/************************************************************************
The page cursor

(c) 1994-1996 Innobase Oy

Created 10/4/1994 Heikki Tuuri
*************************************************************************/

#include "page0page.h"
#include "buf0types.h"


/*************************************************************
Gets pointer to the page frame where the cursor is positioned. */
UNIV_INLINE
page_t*
page_cur_get_page(
/*==============*/
				/* out: page */
	page_cur_t*	cur)	/* in: page cursor */
{
	ut_ad(cur);

	return(page_align(cur->rec));
}

/*************************************************************
Gets pointer to the buffer block where the cursor is positioned. */
UNIV_INLINE
buf_block_t*
page_cur_get_block(
/*===============*/
				/* out: page */
	page_cur_t*	cur)	/* in: page cursor */
{
	ut_ad(cur);
	ut_ad(page_align(cur->rec) == cur->block->frame);
	return(cur->block);
}

/*************************************************************
Gets pointer to the page frame where the cursor is positioned. */
UNIV_INLINE
page_zip_des_t*
page_cur_get_page_zip(
/*==================*/
				/* out: page */
	page_cur_t*	cur)	/* in: page cursor */
{
	return(buf_block_get_page_zip(page_cur_get_block(cur)));
}

/*************************************************************
Gets the record where the cursor is positioned. */
UNIV_INLINE
rec_t*
page_cur_get_rec(
/*=============*/
				/* out: record */
	page_cur_t*	cur)	/* in: page cursor */
{
	ut_ad(cur);
	ut_ad(page_align(cur->rec) == cur->block->frame);

	return(cur->rec);
}

/*************************************************************
Sets the cursor object to point before the first user record
on the page. */
UNIV_INLINE
void
page_cur_set_before_first(
/*======================*/
	buf_block_t*	block,	/* in: index page */
	page_cur_t*	cur)	/* in: cursor */
{
	cur->rec = page_get_infimum_rec(buf_block_get_frame(block));
	cur->block = block;
}

/*************************************************************
Sets the cursor object to point after the last user record on
the page. */
UNIV_INLINE
void
page_cur_set_after_last(
/*====================*/
	buf_block_t*	block,	/* in: index page */
	page_cur_t*	cur)	/* in: cursor */
{
	cur->rec = page_get_supremum_rec(buf_block_get_frame(block));
	cur->block = block;
}

/*************************************************************
Returns TRUE if the cursor is before first user record on page. */
UNIV_INLINE
ibool
page_cur_is_before_first(
/*=====================*/
					/* out: TRUE if at start */
	const page_cur_t*	cur)	/* in: cursor */
{
	return(page_rec_is_infimum(cur->rec));
}

/*************************************************************
Returns TRUE if the cursor is after last user record. */
UNIV_INLINE
ibool
page_cur_is_after_last(
/*===================*/
					/* out: TRUE if at end */
	const page_cur_t*	cur)	/* in: cursor */
{
	return(page_rec_is_supremum(cur->rec));
}

/**************************************************************
Positions the cursor on the given record. */
UNIV_INLINE
void
page_cur_position(
/*==============*/
	rec_t*		rec,	/* in: record on a page */
	buf_block_t*	block,	/* in: buffer block containing the record */
	page_cur_t*	cur)	/* out: page cursor */
{
	ut_ad(rec && block && cur);
	ut_ad(page_align(rec) == block->frame);

	cur->rec = rec;
	cur->block = block;
}

/**************************************************************
Invalidates a page cursor by setting the record pointer NULL. */
UNIV_INLINE
void
page_cur_invalidate(
/*================*/
	page_cur_t*	cur)	/* in: page cursor */
{
	ut_ad(cur);

	cur->rec = NULL;
	cur->block = NULL;
}

/**************************************************************
Moves the cursor to the next record on page. */
UNIV_INLINE
void
page_cur_move_to_next(
/*==================*/
	page_cur_t*	cur)	/* in: cursor; must not be after last */
{
	ut_ad(!page_cur_is_after_last(cur));

