/*****************************************************************************

Copyright (c) 1996, 2023, Oracle and/or its affiliates.

This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License, version 2.0,
as published by the Free Software Foundation.

This program is also distributed with certain software (including
but not limited to OpenSSL) that is licensed under separate terms,
as designated in a particular file or component or in included license
documentation.  The authors of MySQL hereby grant you an additional
permission to link the program and your derivative works with the
separately licensed software that they have included with MySQL.

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, version 2.0, 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/btr0pcur.ic
The index tree persistent cursor

Created 2/23/1996 Heikki Tuuri
*******************************************************/


/*********************************************************//**
Gets the rel_pos field for a cursor whose position has been stored.
@return BTR_PCUR_ON, ... */
UNIV_INLINE
ulint
btr_pcur_get_rel_pos(
/*=================*/
	const btr_pcur_t*	cursor)	/*!< in: persistent cursor */
{
	ut_ad(cursor);
	ut_ad(cursor->old_rec);
	ut_ad(cursor->old_stored);
	ut_ad(cursor->pos_state == BTR_PCUR_WAS_POSITIONED
	      || cursor->pos_state == BTR_PCUR_IS_POSITIONED);

	return(cursor->rel_pos);
}

#ifdef UNIV_DEBUG
/*********************************************************//**
Returns the btr cursor component of a persistent cursor.
@return pointer to btr cursor component */
UNIV_INLINE
btr_cur_t*
btr_pcur_get_btr_cur(
/*=================*/
	const btr_pcur_t*	cursor)	/*!< in: persistent cursor */
{
	const btr_cur_t*	btr_cur = &cursor->btr_cur;
	return((btr_cur_t*) btr_cur);
}

/*********************************************************//**
Returns the page cursor component of a persistent cursor.
@return pointer to page cursor component */
UNIV_INLINE
page_cur_t*
btr_pcur_get_page_cur(
/*==================*/
	const btr_pcur_t*	cursor)	/*!< in: persistent cursor */
{
	return(btr_cur_get_page_cur(btr_pcur_get_btr_cur(cursor)));
}

/*********************************************************//**
Returns the page of a persistent cursor.
@return pointer to the page */
UNIV_INLINE
page_t*
btr_pcur_get_page(
/*==============*/
	const btr_pcur_t*	cursor)	/*!< in: persistent cursor */
{
	ut_ad(cursor->pos_state == BTR_PCUR_IS_POSITIONED);

	return(btr_cur_get_page(btr_pcur_get_btr_cur(cursor)));
}

/*********************************************************//**
Returns the buffer block of a persistent cursor.
@return pointer to the block */
UNIV_INLINE
buf_block_t*
btr_pcur_get_block(
/*===============*/
	const btr_pcur_t*	cursor)	/*!< in: persistent cursor */
{
	ut_ad(cursor->pos_state == BTR_PCUR_IS_POSITIONED);

	return(btr_cur_get_block(btr_pcur_get_btr_cur(cursor)));
}

/*********************************************************//**
Returns the record of a persistent cursor.
@return pointer to the record */
UNIV_INLINE
rec_t*
btr_pcur_get_rec(
/*=============*/
	const btr_pcur_t*	cursor)	/*!< in: persistent cursor */
{
	ut_ad(cursor->pos_state == BTR_PCUR_IS_POSITIONED);
	ut_ad(cursor->latch_mode != BTR_NO_LATCHES);

	return(btr_cur_get_rec(btr_pcur_get_btr_cur(cursor)));
}
#endif /* UNIV_DEBUG */

/**************************************************************//**
Gets the up_match value for a pcur after a search.
@return number of matched fields at the cursor or to the right if
search mode was PAGE_CUR_GE, otherwise undefined */
UNIV_INLINE
ulint
btr_pcur_get_up_match(
/*==================*/
	const btr_pcur_t*	cursor) /*!< in: persistent cursor */
{
	const btr_cur_t*	btr_cursor;

	ut_ad((cursor->pos_state == BTR_PCUR_WAS_POSITIONED)
	      || (cursor->pos_state == BTR_PCUR_IS_POSITIONED));

	btr_cursor = btr_pcur_get_btr_cur(cursor);

	ut_ad(btr_cursor->up_match != ULINT_UNDEFINED);

	return(btr_cursor->up_match);
}

/**************************************************************//**
Gets the low_match value for a pcur after a search.
@return number of matched fields at the cursor or to the right if
search mode was PAGE_CUR_LE, otherwise undefined */
UNIV_INLINE
ulint
btr_pcur_get_low_match(
/*===================*/
	const btr_pcur_t*	cursor) /*!< in: persistent cursor */
{
	const btr_cur_t*	btr_cursor;

