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/*****************************************************************************
Copyright (c) 1996, 2009, Innobase Oy. All Rights Reserved.
This program is free software; you can redistribute it and/or modify it under
the terms of the GNU General Public License as published by the Free Software
Foundation; version 2 of the License.
This program is distributed in the hope that it will be useful, but WITHOUT
ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.
You should have received a copy of the GNU General Public License along with
this program; if not, write to the Free Software Foundation, Inc., 59 Temple
Place, Suite 330, Boston, MA 02111-1307 USA
*****************************************************************************/
/**************************************************//**
@file include/trx0purge.h
Purge old versions
Created 3/26/1996 Heikki Tuuri
*******************************************************/
#ifndef trx0purge_h
#define trx0purge_h
#include "univ.i"
#include "trx0types.h"
#include "mtr0mtr.h"
#include "trx0sys.h"
#include "que0types.h"
#include "page0page.h"
#include "usr0sess.h"
#include "fil0fil.h"
/** The global data structure coordinating a purge */
extern trx_purge_t* purge_sys;
/** A dummy undo record used as a return value when we have a whole undo log
which needs no purge */
extern trx_undo_rec_t trx_purge_dummy_rec;
/********************************************************************//**
Calculates the file address of an undo log header when we have the file
address of its history list node.
@return file address of the log */
UNIV_INLINE
fil_addr_t
trx_purge_get_log_from_hist(
/*========================*/
fil_addr_t node_addr); /*!< in: file address of the history
list node of the log */
/*****************************************************************//**
Checks if trx_id is >= purge_view: then it is guaranteed that its update
undo log still exists in the system.
@return TRUE if is sure that it is preserved, also if the function
returns FALSE, it is possible that the undo log still exists in the
system */
UNIV_INTERN
ibool
trx_purge_update_undo_must_exist(
/*=============================*/
trx_id_t trx_id);/*!< in: transaction id */
/********************************************************************//**
Creates the global purge system control structure and inits the history
mutex. */
UNIV_INTERN
void
trx_purge_sys_create(void);
/*======================*/
/********************************************************************//**
Adds the update undo log as the first log in the history list. Removes the
update undo log segment from the rseg slot if it is too big for reuse. */
UNIV_INTERN
void
trx_purge_add_update_undo_to_history(
/*=================================*/
trx_t* trx, /*!< in: transaction */
page_t* undo_page, /*!< in: update undo log header page,
x-latched */
mtr_t* mtr); /*!< in: mtr */
/********************************************************************//**
Fetches the next undo log record from the history list to purge. It must be
released with the corresponding release function.
@return copy of an undo log record or pointer to trx_purge_dummy_rec,
if the whole undo log can skipped in purge; NULL if none left */
UNIV_INTERN
trx_undo_rec_t*
trx_purge_fetch_next_rec(
/*=====================*/
roll_ptr_t* roll_ptr,/*!< out: roll pointer to undo record */
trx_undo_inf_t** cell, /*!< out: storage cell for the record in the
purge array */
mem_heap_t* heap); /*!< in: memory heap where copied */
/*******************************************************************//**
Releases a reserved purge undo record. */
UNIV_INTERN
void
trx_purge_rec_release(
/*==================*/
trx_undo_inf_t* cell); /*!< in: storage cell */
/*******************************************************************//**
This function runs a purge batch.
@return number of undo log pages handled in the batch */
UNIV_INTERN
ulint
trx_purge(void);
/*===========*/
/******************************************************************//**
Prints information of the purge system to stderr. */
UNIV_INTERN
void
trx_purge_sys_print(void);
/*======================*/
/** The control structure used in the purge operation */
struct trx_purge_struct{
ulint state; /*!< Purge system state */
sess_t* sess; /*!< System session running the purge
query */
trx_t* trx; /*!< System transaction running the purge
query: this trx is not in the trx list
of the trx system and it never ends */
que_t* query; /*!< The query graph which will do the
parallelized purge operation */
rw_lock_t latch; /*!< The latch protecting the purge view.
A purge operation must acquire an
x-latch here for the instant at which
it changes the purge view: an undo
log operation can prevent this by
obtaining an s-latch here. */
read_view_t* view; /*!< The purge will not remove undo logs
which are >= this view (purge view) */
mutex_t mutex; /*!< Mutex protecting the fields below */
ulint n_pages_handled;/*!< Approximate number of undo log
pages processed in purge */
ulint handle_limit; /*!< Target of how many pages to get
processed in the current purge */
/*------------------------------*/
/* The following two fields form the 'purge pointer' which advances
during a purge, and which is used in history list truncation */
trx_id_t purge_trx_no; /*!< Purge has advanced past all
transactions whose number is less
than this */
undo_no_t purge_undo_no; /*!< Purge has advanced past all records
whose undo number is less than this */
/*-----------------------------*/
ibool next_stored; /*!< TRUE if the info of the next record
to purge is stored below: if yes, then
the transaction number and the undo
number of the record are stored in
purge_trx_no and purge_undo_no above */
trx_rseg_t* rseg; /*!< Rollback segment for the next undo
record to purge */
ulint page_no; /*!< Page number for the next undo
record to purge, page number of the
log header, if dummy record */
ulint offset; /*!< Page offset for the next undo
record to purge, 0 if the dummy
record */
ulint hdr_page_no; /*!< Header page of the undo log where
the next record to purge belongs */
ulint hdr_offset; /*!< Header byte offset on the page */
/*-----------------------------*/
trx_undo_arr_t* arr; /*!< Array of transaction numbers and
undo numbers of the undo records
currently under processing in purge */
mem_heap_t* heap; /*!< Temporary storage used during a
purge: can be emptied after purge
completes */
};
#define TRX_PURGE_ON 1 /* purge operation is running */
#define TRX_STOP_PURGE 2 /* purge operation is stopped, or
it should be stopped */
#ifndef UNIV_NONINL
#include "trx0purge.ic"
#endif
#endif
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