mariadb/include/lock0lock.h

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

Copyright (c) 1996, 2009, Innobase Oy. 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., 59 Temple
Place, Suite 330, Boston, MA 02111-1307 USA

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

/**************************************************//**
@file include/lock0lock.h
The transaction lock system

Created 5/7/1996 Heikki Tuuri
*******************************************************/

#ifndef lock0lock_h
#define lock0lock_h

#include "univ.i"
#include "buf0types.h"
#include "trx0types.h"
#include "mtr0types.h"
#include "rem0types.h"
#include "dict0types.h"
#include "que0types.h"
#include "lock0types.h"
#include "read0types.h"
#include "hash0hash.h"
#include "ut0vec.h"

#ifdef UNIV_DEBUG
extern ibool	lock_print_waits;
#endif /* UNIV_DEBUG */
/* Buffer for storing information about the most recent deadlock error */
extern FILE*	lock_latest_err_file;

/*********************************************************************//**
Gets the size of a lock struct.
@return	size in bytes */
UNIV_INTERN
ulint
lock_get_size(void);
/*===============*/
/*********************************************************************//**
Creates the lock system at database start. */
UNIV_INTERN
void
lock_sys_create(
/*============*/
	ulint	n_cells);	/*!< in: number of slots in lock hash table */
/*********************************************************************//**
Closes the lock system at database shutdown. */
UNIV_INTERN
void
lock_sys_close(void);
/*================*/
/*********************************************************************//**
Checks if some transaction has an implicit x-lock on a record in a clustered
index.
@return	transaction which has the x-lock, or NULL */
UNIV_INLINE
trx_t*
lock_clust_rec_some_has_impl(
/*=========================*/
	const rec_t*	rec,	/*!< in: user record */
	dict_index_t*	index,	/*!< in: clustered index */
	const ulint*	offsets);/*!< in: rec_get_offsets(rec, index) */
/*********************************************************************//**
Gets the heap_no of the smallest user record on a page.
@return	heap_no of smallest user record, or PAGE_HEAP_NO_SUPREMUM */
UNIV_INLINE
ulint
lock_get_min_heap_no(
/*=================*/
	const buf_block_t*	block);	/*!< in: buffer block */
/*************************************************************//**
Updates the lock table when we have reorganized a page. NOTE: we copy
also the locks set on the infimum of the page; the infimum may carry
locks if an update of a record is occurring on the page, and its locks
were temporarily stored on the infimum. */
UNIV_INTERN
void
lock_move_reorganize_page(
/*======================*/
	const buf_block_t*	block,	/*!< in: old index page, now
					reorganized */
	const buf_block_t*	oblock);/*!< in: copy of the old, not
					reorganized page */
/*************************************************************//**
Moves the explicit locks on user records to another page if a record
list end is moved to another page. */
UNIV_INTERN
void
lock_move_rec_list_end(
/*===================*/
	const buf_block_t*	new_block,	/*!< in: index page to move to */
	const buf_block_t*	block,		/*!< in: index page */
	const rec_t*		rec);		/*!< in: record on page: this
						is the first record moved */
/*************************************************************//**
Moves the explicit locks on user records to another page if a record
list start is moved to another page. */
UNIV_INTERN
void
lock_move_rec_list_start(
/*=====================*/
	const buf_block_t*	new_block,	/*!< in: index page to move to */
	const buf_block_t*	block,		/*!< in: index page */
	const rec_t*		rec,		/*!< in: record on page:
						this is the first
						record NOT copied */
	const rec_t*		old_end);	/*!< in: old
						previous-to-last
						record on new_page
						before the records
						were copied */
/*************************************************************//**
Updates the lock table when a page is split to the right. */
UNIV_INTERN
void
lock_update_split_right(
/*====================*/
	const buf_block_t*	right_block,	/*!< in: right page */
	const buf_block_t*	left_block);	/*!< in: left page */
/*************************************************************//**
Updates the lock table when a page is merged to the right. */
UNIV_INTERN
void
lock_update_merge_right(
/*====================*/
	const buf_block_t*	right_block,	/*!< in: right page to
						which merged */
	const rec_t*		orig_succ,	/*!< in: original
						successor of infimum
						on the right page
						before merge */
	const buf_block_t*	left_block);	/*!< in: merged index
						page which will be
						discarded */
/*************************************************************//**
Updates the lock table when the root page is copied to another in
btr_root_raise_and_insert. Note that we leave lock structs on the
root page, even though they do not make sense on other than leaf
pages: the reason is that in a pessimistic update the infimum record
of the root page will act as a dummy carrier of the locks of the record
to be updated. */
UNIV_INTERN
void
lock_update_root_raise(
/*===================*/
	const buf_block_t*	block,	/*!< in: index page to which copied */
	const buf_block_t*	root);	/*!< in: root page */
/*************************************************************//**
Updates the lock table when a page is copied to another and the original page
is removed from the chain of leaf pages, except if page is the root! */
UNIV_INTERN
void
lock_update_copy_and_discard(
/*=========================*/
	const buf_block_t*	new_block,	/*!< in: index page to
						which copied */
	const buf_block_t*	block);		/*!< in: index page;
						NOT the root! */