	ut_ad((cursor->pos_state == BTR_PCUR_WAS_POSITIONED)
	      || (cursor->pos_state == BTR_PCUR_IS_POSITIONED));

	btr_cursor = btr_pcur_get_btr_cur(cursor);
	ut_ad(btr_cursor->low_match != ULINT_UNDEFINED);

	return(btr_cursor->low_match);
}

/*********************************************************//**
Checks if the persistent cursor is after the last user record on
a page. */
UNIV_INLINE
ibool
btr_pcur_is_after_last_on_page(
/*===========================*/
	const btr_pcur_t*	cursor)	/*!< in: persistent cursor */
{
	ut_ad(cursor->pos_state == BTR_PCUR_IS_POSITIONED);
	ut_ad(cursor->latch_mode != BTR_NO_LATCHES);

	return(page_cur_is_after_last(btr_pcur_get_page_cur(cursor)));
}

/*********************************************************//**
Checks if the persistent cursor is before the first user record on
a page. */
UNIV_INLINE
ibool
btr_pcur_is_before_first_on_page(
/*=============================*/
	const btr_pcur_t*	cursor)	/*!< in: persistent cursor */
{
	ut_ad(cursor->pos_state == BTR_PCUR_IS_POSITIONED);
	ut_ad(cursor->latch_mode != BTR_NO_LATCHES);

	return(page_cur_is_before_first(btr_pcur_get_page_cur(cursor)));
}

/*********************************************************//**
Checks if the persistent cursor is on a user record. */
UNIV_INLINE
ibool
btr_pcur_is_on_user_rec(
/*====================*/
	const btr_pcur_t*	cursor)	/*!< in: persistent cursor */
{
	ut_ad(cursor->pos_state == BTR_PCUR_IS_POSITIONED);
	ut_ad(cursor->latch_mode != BTR_NO_LATCHES);

	if (btr_pcur_is_before_first_on_page(cursor)
	    || btr_pcur_is_after_last_on_page(cursor)) {

		return(FALSE);
	}

	return(TRUE);
}

/*********************************************************//**
Checks if the persistent cursor is before the first user record in
the index tree. */
UNIV_INLINE
ibool
btr_pcur_is_before_first_in_tree(
/*=============================*/
	btr_pcur_t*	cursor,	/*!< in: persistent cursor */
	mtr_t*		mtr)	/*!< in: mtr */
{
	ut_ad(cursor->pos_state == BTR_PCUR_IS_POSITIONED);
	ut_ad(cursor->latch_mode != BTR_NO_LATCHES);

	if (btr_page_get_prev(btr_pcur_get_page(cursor), mtr) != FIL_NULL) {

		return(FALSE);
	}

	return(page_cur_is_before_first(btr_pcur_get_page_cur(cursor)));
}

/*********************************************************//**
Checks if the persistent cursor is after the last user record in
the index tree. */
UNIV_INLINE
ibool
btr_pcur_is_after_last_in_tree(
/*===========================*/
	btr_pcur_t*	cursor,	/*!< in: persistent cursor */
	mtr_t*		mtr)	/*!< in: mtr */
{
	ut_ad(cursor->pos_state == BTR_PCUR_IS_POSITIONED);
	ut_ad(cursor->latch_mode != BTR_NO_LATCHES);

	if (btr_page_get_next(btr_pcur_get_page(cursor), mtr) != FIL_NULL) {

		return(FALSE);
	}

	return(page_cur_is_after_last(btr_pcur_get_page_cur(cursor)));
}

/*********************************************************//**
Moves the persistent cursor to the next record on the same page. */
UNIV_INLINE
void
btr_pcur_move_to_next_on_page(
/*==========================*/
	btr_pcur_t*	cursor)	/*!< in/out: persistent cursor */
{
	ut_ad(cursor->pos_state == BTR_PCUR_IS_POSITIONED);
	ut_ad(cursor->latch_mode != BTR_NO_LATCHES);

	page_cur_move_to_next(btr_pcur_get_page_cur(cursor));

	cursor->old_stored = false;
}

/*********************************************************//**
Moves the persistent cursor to the previous record on the same page. */
UNIV_INLINE
void
btr_pcur_move_to_prev_on_page(
/*==========================*/
	btr_pcur_t*	cursor)	/*!< in/out: persistent cursor */
{
	ut_ad(cursor->pos_state == BTR_PCUR_IS_POSITIONED);
	ut_ad(cursor->latch_mode != BTR_NO_LATCHES);

