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/*****************************************************************************
Copyright (c) 1996, 2011, Oracle and/or its affiliates. All Rights Reserved.
Copyright (c) 2017, MariaDB Corporation. 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.,
51 Franklin Street, Suite 500, Boston, MA 02110-1335 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 */
/********************************************************************//**
Creates the global purge system control structure and inits the history
mutex. */
UNIV_INTERN
void
trx_purge_sys_create(
/*=================*/
ulint n_purge_threads,/*!< in: number of purge threads */
ib_bh_t* ib_bh); /*!< in/own: UNDO log min binary heap*/
/********************************************************************//**
Frees the global purge system control structure. */
UNIV_INTERN
void
trx_purge_sys_close(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 */
/*******************************************************************//**
This function runs a purge batch.
@return number of undo log pages handled in the batch */
UNIV_INTERN
ulint
trx_purge(
/*======*/
ulint n_purge_threads, /*!< in: number of purge tasks to
submit to task queue. */
ulint limit, /*!< in: the maximum number of
records to purge in one batch */
bool truncate); /*!< in: truncate history if true */
/*******************************************************************//**
Stop purge and wait for it to stop, move to PURGE_STATE_STOP. */
UNIV_INTERN
void
trx_purge_stop(void);
/*================*/
/*******************************************************************//**
Resume purge, move to PURGE_STATE_RUN. */
UNIV_INTERN
void
trx_purge_run(void);
/*================*/
/** Purge states */
enum purge_state_t {
PURGE_STATE_INIT, /*!< Purge instance created */
PURGE_STATE_RUN, /*!< Purge should be running */
PURGE_STATE_STOP, /*!< Purge should be stopped */
PURGE_STATE_EXIT, /*!< Purge has been shutdown */
PURGE_STATE_DISABLED /*!< Purge was never started */
};
/*******************************************************************//**
Get the purge state.
@return purge state. */
UNIV_INTERN
purge_state_t
trx_purge_state(void);
/*=================*/
/** This is the purge pointer/iterator. We need both the undo no and the
transaction no up to which purge has parsed and applied the records. */
struct purge_iter_t {
trx_id_t trx_no; /*!< Purge has advanced past all
transactions whose number is less
than this */
undo_no_t undo_no; /*!< Purge has advanced past all records
whose undo number is less than this */
};
/** The control structure used in the purge operation */
struct trx_purge_t{
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 */
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. It also
protects state and running */
os_event_t event; /*!< State signal event;
os_event_set() and os_event_reset()
are protected by trx_purge_t::latch
X-lock */
ulint n_stop; /*!< Counter to track number stops */
volatile bool running; /*!< true, if purge is active,
we check this without the latch too */
volatile purge_state_t state; /*!< Purge coordinator thread states,
we check this in several places
without holding the latch. */
que_t* query; /*!< The query graph which will do the
parallelized purge operation */
read_view_t* view; /*!< The purge will not remove undo logs
which are >= this view (purge view) */
volatile ulint n_submitted; /*!< Count of total tasks submitted
to the task queue */
volatile ulint n_completed; /*!< Count of total tasks completed */
/*------------------------------*/
/* The following two fields form the 'purge pointer' which advances
during a purge, and which is used in history list truncation */
purge_iter_t iter; /* Limit up to which we have read and
parsed the UNDO log records. Not
necessarily purged from the indexes.
Note that this can never be less than
the limit below, we check for this
invariant in trx0purge.cc */
purge_iter_t limit; /* The 'purge pointer' which advances
during a purge, and which is used in
history list truncation */
#ifdef UNIV_DEBUG
purge_iter_t done; /* Indicate 'purge pointer' which have
purged already accurately. */
#endif /* UNIV_DEBUG */
/*-----------------------------*/
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 */
/*-----------------------------*/
mem_heap_t* heap; /*!< Temporary storage used during a
purge: can be emptied after purge
completes */
/*-----------------------------*/
ib_bh_t* ib_bh; /*!< Binary min-heap, ordered on
rseg_queue_t::trx_no. It is protected
by the bh_mutex */
ib_mutex_t bh_mutex; /*!< Mutex protecting ib_bh */
};
/** Info required to purge a record */
struct trx_purge_rec_t {
trx_undo_rec_t* undo_rec; /*!< Record to purge */
roll_ptr_t roll_ptr; /*!< File pointr to UNDO record */
};
#ifndef UNIV_NONINL
#include "trx0purge.ic"
#endif
#endif
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