/*************************************************************//**
Updates the lock table when a page is split to the left. */
UNIV_INTERN
void
lock_update_split_left(
/*===================*/
	const buf_block_t*	right_block,	/*!< in: right page */
	const buf_block_t*	left_block);	/*!< in: left page */
/*************************************************************//**
Updates the lock table when a page is merged to the left. */
UNIV_INTERN
void
lock_update_merge_left(
/*===================*/
	const buf_block_t*	left_block,	/*!< in: left page to
						which merged */
	const rec_t*		orig_pred,	/*!< in: original predecessor
						of supremum on the left page
						before merge */
	const buf_block_t*	right_block);	/*!< in: merged index page
						which will be discarded */
/*************************************************************//**
Resets the original locks on heir and replaces them with gap type locks
inherited from rec. */
UNIV_INTERN
void
lock_rec_reset_and_inherit_gap_locks(
/*=================================*/
	const buf_block_t*	heir_block,	/*!< in: block containing the
						record which inherits */
	const buf_block_t*	block,		/*!< in: block containing the
						record from which inherited;
						does NOT reset the locks on
						this record */
	ulint			heir_heap_no,	/*!< in: heap_no of the
						inheriting record */
	ulint			heap_no);	/*!< in: heap_no of the
						donating record */
/*************************************************************//**
Updates the lock table when a page is discarded. */
UNIV_INTERN
void
lock_update_discard(
/*================*/
	const buf_block_t*	heir_block,	/*!< in: index page
						which will inherit the locks */
	ulint			heir_heap_no,	/*!< in: heap_no of the record
						which will inherit the locks */
	const buf_block_t*	block);		/*!< in: index page
						which will be discarded */
/*************************************************************//**
Updates the lock table when a new user record is inserted. */
UNIV_INTERN
void
lock_update_insert(
/*===============*/
	const buf_block_t*	block,	/*!< in: buffer block containing rec */
	const rec_t*		rec);	/*!< in: the inserted record */
/*************************************************************//**
Updates the lock table when a record is removed. */
UNIV_INTERN
void
lock_update_delete(
/*===============*/
	const buf_block_t*	block,	/*!< in: buffer block containing rec */
	const rec_t*		rec);	/*!< in: the record to be removed */
/*********************************************************************//**
Stores on the page infimum record the explicit locks of another record.
This function is used to store the lock state of a record when it is
updated and the size of the record changes in the update. The record
is in such an update moved, perhaps to another page. The infimum record
acts as a dummy carrier record, taking care of lock releases while the
actual record is being moved. */
UNIV_INTERN
void
lock_rec_store_on_page_infimum(
/*===========================*/
	const buf_block_t*	block,	/*!< in: buffer block containing rec */
	const rec_t*		rec);	/*!< in: record whose lock state
					is stored on the infimum
					record of the same page; lock
					bits are reset on the
					record */
/*********************************************************************//**
Restores the state of explicit lock requests on a single record, where the
state was stored on the infimum of the page. */
UNIV_INTERN
void
lock_rec_restore_from_page_infimum(
/*===============================*/
	const buf_block_t*	block,	/*!< in: buffer block containing rec */
	const rec_t*		rec,	/*!< in: record whose lock state
					is restored */
	const buf_block_t*	donator);/*!< in: page (rec is not
					necessarily on this page)
					whose infimum stored the lock
					state; lock bits are reset on
					the infimum */
/*********************************************************************//**
Returns TRUE if there are explicit record locks on a page.
@return	TRUE if there are explicit record locks on the page */
UNIV_INTERN
ibool
lock_rec_expl_exist_on_page(
/*========================*/
	ulint	space,	/*!< in: space id */
	ulint	page_no);/*!< in: page number */
/*********************************************************************//**
Checks if locks of other transactions prevent an immediate insert of
a record. If they do, first tests if the query thread should anyway
be suspended for some reason; if not, then puts the transaction and
the query thread to the lock wait state and inserts a waiting request
for a gap x-lock to the lock queue.
@return	DB_SUCCESS, DB_LOCK_WAIT, DB_DEADLOCK, or DB_QUE_THR_SUSPENDED */
UNIV_INTERN
ulint
lock_rec_insert_check_and_lock(
/*===========================*/
	ulint		flags,	/*!< in: if BTR_NO_LOCKING_FLAG bit is
				set, does nothing */
	const rec_t*	rec,	/*!< in: record after which to insert */
	buf_block_t*	block,	/*!< in/out: buffer block of rec */
	dict_index_t*	index,	/*!< in: index */
	que_thr_t*	thr,	/*!< in: query thread */
	mtr_t*		mtr,	/*!< in/out: mini-transaction */
	ibool*		inherit);/*!< out: set to TRUE if the new
				inserted record maybe should inherit
				LOCK_GAP type locks from the successor
				record */
/*********************************************************************//**
Checks if locks of other transactions prevent an immediate modify (update,
delete mark, or delete unmark) of a clustered index record. If they do,
first tests if the query thread should anyway be suspended for some
reason; if not, then puts the transaction and the query thread to the
lock wait state and inserts a waiting request for a record x-lock to the
lock queue.
@return	DB_SUCCESS, DB_LOCK_WAIT, DB_DEADLOCK, or DB_QUE_THR_SUSPENDED */
UNIV_INTERN
ulint
