trx0undo.c

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	mlog_catenate_dulint_compressed(mtr, trx_id);
}	

/*******************************************************************
Creates a new undo log header in file. NOTE that this function has its own
log record type MLOG_UNDO_HDR_CREATE. You must NOT change the operation of
this function! */
static
ulint
trx_undo_header_create(
/*===================*/
				/* out: header byte offset on page */
	page_t*	undo_page,	/* in: undo log segment header page,
				x-latched; it is assumed that there are
				TRX_UNDO_LOG_XA_HDR_SIZE bytes free space
				on it */
	dulint	trx_id,		/* in: transaction id */
	mtr_t*	mtr)		/* in: mtr */
{
	trx_upagef_t*	page_hdr;
	trx_usegf_t*	seg_hdr;
	trx_ulogf_t*	log_hdr;
	trx_ulogf_t*	prev_log_hdr;
	ulint		prev_log;
	ulint		free;
	ulint		new_free;
	
	ut_ad(mtr && undo_page);
	
	page_hdr = undo_page + TRX_UNDO_PAGE_HDR;
	seg_hdr = undo_page + TRX_UNDO_SEG_HDR;

	free = mach_read_from_2(page_hdr + TRX_UNDO_PAGE_FREE);

	log_hdr = undo_page + free;
	
	new_free = free + TRX_UNDO_LOG_OLD_HDR_SIZE;

	ut_a(free + TRX_UNDO_LOG_XA_HDR_SIZE < UNIV_PAGE_SIZE - 100);
	
	mach_write_to_2(page_hdr + TRX_UNDO_PAGE_START, new_free);

	mach_write_to_2(page_hdr + TRX_UNDO_PAGE_FREE, new_free);
	
	mach_write_to_2(seg_hdr + TRX_UNDO_STATE, TRX_UNDO_ACTIVE);

	prev_log = mach_read_from_2(seg_hdr + TRX_UNDO_LAST_LOG);

	if (prev_log != 0) {
		prev_log_hdr = undo_page + prev_log;

		mach_write_to_2(prev_log_hdr + TRX_UNDO_NEXT_LOG, free);
	}

	mach_write_to_2(seg_hdr + TRX_UNDO_LAST_LOG, free);

	log_hdr = undo_page + free;
	
	mach_write_to_2(log_hdr + TRX_UNDO_DEL_MARKS, TRUE);

	mach_write_to_8(log_hdr + TRX_UNDO_TRX_ID, trx_id);
	mach_write_to_2(log_hdr + TRX_UNDO_LOG_START, new_free);

	mach_write_to_1(log_hdr + TRX_UNDO_XID_EXISTS, FALSE);
	mach_write_to_1(log_hdr + TRX_UNDO_DICT_TRANS, FALSE);

	mach_write_to_2(log_hdr + TRX_UNDO_NEXT_LOG, 0);
	mach_write_to_2(log_hdr + TRX_UNDO_PREV_LOG, prev_log);

	/* Write the log record about the header creation */
	trx_undo_header_create_log(undo_page, trx_id, mtr);
	
	return(free);
}

/************************************************************************
Write X/Open XA Transaction Identification (XID) to undo log header */
static
void
trx_undo_write_xid(
/*===============*/
	trx_ulogf_t*	log_hdr,/* in: undo log header */
	const XID*	xid,	/* in: X/Open XA Transaction Identification */
	mtr_t*		mtr)	/* in: mtr */
{
	mlog_write_ulint(log_hdr + TRX_UNDO_XA_FORMAT,
			(ulint)xid->formatID, MLOG_4BYTES, mtr);

	mlog_write_ulint(log_hdr + TRX_UNDO_XA_TRID_LEN,
			(ulint)xid->gtrid_length, MLOG_4BYTES, mtr);

	mlog_write_ulint(log_hdr + TRX_UNDO_XA_BQUAL_LEN,
			(ulint)xid->bqual_length, MLOG_4BYTES, mtr);

	mlog_write_string(log_hdr + TRX_UNDO_XA_XID, (const byte*) xid->data,
							XIDDATASIZE, mtr);
}

