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

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Copyright (c) 2017, 2020, MariaDB Corporation.

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

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

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

#ifndef lock0lock_h
#define lock0lock_h

#include "buf0types.h"
#include "trx0types.h"
#include "mtr0types.h"
#include "rem0types.h"
#include "que0types.h"
#include "lock0types.h"
#include "hash0hash.h"
#include "srv0srv.h"
#include "ut0vec.h"
#include "gis0rtree.h"
#include "lock0prdt.h"

/** Alternatives for innodb_lock_schedule_algorithm, which can be changed by
	setting innodb_lock_schedule_algorithm. */
enum innodb_lock_schedule_algorithm_t {
	/*!< First Come First Served */
	INNODB_LOCK_SCHEDULE_ALGORITHM_FCFS,
	/*!< Variance-Aware-Transaction-Scheduling */
	INNODB_LOCK_SCHEDULE_ALGORITHM_VATS
};

extern ulong innodb_lock_schedule_algorithm;

// Forward declaration
class ReadView;

/** The value of innodb_deadlock_detect */
extern my_bool	innobase_deadlock_detect;

/*********************************************************************//**
Gets the size of a lock struct.
@return size in bytes */
ulint
lock_get_size(void);
/*===============*/
/*********************************************************************//**
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. */
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. */
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. */
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. */
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. */
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. */
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! */
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. */
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. */
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 */
/*************************************************************//**
Updates the lock table when a page is split and merged to
two pages. */
UNIV_INTERN
void
lock_update_split_and_merge(
	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: right page from which merged */
/*************************************************************//**
Resets the original locks on heir and replaces them with gap type locks
inherited from rec. */
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. */
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. */
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. */
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. */
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. */
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 */
/*********************************************************************//**
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, or DB_DEADLOCK */
dberr_t
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 */
	bool*		inherit)/*!< out: set to true if the new
				inserted record maybe should inherit
				LOCK_GAP type locks from the successor
				record */
	MY_ATTRIBUTE((warn_unused_result));

/*********************************************************************//**
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, or DB_DEADLOCK */
dberr_t
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 rec_offs*		offsets,/*!< in: rec_get_offsets(rec, index) */
	que_thr_t*		thr)	/*!< in: query thread */
	MY_ATTRIBUTE((warn_unused_result));
/*********************************************************************//**
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, or DB_DEADLOCK */
dberr_t
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
				(can be NULL if BTR_NO_LOCKING_FLAG) */
	mtr_t*		mtr)	/*!< in/out: mini-transaction */
	MY_ATTRIBUTE((warn_unused_result));
/*********************************************************************//**
Like lock_clust_rec_read_check_and_lock(), but reads a
secondary index record.
@return DB_SUCCESS, DB_SUCCESS_LOCKED_REC, DB_LOCK_WAIT, or DB_DEADLOCK */
dberr_t
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 rec_offs*		offsets,/*!< in: rec_get_offsets(rec, index) */
	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 */
	unsigned		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_SUCCESS_LOCKED_REC, DB_LOCK_WAIT, or DB_DEADLOCK */
dberr_t
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 rec_offs*		offsets,/*!< in: rec_get_offsets(rec, index) */
	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 */
	unsigned		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, or DB_DEADLOCK */
dberr_t
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 */
	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 */
	unsigned		gap_mode,/*!< in: LOCK_ORDINARY, LOCK_GAP, or
					LOCK_REC_NOT_GAP */
	que_thr_t*		thr)	/*!< in: query thread */
	MY_ATTRIBUTE((warn_unused_result));
/*********************************************************************//**
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 */
bool
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 rec_offs*	offsets,/*!< in: rec_get_offsets(rec, index) */
	ReadView*	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 */
bool
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 dict_index_t*     index,  /*!< in: index */
	const ReadView*	view)	/*!< in: consistent read view */
	MY_ATTRIBUTE((warn_unused_result));
/*********************************************************************//**
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, or DB_DEADLOCK */
dberr_t
lock_table(
/*=======*/
	unsigned	flags,	/*!< in: if BTR_NO_LOCKING_FLAG bit is set,
				does nothing */
	dict_table_t*	table,	/*!< in/out: database table
				in dictionary cache */
	lock_mode	mode,	/*!< in: lock mode */
	que_thr_t*	thr)	/*!< in: query thread */
	MY_ATTRIBUTE((warn_unused_result));
/*********************************************************************//**
Creates a table IX lock object for a resurrected transaction. */
void
lock_table_ix_resurrect(
/*====================*/
	dict_table_t*	table,	/*!< in/out: table */
	trx_t*		trx);	/*!< in/out: transaction */