lock_clust_rec_modify_check_and_lock(
/*=================================*/
	ulint			flags,	/*!< in: if BTR_NO_LOCKING_FLAG
					bit is set, does nothing */
	const buf_block_t*	block,	/*!< in: buffer block of rec */
	const rec_t*		rec,	/*!< in: record which should be
					modified */
	dict_index_t*		index,	/*!< in: clustered index */
	const ulint*		offsets,/*!< in: rec_get_offsets(rec, index) */
	que_thr_t*		thr);	/*!< in: query thread */
/*********************************************************************//**
Checks if locks of other transactions prevent an immediate modify
(delete mark or delete unmark) of a secondary index record.
@return	DB_SUCCESS, DB_LOCK_WAIT, DB_DEADLOCK, or DB_QUE_THR_SUSPENDED */
UNIV_INTERN
ulint
lock_sec_rec_modify_check_and_lock(
/*===============================*/
	ulint		flags,	/*!< in: if BTR_NO_LOCKING_FLAG
				bit is set, does nothing */
	buf_block_t*	block,	/*!< in/out: buffer block of rec */
	const rec_t*	rec,	/*!< in: record which should be
				modified; NOTE: as this is a secondary
				index, we always have to modify the
				clustered index record first: see the
				comment below */
	dict_index_t*	index,	/*!< in: secondary index */
	que_thr_t*	thr,	/*!< in: query thread */
	mtr_t*		mtr);	/*!< in/out: mini-transaction */
/*********************************************************************//**
Like the counterpart for a clustered index below, but now we read a
secondary index record.
@return	DB_SUCCESS, DB_LOCK_WAIT, DB_DEADLOCK, or DB_QUE_THR_SUSPENDED */
UNIV_INTERN
ulint
lock_sec_rec_read_check_and_lock(
/*=============================*/
	ulint			flags,	/*!< in: if BTR_NO_LOCKING_FLAG
					bit is set, does nothing */
	const buf_block_t*	block,	/*!< in: buffer block of rec */
	const rec_t*		rec,	/*!< in: user record or page
					supremum record which should
					be read or passed over by a
					read cursor */
	dict_index_t*		index,	/*!< in: secondary index */
	const ulint*		offsets,/*!< in: rec_get_offsets(rec, index) */
	enum lock_mode		mode,	/*!< in: mode of the lock which
					the read cursor should set on
					records: LOCK_S or LOCK_X; the
					latter is possible in
					SELECT FOR UPDATE */
	ulint			gap_mode,/*!< in: LOCK_ORDINARY, LOCK_GAP, or
					LOCK_REC_NOT_GAP */
	que_thr_t*		thr);	/*!< in: query thread */
/*********************************************************************//**
Checks if locks of other transactions prevent an immediate read, or passing
over by a read cursor, of a clustered index record. If they do, first tests
if the query thread should anyway be suspended for some reason; if not, then
puts the transaction and the query thread to the lock wait state and inserts a
waiting request for a record lock to the lock queue. Sets the requested mode
lock on the record.
@return	DB_SUCCESS, DB_LOCK_WAIT, DB_DEADLOCK, or DB_QUE_THR_SUSPENDED */
UNIV_INTERN
ulint
lock_clust_rec_read_check_and_lock(
/*===============================*/
	ulint			flags,	/*!< in: if BTR_NO_LOCKING_FLAG
					bit is set, does nothing */
	const buf_block_t*	block,	/*!< in: buffer block of rec */
	const rec_t*		rec,	/*!< in: user record or page
					supremum record which should
					be read or passed over by a
					read cursor */
	dict_index_t*		index,	/*!< in: clustered index */
	const ulint*		offsets,/*!< in: rec_get_offsets(rec, index) */
	enum lock_mode		mode,	/*!< in: mode of the lock which
					the read cursor should set on
					records: LOCK_S or LOCK_X; the
					latter is possible in
					SELECT FOR UPDATE */
	ulint			gap_mode,/*!< in: LOCK_ORDINARY, LOCK_GAP, or
					LOCK_REC_NOT_GAP */
	que_thr_t*		thr);	/*!< in: query thread */
/*********************************************************************//**
Checks if locks of other transactions prevent an immediate read, or passing
over by a read cursor, of a clustered index record. If they do, first tests
if the query thread should anyway be suspended for some reason; if not, then
puts the transaction and the query thread to the lock wait state and inserts a
waiting request for a record lock to the lock queue. Sets the requested mode
lock on the record. This is an alternative version of
lock_clust_rec_read_check_and_lock() that does not require the parameter
"offsets".
@return	DB_SUCCESS, DB_LOCK_WAIT, DB_DEADLOCK, or DB_QUE_THR_SUSPENDED */
UNIV_INTERN
ulint
lock_clust_rec_read_check_and_lock_alt(
/*===================================*/
	ulint			flags,	/*!< in: if BTR_NO_LOCKING_FLAG
					bit is set, does nothing */
	const buf_block_t*	block,	/*!< in: buffer block of rec */
	const rec_t*		rec,	/*!< in: user record or page
					supremum record which should
					be read or passed over by a
					read cursor */
	dict_index_t*		index,	/*!< in: clustered index */
	enum lock_mode		mode,	/*!< in: mode of the lock which
					the read cursor should set on
					records: LOCK_S or LOCK_X; the
					latter is possible in
					SELECT FOR UPDATE */
	ulint			gap_mode,/*!< in: LOCK_ORDINARY, LOCK_GAP, or
					LOCK_REC_NOT_GAP */
	que_thr_t*		thr);	/*!< in: query thread */
/*********************************************************************//**
Checks that a record is seen in a consistent read.
@return TRUE if sees, or FALSE if an earlier version of the record
should be retrieved */
UNIV_INTERN
ibool
lock_clust_rec_cons_read_sees(
/*==========================*/
	const rec_t*	rec,	/*!< in: user record which should be read or
				passed over by a read cursor */
	dict_index_t*	index,	/*!< in: clustered index */
	const ulint*	offsets,/*!< in: rec_get_offsets(rec, index) */
	read_view_t*	view);	/*!< in: consistent read view */
/*********************************************************************//**
Checks that a non-clustered index record is seen in a consistent read.

