Rollback segment. More...

#include "trx0rseg.h"
#include <stddef.h>
#include <algorithm>
#include "clone0clone.h"
#include "fsp0sysspace.h"
#include "fut0lst.h"
#include "log0chkp.h"
#include "srv0mon.h"
#include "srv0srv.h"
#include "srv0start.h"
#include "trx0purge.h"
#include "trx0undo.h"

Functions
page_no_t	trx_rseg_header_create (space_id_t space_id, const page_size_t &page_size, page_no_t max_size, ulint rseg_slot, mtr_t *mtr)
	Creates a rollback segment header. More...

void	trx_rseg_mem_free (trx_rseg_t *rseg)
	Free an instance of the rollback segment in memory. More...

static void	trx_rseg_persist_gtid (trx_rseg_t *rseg, trx_id_t gtid_trx_no)

static trx_rseg_t *	trx_rseg_mem_initialize (ulint id, space_id_t space_id, page_no_t page_no, const page_size_t &page_size)

static trx_rseg_t *	trx_rseg_physical_initialize (trx_rseg_t rseg, purge_pq_t purge_queue, trx_id_t gtid_trx_no, mtr_t *mtr)

page_no_t	trx_rseg_get_page_no (space_id_t space_id, ulint rseg_id)
	Return a page number from a slot in the rseg_array page of an undo tablespace. More...

void	trx_rseg_init_thread (void *arg, trx_id_t gtid_trx_no)
	Thread to initialize rollback segments in parallel. More...

trx_rseg_t *	trx_rseg_mem_create (ulint id, space_id_t space_id, page_no_t page_no, const page_size_t &page_size, trx_id_t gtid_trx_no, purge_pq_t purge_queue, mtr_t mtr)
	Create and initialize a rollback segment object. More...

void	trx_rsegs_init_start (purge_pq_t *purge_queue)
	Read each rollback segment slot in the TRX_SYS page and the RSEG_ARRAY page of each undo tablespace. More...

void	trx_rsegs_init_end ()

void	trx_rsegs_parallel_init (purge_pq_t *purge_queue)
	Initialize rollback segments in parallel. More...

void	trx_rsegs_init (purge_pq_t *purge_queue)
	Read each rollback segment slot in the TRX_SYS page and the RSEG_ARRAY page of each undo tablespace. More...

page_no_t	trx_rseg_create (space_id_t space_id, ulint rseg_id)
	Create a rollback segment in the given tablespace. More...

bool	trx_rseg_add_rollback_segments (space_id_t space_id, ulong target_rsegs, Rsegs rsegs, ulint const n_total_created)
	This does two things to the target tablespace. More...

bool	trx_rseg_adjust_rollback_segments (ulong target_rollback_segments)
	Add more rsegs to the rseg list in each tablespace until there are srv_rollback_segments of them. More...

bool	trx_rseg_init_rollback_segments (space_id_t space_id, ulong target_rollback_segments)
	Create the requested number of Rollback Segments in a newly created undo tablespace and add them to the Rsegs object. More...

void	trx_rseg_get_n_undo_tablespaces (Space_Ids *spaces_to_open)
	Build a list of unique undo tablespaces found in the TRX_SYS page. More...

void	trx_rseg_upgrade_undo_tablespaces ()
	Upgrade the TRX_SYS page so that it no longer tracks rsegs in undo tablespaces. More...

void	trx_rseg_array_create (space_id_t space_id, mtr_t *mtr)
	Create the file page for the rollback segment directory in an undo tablespace. More...

Variables
static std::atomic< uint32_t >	active_rseg_init_threads {1}

Detailed Description

Rollback segment.

Created 3/26/1996 Heikki Tuuri

Function Documentation

◆ trx_rseg_add_rollback_segments()

bool trx_rseg_add_rollback_segments	(	space_id_t	space_id,
		ulong	target_rsegs,
		Rsegs *	rsegs,
		ulint *const	n_total_created
	)

This does two things to the target tablespace.

Find or create (trx_rseg_create) the requested number of rollback segments.

Make sure each rollback segment is tracked in memory (trx_rseg_mem_create). All existing rollback segments were found earlier in trx_rsegs_init(). This will add new ones if we need them according to target_rsegs.

Parameters

[in]	space_id	tablespace ID that should contain rollback segments
[in]	target_rsegs	target number of rollback segments per tablespace
[in]	rsegs	list of rsegs to add to
[in,out]	n_total_created	A running total of rollback segment created in undo tablespaces

Returns: true if all rsegs are added, false if not.

