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*****************************************************************************/

/**************************************************//**
@file include/trx0roll.h
Transaction rollback

Created 3/26/1996 Heikki Tuuri
*******************************************************/

#ifndef trx0roll_h
#define trx0roll_h

#include "univ.i"
#include "btr0types.h"
#include "trx0trx.h"
#include "trx0types.h"
#include "mtr0mtr.h"
#include "trx0sys.h"

extern bool		trx_rollback_or_clean_is_active;
extern const trx_t*	trx_roll_crash_recv_trx;

/*******************************************************************//**
Determines if this transaction is rolling back an incomplete transaction
in crash recovery.
@return TRUE if trx is an incomplete transaction that is being rolled
back in crash recovery */
UNIV_INTERN
ibool
trx_is_recv(
/*========*/
	const trx_t*	trx);	/*!< in: transaction */
/*******************************************************************//**
Returns a transaction savepoint taken at this point in time.
@return	savepoint */
UNIV_INTERN
trx_savept_t
trx_savept_take(
/*============*/
	trx_t*	trx);	/*!< in: transaction */
/*******************************************************************//**
Frees an undo number array. */
UNIV_INTERN
void
trx_undo_arr_free(
/*==============*/
	trx_undo_arr_t*	arr);	/*!< in: undo number array */
/*******************************************************************//**
Returns pointer to nth element in an undo number array.
@return	pointer to the nth element */
UNIV_INLINE
trx_undo_inf_t*
trx_undo_arr_get_nth_info(
/*======================*/
	trx_undo_arr_t*	arr,	/*!< in: undo number array */
	ulint		n);	/*!< in: position */
/********************************************************************//**
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. Inserts the
undo number of the popped undo record to the array of currently processed
undo numbers in the transaction. When the query thread finishes processing
of this undo record, it must be released with trx_undo_rec_release.
@return 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 */
UNIV_INTERN
trx_undo_rec_t*
trx_roll_pop_top_rec_of_trx(
/*========================*/
	trx_t*		trx,	/*!< in: transaction */
	undo_no_t	limit,	/*!< in: least undo number we need */
	roll_ptr_t*	roll_ptr,/*!< out: roll pointer to undo record */
	mem_heap_t*	heap);	/*!< in: memory heap where copied */
/********************************************************************//**
Reserves an undo log record for a query thread to undo. This should be
called if the query thread gets the undo log record not using the pop
function above.
@return	TRUE if succeeded */
UNIV_INTERN
ibool
trx_undo_rec_reserve(
/*=================*/
	trx_t*		trx,	/*!< in/out: transaction */
	undo_no_t	undo_no);/*!< in: undo number of the record */
/*******************************************************************//**
Releases a reserved undo record. */
UNIV_INTERN
void
trx_undo_rec_release(
/*=================*/
	trx_t*		trx,	/*!< in/out: transaction */
	undo_no_t	undo_no);/*!< in: undo number */
/** Report progress when rolling back a row of a recovered transaction.
@return	whether the rollback should be aborted due to pending shutdown */
UNIV_INTERN
bool
trx_roll_must_shutdown();
/*******************************************************************//**
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. */
UNIV_INTERN
void
trx_rollback_or_clean_recovered(
/*============================*/
	ibool	all);	/*!< in: FALSE=roll back dictionary transactions;
			TRUE=roll back all non-PREPARED transactions */
/*******************************************************************//**
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.
@return	a dummy parameter */
extern "C" UNIV_INTERN
os_thread_ret_t
DECLARE_THREAD(trx_rollback_or_clean_all_recovered)(
/*================================================*/
	void*	arg MY_ATTRIBUTE((unused)));
			/*!< in: a dummy parameter required by
			os_thread_create */
/*********************************************************************//**
Creates a rollback command node struct.
@return	own: rollback node struct */
UNIV_INTERN
roll_node_t*
roll_node_create(
/*=============*/
	mem_heap_t*	heap);	/*!< in: mem heap where created */
/***********************************************************//**
Performs an execution step for a rollback command node in a query graph.
@return	query thread to run next, or NULL */
UNIV_INTERN
que_thr_t*
trx_rollback_step(
/*==============*/
	que_thr_t*	thr);	/*!< in: query thread */
/*******************************************************************//**
Rollback a transaction used in MySQL.
@return	error code or DB_SUCCESS */
UNIV_INTERN
dberr_t
trx_rollback_for_mysql(
/*===================*/
	trx_t*	trx)	/*!< in/out: transaction */
	MY_ATTRIBUTE((nonnull));
/*******************************************************************//**
Rollback the latest SQL statement for MySQL.
@return	error code or DB_SUCCESS */
UNIV_INTERN
dberr_t
trx_rollback_last_sql_stat_for_mysql(
/*=================================*/
	trx_t*	trx)	/*!< in/out: transaction */
	MY_ATTRIBUTE((nonnull));
/*******************************************************************//**
Rollback a transaction to a given savepoint or do a complete rollback.
@return	error code or DB_SUCCESS */
UNIV_INTERN
dberr_t
trx_rollback_to_savepoint(
/*======================*/
	trx_t*		trx,	/*!< in: transaction handle */
	trx_savept_t*	savept)	/*!< in: pointer to savepoint undo number, if
				partial rollback requested, or NULL for
				complete rollback */
	MY_ATTRIBUTE((nonnull(1)));
/*******************************************************************//**
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.
@return if no savepoint of the name found then DB_NO_SAVEPOINT,
otherwise DB_SUCCESS */
UNIV_INTERN
dberr_t
trx_rollback_to_savepoint_for_mysql(
/*================================*/
	trx_t*		trx,			/*!< in: transaction handle */
	const char*	savepoint_name,		/*!< in: savepoint name */
	ib_int64_t*	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 */
	MY_ATTRIBUTE((nonnull, warn_unused_result));
/*******************************************************************//**
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.
@return	always DB_SUCCESS */
UNIV_INTERN
dberr_t
trx_savepoint_for_mysql(
/*====================*/
	trx_t*		trx,			/*!< in: transaction handle */
	const char*	savepoint_name,		/*!< in: savepoint name */
	ib_int64_t	binlog_cache_pos)	/*!< in: MySQL binlog cache
						position corresponding to this
						connection at the time of the
						savepoint */
	MY_ATTRIBUTE((nonnull));
/*******************************************************************//**
Releases a named savepoint. Savepoints which
were set after this savepoint are deleted.
@return if no savepoint of the name found then DB_NO_SAVEPOINT,
otherwise DB_SUCCESS */
UNIV_INTERN
dberr_t
trx_release_savepoint_for_mysql(
/*============================*/
	trx_t*		trx,			/*!< in: transaction handle */
	const char*	savepoint_name)		/*!< in: savepoint name */
	MY_ATTRIBUTE((nonnull, warn_unused_result));
/*******************************************************************//**
Frees savepoint structs starting from savep. */
UNIV_INTERN
void
trx_roll_savepoints_free(
/*=====================*/
	trx_t*			trx,	/*!< in: transaction handle */
	trx_named_savept_t*	savep);	/*!< in: free all savepoints > this one;
					if this is NULL, free all savepoints
					of trx */