NOTE that a non-clustered index page contains so little information on
its modifications that also in the case FALSE, the present version of
rec may be the right, but we must check this from the clustered index
record.

@return TRUE if certainly sees, or FALSE if an earlier version of the
clustered index record might be needed */
UNIV_INTERN
ulint
lock_sec_rec_cons_read_sees(
/*========================*/
	const rec_t*		rec,	/*!< in: user record which
					should be read or passed over
					by a read cursor */
	const read_view_t*	view);	/*!< in: consistent read view */
/*********************************************************************//**
Locks the specified database table in the mode given. If the lock cannot
be granted immediately, the query thread is put to wait.
@return	DB_SUCCESS, DB_LOCK_WAIT, DB_DEADLOCK, or DB_QUE_THR_SUSPENDED */
UNIV_INTERN
ulint
lock_table(
/*=======*/
	ulint		flags,	/*!< in: if BTR_NO_LOCKING_FLAG bit is set,
				does nothing */
	dict_table_t*	table,	/*!< in: database table in dictionary cache */
	enum lock_mode	mode,	/*!< in: lock mode */
	que_thr_t*	thr);	/*!< in: query thread */
/*************************************************************//**
Removes a granted record lock of a transaction from the queue and grants
locks to other transactions waiting in the queue if they now are entitled
to a lock. */
UNIV_INTERN
void
lock_rec_unlock(
/*============*/
	trx_t*			trx,	/*!< in: transaction that has
					set a record lock */
	const buf_block_t*	block,	/*!< in: buffer block containing rec */
	const rec_t*		rec,	/*!< in: record */
	enum lock_mode		lock_mode);/*!< in: LOCK_S or LOCK_X */
/*********************************************************************//**
Releases transaction locks, and releases possible other transactions waiting
because of these locks. */
UNIV_INTERN
void
lock_release_off_kernel(
/*====================*/
	trx_t*	trx);	/*!< in: transaction */
/*********************************************************************//**
Cancels a waiting lock request and releases possible other transactions
waiting behind it. */
UNIV_INTERN
void
lock_cancel_waiting_and_release(
/*============================*/
	lock_t*	lock);	/*!< in: waiting lock request */

