Transaction rollback. More...

#include <sys/types.h>
#include "clone0clone.h"
#include "dict0dd.h"
#include "fsp0fsp.h"
#include "ha_prototypes.h"
#include "lock0lock.h"
#include "mach0data.h"
#include "os0thread-create.h"
#include "pars0pars.h"
#include "que0que.h"
#include "read0read.h"
#include "row0mysql.h"
#include "row0undo.h"
#include "sql_thd_internal_api.h"
#include "srv0mon.h"
#include "srv0start.h"
#include "trx0rec.h"
#include "trx0roll.h"
#include "trx0rseg.h"
#include "trx0sys.h"
#include "trx0trx.h"
#include "trx0undo.h"
#include "usr0sess.h"
#include "current_thd.h"

Functions
static void	trx_rollback_finish (trx_t *trx)
	Finishes a transaction rollback. More...

static void	trx_rollback_to_savepoint_low (trx_t trx, trx_savept_t savept)
	Rollback a transaction used in MySQL. More...

dberr_t	trx_rollback_to_savepoint (trx_t trx, trx_savept_t savept)
	Rollback a transaction to a given savepoint or do a complete rollback. More...

static dberr_t	trx_rollback_for_mysql_low (trx_t *trx)
	Rollback a transaction used in MySQL. More...

static dberr_t	trx_rollback_low (trx_t *trx)
	Rollback a transaction used in MySQL. More...

dberr_t	trx_rollback_for_mysql (trx_t *trx)
	Rollback a transaction used in MySQL. More...

dberr_t	trx_rollback_last_sql_stat_for_mysql (trx_t *trx)
	Rollback the latest SQL statement for MySQL. More...

static trx_named_savept_t *	trx_savepoint_find (trx_t trx, const char name)
	Search for a savepoint using name. More...

static void	trx_roll_savepoint_free (trx_t trx, trx_named_savept_t savep)
	Frees a single savepoint struct. More...

void	trx_roll_savepoints_free (trx_t trx, trx_named_savept_t savep)
	Frees savepoint structs starting from savep. More...

static dberr_t	trx_rollback_to_savepoint_for_mysql_low (trx_t trx, trx_named_savept_t savep, int64_t *mysql_binlog_cache_pos)
	Rolls back a transaction back to a named savepoint. More...

dberr_t	trx_rollback_to_savepoint_for_mysql (trx_t trx, const char savepoint_name, int64_t *mysql_binlog_cache_pos)
	Rolls back a transaction back to a named savepoint. More...

dberr_t	trx_savepoint_for_mysql (trx_t trx, const char savepoint_name, int64_t binlog_cache_pos)
	Creates a named savepoint. More...

dberr_t	trx_release_savepoint_for_mysql (trx_t trx, const char savepoint_name)
	Releases only the named savepoint. More...

bool	trx_is_recv (const trx_t *trx)
	Determines if this transaction is rolling back an incomplete transaction in crash recovery. More...

trx_savept_t	trx_savept_take (trx_t *trx)
	Returns a transaction savepoint taken at this point in time. More...

static void	trx_rollback_active (trx_t *trx)
	Roll back an active transaction. More...

static bool	trx_rollback_or_clean_resurrected (trx_t *trx, bool all)
	Rollback or clean up any resurrected incomplete transactions. More...

void	trx_rollback_or_clean_recovered (bool all)
	Rollback or clean up any incomplete transactions which were encountered in crash recovery. More...

void	trx_recovery_rollback (THD *thd)
	Rollback or clean up any incomplete transactions which were encountered in crash recovery. More...

void	trx_recovery_rollback_thread ()
	Rollback or clean up any incomplete transactions which were encountered in crash recovery. More...

static void	trx_roll_try_truncate (trx_t trx, trx_undo_ptr_t undo_ptr)
	Tries truncate the undo logs. More...

static const page_t *	trx_roll_pop_top_rec (trx_t trx, trx_undo_t undo, mtr_t mtr, uint32_t undo_offset)
	Pops the topmost undo log record in a single undo log and updates the info about the topmost record in the undo log memory struct. More...