/** Sets a lock on a table based on the given mode.
@param[in]	table	table to lock
@param[in,out]	trx	transaction
@param[in]	mode	LOCK_X or LOCK_S
@return error code or DB_SUCCESS. */
dberr_t
lock_table_for_trx(
	dict_table_t*	table,
	trx_t*		trx,
	enum lock_mode	mode)
	MY_ATTRIBUTE((nonnull, warn_unused_result));

/*************************************************************//**
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. */
void
lock_rec_unlock(
/*============*/
	trx_t*			trx,	/*!< in/out: transaction that has
					set a record lock */
	const buf_block_t*	block,	/*!< in: buffer block containing rec */
	const rec_t*		rec,	/*!< in: record */
	lock_mode		lock_mode);/*!< in: LOCK_S or LOCK_X */

/** Release the explicit locks of a committing transaction,
and release possible other transactions waiting because of these locks. */
void lock_release(trx_t* trx);

/*************************************************************//**
Get the lock hash table */
UNIV_INLINE
hash_table_t*
lock_hash_get(
/*==========*/
	ulint	mode);	/*!< in: lock mode */

/**********************************************************************//**
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 */
ulint
lock_rec_find_set_bit(
/*==================*/
	const lock_t*	lock);	/*!< in: record lock with at least one
				bit set */

/*********************************************************************//**
Checks if a lock request lock1 has to wait for request lock2.
@return whether lock1 has to wait for lock2 to be removed */
bool
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 */
/*********************************************************************//**
Reports that a transaction id is insensible, i.e., in the future. */
ATTRIBUTE_COLD
void
lock_report_trx_id_insanity(
/*========================*/
	trx_id_t	trx_id,		/*!< in: trx id */
	const rec_t*	rec,		/*!< in: user record */
	dict_index_t*	index,		/*!< in: index */
	const rec_offs*	offsets,	/*!< in: rec_get_offsets(rec, index) */
	trx_id_t	max_trx_id);	/*!< in: trx_sys.get_max_trx_id() */
/*********************************************************************//**
Prints info of locks for all transactions.
@return FALSE if not able to obtain lock mutex and exits without
printing info */
ibool
lock_print_info_summary(
/*====================*/
	FILE*	file,	/*!< in: file where to print */
	ibool   nowait)	/*!< in: whether to wait for the lock mutex */
	MY_ATTRIBUTE((warn_unused_result));

/** Prints transaction lock wait and MVCC state.
@param[in,out]	file	file where to print
@param[in]	trx	transaction
@param[in]	now	current time */
void
lock_trx_print_wait_and_mvcc_state(FILE* file, const trx_t* trx, time_t now);

/*********************************************************************//**
Prints info of locks for each transaction. This function assumes that the
caller holds the lock mutex and more importantly it will release the lock
mutex on behalf of the caller. (This should be fixed in the future). */
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.
The caller must be holding lock_sys.mutex. */
ulint
lock_number_of_rows_locked(
/*=======================*/
	const trx_lock_t*	trx_lock)	/*!< in: transaction locks */
	MY_ATTRIBUTE((warn_unused_result));

/*********************************************************************//**
Return the number of table locks for a transaction.
The caller must be holding lock_sys.mutex. */
ulint
lock_number_of_tables_locked(
/*=========================*/
	const trx_lock_t*	trx_lock)	/*!< in: transaction locks */
	MY_ATTRIBUTE((warn_unused_result));

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

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

/** Determine which table a lock is associated with.
@param[in]	lock	the lock
@return name of the table */
const table_name_t&
lock_get_table_name(
	const lock_t*	lock);