/*********************************************************************//**
Removes locks on a table to be dropped or truncated.
If remove_also_table_sx_locks is TRUE then table-level S and X locks are
also removed in addition to other table-level and record-level locks.
No lock, that is going to be removed, is allowed to be a wait lock. */
UNIV_INTERN
void
lock_remove_all_on_table(
/*=====================*/
	dict_table_t*	table,			/*!< in: table to be dropped
						or truncated */
	ibool		remove_also_table_sx_locks);/*!< in: also removes
						table S and X locks */

/*********************************************************************//**
Calculates the fold value of a page file address: used in inserting or
searching for a lock in the hash table.
@return	folded value */
UNIV_INLINE
ulint
lock_rec_fold(
/*==========*/
	ulint	space,	/*!< in: space */
	ulint	page_no)/*!< in: page number */
	__attribute__((const));
/*********************************************************************//**
Calculates the hash value of a page file address: used in inserting or
searching for a lock in the hash table.
@return	hashed value */
UNIV_INLINE
ulint
lock_rec_hash(
/*==========*/
	ulint	space,	/*!< in: space */
	ulint	page_no);/*!< in: page number */

/**********************************************************************//**
Looks for a set bit in a record lock bitmap. Returns ULINT_UNDEFINED,
if none found.
@return bit index == heap number of the record, or ULINT_UNDEFINED if
none found */
UNIV_INTERN
ulint
lock_rec_find_set_bit(
/*==================*/
	const lock_t*	lock);	/*!< in: record lock with at least one
				bit set */