static trx_undo_rec_t *	trx_roll_pop_top_rec_of_trx_low (trx_t trx, trx_undo_ptr_t undo_ptr, undo_no_t limit, roll_ptr_t roll_ptr, mem_heap_t heap)
	Pops the topmost record when the two undo logs of a transaction are seen as a single stack of records ordered by their undo numbers. More...

trx_undo_rec_t *	trx_roll_pop_top_rec_of_trx (trx_t trx, undo_no_t limit, roll_ptr_t roll_ptr, mem_heap_t *heap)
	Get next undo log record from redo and noredo rollback segments. More...

static que_t *	trx_roll_graph_build (trx_t &trx, bool partial_rollback)
	Builds an undo 'query' graph for a transaction. More...

static que_thr_t *	trx_rollback_start (trx_t &trx, ib_id_t roll_limit, bool partial_rollback)
	Starts a rollback operation, creates the UNDO graph that will do the actual undo operation. More...

roll_node_t *	roll_node_create (mem_heap_t *heap)
	Creates a rollback command node struct. More...

que_thr_t *	trx_rollback_step (que_thr_t *thr)
	Performs an execution step for a rollback command node in a query graph. More...

Variables
static const ulint	TRX_ROLL_TRUNC_THRESHOLD = 1
	This many pages must be undone before a truncate is tried within rollback. More...

static const trx_t *	trx_roll_crash_recv_trx = nullptr
	In crash recovery, the current trx to be rolled back; NULL otherwise. More...

static undo_no_t	trx_roll_max_undo_no
	In crash recovery we set this to the undo n:o of the current trx to be rolled back. More...

static ulint	trx_roll_progress_printed_pct
	Auxiliary variable which tells the previous progress % we printed. More...

Detailed Description

Transaction rollback.

Created 3/26/1996 Heikki Tuuri

Function Documentation

◆ roll_node_create()

roll_node_t * roll_node_create ( mem_heap_t * heap )

Creates a rollback command node struct.

Returns: own: rollback node struct

Parameters

heap	in: mem heap where created

◆ trx_is_recv()

bool trx_is_recv ( const trx_t * trx )

Determines if this transaction is rolling back an incomplete transaction in crash recovery.

Returns: true if trx is an incomplete transaction that is being rolled back in crash recovery

Parameters

trx	in: transaction

◆ trx_recovery_rollback()

void trx_recovery_rollback ( THD * thd )

Rollback or clean up any incomplete transactions which were encountered in crash recovery.

If the transaction already was committed, then we clean up a possible insert undo log. If the transaction was not yet committed, then we roll it back. Note: this is done in a background thread.

◆ trx_recovery_rollback_thread()

void trx_recovery_rollback_thread ( )

Rollback or clean up any incomplete transactions which were encountered in crash recovery.

If the transaction already was committed, then we clean up a possible insert undo log. If the transaction was not yet committed, then we roll it back. Note: this is done in a background thread.

◆ trx_release_savepoint_for_mysql()

dberr_t trx_release_savepoint_for_mysql	(	trx_t *	trx,
		const char *	savepoint_name
	)

Releases only the named savepoint.

Releases a named savepoint.

Savepoints which were set after this savepoint are left as is.

Returns: if no savepoint of the name found then DB_NO_SAVEPOINT, otherwise DB_SUCCESS

Parameters

trx	in: transaction handle
savepoint_name	in: savepoint name

◆ trx_roll_graph_build()

static que_t * trx_roll_graph_build	(	trx_t &	trx,
		bool	partial_rollback
	)

static

Builds an undo 'query' graph for a transaction.

The actual rollback is performed by executing this query graph like a query subprocedure call. The reply about the completion of the rollback will be sent by this graph.

