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/*****************************************************************************
Copyright (c) 1996, 2016, 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.h
Transaction undo log
Created 3/26/1996 Heikki Tuuri
*******************************************************/
#ifndef trx0undo_h
#define trx0undo_h
#ifndef UNIV_INNOCHECKSUM
#include "trx0sys.h"
/** The LSB of the "is insert" flag in DB_ROLL_PTR */
#define ROLL_PTR_INSERT_FLAG_POS 55
/** The LSB of the 7-bit trx_rseg_t::id in DB_ROLL_PTR */
#define ROLL_PTR_RSEG_ID_POS 48
/** The LSB of the 32-bit undo log page number in DB_ROLL_PTR */
#define ROLL_PTR_PAGE_POS 16
/** The LSB of the 16-bit byte offset within an undo log page in DB_ROLL_PTR */
#define ROLL_PTR_BYTE_POS 0
/***********************************************************************//**
Builds a roll pointer.
@return roll pointer */
UNIV_INLINE
roll_ptr_t
trx_undo_build_roll_ptr(
/*====================*/
ibool is_insert, /*!< in: TRUE if insert undo log */
ulint rseg_id, /*!< in: rollback segment id */
ulint page_no, /*!< in: page number */
ulint offset); /*!< in: offset of the undo entry within page */
/***********************************************************************//**
Decodes a roll pointer. */
UNIV_INLINE
void
trx_undo_decode_roll_ptr(
/*=====================*/
roll_ptr_t roll_ptr, /*!< in: roll pointer */
ibool* is_insert, /*!< out: TRUE if insert undo log */
ulint* rseg_id, /*!< out: rollback segment id */
ulint* page_no, /*!< out: page number */
ulint* offset); /*!< out: offset of the undo
entry within page */
/***********************************************************************//**
Returns TRUE if the roll pointer is of the insert type.
@return TRUE if insert undo log */
UNIV_INLINE
ibool
trx_undo_roll_ptr_is_insert(
/*========================*/
roll_ptr_t roll_ptr); /*!< in: roll pointer */
/***********************************************************************//**
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 */
MY_ATTRIBUTE((warn_unused_result));
/** Write DB_ROLL_PTR.
@param[out] ptr buffer
@param[in] roll_ptr DB_ROLL_PTR value */
inline void trx_write_roll_ptr(byte* ptr, roll_ptr_t roll_ptr)
{
compile_time_assert(DATA_ROLL_PTR_LEN == 7);
mach_write_to_7(ptr, roll_ptr);
}
/** Read DB_ROLL_PTR.
@param[in] ptr buffer
@return roll ptr */
inline roll_ptr_t trx_read_roll_ptr(const byte* ptr)
{
compile_time_assert(DATA_ROLL_PTR_LEN == 7);
return mach_read_from_7(ptr);
}
/** 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
page_t*
trx_undo_page_get(const page_id_t page_id, mtr_t* 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
page_t*
trx_undo_page_get_s_latched(const page_id_t page_id, mtr_t* mtr);
/******************************************************************//**
Returns the next undo log record on the page in the specified log, or
NULL if none exists.
@return pointer to record, NULL if none */
UNIV_INLINE
trx_undo_rec_t*
trx_undo_page_get_next_rec(
/*=======================*/
trx_undo_rec_t* rec, /*!< in: undo log record */
ulint page_no,/*!< in: undo log header page number */
ulint offset);/*!< in: undo log header offset on page */
/***********************************************************************//**
Gets the previous record in an undo log.
@return undo log record, the page s-latched, NULL if none */
trx_undo_rec_t*
trx_undo_get_prev_rec(
/*==================*/
trx_undo_rec_t* rec, /*!< in: undo record */
ulint page_no,/*!< in: undo log header page number */
ulint offset, /*!< in: undo log header offset on page */
bool shared, /*!< in: true=S-latch, false=X-latch */
mtr_t* mtr); /*!< in: mtr */
/***********************************************************************//**
Gets the next record in an undo log.
@return undo log record, the page s-latched, NULL if none */
trx_undo_rec_t*
trx_undo_get_next_rec(
/*==================*/
trx_undo_rec_t* rec, /*!< in: undo record */
ulint page_no,/*!< in: undo log header page number */
ulint offset, /*!< in: undo log header offset on page */
mtr_t* mtr); /*!< in: mtr */
/** Gets the first record in an undo log.
@param[in] space undo log header space
@param[in] page_no undo log header page number
@param[in] offset undo log header offset on page
@param[in] mode latching mode: RW_S_LATCH or RW_X_LATCH
@param[in,out] mtr mini-transaction
@return undo log record, the page latched, NULL if none */
trx_undo_rec_t*
trx_undo_get_first_rec(
fil_space_t* space,
ulint page_no,
ulint offset,
ulint mode,
mtr_t* mtr);
/** Allocate an undo log page.