◆ trx_rseg_adjust_rollback_segments()

bool trx_rseg_adjust_rollback_segments ( ulong target_rollback_segments )

Add more rsegs to the rseg list in each tablespace until there are srv_rollback_segments of them.

Use any rollback segment that already exists so that the purge_queue can be filled and processed with any existing undo log. If the rollback segments do not exist in this tablespace and we need them according to target_rollback_segments, then build them in the tablespace.

Parameters

[in] target_rollback_segments new number of rollback segments per space

Returns: true if all necessary rollback segments and trx_rseg_t objects were created.

The number of rollback segments created in the datafile.

◆ trx_rseg_array_create()

void trx_rseg_array_create	(	space_id_t	space_id,
		mtr_t *	mtr
	)

Create the file page for the rollback segment directory in an undo tablespace.

This function is called just after an undo tablespace is created so the next page created here should by FSP_FSEG_DIR_PAGE_NUM.

Parameters

[in]	space_id	Undo Tablespace ID
[in]	mtr	mtr

◆ trx_rseg_create()

page_no_t trx_rseg_create	(	space_id_t	space_id,
		ulint	rseg_id
	)

Create a rollback segment in the given tablespace.

This could be either the system tablespace, the temporary tablespace, or an undo tablespace.

Parameters

[in]	space_id	tablespace to get the rollback segment
[in]	rseg_id	slot number of the rseg within this tablespace

Returns: page number of the rollback segment header page created

◆ trx_rseg_get_n_undo_tablespaces()

void trx_rseg_get_n_undo_tablespaces ( Space_Ids * spaces_to_open )

Build a list of unique undo tablespaces found in the TRX_SYS page.

Do not count the system tablespace. The vector will be sorted on space id.

Parameters

[in,out] spaces_to_open list of undo tablespaces found.

◆ trx_rseg_get_page_no()

page_no_t trx_rseg_get_page_no	(	space_id_t	space_id,
		ulint	rseg_id
	)

Return a page number from a slot in the rseg_array page of an undo tablespace.

Parameters

[in]	space_id	undo tablespace ID
[in]	rseg_id	rollback segment ID

Returns: page_no Page number of the rollback segment header page

◆ trx_rseg_header_create()

page_no_t trx_rseg_header_create	(	space_id_t	space_id,
		const page_size_t &	page_size,
		page_no_t	max_size,
		ulint	rseg_slot,
		mtr_t *	mtr
	)

Creates a rollback segment header.

This function is called only when a new rollback segment is created in the database.

Parameters

[in]	space_id	Space id
[in]	page_size	Page size
[in]	max_size	Max size in pages
[in]	rseg_slot	Rseg id == slot number in RSEG_ARRAY
[in,out]	mtr	Mini-transaction

Returns: page number of the created segment, FIL_NULL if fail

◆ trx_rseg_init_rollback_segments()

bool trx_rseg_init_rollback_segments	(	space_id_t	space_id,
		ulong	target_rollback_segments
	)

Create the requested number of Rollback Segments in a newly created undo tablespace and add them to the Rsegs object.

Parameters

[in]	space_id	undo tablespace ID
[in]	target_rollback_segments	number of rollback segments per space

Returns: true if all necessary rollback segments and trx_rseg_t objects were created.

The number of rollback segments created in the datafile.

◆ trx_rseg_init_thread()

void trx_rseg_init_thread	(	void *	arg,
		trx_id_t	gtid_trx_no
	)

Thread to initialize rollback segments in parallel.

Parameters

[in]	arg	purge queue
[in]	gtid_trx_no	GTID to be set in the rollback segment

◆ trx_rseg_mem_create()

trx_rseg_t * trx_rseg_mem_create	(	ulint	id,
		space_id_t	space_id,
		page_no_t	page_no,
		const page_size_t &	page_size,
		trx_id_t	gtid_trx_no,
		purge_pq_t *	purge_queue,
		mtr_t *	mtr
	)

Create and initialize a rollback segment object.

Some of the values for the fields are read from the segment header page. The caller must insert it into the correct list.

Parameters

[in]	id	Rollback segment id
[in]	space_id	Space where the segment is placed
[in]	page_no	Page number of the segment header
[in]	page_size	Page size
[in]	gtid_trx_no	Trx number up to which GTID is persisted
[in,out]	purge_queue	Rseg queue
[in,out]	mtr	Mini-transaction

Returns: own: rollback segment object

◆ trx_rseg_mem_free()

void trx_rseg_mem_free ( trx_rseg_t * rseg )

Free an instance of the rollback segment in memory.