Parameters

[in,out]	trx	transaction
[in]	partial_rollback	true if partial rollback

Returns: the query graph

◆ trx_roll_pop_top_rec()

static const page_t * trx_roll_pop_top_rec	(	trx_t *	trx,
		trx_undo_t *	undo,
		mtr_t *	mtr,
		uint32_t *	undo_offset
	)

static

Pops the topmost undo log record in a single undo log and updates the info about the topmost record in the undo log memory struct.

Parameters

[in]	trx	transaction
[in]	undo	undo log
[in]	mtr	mtr
[out]	undo_offset	offset of undo record in the page

Returns: Undo page where undo log record resides, the page s-latched

◆ trx_roll_pop_top_rec_of_trx()

trx_undo_rec_t * trx_roll_pop_top_rec_of_trx	(	trx_t *	trx,
		undo_no_t	limit,
		roll_ptr_t *	roll_ptr,
		mem_heap_t *	heap
	)

Get next undo log record from redo and noredo rollback segments.

Returns: undo log record copied to heap, NULL if none left, or if the undo number of the top record would be less than the limit

Parameters

trx	in: transaction
limit	in: least undo number we need
roll_ptr	out: roll pointer to undo record
heap	in: memory heap where copied

◆ trx_roll_pop_top_rec_of_trx_low()

static trx_undo_rec_t * trx_roll_pop_top_rec_of_trx_low	(	trx_t *	trx,
		trx_undo_ptr_t *	undo_ptr,
		undo_no_t	limit,
		roll_ptr_t *	roll_ptr,
		mem_heap_t *	heap
	)

static

Pops the topmost record when the two undo logs of a transaction are seen as a single stack of records ordered by their undo numbers.

Returns: undo log record copied to heap, NULL if none left, or if the undo number of the top record would be less than the limit

Parameters

trx	in/out: transaction
undo_ptr	in: rollback segment to look for next undo log record.
limit	in: least undo number we need
roll_ptr	out: roll pointer to undo record
heap	in/out: memory heap where copied

◆ trx_roll_savepoint_free()

static void trx_roll_savepoint_free	(	trx_t *	trx,
		trx_named_savept_t *	savep
	)

static

Frees a single savepoint struct.

Parameters

trx	in: transaction handle
savep	in: savepoint to free

◆ trx_roll_savepoints_free()

void trx_roll_savepoints_free	(	trx_t *	trx,
		trx_named_savept_t *	savep
	)

Frees savepoint structs starting from savep.

Parameters

[in]	trx	Transaction handle
[in]	savep	Free all savepoints starting with this savepoint i, if savep is nullptr free all save points

◆ trx_roll_try_truncate()

static void trx_roll_try_truncate	(	trx_t *	trx,
		trx_undo_ptr_t *	undo_ptr
	)

static

Tries truncate the undo logs.

Parameters

trx	in/out: transaction
undo_ptr	in: rollback segment to look for next undo log record.

◆ trx_rollback_active()

static void trx_rollback_active ( trx_t * trx )

static

Roll back an active transaction.

Parameters

trx	in/out: transaction

◆ trx_rollback_finish()

static void trx_rollback_finish ( trx_t * trx )

static

Finishes a transaction rollback.

in: transaction

Parameters

trx	in: transaction

◆ trx_rollback_for_mysql()

dberr_t trx_rollback_for_mysql ( trx_t * trx )

Rollback a transaction used in MySQL.

Returns: error code or DB_SUCCESS

Parameters

trx	in/out: transaction

◆ trx_rollback_for_mysql_low()

static dberr_t trx_rollback_for_mysql_low ( trx_t * trx )

static

Rollback a transaction used in MySQL.

Returns: error code or DB_SUCCESS

Parameters

trx	in/out: transaction

◆ trx_rollback_last_sql_stat_for_mysql()

dberr_t trx_rollback_last_sql_stat_for_mysql ( trx_t * trx )

Rollback the latest SQL statement for MySQL.

Returns: error code or DB_SUCCESS

Parameters

trx	in/out: transaction

◆ trx_rollback_low()

static dberr_t trx_rollback_low ( trx_t * trx )

static

Rollback a transaction used in MySQL.

