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

Copyright (c) 1994, 2011, Oracle and/or its affiliates. All Rights Reserved.

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 St, Fifth Floor, Boston, MA 02110-1301 USA

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

/**************************************************//**
@file include/btr0btr.ic
The B-tree

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

#include "mach0data.h"
#ifndef UNIV_HOTBACKUP
#include "mtr0mtr.h"
#include "mtr0log.h"
#include "page0zip.h"

#define BTR_MAX_NODE_LEVEL	50	/*!< Maximum B-tree page level
					(not really a hard limit).
					Used in debug assertions
					in btr_page_set_level and
					btr_page_get_level_low */

/**************************************************************//**
Gets a buffer page and declares its latching order level. */
UNIV_INLINE
buf_block_t*
btr_block_get_func(
/*===============*/
	ulint		space,		/*!< in: space id */
	ulint		zip_size,	/*!< in: compressed page size in bytes
					or 0 for uncompressed pages */
	ulint		page_no,	/*!< in: page number */
	ulint		mode,		/*!< in: latch mode */
	const char*	file,		/*!< in: file name */
	ulint		line,		/*!< in: line where called */
#ifdef UNIV_SYNC_DEBUG
	const dict_index_t*	index,	/*!< in: index tree, may be NULL
					if it is not an insert buffer tree */
#endif /* UNIV_SYNC_DEBUG */
	mtr_t*		mtr)		/*!< in/out: mtr */
{
	buf_block_t*	block;

	block = buf_page_get_gen(space, zip_size, page_no, mode,
				 NULL, BUF_GET, file, line, mtr);

	if (mode != RW_NO_LATCH) {

		buf_block_dbg_add_level(
			block, index != NULL && dict_index_is_ibuf(index)
			? SYNC_IBUF_TREE_NODE : SYNC_TREE_NODE);
	}

	return(block);
}

/**************************************************************//**
Sets the index id field of a page. */
UNIV_INLINE
void
btr_page_set_index_id(
/*==================*/
	page_t*		page,	/*!< in: page to be created */
	page_zip_des_t*	page_zip,/*!< in: compressed page whose uncompressed
				part will be updated, or NULL */
	index_id_t	id,	/*!< in: index id */
	mtr_t*		mtr)	/*!< in: mtr */
{
	if (UNIV_LIKELY_NULL(page_zip)) {
		mach_write_to_8(page + (PAGE_HEADER + PAGE_INDEX_ID), id);
		page_zip_write_header(page_zip,
				      page + (PAGE_HEADER + PAGE_INDEX_ID),
				      8, mtr);
	} else {
		mlog_write_ull(page + (PAGE_HEADER + PAGE_INDEX_ID), id, mtr);
	}
}
#endif /* !UNIV_HOTBACKUP */

/**************************************************************//**
Gets the index id field of a page.
@return	index id */
UNIV_INLINE
index_id_t
btr_page_get_index_id(
/*==================*/
	const page_t*	page)	/*!< in: index page */
{
	return(mach_read_from_8(page + PAGE_HEADER + PAGE_INDEX_ID));
}

#ifndef UNIV_HOTBACKUP
/********************************************************//**
Gets the node level field in an index page.
@return	level, leaf level == 0 */
UNIV_INLINE
ulint
btr_page_get_level_low(
/*===================*/
	const 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.
@return	level, leaf level == 0 */
UNIV_INLINE
ulint
btr_page_get_level(
/*===============*/
	const 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 */
	page_zip_des_t*	page_zip,/*!< in: compressed page whose uncompressed
				part will be updated, or NULL */
	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);

	if (UNIV_LIKELY_NULL(page_zip)) {
		mach_write_to_2(page + (PAGE_HEADER + PAGE_LEVEL), level);
		page_zip_write_header(page_zip,
				      page + (PAGE_HEADER + PAGE_LEVEL),
				      2, mtr);
	} else {
		mlog_write_ulint(page + (PAGE_HEADER + PAGE_LEVEL), level,
				 MLOG_2BYTES, mtr);
	}
}

