & ranges )

private

Create the execution contexts based on the ranges.

Parameters

[in] ranges Ranges for which to create the contexts.

Returns: DB_SUCCESS or error code.

◆ create_persistent_cursor()

std::shared_ptr< Parallel_reader::Scan_ctx::Iter > Parallel_reader::Scan_ctx::create_persistent_cursor	(	const page_cur_t &	page_cursor,
		mtr_t *	mtr
	)		const

private

Create the persistent cursor that will be used to traverse the partition and position on the the start row.

Parameters

[in]	page_cursor	Current page cursor
[in]	mtr	Mini-transaction covering the read.

Returns: Start iterator.

◆ create_range()

void Parallel_reader::Scan_ctx::create_range	(	Ranges &	ranges,
		page_cur_t &	leaf_page_cursor,
		mtr_t *	mtr
	)		const

private

Create and add the range to the scan ranges.

Parameters

[in,out]	ranges	Ranges to scan.
[in,out]	leaf_page_cursor	Leaf page cursor on which to create the persistent cursor.
[in,out]	mtr	Mini-transaction

◆ create_ranges()

dberr_t Parallel_reader::Scan_ctx::create_ranges	(	const Scan_range &	scan_range,
		page_no_t	page_no,
		size_t	depth,
		const size_t	split_level,
		Ranges &	ranges,
		mtr_t *	mtr
	)

private

Find the subtrees to scan in a block.

Parameters

[in]	scan_range	Partition based on this scan range.
[in]	page_no	Page to partition at if at required level.
[in]	depth	Sub-range current level.
[in]	split_level	Sub-range starting level (0 == root).
[in,out]	ranges	Ranges to scan.
[in,out]	mtr	Mini-transaction

◆ id()

size_t Parallel_reader::Scan_ctx::id ( ) const

inlineprivate

Returns: the scan context ID.

◆ index_s_lock()

void Parallel_reader::Scan_ctx::index_s_lock ( )

private

S lock the index.

◆ index_s_own()

bool Parallel_reader::Scan_ctx::index_s_own ( ) const

inlineprivate

Returns: true if at least one thread owns the S latch on the index.

◆ index_s_unlock()

void Parallel_reader::Scan_ctx::index_s_unlock ( )

private

S unlock the index.

◆ is_error_set()

bool Parallel_reader::Scan_ctx::is_error_set ( ) const

inlineprivate

Returns: true if in error state.

◆ max_threads()

size_t Parallel_reader::Scan_ctx::max_threads ( ) const

inlineprivate

Returns: the maximum number of threads configured.

◆ operator=() [1/2]

Scan_ctx & Parallel_reader::Scan_ctx::operator= ( const Scan_ctx & )

privatedelete

◆ operator=() [2/2]

Scan_ctx & Parallel_reader::Scan_ctx::operator= ( Scan_ctx && )

privatedelete

◆ partition()

dberr_t Parallel_reader::Scan_ctx::partition	(	const Scan_range &	scan_range,
		Ranges &	ranges,
		size_t	split_level
	)

private

Partition the B+Tree for parallel read.

Parameters

[in]	scan_range	Range for partitioning.
[in,out]	ranges	Ranges to scan.
[in]	split_level	Sub-range required level (0 == root).

Returns: the partition scan ranges.

◆ release_threads()

void Parallel_reader::Scan_ctx::release_threads ( size_t unused_threads )

inlineprivate

Release unused threads back to the pool.

Parameters

[in] unused_threads Number of threads to "release".

◆ search()

page_no_t Parallel_reader::Scan_ctx::search	(	const buf_block_t *	block,
		const dtuple_t *	key
	)		const

private

Find the page number of the node that contains the search key.

If the key is null then we assume -infinity.

Parameters

[in]	block	Page to look in.
[in]	key	Key of the first record in the range.

Returns: the left child page number.

◆ set_error_state()

void Parallel_reader::Scan_ctx::set_error_state ( dberr_t err )

inlineprivate

Set the error state.

Parameters

[in] err Error state to set to.

◆ start_range()

page_cur_t Parallel_reader::Scan_ctx::start_range	(	page_no_t	page_no,
		mtr_t *	mtr,
		const dtuple_t *	key,
		Savepoints &	savepoints
	)		const

private

Traverse from given sub-tree page number to start of the scan range from the given page number.

Parameters

[in]	page_no	Page number of sub-tree.
[in,out]	mtr	Mini-transaction.
[in]	key	Key of the first record in the range.
[in,out]	savepoints	Blocks S latched and accessed.

Returns: the leaf node page cursor.

Friends And Related Function Documentation

◆ Parallel_reader

friend class Parallel_reader

friend

Member Data Documentation

◆ m_config

Config Parallel_reader::Scan_ctx::m_config

private

Parallel scan configuration.

◆ m_depth

size_t Parallel_reader::Scan_ctx::m_depth {}

private

Depth of the Btree.

◆ m_err

std::atomic<dberr_t> Parallel_reader::Scan_ctx::m_err {DB_SUCCESS}

mutableprivate

Error during parallel read.

◆ m_f

F Parallel_reader::Scan_ctx::m_f

private

Callback function.

◆ m_id

size_t Parallel_reader::Scan_ctx::m_id {std::numeric_limits<size_t>::max()}

private

Context ID.

◆ m_reader

Parallel_reader* Parallel_reader::Scan_ctx::m_reader {}

private

The parallel reader.

◆ m_s_locks

std::atomic_size_t Parallel_reader::Scan_ctx::m_s_locks {}

private

Number of threads that have S locked the index.

◆ m_trx

const trx_t* Parallel_reader::Scan_ctx::m_trx {}

private

Covering transaction.

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

storage/innobase/include/row0pread.h
storage/innobase/row/row0pread.cc

Classes

Public Member Functions

Private Types

Private Member Functions

Private Attributes

Friends

Detailed Description

Member Typedef Documentation

◆ Config

◆ Range

◆ Ranges

◆ Savepoint

◆ Savepoints

Constructor & Destructor Documentation

◆ Scan_ctx() [1/3]

◆ ~Scan_ctx()

◆ Scan_ctx() [2/3]

◆ Scan_ctx() [3/3]

Member Function Documentation

◆ block_get_s_latched()

◆ check_visibility()

◆ copy_row()

◆ create_context()

◆ create_contexts()

◆ create_persistent_cursor()

◆ create_range()

◆ create_ranges()

◆ id()

◆ index_s_lock()

◆ index_s_own()

◆ index_s_unlock()

◆ is_error_set()

◆ max_threads()

◆ operator=() [1/2]

◆ operator=() [2/2]

◆ partition()

◆ release_threads()

◆ search()

◆ set_error_state()

◆ start_range()

Friends And Related Function Documentation

◆ Parallel_reader

Member Data Documentation

◆ m_config

◆ m_depth

◆ m_err

◆ m_f

◆ m_id

◆ m_reader

◆ m_s_locks

◆ m_trx