/*********************************************************************//**
Gets the source table of an ALTER TABLE transaction.  The table must be
covered by an IX or IS table lock.
@return the source table of transaction, if it is covered by an IX or
IS table lock; dest if there is no source table, and NULL if the
transaction is locking more than two tables or an inconsistency is
found */
UNIV_INTERN
dict_table_t*
lock_get_src_table(
/*===============*/
	trx_t*		trx,	/*!< in: transaction */
	dict_table_t*	dest,	/*!< in: destination of ALTER TABLE */
	enum lock_mode*	mode);	/*!< out: lock mode of the source table */
/*********************************************************************//**
Determine if the given table is exclusively "owned" by the given
transaction, i.e., transaction holds LOCK_IX and possibly LOCK_AUTO_INC
on the table.
@return TRUE if table is only locked by trx, with LOCK_IX, and
possibly LOCK_AUTO_INC */
UNIV_INTERN
ibool
lock_is_table_exclusive(
/*====================*/
	dict_table_t*	table,	/*!< in: table */
	trx_t*		trx);	/*!< in: transaction */
/*********************************************************************//**
Checks if a lock request lock1 has to wait for request lock2.
@return	TRUE if lock1 has to wait for lock2 to be removed */
UNIV_INTERN
ibool
lock_has_to_wait(
/*=============*/
	const lock_t*	lock1,	/*!< in: waiting lock */
	const lock_t*	lock2);	/*!< in: another lock; NOTE that it is
				assumed that this has a lock bit set
				on the same record as in lock1 if the
				locks are record locks */
/*********************************************************************//**
Checks that a transaction id is sensible, i.e., not in the future.
@return	TRUE if ok */
UNIV_INTERN
ibool
lock_check_trx_id_sanity(
/*=====================*/
	trx_id_t	trx_id,		/*!< in: trx id */
	const rec_t*	rec,		/*!< in: user record */
	dict_index_t*	index,		/*!< in: clustered index */
	const ulint*	offsets,	/*!< in: rec_get_offsets(rec, index) */
	ibool		has_kernel_mutex);/*!< in: TRUE if the caller owns the
					kernel mutex */
/*********************************************************************//**
Prints info of a table lock. */
UNIV_INTERN
void
lock_table_print(
/*=============*/
	FILE*		file,	/*!< in: file where to print */
	const lock_t*	lock);	/*!< in: table type lock */
/*********************************************************************//**
Prints info of a record lock. */
UNIV_INTERN
void
lock_rec_print(
/*===========*/
	FILE*		file,	/*!< in: file where to print */
	const lock_t*	lock);	/*!< in: record type lock */
/*********************************************************************//**
Prints info of locks for all transactions.
@return FALSE if not able to obtain kernel mutex
and exits without printing info */
UNIV_INTERN
ibool
lock_print_info_summary(
/*====================*/
	FILE*	file,	/*!< in: file where to print */
	ibool   nowait);/*!< in: whether to wait for the kernel mutex */
/*************************************************************************
Prints info of locks for each transaction. */
UNIV_INTERN
void
lock_print_info_all_transactions(
/*=============================*/
	FILE*	file);	/*!< in: file where to print */
/*********************************************************************//**
Return approximate number or record locks (bits set in the bitmap) for
this transaction. Since delete-marked records may be removed, the
record count will not be precise. */
UNIV_INTERN
ulint
lock_number_of_rows_locked(
/*=======================*/
	trx_t*	trx);	/*!< in: transaction */
/*******************************************************************//**
Check if a transaction holds any autoinc locks.
@return TRUE if the transaction holds any AUTOINC locks. */
UNIV_INTERN
ibool
lock_trx_holds_autoinc_locks(
/*=========================*/
	const trx_t*	trx);		/*!< in: transaction */
/*******************************************************************//**
Release all the transaction's autoinc locks. */
UNIV_INTERN
void
lock_release_autoinc_locks(
/*=======================*/
	trx_t*		trx);		/*!< in/out: transaction */

/*******************************************************************//**
Gets the type of a lock. Non-inline version for using outside of the
lock module.
@return	LOCK_TABLE or LOCK_REC */
UNIV_INTERN
ulint
lock_get_type(
/*==========*/
	const lock_t*	lock);	/*!< in: lock */

/*******************************************************************//**
Gets the id of the transaction owning a lock.
@return	transaction id */
UNIV_INTERN
ullint
lock_get_trx_id(
/*============*/
	const lock_t*	lock);	/*!< in: lock */

/*******************************************************************//**
Gets the mode of a lock in a human readable string.
The string should not be free()'d or modified.
@return	lock mode */
UNIV_INTERN
const char*
lock_get_mode_str(
/*==============*/
	const lock_t*	lock);	/*!< in: lock */

/*******************************************************************//**
Gets the type of a lock in a human readable string.
The string should not be free()'d or modified.
@return	lock type */
UNIV_INTERN
const char*
lock_get_type_str(
/*==============*/
	const lock_t*	lock);	/*!< in: lock */