/************************************************************************
Read X/Open XA Transaction Identification (XID) from undo log header */
static
void
trx_undo_read_xid(
/*==============*/
	trx_ulogf_t*	log_hdr,/* in: undo log header */
	XID*		xid)	/* out: X/Open XA Transaction Identification */
{
	xid->formatID = (long)mach_read_from_4(log_hdr + TRX_UNDO_XA_FORMAT);
	
	xid->gtrid_length =
			(long)mach_read_from_4(log_hdr + TRX_UNDO_XA_TRID_LEN);
	xid->bqual_length =
		  (long)mach_read_from_4(log_hdr + TRX_UNDO_XA_BQUAL_LEN);

	memcpy(xid->data, log_hdr + TRX_UNDO_XA_XID, XIDDATASIZE);
}

/*******************************************************************
Adds space for the XA XID after an undo log old-style header. */
static
void
trx_undo_header_add_space_for_xid(
/*==============================*/
	page_t*		undo_page,/* in: undo log segment header page */
	trx_ulogf_t*	log_hdr,/* in: undo log header */
	mtr_t*		mtr)	/* in: mtr */
{
	trx_upagef_t*	page_hdr;
	ulint		free;
	ulint		new_free;

	page_hdr = undo_page + TRX_UNDO_PAGE_HDR;

	free = mach_read_from_2(page_hdr + TRX_UNDO_PAGE_FREE);

	/* free is now the end offset of the old style undo log header */

	ut_a(free == (ulint)(log_hdr - undo_page) + TRX_UNDO_LOG_OLD_HDR_SIZE);

	new_free = free + (TRX_UNDO_LOG_XA_HDR_SIZE
						- TRX_UNDO_LOG_OLD_HDR_SIZE);

	/* Add space for a XID after the header, update the free offset
	fields on the undo log page and in the undo log header */

	mlog_write_ulint(page_hdr + TRX_UNDO_PAGE_START, new_free,
							MLOG_2BYTES, mtr);

	mlog_write_ulint(page_hdr + TRX_UNDO_PAGE_FREE, new_free,
							MLOG_2BYTES, mtr);

	mlog_write_ulint(log_hdr + TRX_UNDO_LOG_START, new_free,
							MLOG_2BYTES, mtr);
}

/**************************************************************************
Writes the mtr log entry of an undo log header reuse. */
UNIV_INLINE
void
trx_undo_insert_header_reuse_log(
/*=============================*/
	page_t* undo_page,	/* in: undo log header page */
	dulint	trx_id,		/* in: transaction id */
	mtr_t*	mtr)		/* in: mtr */
{
	mlog_write_initial_log_record(undo_page, MLOG_UNDO_HDR_REUSE, mtr);

	mlog_catenate_dulint_compressed(mtr, trx_id);
}	

/***************************************************************
Parses the redo log entry of an undo log page header create or reuse. */

byte*
trx_undo_parse_page_header(
/*=======================*/
			/* out: end of log record or NULL */
	ulint	type,	/* in: MLOG_UNDO_HDR_CREATE or MLOG_UNDO_HDR_REUSE */
	byte*	ptr,	/* in: buffer */
	byte*	end_ptr,/* in: buffer end */
	page_t*	page,	/* in: page or NULL */
	mtr_t*	mtr)	/* in: mtr or NULL */
{
	dulint	trx_id;
	
	ptr = mach_dulint_parse_compressed(ptr, end_ptr, &trx_id);

	if (ptr == NULL) {

		return(NULL);
	}

	if (page) {
		if (type == MLOG_UNDO_HDR_CREATE) {
			trx_undo_header_create(page, trx_id, mtr);
		} else {
			ut_ad(type == MLOG_UNDO_HDR_REUSE);
			trx_undo_insert_header_reuse(page, trx_id, mtr);
		}
	}

	return(ptr);
}	

/*******************************************************************
Initializes a cached insert undo log header page for new use. NOTE that this
function has its own log record type MLOG_UNDO_HDR_REUSE. You must NOT change
the operation of this function! */
static
ulint
trx_undo_insert_header_reuse(
/*=========================*/
				/* out: undo log header byte offset on page */
	page_t*	undo_page,	/* in: insert undo log segment header page,
				x-latched */
	dulint	trx_id,		/* in: transaction id */
	mtr_t*	mtr)		/* in: mtr */
{
	trx_upagef_t*	page_hdr;
	trx_usegf_t*	seg_hdr;
	trx_ulogf_t*	log_hdr;
	ulint		free;
	ulint		new_free;
	
	ut_ad(mtr && undo_page);
	
	page_hdr = undo_page + TRX_UNDO_PAGE_HDR;
	seg_hdr = undo_page + TRX_UNDO_SEG_HDR;

	free = TRX_UNDO_SEG_HDR + TRX_UNDO_SEG_HDR_SIZE;

	ut_a(free + TRX_UNDO_LOG_XA_HDR_SIZE < UNIV_PAGE_SIZE - 100);

	log_hdr = undo_page + free;
	
	new_free = free + TRX_UNDO_LOG_OLD_HDR_SIZE;