/** A cell of trx_undo_arr_t; used during a rollback and a purge */
struct	trx_undo_inf_t{
	ibool		in_use;	/*!< true if cell is being used */
	trx_id_t	trx_no;	/*!< transaction number: not defined during
				a rollback */
	undo_no_t	undo_no;/*!< undo number of an undo record */
};

/** During a rollback and a purge, undo numbers of undo records currently being
processed are stored in this array */

struct trx_undo_arr_t{
	ulint		n_cells;	/*!< number of cells in the array */
	ulint		n_used;		/*!< number of cells in use */
	trx_undo_inf_t*	infos;		/*!< the array of undo infos */
	mem_heap_t*	heap;		/*!< memory heap from which allocated */
};

/** Rollback node states */
enum roll_node_state {
	ROLL_NODE_NONE = 0,		/*!< Unknown state */
	ROLL_NODE_SEND,			/*!< about to send a rollback signal to
					the transaction */
	ROLL_NODE_WAIT			/*!< rollback signal sent to the
				       	transaction, waiting for completion */
};

/** Rollback command node in a query graph */
struct roll_node_t{
	que_common_t		common;	/*!< node type: QUE_NODE_ROLLBACK */
	enum roll_node_state	state;	/*!< node execution state */
	ibool			partial;/*!< TRUE if we want a partial
					rollback */
	trx_savept_t		savept;	/*!< savepoint to which to
					roll back, in the case of a
					partial rollback */
	que_thr_t*		undo_thr;/*!< undo query graph */
};

/** A savepoint set with SQL's "SAVEPOINT savepoint_id" command */
struct trx_named_savept_t{
	char*		name;		/*!< savepoint name */
	trx_savept_t	savept;		/*!< the undo number corresponding to
					the savepoint */
	ib_int64_t	mysql_binlog_cache_pos;
					/*!< the MySQL binlog cache position
					corresponding to this savepoint, not
					defined if the MySQL binlogging is not
					enabled */
	UT_LIST_NODE_T(trx_named_savept_t)
			trx_savepoints;	/*!< the list of savepoints of a
					transaction */
};

#ifndef UNIV_NONINL
#include "trx0roll.ic"
#endif

#endif