Parameters

[in,out] trx transaction

Returns: error code or DB_SUCCESS

◆ trx_rollback_or_clean_recovered()

void trx_rollback_or_clean_recovered ( bool all )

Rollback or clean up any incomplete transactions which were encountered in crash recovery.

If the transaction already was committed, then we clean up a possible insert undo log. If the transaction was not yet committed, then we roll it back.

Parameters

all	in: false=roll back dictionary transactions; true=roll back all non-PREPARED transactions

◆ trx_rollback_or_clean_resurrected()

static bool trx_rollback_or_clean_resurrected	(	trx_t *	trx,
		bool	all
	)

static

Rollback or clean up any resurrected incomplete transactions.

It assumes that the caller holds the trx_sys_t::mutex and it will release the lock if it does a clean up or rollback.

Returns: true if the transaction was cleaned up or rolled back and trx_sys->mutex was released.

Parameters

trx	in: transaction to rollback or clean
all	in: false=roll back dictionary transactions; true=roll back all non-PREPARED transactions

◆ trx_rollback_start()

static que_thr_t * trx_rollback_start	(	trx_t &	trx,
		ib_id_t	roll_limit,
		bool	partial_rollback
	)

static

Starts a rollback operation, creates the UNDO graph that will do the actual undo operation.

Parameters

[in]	trx	transaction
[in]	roll_limit	rollback to undo no (for partial undo), 0 if we are rolling back the entire transaction
[in]	partial_rollback	true if partial rollback

Returns: query graph thread that will perform the UNDO operations.

◆ trx_rollback_step()

que_thr_t * trx_rollback_step ( que_thr_t * thr )

Performs an execution step for a rollback command node in a query graph.

Returns: query thread to run next, or NULL

Parameters

thr	in: query thread

◆ trx_rollback_to_savepoint()

dberr_t trx_rollback_to_savepoint	(	trx_t *	trx,
		trx_savept_t *	savept
	)

Rollback a transaction to a given savepoint or do a complete rollback.

Returns: error code or DB_SUCCESS

Parameters

trx	in: transaction handle
savept	in: pointer to savepoint undo number, if partial rollback requested, or NULL for complete rollback

◆ trx_rollback_to_savepoint_for_mysql()

dberr_t trx_rollback_to_savepoint_for_mysql	(	trx_t *	trx,
		const char *	savepoint_name,
		int64_t *	mysql_binlog_cache_pos
	)

Rolls back a transaction back to a named savepoint.

Modifications after the savepoint are undone but InnoDB does NOT release the corresponding locks which are stored in memory. If a lock is 'implicit', that is, a new inserted row holds a lock where the lock information is carried by the trx id stored in the row, these locks are naturally released in the rollback. Savepoints which were set after this savepoint are deleted.

Returns: if no savepoint of the name found then DB_NO_SAVEPOINT, otherwise DB_SUCCESS

Parameters

trx	in: transaction handle
savepoint_name	in: savepoint name
mysql_binlog_cache_pos	out: the MySQL binlog cache position corresponding to this savepoint; MySQL needs this information to remove the binlog entries of the queries executed after the savepoint

◆ trx_rollback_to_savepoint_for_mysql_low()

static dberr_t trx_rollback_to_savepoint_for_mysql_low	(	trx_t *	trx,
		trx_named_savept_t *	savep,
		int64_t *	mysql_binlog_cache_pos
	)

static

Rolls back a transaction back to a named savepoint.

Modifications after the savepoint are undone but InnoDB does NOT release the corresponding locks which are stored in memory. If a lock is 'implicit', that is, a new inserted row holds a lock where the lock information is carried by the trx id stored in the row, these locks are naturally released in the rollback. Savepoints which were set after this savepoint are deleted.