	/* Insert undo data is not needed after commit: we may free all
	the space on the page */

	ut_a(mach_read_from_2(undo_page + TRX_UNDO_PAGE_HDR
					+ TRX_UNDO_PAGE_TYPE)
						== TRX_UNDO_INSERT);

	mach_write_to_2(page_hdr + TRX_UNDO_PAGE_START, new_free);
	
	mach_write_to_2(page_hdr + TRX_UNDO_PAGE_FREE, new_free);
	
	mach_write_to_2(seg_hdr + TRX_UNDO_STATE, TRX_UNDO_ACTIVE);

	log_hdr = undo_page + free;
	
	mach_write_to_8(log_hdr + TRX_UNDO_TRX_ID, trx_id);
	mach_write_to_2(log_hdr + TRX_UNDO_LOG_START, new_free);

	mach_write_to_1(log_hdr + TRX_UNDO_XID_EXISTS, FALSE);
	mach_write_to_1(log_hdr + TRX_UNDO_DICT_TRANS, FALSE);

	/* Write the log record MLOG_UNDO_HDR_REUSE */
	trx_undo_insert_header_reuse_log(undo_page, trx_id, mtr);
	
	return(free);
}	

/**************************************************************************
Writes the redo log entry of an update undo log header discard. */
UNIV_INLINE
void
trx_undo_discard_latest_log(
/*========================*/
	page_t* undo_page,	/* in: undo log header page */
	mtr_t*	mtr)		/* in: mtr */
{
	mlog_write_initial_log_record(undo_page, MLOG_UNDO_HDR_DISCARD, mtr);
}	

/***************************************************************
Parses the redo log entry of an undo log page header discard. */

byte*
trx_undo_parse_discard_latest(
/*==========================*/
			/* out: end of log record or NULL */
	byte*	ptr,	/* in: buffer */
	byte*	end_ptr __attribute__((unused)), /* in: buffer end */
	page_t*	page,	/* in: page or NULL */
	mtr_t*	mtr)	/* in: mtr or NULL */
{
	ut_ad(end_ptr);

	if (page) {
		trx_undo_discard_latest_update_undo(page, mtr);
	}

	return(ptr);
}	

/**************************************************************************
If an update undo log can be discarded immediately, this function frees the
space, resetting the page to the proper state for caching. */
static
void
trx_undo_discard_latest_update_undo(
/*================================*/
	page_t*	undo_page,	/* in: header page of an undo log of size 1 */
	mtr_t*	mtr)		/* in: mtr */
{
	trx_usegf_t*	seg_hdr;
	trx_upagef_t*	page_hdr;
	trx_ulogf_t*	log_hdr;
	trx_ulogf_t*	prev_log_hdr;
	ulint		free;
	ulint		prev_hdr_offset;

	seg_hdr = undo_page + TRX_UNDO_SEG_HDR;
	page_hdr = undo_page + TRX_UNDO_PAGE_HDR;

	free = mach_read_from_2(seg_hdr + TRX_UNDO_LAST_LOG);
	log_hdr = undo_page + free;

	prev_hdr_offset = mach_read_from_2(log_hdr + TRX_UNDO_PREV_LOG);
	
	if (prev_hdr_offset != 0) {
		prev_log_hdr = undo_page + prev_hdr_offset;

		mach_write_to_2(page_hdr + TRX_UNDO_PAGE_START,
			mach_read_from_2(prev_log_hdr + TRX_UNDO_LOG_START));
		mach_write_to_2(prev_log_hdr + TRX_UNDO_NEXT_LOG, 0);
	}

	mach_write_to_2(page_hdr + TRX_UNDO_PAGE_FREE, free);

	mach_write_to_2(seg_hdr + TRX_UNDO_STATE, TRX_UNDO_CACHED);
	mach_write_to_2(seg_hdr + TRX_UNDO_LAST_LOG, prev_hdr_offset);

	trx_undo_discard_latest_log(undo_page, mtr);
}

/************************************************************************
Tries to add a page to the undo log segment where the undo log is placed. */

ulint
trx_undo_add_page(
/*==============*/
				/* out: page number if success, else
				FIL_NULL */
	trx_t*		trx,	/* in: transaction */
	trx_undo_t*	undo,	/* in: undo log memory object */
	mtr_t*		mtr)	/* in: mtr which does not have a latch to any
				undo log page; the caller must have reserved
				the rollback segment mutex */
{
	page_t*		header_page;
	page_t*		new_page;
	trx_rseg_t*	rseg;
	ulint		page_no;
	ulint		n_reserved;
	ibool		success;
	
