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/*****************************************************************************
Copyright (c) 1996, 2013, Oracle and/or its affiliates. All Rights Reserved.
Copyright (c) 2017, 2021, MariaDB Corporation.
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, Fifth Floor, Boston, MA 02110-1335 USA
*****************************************************************************/
/**************************************************//**
@file include/trx0undo.ic
Transaction undo log
Created 3/26/1996 Heikki Tuuri
*******************************************************/
#include "data0type.h"
#include "page0page.h"
/***********************************************************************//**
Builds a roll pointer.
@return roll pointer */
UNIV_INLINE
roll_ptr_t
trx_undo_build_roll_ptr(
/*====================*/
bool is_insert, /*!< in: TRUE if insert undo log */
ulint rseg_id, /*!< in: rollback segment id */
uint32_t page_no, /*!< in: page number */
uint16_t offset) /*!< in: offset of the undo entry within page */
{
compile_time_assert(DATA_ROLL_PTR_LEN == 7);
ut_ad(rseg_id < TRX_SYS_N_RSEGS);
return roll_ptr_t{is_insert} << ROLL_PTR_INSERT_FLAG_POS |
roll_ptr_t{rseg_id} << ROLL_PTR_RSEG_ID_POS |
roll_ptr_t{page_no} << ROLL_PTR_PAGE_POS | offset;
}
/***********************************************************************//**
Decodes a roll pointer. */
UNIV_INLINE
void
trx_undo_decode_roll_ptr(
/*=====================*/
roll_ptr_t roll_ptr, /*!< in: roll pointer */
bool* is_insert, /*!< out: TRUE if insert undo log */
ulint* rseg_id, /*!< out: rollback segment id */
uint32_t* page_no, /*!< out: page number */
uint16_t* offset) /*!< out: offset of the undo
entry within page */
{
compile_time_assert(DATA_ROLL_PTR_LEN == 7);
ut_ad(roll_ptr < (1ULL << 56));
*offset= static_cast<uint16_t>(roll_ptr);
*page_no= static_cast<uint32_t>(roll_ptr >> 16);
*rseg_id= static_cast<ulint>(roll_ptr >> 48 & 0x7F);
*is_insert= static_cast<bool>(roll_ptr >> 55);
}
/***********************************************************************//**
Determine if DB_ROLL_PTR is of the insert type.
@return true if insert */
UNIV_INLINE
bool
trx_undo_roll_ptr_is_insert(
/*========================*/
roll_ptr_t roll_ptr) /*!< in: roll pointer */
{
compile_time_assert(DATA_ROLL_PTR_LEN == 7);
ut_ad(roll_ptr < (1ULL << (ROLL_PTR_INSERT_FLAG_POS + 1)));
return static_cast<bool>(roll_ptr >> ROLL_PTR_INSERT_FLAG_POS);
}
/***********************************************************************//**
Returns true if the record is of the insert type.
@return true if the record was freshly inserted (not updated). */
UNIV_INLINE
bool
trx_undo_trx_id_is_insert(
/*======================*/
const byte* trx_id) /*!< in: DB_TRX_ID, followed by DB_ROLL_PTR */
{
compile_time_assert(DATA_TRX_ID + 1 == DATA_ROLL_PTR);
return bool(trx_id[DATA_TRX_ID_LEN] >> 7);
}
/** Gets an undo log page and x-latches it.
@param[in] page_id page id
@param[in,out] mtr mini-transaction
@return pointer to page x-latched */
UNIV_INLINE
buf_block_t*
trx_undo_page_get(const page_id_t page_id, mtr_t* mtr)
{
return buf_page_get(page_id, 0, RW_X_LATCH, mtr);
}
/** Gets an undo log page and s-latches it.
@param[in] page_id page id
@param[in,out] mtr mini-transaction
@return pointer to page s-latched */
UNIV_INLINE
buf_block_t*
trx_undo_page_get_s_latched(const page_id_t page_id, mtr_t* mtr)
{
return buf_page_get(page_id, 0, RW_S_LATCH, mtr);
}
/** Determine the end offset of undo log records of an undo log page.
@param[in] undo_page undo log page
@param[in] page_no undo log header page number
@param[in] offset undo log header offset
@return end offset */
inline
uint16_t trx_undo_page_get_end(const buf_block_t *undo_page, uint32_t page_no,
uint16_t offset)
{
if (page_no == undo_page->page.id().page_no())
if (uint16_t end = mach_read_from_2(TRX_UNDO_NEXT_LOG + offset +
undo_page->page.frame))
return end;
return mach_read_from_2(TRX_UNDO_PAGE_HDR + TRX_UNDO_PAGE_FREE +
undo_page->page.frame);
}
/** Get the next record in an undo log.
@param[in] undo_page undo log page
@param[in] rec undo record offset in the page
@param[in] page_no undo log header page number
@param[in] offset undo log header offset on page
@return undo log record, the page latched, NULL if none */
inline trx_undo_rec_t*
trx_undo_page_get_next_rec(const buf_block_t *undo_page, uint16_t rec,
uint32_t page_no, uint16_t offset)
{
uint16_t end= trx_undo_page_get_end(undo_page, page_no, offset);
uint16_t next= mach_read_from_2(undo_page->page.frame + rec);
return next == end ? nullptr : undo_page->page.frame + next;
}
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