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

/*******************************************************************//**
Check if there are any locks (table or rec) against table.
@return TRUE if locks exist */
bool
lock_table_has_locks(
/*=================*/
	const dict_table_t*	table);	/*!< in: check if there are any locks
					held on records in this table or on the
					table itself */

/** A task which wakes up threads whose lock wait may have lasted too long */
void lock_wait_timeout_task(void*);

/********************************************************************//**
Releases a user OS thread waiting for a lock to be released, if the
thread is already suspended. */
void
lock_wait_release_thread_if_suspended(
/*==================================*/
	que_thr_t*	thr);	/*!< in: query thread associated with the
				user OS thread	 */

/***************************************************************//**
Puts a user OS thread to wait for a lock to be released. If an error
occurs during the wait trx->error_state associated with thr is
!= DB_SUCCESS when we return. DB_LOCK_WAIT_TIMEOUT and DB_DEADLOCK
are possible errors. DB_DEADLOCK is returned if selective deadlock
resolution chose this transaction as a victim. */
void
lock_wait_suspend_thread(
/*=====================*/
	que_thr_t*	thr);	/*!< in: query thread associated with the
				user OS thread */
/*********************************************************************//**
Unlocks AUTO_INC type locks that were possibly reserved by a trx. This
function should be called at the the end of an SQL statement, by the
connection thread that owns the transaction (trx->mysql_thd). */
void
lock_unlock_table_autoinc(
/*======================*/
	trx_t*	trx);			/*!< in/out: transaction */
/*********************************************************************//**
Check whether the transaction has already been rolled back because it
was selected as a deadlock victim, or if it has to wait then cancel
the wait lock.
@return DB_DEADLOCK, DB_LOCK_WAIT or DB_SUCCESS */
dberr_t
lock_trx_handle_wait(
/*=================*/
	trx_t*	trx);	/*!< in/out: trx lock state */
/*********************************************************************//**
Get the number of locks on a table.
@return number of locks */
ulint
lock_table_get_n_locks(
/*===================*/
	const dict_table_t*	table);	/*!< in: table */
/*******************************************************************//**
Initialise the trx lock list. */
void
lock_trx_lock_list_init(
/*====================*/
	trx_lock_list_t*	lock_list);	/*!< List to initialise */

/*********************************************************************//**
Checks that a transaction id is sensible, i.e., not in the future.
@return true if ok */
bool
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: index */
	const rec_offs*	offsets);	/*!< in: rec_get_offsets(rec, index) */
#ifdef UNIV_DEBUG
/*******************************************************************//**
Check if the transaction holds any locks on the sys tables
or its records.
@return the strongest lock found on any sys table or 0 for none */
const lock_t*
lock_trx_has_sys_table_locks(
/*=========================*/
	const trx_t*	trx)	/*!< in: transaction to check */
	MY_ATTRIBUTE((nonnull, warn_unused_result));

/** Check if the transaction holds an explicit exclusive lock on a record.
@param[in]	trx	transaction
@param[in]	table	table
@param[in]	block	leaf page
@param[in]	heap_no	heap number identifying the record
@return whether an explicit X-lock is held */
bool
lock_trx_has_expl_x_lock(
	const trx_t*		trx,	/*!< in: transaction to check */
	const dict_table_t*	table,	/*!< in: table to check */
	const buf_block_t*	block,	/*!< in: buffer block of the record */
	ulint			heap_no)/*!< in: record heap number */
	MY_ATTRIBUTE((nonnull, warn_unused_result));
#endif /* UNIV_DEBUG */

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

typedef ib_mutex_t LockMutex;

/** The lock system struct */
class lock_sys_t
{
  bool m_initialised;

public:
	MY_ALIGNED(CACHE_LINE_SIZE)
	LockMutex	mutex;			/*!< Mutex protecting the
						locks */
  /** record locks */
  hash_table_t rec_hash;
  /** predicate locks for SPATIAL INDEX */
  hash_table_t prdt_hash;
  /** page locks for SPATIAL INDEX */
  hash_table_t prdt_page_hash;