@param[in,out] undo undo log
@param[in,out] mtr mini-transaction that does not hold any page latch
@return X-latched block if success
@retval NULL on failure */
buf_block_t* trx_undo_add_page(trx_undo_t* undo, mtr_t* mtr)
MY_ATTRIBUTE((nonnull, warn_unused_result));
/** Free the last undo log page. The caller must hold the rseg mutex.
@param[in,out] undo undo log
@param[in,out] mtr mini-transaction that does not hold any undo log page
or that has allocated the undo log page */
void
trx_undo_free_last_page(trx_undo_t* undo, mtr_t* mtr)
MY_ATTRIBUTE((nonnull));
/** Truncate the tail of an undo log during rollback.
@param[in,out] undo undo log
@param[in] limit all undo logs after this limit will be discarded
@param[in] is_temp whether this is temporary undo log */
void trx_undo_truncate_end(trx_undo_t& undo, undo_no_t limit, bool is_temp);
/** Truncate the head of an undo log.
NOTE that only whole pages are freed; the header page is not
freed, but emptied, if all the records there are below the limit.
@param[in,out] rseg rollback segment
@param[in] hdr_page_no header page number
@param[in] hdr_offset header offset on the page
@param[in] limit first undo number to preserve
(everything below the limit will be truncated) */
void
trx_undo_truncate_start(
trx_rseg_t* rseg,
ulint hdr_page_no,
ulint hdr_offset,
undo_no_t limit);
/** Mark that an undo log header belongs to a data dictionary transaction.
@param[in] trx dictionary transaction
@param[in,out] undo undo log
@param[in,out] mtr mini-transaction */
void trx_undo_mark_as_dict(const trx_t* trx, trx_undo_t* undo, mtr_t* mtr);
/** Assign an undo log for a persistent transaction.
A new undo log is created or a cached undo log reused.
@param[in,out] trx transaction
@param[out] err error code
@param[in,out] mtr mini-transaction
@return the undo log block
@retval NULL on error */
buf_block_t*
trx_undo_assign(trx_t* trx, dberr_t* err, mtr_t* mtr)
MY_ATTRIBUTE((nonnull));
/** Assign an undo log for a transaction.
A new undo log is created or a cached undo log reused.
@param[in,out] trx transaction
@param[in] rseg rollback segment
@param[out] undo the undo log
@param[out] err error code
@param[in,out] mtr mini-transaction
@return the undo log block
@retval NULL on error */
buf_block_t*
trx_undo_assign_low(trx_t* trx, trx_rseg_t* rseg, trx_undo_t** undo,
dberr_t* err, mtr_t* mtr)
MY_ATTRIBUTE((nonnull, warn_unused_result));
/******************************************************************//**
Sets the state of the undo log segment at a transaction finish.
@return undo log segment header page, x-latched */
page_t*
trx_undo_set_state_at_finish(
/*=========================*/
trx_undo_t* undo, /*!< in: undo log memory copy */
mtr_t* mtr); /*!< in: mtr */
/** Set the state of the undo log segment at a XA PREPARE or XA ROLLBACK.
@param[in,out] trx transaction
@param[in,out] undo undo log
@param[in] rollback false=XA PREPARE, true=XA ROLLBACK
@param[in,out] mtr mini-transaction */
void trx_undo_set_state_at_prepare(trx_t *trx, trx_undo_t *undo, bool rollback,
mtr_t *mtr)
MY_ATTRIBUTE((nonnull));
/** Free temporary undo log after commit or rollback.
The information is not needed after a commit or rollback, therefore
the data can be discarded.
@param undo temporary undo log */
void trx_undo_commit_cleanup(trx_undo_t *undo);
/** At shutdown, frees the undo logs of a transaction. */
void
trx_undo_free_at_shutdown(trx_t *trx);
/** Parse MLOG_UNDO_INIT.
@param[in] ptr log record
@param[in] end_ptr end of log record buffer
@param[in,out] page page or NULL
@param[in,out] mtr mini-transaction
@return end of log record
@retval NULL if the log record is incomplete */
byte*
trx_undo_parse_page_init(const byte* ptr, const byte* end_ptr, page_t* page);
/** Parse MLOG_UNDO_HDR_REUSE for crash-upgrade from MariaDB 10.2.
@param[in] ptr redo log record
@param[in] end_ptr end of log buffer
@param[in,out] page undo page or NULL
@return end of log record or NULL */
byte*
trx_undo_parse_page_header_reuse(
const byte* ptr,
const byte* end_ptr,
page_t* page);
/** Parse the redo log entry of an undo log page header create.
@param[in] ptr redo log record
@param[in] end_ptr end of log buffer
@param[in,out] page page frame or NULL
@param[in,out] mtr mini-transaction or NULL
@return end of log record or NULL */
byte*
trx_undo_parse_page_header(
const byte* ptr,
const byte* end_ptr,
page_t* page,
mtr_t* mtr);
/** Read an undo log when starting up the database.