Returns: if no savepoint of the name found then DB_NO_SAVEPOINT, otherwise DB_SUCCESS

Parameters

trx	in/out: transaction
savep	in/out: savepoint
mysql_binlog_cache_pos	out: the MySQL binlog cache position corresponding to this savepoint; MySQL needs this information to remove the binlog entries of the queries executed after the savepoint

◆ trx_rollback_to_savepoint_low()

static void trx_rollback_to_savepoint_low	(	trx_t *	trx,
		trx_savept_t *	savept
	)

static

Rollback a transaction used in MySQL.

Parameters

trx	in: transaction handle
savept	in: pointer to savepoint undo number, if partial rollback requested, or NULL for complete rollback

◆ trx_savepoint_find()

static trx_named_savept_t * trx_savepoint_find	(	trx_t *	trx,
		const char *	name
	)

static

Search for a savepoint using name.

Returns: savepoint if found else NULL

Parameters

trx	in: transaction
name	in: savepoint name

◆ trx_savepoint_for_mysql()

dberr_t trx_savepoint_for_mysql	(	trx_t *	trx,
		const char *	savepoint_name,
		int64_t	binlog_cache_pos
	)

Creates a named savepoint.

If the transaction is not yet started, starts it. If there is already a savepoint of the same name, this call erases that old savepoint and replaces it with a new. Savepoints are deleted in a transaction commit or rollback.

Returns: always DB_SUCCESS

Parameters

trx	in: transaction handle
savepoint_name	in: savepoint name
binlog_cache_pos	in: MySQL binlog cache position corresponding to this connection at the time of the savepoint

◆ trx_savept_take()

trx_savept_t trx_savept_take ( trx_t * trx )

Returns a transaction savepoint taken at this point in time.

Returns: savepoint

Parameters

trx	in: transaction

Variable Documentation

◆ trx_roll_crash_recv_trx

const trx_t* trx_roll_crash_recv_trx = nullptr

static

In crash recovery, the current trx to be rolled back; NULL otherwise.

◆ trx_roll_max_undo_no

undo_no_t trx_roll_max_undo_no

static

In crash recovery we set this to the undo n:o of the current trx to be rolled back.

Then we can print how many % the rollback has progressed.

◆ trx_roll_progress_printed_pct

ulint trx_roll_progress_printed_pct

static

Auxiliary variable which tells the previous progress % we printed.

◆ TRX_ROLL_TRUNC_THRESHOLD

const ulint TRX_ROLL_TRUNC_THRESHOLD = 1

static

This many pages must be undone before a truncate is tried within rollback.

Functions

Variables

Detailed Description

Function Documentation

◆ roll_node_create()

◆ trx_is_recv()

◆ trx_recovery_rollback()

◆ trx_recovery_rollback_thread()

◆ trx_release_savepoint_for_mysql()

◆ trx_roll_graph_build()

◆ trx_roll_pop_top_rec()

◆ trx_roll_pop_top_rec_of_trx()

◆ trx_roll_pop_top_rec_of_trx_low()

◆ trx_roll_savepoint_free()

◆ trx_roll_savepoints_free()

◆ trx_roll_try_truncate()

◆ trx_rollback_active()

◆ trx_rollback_finish()

◆ trx_rollback_for_mysql()

◆ trx_rollback_for_mysql_low()

◆ trx_rollback_last_sql_stat_for_mysql()

◆ trx_rollback_low()

◆ trx_rollback_or_clean_recovered()

◆ trx_rollback_or_clean_resurrected()

◆ trx_rollback_start()

◆ trx_rollback_step()

◆ trx_rollback_to_savepoint()

◆ trx_rollback_to_savepoint_for_mysql()

◆ trx_rollback_to_savepoint_for_mysql_low()

◆ trx_rollback_to_savepoint_low()

◆ trx_savepoint_find()

◆ trx_savepoint_for_mysql()

◆ trx_savept_take()

Variable Documentation

◆ trx_roll_crash_recv_trx

◆ trx_roll_max_undo_no

◆ trx_roll_progress_printed_pct

◆ TRX_ROLL_TRUNC_THRESHOLD