	MY_ALIGNED(CACHE_LINE_SIZE)
	LockMutex	wait_mutex;		/*!< Mutex protecting the
						next two fields */
	srv_slot_t*	waiting_threads;	/*!< Array  of user threads
						suspended while waiting for
						locks within InnoDB, protected
						by the lock_sys.wait_mutex;
						os_event_set() and
						os_event_reset() on
						waiting_threads[]->event
						are protected by
						trx_t::mutex */
	srv_slot_t*	last_slot;		/*!< highest slot ever used
						in the waiting_threads array,
						protected by
						lock_sys.wait_mutex */

	ulint		n_lock_max_wait_time;	/*!< Max wait time */

	std::unique_ptr<tpool::timer>	timeout_timer; /*!< Thread pool timer task */
	bool timeout_timer_active;


  /**
    Constructor.

    Some members may require late initialisation, thus we just mark object as
    uninitialised. Real initialisation happens in create().
  */
  lock_sys_t(): m_initialised(false) {}


  bool is_initialised() { return m_initialised; }


  /**
    Creates the lock system at database start.

    @param[in] n_cells number of slots in lock hash table
  */
  void create(ulint n_cells);


  /**
    Resize the lock hash table.

    @param[in] n_cells number of slots in lock hash table
  */
  void resize(ulint n_cells);


  /** Closes the lock system at database shutdown. */
  void close();

  /** @return the hash value for a page address */
  ulint hash(const page_id_t id) const
  { ut_ad(mutex_own(&mutex)); return rec_hash.calc_hash(id.fold()); }

  /** Get the first lock on a page.
  @param lock_hash   hash table to look at
  @param id          page number
  @return first lock
  @retval nullptr if none exists */
  lock_t *get_first(const hash_table_t &lock_hash, const page_id_t id) const
  {
    ut_ad(&lock_hash == &rec_hash || &lock_hash == &prdt_hash ||
          &lock_hash == &prdt_page_hash);
    for (lock_t *lock= static_cast<lock_t*>
         (HASH_GET_FIRST(&lock_hash, hash(id)));
         lock; lock= static_cast<lock_t*>(HASH_GET_NEXT(hash, lock)))
      if (lock->un_member.rec_lock.page_id == id)
         return lock;
    return nullptr;
  }

  /** Get the first record lock on a page.
  @param id          page number
  @return first lock
  @retval nullptr if none exists */
  lock_t *get_first(const page_id_t id) const
  { return get_first(rec_hash, id); }
  /** Get the first predicate lock on a SPATIAL INDEX page.
  @param id          page number
  @return first lock
  @retval nullptr if none exists */
  lock_t *get_first_prdt(const page_id_t id) const
  { return get_first(prdt_hash, id); }
  /** Get the first predicate lock on a SPATIAL INDEX page.
  @param id          page number
  @return first lock
  @retval nullptr if none exists */
  lock_t *get_first_prdt_page(const page_id_t id) const
  { return get_first(prdt_page_hash, id); }
};

/*********************************************************************//**
Creates a new record lock and inserts it to the lock queue. Does NOT check
for deadlocks or lock compatibility!
@return created lock */
UNIV_INLINE
lock_t*
lock_rec_create(
/*============*/
#ifdef WITH_WSREP
	lock_t*			c_lock,	/*!< conflicting lock */
	que_thr_t*		thr,	/*!< thread owning trx */
#endif
	unsigned		type_mode,/*!< in: lock mode and wait
					flag, type is ignored and
					replaced by LOCK_REC */
	const buf_block_t*	block,	/*!< in: buffer block containing
					the record */
	ulint			heap_no,/*!< in: heap number of the record */
	dict_index_t*		index,	/*!< in: index of record */
	trx_t*			trx,	/*!< in,out: transaction */
	bool			caller_owns_trx_mutex);
					/*!< in: true if caller owns
					trx mutex */

/*************************************************************//**
Removes a record lock request, waiting or granted, from the queue. */
void
lock_rec_discard(
/*=============*/
	lock_t*		in_lock);	/*!< in: record lock object: all
					record locks which are contained
					in this lock object are removed */