/*******************************************************************//**
Gets the id of the table on which the lock is.
@return	id of the table */
UNIV_INTERN
ullint
lock_get_table_id(
/*==============*/
	const lock_t*	lock);	/*!< in: lock */

/*******************************************************************//**
Gets the name of the table on which the lock is.
The string should not be free()'d or modified.
@return	name of the table */
UNIV_INTERN
const char*
lock_get_table_name(
/*================*/
	const lock_t*	lock);	/*!< in: lock */

/*******************************************************************//**
For a record lock, gets the index on which the lock is.
@return	index */
UNIV_INTERN
const dict_index_t*
lock_rec_get_index(
/*===============*/
	const lock_t*	lock);	/*!< in: lock */

/*******************************************************************//**
For a record lock, gets the name of the index on which the lock is.
The string should not be free()'d or modified.
@return	name of the index */
UNIV_INTERN
const char*
lock_rec_get_index_name(
/*====================*/
	const lock_t*	lock);	/*!< in: lock */

/*******************************************************************//**
For a record lock, gets the tablespace number on which the lock is.
@return	tablespace number */
UNIV_INTERN
ulint
lock_rec_get_space_id(
/*==================*/
	const lock_t*	lock);	/*!< in: lock */

/*******************************************************************//**
For a record lock, gets the page number on which the lock is.
@return	page number */
UNIV_INTERN
ulint
lock_rec_get_page_no(
/*=================*/
	const lock_t*	lock);	/*!< in: lock */

/** Lock modes and types */
/* @{ */
#define LOCK_MODE_MASK	0xFUL	/*!< mask used to extract mode from the
				type_mode field in a lock */
/** Lock types */
/* @{ */
#define LOCK_TABLE	16	/*!< table lock */
#define	LOCK_REC	32	/*!< record lock */
#define LOCK_TYPE_MASK	0xF0UL	/*!< mask used to extract lock type from the
				type_mode field in a lock */
#if LOCK_MODE_MASK & LOCK_TYPE_MASK
# error "LOCK_MODE_MASK & LOCK_TYPE_MASK"
#endif

#define LOCK_WAIT	256	/*!< Waiting lock flag; when set, it
				means that the lock has not yet been
				granted, it is just waiting for its
				turn in the wait queue */
/* Precise modes */
#define LOCK_ORDINARY	0	/*!< this flag denotes an ordinary
				next-key lock in contrast to LOCK_GAP
				or LOCK_REC_NOT_GAP */
#define LOCK_GAP	512	/*!< when this bit is set, it means that the
				lock holds only on the gap before the record;
				for instance, an x-lock on the gap does not
				give permission to modify the record on which
				the bit is set; locks of this type are created
				when records are removed from the index chain
				of records */
#define LOCK_REC_NOT_GAP 1024	/*!< this bit means that the lock is only on
				the index record and does NOT block inserts
				to the gap before the index record; this is
				used in the case when we retrieve a record
				with a unique key, and is also used in
				locking plain SELECTs (not part of UPDATE
				or DELETE) when the user has set the READ
				COMMITTED isolation level */
#define LOCK_INSERT_INTENTION 2048 /*!< this bit is set when we place a waiting
				gap type record lock request in order to let
				an insert of an index record to wait until
				there are no conflicting locks by other
				transactions on the gap; note that this flag
				remains set when the waiting lock is granted,
				or if the lock is inherited to a neighboring
				record */
#if (LOCK_WAIT|LOCK_GAP|LOCK_REC_NOT_GAP|LOCK_INSERT_INTENTION)&LOCK_MODE_MASK
# error
#endif
#if (LOCK_WAIT|LOCK_GAP|LOCK_REC_NOT_GAP|LOCK_INSERT_INTENTION)&LOCK_TYPE_MASK
# error
#endif
/* @} */

/** Lock operation struct */
typedef struct lock_op_struct	lock_op_t;
/** Lock operation struct */
struct lock_op_struct{
	dict_table_t*	table;	/*!< table to be locked */
	enum lock_mode	mode;	/*!< lock mode */
};

/** The lock system struct */
struct lock_sys_struct{
	hash_table_t*	rec_hash;	/*!< hash table of the record locks */
};

/** The lock system */
extern lock_sys_t*	lock_sys;


#ifndef UNIV_NONINL
#include "lock0lock.ic"
#endif

#endif