	page_cur_move_to_prev(btr_pcur_get_page_cur(cursor));

	cursor->old_stored = false;
}

/*********************************************************//**
Moves the persistent cursor to the last record on the same page. */
UNIV_INLINE
void
btr_pcur_move_to_last_on_page(
/*==========================*/
	btr_pcur_t*	cursor,	/*!< in: persistent cursor */
	mtr_t*		mtr)	/*!< in: mtr */
{
	UT_NOT_USED(mtr);
	ut_ad(cursor->latch_mode != BTR_NO_LATCHES);

	page_cur_set_after_last(btr_pcur_get_block(cursor),
				btr_pcur_get_page_cur(cursor));

	cursor->old_stored = false;
}

/*********************************************************//**
Moves the persistent cursor to the next user record in the tree. If no user
records are left, the cursor ends up 'after last in tree'.
@return TRUE if the cursor moved forward, ending on a user record */
UNIV_INLINE
ibool
btr_pcur_move_to_next_user_rec(
/*===========================*/
	btr_pcur_t*	cursor,	/*!< in: persistent cursor; NOTE that the
				function may release the page latch */
	mtr_t*		mtr)	/*!< in: mtr */
{
	ut_ad(cursor->pos_state == BTR_PCUR_IS_POSITIONED);
	ut_ad(cursor->latch_mode != BTR_NO_LATCHES);
	cursor->old_stored = false;
loop:
	if (btr_pcur_is_after_last_on_page(cursor)) {

		if (btr_pcur_is_after_last_in_tree(cursor, mtr)) {

			return(FALSE);
		}

		btr_pcur_move_to_next_page(cursor, mtr);
	} else {
		btr_pcur_move_to_next_on_page(cursor);
	}

	if (btr_pcur_is_on_user_rec(cursor)) {

		return(TRUE);
	}

	goto loop;
}

/*********************************************************//**
Moves the persistent cursor to the next record in the tree. If no records are
left, the cursor stays 'after last in tree'.
@return TRUE if the cursor was not after last in tree */
UNIV_INLINE
ibool
btr_pcur_move_to_next(
/*==================*/
	btr_pcur_t*	cursor,	/*!< in: persistent cursor; NOTE that the
				function may release the page latch */
	mtr_t*		mtr)	/*!< in: mtr */
{
	ut_ad(cursor->pos_state == BTR_PCUR_IS_POSITIONED);
	ut_ad(cursor->latch_mode != BTR_NO_LATCHES);

	cursor->old_stored = false;

	if (btr_pcur_is_after_last_on_page(cursor)) {

		if (btr_pcur_is_after_last_in_tree(cursor, mtr)) {

			return(FALSE);
		}

		btr_pcur_move_to_next_page(cursor, mtr);

		return(TRUE);
	}

	btr_pcur_move_to_next_on_page(cursor);

	return(TRUE);
}

/**************************************************************//**
Commits the mtr and sets the pcur latch mode to BTR_NO_LATCHES,
that is, the cursor becomes detached.
Function btr_pcur_store_position should be used before calling this,
if restoration of cursor is wanted later. */
UNIV_INLINE
void
btr_pcur_commit_specify_mtr(
/*========================*/
	btr_pcur_t*	pcur,	/*!< in: persistent cursor */
	mtr_t*		mtr)	/*!< in: mtr to commit */
{
	ut_ad(pcur->pos_state == BTR_PCUR_IS_POSITIONED);

	pcur->latch_mode = BTR_NO_LATCHES;

	mtr_commit(mtr);

	pcur->pos_state = BTR_PCUR_WAS_POSITIONED;
}

/**************************************************************//**
Sets the old_rec_buf field to NULL. */
UNIV_INLINE
void
btr_pcur_init(
/*==========*/
	btr_pcur_t*	pcur)	/*!< in: persistent cursor */
{
	pcur->old_stored = false;
	pcur->old_rec_buf = NULL;
	pcur->old_rec = NULL;

	pcur->btr_cur.rtr_info = NULL;
	pcur->import_ctx = NULL;
}

/** Free old_rec_buf.
@param[in]	pcur	Persistent cursor holding old_rec to be freed. */
UNIV_INLINE
void
btr_pcur_free(
	btr_pcur_t*	pcur)
{
	ut_free(pcur->old_rec_buf);
}

