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