@param[in,out] rseg rollback segment
@param[in] id rollback segment slot
@param[in] page_no undo log segment page number
@param[in,out] max_trx_id the largest observed transaction ID
@return the undo log
@retval nullptr on error */
trx_undo_t *
trx_undo_mem_create_at_db_start(trx_rseg_t *rseg, ulint id, uint32_t page_no,
trx_id_t &max_trx_id);
#endif /* !UNIV_INNOCHECKSUM */
/** the only rollback segment type since MariaDB 10.3.1 */
constexpr uint16_t TRX_UNDO_UPDATE= 2;
/* TRX_UNDO_STATE values of an undo log segment */
/** contains an undo log of an active transaction */
constexpr uint16_t TRX_UNDO_ACTIVE = 1;
/** cached for quick reuse */
constexpr uint16_t TRX_UNDO_CACHED = 2;
/** can be freed in purge when all undo data in it is removed */
constexpr uint16_t TRX_UNDO_TO_PURGE = 4;
/** contains an undo log of a prepared transaction */
constexpr uint16_t TRX_UNDO_PREPARED = 5;
#ifndef UNIV_INNOCHECKSUM
/** Transaction undo log memory object; modified by the thread associated
with the transaction. */
struct trx_undo_t {
/*-----------------------------*/
ulint id; /*!< undo log slot number within the
rollback segment */
ulint state; /*!< state of the corresponding undo log
segment */
trx_id_t trx_id; /*!< id of the trx assigned to the undo
log */
XID xid; /*!< X/Open XA transaction
identification */
ibool dict_operation; /*!< TRUE if a dict operation trx */
table_id_t table_id; /*!< if a dict operation, then the table
id */
trx_rseg_t* rseg; /*!< rseg where the undo log belongs */
/*-----------------------------*/
ulint hdr_page_no; /*!< page number of the header page in
the undo log */
ulint hdr_offset; /*!< header offset of the undo log on
the page */
ulint last_page_no; /*!< page number of the last page in the
undo log; this may differ from
top_page_no during a rollback */
ulint size; /*!< current size in pages */
/*-----------------------------*/
ulint top_page_no; /*!< page number where the latest undo
log record was catenated; during
rollback the page from which the latest
undo record was chosen */
ulint top_offset; /*!< offset of the latest undo record,
i.e., the topmost element in the undo
log if we think of it as a stack */
undo_no_t top_undo_no; /*!< undo number of the latest record
(IB_ID_MAX if the undo log is empty) */
buf_block_t* guess_block; /*!< guess for the buffer block where
the top page might reside */
/** @return whether the undo log is empty */
bool empty() const { return top_undo_no == IB_ID_MAX; }
/*-----------------------------*/
UT_LIST_NODE_T(trx_undo_t) undo_list;
/*!< undo log objects in the rollback
segment are chained into lists */
};
#endif /* !UNIV_INNOCHECKSUM */
/** The offset of the undo log page header on pages of the undo log */
#define TRX_UNDO_PAGE_HDR FSEG_PAGE_DATA
/*-------------------------------------------------------------*/
/** Transaction undo log page header offsets */
/* @{ */
#define TRX_UNDO_PAGE_TYPE 0 /*!< unused; 0 (before MariaDB 10.3.1:
1=TRX_UNDO_INSERT or
2=TRX_UNDO_UPDATE) */
#define TRX_UNDO_PAGE_START 2 /*!< Byte offset where the undo log
records for the LATEST transaction
start on this page (remember that
in an update undo log, the first page
can contain several undo logs) */
#define TRX_UNDO_PAGE_FREE 4 /*!< On each page of the undo log this
field contains the byte offset of the
first free byte on the page */
#define TRX_UNDO_PAGE_NODE 6 /*!< The file list node in the chain
of undo log pages */
/*-------------------------------------------------------------*/
#define TRX_UNDO_PAGE_HDR_SIZE (6 + FLST_NODE_SIZE)
/*!< Size of the transaction undo
log page header, in bytes */
/* @} */
/** An update undo segment with just one page can be reused if it has
at most this many bytes used; we must leave space at least for one new undo
log header on the page */
#define TRX_UNDO_PAGE_REUSE_LIMIT (3 << (srv_page_size_shift - 2))
/* An update undo log segment may contain several undo logs on its first page
if the undo logs took so little space that the segment could be cached and
reused. All the undo log headers are then on the first page, and the last one
owns the undo log records on subsequent pages if the segment is bigger than
one page. If an undo log is stored in a segment, then on the first page it is
allowed to have zero undo records, but if the segment extends to several
pages, then all the rest of the pages must contain at least one undo log