/**************************************************************//**
Initializes and opens a persistent cursor to an index tree. It should be
closed with btr_pcur_close. */
UNIV_INLINE
void
btr_pcur_open_low(
/*==============*/
	dict_index_t*	index,	/*!< in: index */
	ulint		level,	/*!< in: level in the btree */
	const dtuple_t*	tuple,	/*!< in: tuple on which search done */
	page_cur_mode_t	mode,	/*!< in: PAGE_CUR_L, ...;
				NOTE that if the search is made using a unique
				prefix of a record, mode should be
				PAGE_CUR_LE, not PAGE_CUR_GE, as the latter
				may end up on the previous page from the
				record! */
	ulint		latch_mode,/*!< in: BTR_SEARCH_LEAF, ... */
	btr_pcur_t*	cursor, /*!< in: memory buffer for persistent cursor */
	const char*	file,	/*!< in: file name */
	ulint		line,	/*!< in: line where called */
	mtr_t*		mtr)	/*!< in: mtr */
{
	btr_cur_t*	btr_cursor;

	/* Initialize the cursor */

	btr_pcur_init(cursor);

	cursor->latch_mode = BTR_LATCH_MODE_WITHOUT_FLAGS(latch_mode);
	cursor->search_mode = mode;

	/* Search with the tree cursor */

	btr_cursor = btr_pcur_get_btr_cur(cursor);

	ut_ad(!dict_index_is_spatial(index));

	if (dict_table_is_intrinsic(index->table)) {
		ut_ad((latch_mode & BTR_MODIFY_LEAF)
		      || (latch_mode & BTR_SEARCH_LEAF)
		      || (latch_mode & BTR_MODIFY_TREE));
		btr_cur_search_to_nth_level_with_no_latch(
			index, level, tuple, mode, btr_cursor,
			file, line, mtr,
			(((latch_mode & BTR_MODIFY_LEAF)
			 || (latch_mode & BTR_MODIFY_TREE)) ? true : false));
	} else {
		btr_cur_search_to_nth_level(
			index, level, tuple, mode, latch_mode,
			btr_cursor, 0, file, line, mtr);
	}

	cursor->pos_state = BTR_PCUR_IS_POSITIONED;

	cursor->trx_if_known = NULL;
}

/**************************************************************//**
Opens an persistent cursor to an index tree without initializing the
cursor. */
UNIV_INLINE
void
btr_pcur_open_with_no_init_func(
/*============================*/
	dict_index_t*	index,	/*!< in: index */
	const dtuple_t*	tuple,	/*!< in: tuple on which search done */
	page_cur_mode_t	mode,	/*!< in: PAGE_CUR_L, ...;
				NOTE that if the search is made using a unique
				prefix of a record, mode should be
				PAGE_CUR_LE, not PAGE_CUR_GE, as the latter
				may end up on the previous page of the
				record! */
	ulint		latch_mode,/*!< in: BTR_SEARCH_LEAF, ...;
				NOTE that if has_search_latch != 0 then
				we maybe do not acquire a latch on the cursor
				page, but assume that the caller uses his
				btr search latch to protect the record! */
	btr_pcur_t*	cursor, /*!< in: memory buffer for persistent cursor */
	ulint		has_search_latch,
				/*!< in: latch mode the caller
				currently has on search system:
				RW_S_LATCH, or 0 */
	const char*	file,	/*!< in: file name */
	ulint		line,	/*!< in: line where called */
	mtr_t*		mtr)	/*!< in: mtr */
{
	btr_cur_t*	btr_cursor;

	cursor->latch_mode = BTR_LATCH_MODE_WITHOUT_INTENTION(latch_mode);
	cursor->search_mode = mode;

	/* Search with the tree cursor */

	btr_cursor = btr_pcur_get_btr_cur(cursor);

	if (dict_table_is_intrinsic(index->table)) {
		ut_ad((latch_mode & BTR_MODIFY_LEAF)
		      || (latch_mode & BTR_SEARCH_LEAF));
		btr_cur_search_to_nth_level_with_no_latch(
			index, 0, tuple, mode, btr_cursor,
			file, line, mtr,
			((latch_mode & BTR_MODIFY_LEAF) ? true : false));
	} else {
		btr_cur_search_to_nth_level(
			index, 0, tuple, mode, latch_mode, btr_cursor,
			has_search_latch, file, line, mtr);
	}

	cursor->pos_state = BTR_PCUR_IS_POSITIONED;

	cursor->old_stored = false;