/** Create a new record lock and inserts it to the lock queue,
without checking for deadlocks or conflicts.
@param[in]	type_mode	lock mode and wait flag; type will be replaced
				with LOCK_REC
@param[in]	page_id		index page number
@param[in]	page		R-tree index page, or NULL
@param[in]	heap_no		record heap number in the index page
@param[in]	index		the index tree
@param[in,out]	trx		transaction
@param[in]	holds_trx_mutex	whether the caller holds trx->mutex
@return created lock */
lock_t*
lock_rec_create_low(
#ifdef WITH_WSREP
	lock_t*		c_lock,	/*!< conflicting lock */
	que_thr_t*	thr,	/*!< thread owning trx */
#endif
	unsigned	type_mode,
	const page_id_t	page_id,
	const page_t*	page,
	ulint		heap_no,
	dict_index_t*	index,
	trx_t*		trx,
	bool		holds_trx_mutex);
/** Enqueue a waiting request for a lock which cannot be granted immediately.
Check for deadlocks.
@param[in]	type_mode	the requested lock mode (LOCK_S or LOCK_X)
				possibly ORed with LOCK_GAP or
				LOCK_REC_NOT_GAP, ORed with
				LOCK_INSERT_INTENTION if this
				waiting lock request is set
				when performing an insert of
				an index record
@param[in]	block		leaf page in the index
@param[in]	heap_no		record heap number in the block
@param[in]	index		index tree
@param[in,out]	thr		query thread
@param[in]	prdt		minimum bounding box (spatial index)
@retval	DB_LOCK_WAIT		if the waiting lock was enqueued
@retval	DB_DEADLOCK		if this transaction was chosen as the victim
@retval	DB_SUCCESS_LOCKED_REC	if the other transaction was chosen as a victim
				(or it happened to commit) */
dberr_t
lock_rec_enqueue_waiting(
#ifdef WITH_WSREP
	lock_t*			c_lock,	/*!< conflicting lock */
#endif
	unsigned		type_mode,
	const buf_block_t*	block,
	ulint			heap_no,
	dict_index_t*		index,
	que_thr_t*		thr,
	lock_prdt_t*		prdt);
/*************************************************************//**
Moves the explicit locks on user records to another page if a record
list start is moved to another page. */
void
lock_rtr_move_rec_list(
/*===================*/
	const buf_block_t*	new_block,	/*!< in: index page to
						move to */
	const buf_block_t*	block,		/*!< in: index page */
	rtr_rec_move_t*		rec_move,	/*!< in: recording records
						moved */
	ulint			num_move);	/*!< in: num of rec to move */

/*************************************************************//**
Removes record lock objects set on an index page which is discarded. This
function does not move locks, or check for waiting locks, therefore the
lock bitmaps must already be reset when this function is called. */
void
lock_rec_free_all_from_discard_page(
/*================================*/
	const buf_block_t*	block);		/*!< in: page to be discarded */

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

/** Test if lock_sys.mutex can be acquired without waiting. */
#define lock_mutex_enter_nowait() 		\
	(lock_sys.mutex.trylock(__FILE__, __LINE__))

/** Test if lock_sys.mutex is owned. */
#define lock_mutex_own() (lock_sys.mutex.is_owned())

/** Acquire the lock_sys.mutex. */
#define lock_mutex_enter() do {			\
	mutex_enter(&lock_sys.mutex);		\
} while (0)

/** Release the lock_sys.mutex. */
#define lock_mutex_exit() do {			\
	lock_sys.mutex.exit();			\
} while (0)

/** Test if lock_sys.wait_mutex is owned. */
#define lock_wait_mutex_own() (lock_sys.wait_mutex.is_owned())

/** Acquire the lock_sys.wait_mutex. */
#define lock_wait_mutex_enter() do {		\
	mutex_enter(&lock_sys.wait_mutex);	\
} while (0)

/** Release the lock_sys.wait_mutex. */
#define lock_wait_mutex_exit() do {		\
	lock_sys.wait_mutex.exit();		\
} while (0)

#ifdef WITH_WSREP
/*********************************************************************//**
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/out: waiting lock request */

/*******************************************************************//**
Get lock mode and table/index name
@return	string containing lock info */
std::string
lock_get_info(
	const lock_t*);

#endif /* WITH_WSREP */

#include "lock0lock.ic"

#endif