	cur->rec = page_rec_get_next(cur->rec);
}

/**************************************************************
Moves the cursor to the previous record on page. */
UNIV_INLINE
void
page_cur_move_to_prev(
/*==================*/
	page_cur_t*	cur)	/* in: page cursor, not before first */
{
	ut_ad(!page_cur_is_before_first(cur));

	cur->rec = page_rec_get_prev(cur->rec);
}

/********************************************************************
Searches the right position for a page cursor. */
UNIV_INLINE
ulint
page_cur_search(
/*============*/
				/* out: number of matched fields on the left */
	buf_block_t*	block,	/* in: buffer block */
	dict_index_t*	index,	/* in: record descriptor */
	const dtuple_t*	tuple,	/* in: data tuple */
	ulint		mode,	/* in: PAGE_CUR_L, PAGE_CUR_LE, PAGE_CUR_G,
				or PAGE_CUR_GE */
	page_cur_t*	cursor)	/* out: page cursor */
{
	ulint		low_matched_fields = 0;
	ulint		low_matched_bytes = 0;
	ulint		up_matched_fields = 0;
	ulint		up_matched_bytes = 0;

	ut_ad(dtuple_check_typed(tuple));

	page_cur_search_with_match(block, index, tuple, mode,
				   &up_matched_fields,
				   &up_matched_bytes,
				   &low_matched_fields,
				   &low_matched_bytes,
				   cursor);
	return(low_matched_fields);
}

/***************************************************************
Inserts a record next to page cursor. Returns pointer to inserted record if
succeed, i.e., enough space available, NULL otherwise. The cursor stays at
the same logical position, but the physical position may change if it is
pointing to a compressed page that was reorganized. */
UNIV_INLINE
rec_t*
page_cur_tuple_insert(
/*==================*/
				/* out: pointer to record if succeed, NULL
				otherwise */
	page_cur_t*	cursor,	/* in/out: a page cursor */
	const dtuple_t*	tuple,	/* in: pointer to a data tuple */
	dict_index_t*	index,	/* in: record descriptor */
	ulint		n_ext,	/* in: number of externally stored columns */
	mtr_t*		mtr)	/* in: mini-transaction handle, or NULL */
{
	mem_heap_t*	heap;
	ulint*		offsets;
	ulint		size
		= rec_get_converted_size(index, tuple, n_ext);
	rec_t*		rec;

	heap = mem_heap_create(size
			       + (4 + REC_OFFS_HEADER_SIZE
				  + dtuple_get_n_fields(tuple))
			       * sizeof *offsets);
	rec = rec_convert_dtuple_to_rec((byte*) mem_heap_alloc(heap, size),
					index, tuple, n_ext);
	offsets = rec_get_offsets(rec, index, NULL, ULINT_UNDEFINED, &heap);

	if (buf_block_get_page_zip(cursor->block)) {
		rec = page_cur_insert_rec_zip(&cursor->rec, cursor->block,
					      index, rec, offsets, mtr);
	} else {
		rec = page_cur_insert_rec_low(cursor->rec,
					      index, rec, offsets, mtr);
	}

	mem_heap_free(heap);
	return(rec);
}

/***************************************************************
Inserts a record next to page cursor. Returns pointer to inserted record if
succeed, i.e., enough space available, NULL otherwise. The cursor stays at
the same logical position, but the physical position may change if it is
pointing to a compressed page that was reorganized. */
UNIV_INLINE
rec_t*
page_cur_rec_insert(
/*================*/
				/* out: pointer to record if succeed, NULL
				otherwise */
	page_cur_t*	cursor,	/* in/out: a page cursor */
	const rec_t*	rec,	/* in: record to insert */
	dict_index_t*	index,	/* in: record descriptor */
	ulint*		offsets,/* in/out: rec_get_offsets(rec, index) */
	mtr_t*		mtr)	/* in: mini-transaction handle, or NULL */
{
	if (buf_block_get_page_zip(cursor->block)) {
		return(page_cur_insert_rec_zip(&cursor->rec, cursor->block,
					       index, rec, offsets, mtr));
	} else {
		return(page_cur_insert_rec_low(cursor->rec,
					       index, rec, offsets, mtr));
	}
}