Parameters

[in] rseg pointer to an rseg to free

◆ trx_rseg_mem_initialize()

static trx_rseg_t * trx_rseg_mem_initialize	(	ulint	id,
		space_id_t	space_id,
		page_no_t	page_no,
		const page_size_t &	page_size
	)

static

◆ trx_rseg_persist_gtid()

static void trx_rseg_persist_gtid	(	trx_rseg_t *	rseg,
		trx_id_t	gtid_trx_no
	)

static

◆ trx_rseg_physical_initialize()

static trx_rseg_t * trx_rseg_physical_initialize	(	trx_rseg_t *	rseg,
		purge_pq_t *	purge_queue,
		trx_id_t	gtid_trx_no,
		mtr_t *	mtr
	)

static

◆ trx_rseg_upgrade_undo_tablespaces()

void trx_rseg_upgrade_undo_tablespaces ( )

Upgrade the TRX_SYS page so that it no longer tracks rsegs in undo tablespaces.

Upgrade the TRX_SYS page so that it no longer tracks rsegs in undo tablespaces other than the system tablespace.

It should only track rollback segments in the system tablespace. Put FIL_NULL in the slots in TRX_SYS. Latch protection is not needed since this is during single-threaded startup.

◆ trx_rsegs_init()

void trx_rsegs_init ( purge_pq_t * purge_queue )

Read each rollback segment slot in the TRX_SYS page and the RSEG_ARRAY page of each undo tablespace.

Create trx_rseg_t objects for all rollback segments found. This runs at database startup and initializes the in-memory lists of trx_rseg_t objects. We need to look at all slots in TRX_SYS and each RSEG_ARRAY page because we need to look for any existing undo log that may need to be recovered by purge. No latch is needed since this is still single-threaded startup. If we find existing rseg slots in TRX_SYS page that reference undo tablespaces and have active undo logs, then quit. They require an upgrade of undo tablespaces and that cannot happen with active undo logs.

Parameters

[in] purge_queue queue of rsegs to purge

◆ trx_rsegs_init_end()

void trx_rsegs_init_end ( )

◆ trx_rsegs_init_start()

void trx_rsegs_init_start ( purge_pq_t * purge_queue )

Read each rollback segment slot in the TRX_SYS page and the RSEG_ARRAY page of each undo tablespace.

Create trx_rseg_t objects for all rollback segments found. This runs at database startup and initializes the in-memory lists of trx_rseg_t objects. We need to look at all slots in TRX_SYS and each RSEG_ARRAY page because we need to look for any existing undo log that may need to be recovered by purge. No latch is needed since this is still single-threaded startup.If we find existing rseg slots in TRX_SYS page that reference undo tablespaces and have active undo logs, then quit. They require an upgrade of undo tablespaces and that cannot happen with active undo logs.

Parameters

[in] purge_queue queue of rsegs to purge

◆ trx_rsegs_parallel_init()

void trx_rsegs_parallel_init ( purge_pq_t * purge_queue )

Initialize rollback segments in parallel.

Parameters

[in] purge_queue queue of rsegs to purge

Parameters

purge_queue in: rseg queue

Variable Documentation

◆ active_rseg_init_threads

std::atomic<uint32_t> active_rseg_init_threads {1}

static

Functions

Variables

Detailed Description

Function Documentation

◆ trx_rseg_add_rollback_segments()

◆ trx_rseg_adjust_rollback_segments()

◆ trx_rseg_array_create()

◆ trx_rseg_create()

◆ trx_rseg_get_n_undo_tablespaces()

◆ trx_rseg_get_page_no()

◆ trx_rseg_header_create()

◆ trx_rseg_init_rollback_segments()

◆ trx_rseg_init_thread()

◆ trx_rseg_mem_create()

◆ trx_rseg_mem_free()

◆ trx_rseg_mem_initialize()

◆ trx_rseg_persist_gtid()

◆ trx_rseg_physical_initialize()

◆ trx_rseg_upgrade_undo_tablespaces()

◆ trx_rsegs_init()

◆ trx_rsegs_init_end()

◆ trx_rsegs_init_start()

◆ trx_rsegs_parallel_init()

Variable Documentation

◆ active_rseg_init_threads