/********************************************************//**
Gets the next index page number.
@return	next page number */
UNIV_INLINE
ulint
btr_page_get_next(
/*==============*/
	const page_t*	page,	/*!< in: index page */
	mtr_t*		mtr __attribute__((unused)))
				/*!< in: mini-transaction handle */
{
	ut_ad(page && mtr);
	ut_ad(mtr_memo_contains_page(mtr, page, MTR_MEMO_PAGE_X_FIX)
	      || mtr_memo_contains_page(mtr, 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 */
	page_zip_des_t*	page_zip,/*!< in: compressed page whose uncompressed
				part will be updated, or NULL */
	ulint		next,	/*!< in: next page number */
	mtr_t*		mtr)	/*!< in: mini-transaction handle */
{
	ut_ad(page && mtr);

	if (UNIV_LIKELY_NULL(page_zip)) {
		mach_write_to_4(page + FIL_PAGE_NEXT, next);
		page_zip_write_header(page_zip, page + FIL_PAGE_NEXT, 4, mtr);
	} else {
		mlog_write_ulint(page + FIL_PAGE_NEXT, next, MLOG_4BYTES, mtr);
	}
}

/********************************************************//**
Gets the previous index page number.
@return	prev page number */
UNIV_INLINE
ulint
btr_page_get_prev(
/*==============*/
	const 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 */
	page_zip_des_t*	page_zip,/*!< in: compressed page whose uncompressed
				part will be updated, or NULL */
	ulint		prev,	/*!< in: previous page number */
	mtr_t*		mtr)	/*!< in: mini-transaction handle */
{
	ut_ad(page && mtr);

	if (UNIV_LIKELY_NULL(page_zip)) {
		mach_write_to_4(page + FIL_PAGE_PREV, prev);
		page_zip_write_header(page_zip, page + FIL_PAGE_PREV, 4, mtr);
	} else {
		mlog_write_ulint(page + FIL_PAGE_PREV, prev, MLOG_4BYTES, mtr);
	}
}

/**************************************************************//**
Gets the child node file address in a node pointer.
NOTE: the offsets array must contain all offsets for the record since
we read the last field according to offsets and assume that it contains
the child page number. In other words offsets must have been retrieved
with rec_get_offsets(n_fields=ULINT_UNDEFINED).
@return	child node address */
UNIV_INLINE
ulint
btr_node_ptr_get_child_page_no(
/*===========================*/
	const rec_t*	rec,	/*!< in: node pointer record */
	const ulint*	offsets)/*!< in: array returned by rec_get_offsets() */
{
	const byte*	field;
	ulint		len;
	ulint		page_no;

	ut_ad(!rec_offs_comp(offsets) || rec_get_node_ptr_flag(rec));

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

	ut_ad(len == 4);

	page_no = mach_read_from_4(field);

	if (UNIV_UNLIKELY(page_no == 0)) {
		fprintf(stderr,
			"InnoDB: a nonsensical page number 0"
			" in a node ptr record at offset %lu\n",
			(ulong) page_offset(rec));
		buf_page_print(page_align(rec), 0, 0);
	}

	return(page_no);
}

/**************************************************************//**
Releases the latches on a leaf page and bufferunfixes it. */
UNIV_INLINE
void
btr_leaf_page_release(
/*==================*/
	buf_block_t*	block,		/*!< in: buffer block */
	ulint		latch_mode,	/*!< in: BTR_SEARCH_LEAF or
					BTR_MODIFY_LEAF */
	mtr_t*		mtr)		/*!< in: mtr */
{
	ut_ad(latch_mode == BTR_SEARCH_LEAF || latch_mode == BTR_MODIFY_LEAF);
	ut_ad(!mtr_memo_contains(mtr, block, MTR_MEMO_MODIFY));

	mtr_memo_release(mtr, block,
			 latch_mode == BTR_SEARCH_LEAF
			 ? MTR_MEMO_PAGE_S_FIX
			 : MTR_MEMO_PAGE_X_FIX);
}
#endif /* !UNIV_HOTBACKUP */