	cursor->trx_if_known = NULL;
}

/*****************************************************************//**
Opens a persistent cursor at either end of an index. */
UNIV_INLINE
void
btr_pcur_open_at_index_side(
/*========================*/
	bool		from_left,	/*!< in: true if open to the low end,
					false if to the high end */
	dict_index_t*	index,		/*!< in: index */
	ulint		latch_mode,	/*!< in: latch mode */
	btr_pcur_t*	pcur,		/*!< in/out: cursor */
	bool		init_pcur,	/*!< in: whether to initialize pcur */
	ulint		level,		/*!< in: level to search for
					(0=leaf) */
	mtr_t*		mtr)		/*!< in/out: mini-transaction */
{
	pcur->latch_mode = BTR_LATCH_MODE_WITHOUT_FLAGS(latch_mode);

	pcur->search_mode = from_left ? PAGE_CUR_G : PAGE_CUR_L;

	if (init_pcur) {
		btr_pcur_init(pcur);
	}

	if (dict_table_is_intrinsic(index->table)) {
		btr_cur_open_at_index_side_with_no_latch(
			from_left, index,
			btr_pcur_get_btr_cur(pcur), level, mtr);
	} else {
		btr_cur_open_at_index_side(
			from_left, index, latch_mode,
			btr_pcur_get_btr_cur(pcur), level, mtr);
	}
	pcur->pos_state = BTR_PCUR_IS_POSITIONED;

	pcur->old_stored = false;

	pcur->trx_if_known = NULL;
}

/**********************************************************************//**
Positions a cursor at a randomly chosen position within a B-tree.
@return true if the index is available and we have put the cursor, false
if the index is unavailable */
UNIV_INLINE
bool
btr_pcur_open_at_rnd_pos_func(
/*==========================*/
	dict_index_t*	index,		/*!< in: index */
	ulint		latch_mode,	/*!< in: BTR_SEARCH_LEAF, ... */
	btr_pcur_t*	cursor,		/*!< in/out: B-tree pcur */
	const char*	file,		/*!< in: file name */
	ulint		line,		/*!< in: line where called */
	mtr_t*		mtr)		/*!< in: mtr */
{
	/* Initialize the cursor */

	cursor->latch_mode = latch_mode;
	cursor->search_mode = PAGE_CUR_G;

	btr_pcur_init(cursor);

	bool	available;

	available = btr_cur_open_at_rnd_pos_func(index, latch_mode,
						 btr_pcur_get_btr_cur(cursor),
						 file, line, mtr);
	cursor->pos_state = BTR_PCUR_IS_POSITIONED;
	cursor->old_stored = false;

	cursor->trx_if_known = NULL;

	return(available);
}

/**************************************************************//**
Frees the possible memory heap of a persistent cursor and sets the latch
mode of the persistent cursor to BTR_NO_LATCHES.
WARNING: this function does not release the latch on the page where the
cursor is currently positioned. The latch is acquired by the
"move to next/previous" family of functions. Since recursive shared locks
are not allowed, you must take care (if using the cursor in S-mode) to
manually release the latch by either calling
btr_leaf_page_release(btr_pcur_get_block(&pcur), pcur.latch_mode, mtr)
or by committing the mini-transaction right after btr_pcur_close().
A subsequent attempt to crawl the same page in the same mtr would cause
an assertion failure. */
UNIV_INLINE
void
btr_pcur_close(
/*===========*/
	btr_pcur_t*	cursor)	/*!< in: persistent cursor */
{
	ut_free(cursor->old_rec_buf);

	if (cursor->btr_cur.rtr_info) {
		rtr_clean_rtr_info(cursor->btr_cur.rtr_info, true);
		cursor->btr_cur.rtr_info = NULL;
	}

	cursor->old_rec = NULL;
	cursor->old_rec_buf = NULL;
	cursor->btr_cur.page_cur.rec = NULL;
	cursor->btr_cur.page_cur.block = NULL;

	cursor->old_rec = NULL;
	cursor->old_stored = false;

	cursor->latch_mode = BTR_NO_LATCHES;
	cursor->pos_state = BTR_PCUR_NOT_POSITIONED;

	cursor->trx_if_known = NULL;
}

/*********************************************************//**
Moves the persistent cursor to the infimum record on the same page. */
UNIV_INLINE
void
btr_pcur_move_before_first_on_page(
/*===============================*/
	btr_pcur_t*	cursor) /*!< in/out: persistent cursor */
{
	ut_ad(cursor->latch_mode != BTR_NO_LATCHES);

	page_cur_set_before_first(btr_pcur_get_block(cursor),
		btr_pcur_get_page_cur(cursor));

	cursor->old_stored = false;
}