#ifdef UNIV_SYNC_DEBUG
	ut_ad(mutex_own(&(trx->undo_mutex)));
	ut_ad(!mutex_own(&kernel_mutex));
	ut_ad(mutex_own(&(trx->rseg->mutex)));
#endif /* UNIV_SYNC_DEBUG */

	rseg = trx->rseg;

	if (rseg->curr_size == rseg->max_size) {

		return(FIL_NULL);
	}

	header_page = trx_undo_page_get(undo->space, undo->hdr_page_no, mtr);

	success = fsp_reserve_free_extents(&n_reserved, undo->space, 1,
							FSP_UNDO, mtr);
	if (!success) {

		return(FIL_NULL);
	}

	page_no = fseg_alloc_free_page_general(header_page + TRX_UNDO_SEG_HDR
						+ TRX_UNDO_FSEG_HEADER,
					undo->top_page_no + 1, FSP_UP,
					TRUE, mtr);

	fil_space_release_free_extents(undo->space, n_reserved);
					
	if (page_no == FIL_NULL) {

		/* No space left */
		
		return(FIL_NULL);
	}

	undo->last_page_no = page_no;

	new_page = trx_undo_page_get(undo->space, page_no, mtr);

	trx_undo_page_init(new_page, undo->type, mtr);
	
	flst_add_last(header_page + TRX_UNDO_SEG_HDR + TRX_UNDO_PAGE_LIST,
		      new_page + TRX_UNDO_PAGE_HDR + TRX_UNDO_PAGE_NODE, mtr);
	undo->size++;
	rseg->curr_size++;

	return(page_no);
}

/************************************************************************
Frees an undo log page that is not the header page. */
static
ulint
trx_undo_free_page(
/*===============*/
				/* out: last page number in remaining log */
	trx_rseg_t* rseg,	/* in: rollback segment */
	ibool	in_history,	/* in: TRUE if the undo log is in the history
				list */
	ulint	space,		/* in: space */
	ulint	hdr_page_no,	/* in: header page number */
	ulint	page_no,	/* in: page number to free: must not be the
				header page */
	mtr_t*	mtr)		/* in: mtr which does not have a latch to any
				undo log page; the caller must have reserved
				the rollback segment mutex */
{
	page_t*		header_page;
	page_t*		undo_page;
	fil_addr_t	last_addr;
	trx_rsegf_t*	rseg_header;
	ulint		hist_size;

	ut_a(hdr_page_no != page_no);
#ifdef UNIV_SYNC_DEBUG
	ut_ad(!mutex_own(&kernel_mutex));
	ut_ad(mutex_own(&(rseg->mutex)));
#endif /* UNIV_SYNC_DEBUG */
	
	undo_page = trx_undo_page_get(space, page_no, mtr);

	header_page = trx_undo_page_get(space, hdr_page_no, mtr);

	flst_remove(header_page + TRX_UNDO_SEG_HDR + TRX_UNDO_PAGE_LIST,
		    undo_page + TRX_UNDO_PAGE_HDR + TRX_UNDO_PAGE_NODE, mtr);

	fseg_free_page(header_page + TRX_UNDO_SEG_HDR + TRX_UNDO_FSEG_HEADER,
							space, page_no, mtr);

	last_addr = flst_get_last(header_page + TRX_UNDO_SEG_HDR
						+ TRX_UNDO_PAGE_LIST, mtr);
	rseg->curr_size--;

	if (in_history) {
		rseg_header = trx_rsegf_get(space, rseg->page_no, mtr);

		hist_size = mtr_read_ulint(rseg_header + TRX_RSEG_HISTORY_SIZE,
							MLOG_4BYTES, mtr);
		ut_ad(hist_size > 0);
		mlog_write_ulint(rseg_header + TRX_RSEG_HISTORY_SIZE,
					hist_size - 1, MLOG_4BYTES, mtr);
	}

	return(last_addr.page);
}

/************************************************************************
Frees an undo log page when there is also the memory object for the undo
log. */
static
void
trx_undo_free_page_in_rollback(
/*===========================*/
	trx_t*		trx __attribute__((unused)), /* in: transaction */
	trx_undo_t*	undo,	/* in: undo log memory copy */
	ulint		page_no,/* in: page number to free: must not be the