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/******************************************************
Purge old versions
(c) 1996 Innobase Oy
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. */
UNIV_INLINE
fil_addr_t
trx_purge_get_log_from_hist(
/*========================*/
/* out: file address of the log */
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. */
ibool
trx_purge_update_undo_must_exist(
/*=============================*/
/* out: 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 */
dulint trx_id);/* in: transaction id */
/************************************************************************
Creates the global purge system control structure and inits the history
mutex. */
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. */
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. */
trx_undo_rec_t*
trx_purge_fetch_next_rec(
/*=====================*/
/* out: copy of an undo log record, or
pointer to the dummy undo log record
&trx_purge_dummy_rec if the whole undo log
can skipped in purge; NULL if none left */
dulint* 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. */
void
trx_purge_rec_release(
/*==================*/
trx_undo_inf_t* cell); /* in: storage cell */
/***********************************************************************
This function runs a purge batch. */
ulint
trx_purge(void);
/*===========*/
/* out: number of undo log pages handled in
the batch */
/**********************************************************************
Prints information of the purge system to stderr. */
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 */
dulint purge_trx_no; /* Purge has advanced past all
transactions whose number is less
than this */
dulint 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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