/******************************************************
The B-tree

(c) 1994-1996 Innobase Oy

Created 6/2/1994 Heikki Tuuri
*******************************************************/

#include "mach0data.h"
#include "mtr0mtr.h"
#include "mtr0log.h"

#define BTR_MAX_NODE_LEVEL	50	/* used in debug checking */

/******************************************************************
Gets a buffer page and declares its latching order level. */
UNIV_INLINE
page_t*
btr_page_get(
/*=========*/
	ulint	space,		/* in: space id */
	ulint	page_no,	/* in: page number */
	ulint	mode,		/* in: latch mode */
	mtr_t*	mtr)		/* in: mtr */
{
	page_t*	page;

	page = buf_page_get(space, page_no, mode, mtr);
#ifdef UNIV_SYNC_DEBUG
	if (mode != RW_NO_LATCH) {
	
		buf_page_dbg_add_level(page, SYNC_TREE_NODE);
	}
#endif
	return(page);
}

/******************************************************************
Sets the index id field of a page. */
UNIV_INLINE
void
btr_page_set_index_id(
/*==================*/
	page_t*		page,	/* in: page to be created */
	dulint		id,	/* in: index id */
	mtr_t*		mtr)	/* in: mtr */
{
	mlog_write_dulint(page + PAGE_HEADER + PAGE_INDEX_ID, id,
							MLOG_8BYTES, mtr);
}

/******************************************************************
Gets the index id field of a page. */
UNIV_INLINE
dulint
btr_page_get_index_id(
/*==================*/
				/* out: index id */
	page_t*		page)	/* in: index page */
{
	return(mach_read_from_8(page + PAGE_HEADER + PAGE_INDEX_ID));
}

/************************************************************
Gets the node level field in an index page. */
UNIV_INLINE
ulint
btr_page_get_level_low(
/*===================*/
			/* out: level, leaf level == 0 */
	page_t*	page)	/* in: index page */
{
	ulint	level;

	ut_ad(page);
	
	level = mach_read_from_2(page + PAGE_HEADER + PAGE_LEVEL);

	ut_ad(level <= BTR_MAX_NODE_LEVEL);

	return(level);
}

/************************************************************
Gets the node level field in an index page. */
UNIV_INLINE
ulint
btr_page_get_level(
/*===============*/
			/* out: level, leaf level == 0 */
	page_t*	page,	/* in: index page */
	mtr_t*	mtr __attribute__((unused))) /* in: mini-transaction handle */
{
	ut_ad(page && mtr);

	return(btr_page_get_level_low(page));	
}

/************************************************************
Sets the node level field in an index page. */
UNIV_INLINE
void
btr_page_set_level(
/*===============*/
	page_t*	page,	/* in: index page */
	ulint	level,	/* in: level, leaf level == 0 */
	mtr_t*	mtr)	/* in: mini-transaction handle */
{
	ut_ad(page && mtr);
	ut_ad(level <= BTR_MAX_NODE_LEVEL);

	mlog_write_ulint(page + PAGE_HEADER + PAGE_LEVEL, level,
							 MLOG_2BYTES, mtr);
}

/************************************************************
Gets the next index page number. */
UNIV_INLINE
ulint
btr_page_get_next(
/*==============*/
			/* out: next page number */
	page_t*	page,	/* in: index page */
	mtr_t*	mtr __attribute__((unused))) /* in: mini-transaction handle */
{
	ut_ad(page && mtr);
	ut_ad(mtr_memo_contains(mtr, buf_block_align(page),
			      				MTR_MEMO_PAGE_X_FIX)
	      || mtr_memo_contains(mtr, buf_block_align(page),
			      				MTR_MEMO_PAGE_S_FIX));

	return(mach_read_from_4(page + FIL_PAGE_NEXT));
}

/************************************************************
Sets the next index page field. */
UNIV_INLINE
void
btr_page_set_next(
/*==============*/
	page_t*	page,	/* in: index page */
	ulint	next,	/* in: next page number */
	mtr_t*	mtr)	/* in: mini-transaction handle */
{
	ut_ad(page && mtr);

	mlog_write_ulint(page + FIL_PAGE_NEXT, next, MLOG_4BYTES, mtr);
}

/************************************************************
Gets the previous index page number. */
UNIV_INLINE
ulint
btr_page_get_prev(
/*==============*/
			/* out: prev page number */
	page_t*	page,	/* in: index page */
	mtr_t*	mtr __attribute__((unused))) /* in: mini-transaction handle */
{
	ut_ad(page && mtr);
	
	return(mach_read_from_4(page + FIL_PAGE_PREV));
}

/************************************************************
Sets the previous index page field. */
UNIV_INLINE
void
btr_page_set_prev(
/*==============*/
	page_t*	page,	/* in: index page */
	ulint	prev,	/* in: previous page number */
	mtr_t*	mtr)	/* in: mini-transaction handle */
{
	ut_ad(page && mtr);

	mlog_write_ulint(page + FIL_PAGE_PREV, prev, MLOG_4BYTES, mtr);
}

/******************************************************************
Gets the child node file address in a node pointer. */
UNIV_INLINE
ulint
btr_node_ptr_get_child_page_no(
/*===========================*/
			   	/* out: child node address */
	rec_t*	rec)		/* in: node pointer record */
{
	ulint	n_fields;
	byte*	field;
	ulint	len;
	ulint	page_no;

	n_fields = rec_get_n_fields(rec);

	/* The child address is in the last field */	
	field = rec_get_nth_field(rec, n_fields - 1, &len);

	ut_ad(len == 4);
	
	page_no = mach_read_from_4(field);

	if (page_no == 0) {
		fprintf(stderr,
"InnoDB: a nonsensical page number 0 in a node ptr record at offset %lu\n",
		       (unsigned long)(rec - buf_frame_align(rec)));
		buf_page_print(buf_frame_align(rec));
	}

	return(page_no);
}

/******************************************************************
Releases the latches on a leaf page and bufferunfixes it. */
UNIV_INLINE
void
btr_leaf_page_release(
/*==================*/
	page_t*	page,		/* in: page */
	ulint	latch_mode,	/* in: BTR_SEARCH_LEAF or BTR_MODIFY_LEAF */
	mtr_t*	mtr)		/* in: mtr */
{
	ut_ad(!mtr_memo_contains(mtr, buf_block_align(page),
							MTR_MEMO_MODIFY));
	if (latch_mode == BTR_SEARCH_LEAF) {
		mtr_memo_release(mtr, buf_block_align(page), 
							MTR_MEMO_PAGE_S_FIX);
	} else {
		ut_ad(latch_mode == BTR_MODIFY_LEAF);
		mtr_memo_release(mtr, buf_block_align(page), 
							MTR_MEMO_PAGE_X_FIX);
	}
}