record. */
/** The offset of the undo log segment header on the first page of the undo
log segment */
#define TRX_UNDO_SEG_HDR (TRX_UNDO_PAGE_HDR + TRX_UNDO_PAGE_HDR_SIZE)
/** Undo log segment header */
/* @{ */
/*-------------------------------------------------------------*/
#define TRX_UNDO_STATE 0 /*!< TRX_UNDO_ACTIVE, ... */
#ifndef UNIV_INNOCHECKSUM
#define TRX_UNDO_LAST_LOG 2 /*!< Offset of the last undo log header
on the segment header page, 0 if
none */
#define TRX_UNDO_FSEG_HEADER 4 /*!< Header for the file segment which
the undo log segment occupies */
#define TRX_UNDO_PAGE_LIST (4 + FSEG_HEADER_SIZE)
/*!< Base node for the list of pages in
the undo log segment; defined only on
the undo log segment's first page */
/*-------------------------------------------------------------*/
/** Size of the undo log segment header */
#define TRX_UNDO_SEG_HDR_SIZE (4 + FSEG_HEADER_SIZE + FLST_BASE_NODE_SIZE)
/* @} */
/** The undo log header. There can be several undo log headers on the first
page of an update undo log segment. */
/* @{ */
/*-------------------------------------------------------------*/
/** Transaction start identifier, or 0 if the undo log segment has been
completely purged and trx_purge_free_segment() has started freeing it */
#define TRX_UNDO_TRX_ID 0
/** Transaction end identifier (if the log is in a history list),
or 0 if the transaction has not been committed */
#define TRX_UNDO_TRX_NO 8
/** Before MariaDB 10.3.1, when purge did not reset DB_TRX_ID of
surviving user records, this used to be called TRX_UNDO_DEL_MARKS.
The value 1 indicates that purge needs to process the undo log segment.
The value 0 indicates that all of it has been processed, and
trx_purge_free_segment() has been invoked, so the log is not safe to access.
Before MariaDB 10.3.1, a log segment may carry the value 0 even before
trx_purge_free_segment() was called, for those undo log records for
which purge would not result in removing delete-marked records. */
#define TRX_UNDO_NEEDS_PURGE 16
#define TRX_UNDO_LOG_START 18 /*!< Offset of the first undo log record
of this log on the header page; purge
may remove undo log record from the
log start, and therefore this is not
necessarily the same as this log
header end offset */
#define TRX_UNDO_XID_EXISTS 20 /*!< TRUE if undo log header includes
X/Open XA transaction identification
XID */
#define TRX_UNDO_DICT_TRANS 21 /*!< TRUE if the transaction is a table
create, index create, or drop
transaction: in recovery
the transaction cannot be rolled back
in the usual way: a 'rollback' rather
means dropping the created or dropped
table, if it still exists */
#define TRX_UNDO_TABLE_ID 22 /*!< Id of the table if the preceding
field is TRUE */
#define TRX_UNDO_NEXT_LOG 30 /*!< Offset of the next undo log header
on this page, 0 if none */
#define TRX_UNDO_PREV_LOG 32 /*!< Offset of the previous undo log
header on this page, 0 if none */
#define TRX_UNDO_HISTORY_NODE 34 /*!< If the log is put to the history
list, the file list node is here */
/*-------------------------------------------------------------*/
/** Size of the undo log header without XID information */
#define TRX_UNDO_LOG_OLD_HDR_SIZE (34 + FLST_NODE_SIZE)
/* Note: the writing of the undo log old header is coded by a log record
MLOG_UNDO_HDR_CREATE. The appending of an XID to the
header is logged separately. In this sense, the XID is not really a member
of the undo log header. TODO: do not append the XID to the log header if XA
is not needed by the user. The XID wastes about 150 bytes of space in every
undo log. In the history list we may have millions of undo logs, which means
quite a large overhead. */
/** X/Open XA Transaction Identification (XID) */
/* @{ */
/** xid_t::formatID */
#define TRX_UNDO_XA_FORMAT (TRX_UNDO_LOG_OLD_HDR_SIZE)
/** xid_t::gtrid_length */
#define TRX_UNDO_XA_TRID_LEN (TRX_UNDO_XA_FORMAT + 4)
/** xid_t::bqual_length */
#define TRX_UNDO_XA_BQUAL_LEN (TRX_UNDO_XA_TRID_LEN + 4)
/** Distributed transaction identifier data */
#define TRX_UNDO_XA_XID (TRX_UNDO_XA_BQUAL_LEN + 4)
/*--------------------------------------------------------------*/
#define TRX_UNDO_LOG_XA_HDR_SIZE (TRX_UNDO_XA_XID + XIDDATASIZE)
/*!< Total size of the undo log header
with the XA XID */
/* @} */
#include "trx0undo.inl"
#endif /* !UNIV_INNOCHECKSUM */
#endif
|