path: root/innobase/include/lock0lock.h

/******************************************************
The transaction lock system

(c) 1996 Innobase Oy

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

#ifndef lock0lock_h
#define lock0lock_h

#include "univ.i"
#include "trx0types.h"
#include "rem0types.h"
#include "dict0types.h"
#include "que0types.h"
#include "page0types.h"
#include "lock0types.h"
#include "read0types.h"
#include "hash0hash.h"

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

/*************************************************************************
Gets the size of a lock struct. */

ulint
lock_get_size(void);
/*===============*/
			/* out: size in bytes */
/*************************************************************************
Creates the lock system at database start. */

void
lock_sys_create(
/*============*/
	ulint	n_cells);	/* in: number of slots in lock hash table */
/*************************************************************************
Checks if some transaction has an implicit x-lock on a record in a secondary
index. */

trx_t*
lock_sec_rec_some_has_impl_off_kernel(
/*==================================*/
				/* out: transaction which has the x-lock, or
				NULL */
	rec_t*		rec,	/* in: user record */
	dict_index_t*	index,	/* in: secondary index */
	const ulint*	offsets);/* in: rec_get_offsets(rec, index) */
/*************************************************************************
Checks if some transaction has an implicit x-lock on a record in a clustered
index. */
UNIV_INLINE
trx_t*
lock_clust_rec_some_has_impl(
/*=========================*/
				/* out: transaction which has the x-lock, or
				NULL */
	rec_t*		rec,	/* in: user record */
	dict_index_t*	index,	/* in: clustered index */
	const ulint*	offsets);/* in: rec_get_offsets(rec, index) */
/*****************************************************************
Resets the lock bits for a single record. Releases transactions
waiting for lock requests here. */

void
lock_rec_reset_and_release_wait(
/*============================*/
	rec_t*	rec);	/* in: record whose locks bits should be reset */
/*****************************************************************
Makes a record to inherit the locks of another record as gap type
locks, but does not reset the lock bits of the other record. Also
waiting lock requests on rec are inherited as GRANTED gap locks. */

void
lock_rec_inherit_to_gap(
/*====================*/
	rec_t*	heir,	/* in: record which inherits */
	rec_t*	rec);	/* in: record from which inherited; does NOT reset
			the locks on this record */
/*****************************************************************
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(
/*======================*/
	page_t*	page,		/* in: old index page */
	page_t*	new_page);	/* in: 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(
/*===================*/
	page_t*	new_page,	/* in: index page to move to */
	page_t*	page,		/* in: index page */
	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(
/*=====================*/
	page_t*	new_page,	/* in: index page to move to */
	page_t*	page,		/* in: index page */
	rec_t*	rec,		/* in: record on page: this is the
				first record NOT copied */
	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(
/*====================*/
	page_t*	right_page,	/* in: right page */
	page_t*	left_page);	/* in: left page */
/*****************************************************************
Updates the lock table when a page is merged to the right. */

void
lock_update_merge_right(
/*====================*/
	rec_t*	orig_succ,	/* in: original successor of infimum
				on the right page before merge */
	page_t*	left_page);	/* 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(
/*===================*/
	page_t*	new_page,	/* in: index page to which copied */
	page_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(
/*=========================*/
	page_t*	new_page,	/* in: index page to which copied */
	page_t*	page);		/* in: index page; NOT the root! */
/*****************************************************************
Updates the lock table when a page is split to the left. */

void
lock_update_split_left(
/*===================*/
	page_t*	right_page,	/* in: right page */
	page_t*	left_page);	/* in: left page */
/*****************************************************************
Updates the lock table when a page is merged to the left. */

void
lock_update_merge_left(
/*===================*/
	page_t*	left_page,	/* in: left page to which merged */
	rec_t*	orig_pred,	/* in: original predecessor of supremum
				on the left page before merge */
	page_t*	right_page);	/* in: merged index page which will be
				discarded */
/*****************************************************************
Resets the original locks on heir and replaces them with gap type locks
inherited from rec. */

void
lock_rec_reset_and_inherit_gap_locks(
/*=================================*/
	rec_t*	heir,	/* in: heir record */
	rec_t*	rec);	/* in: record */
/*****************************************************************
Updates the lock table when a page is discarded. */

void
lock_update_discard(
/*================*/
	rec_t*	heir,	/* in: record which will inherit the locks */
	page_t*	page);	/* in: index page which will be discarded */
/*****************************************************************
Updates the lock table when a new user record is inserted. */

void
lock_update_insert(
/*===============*/
	rec_t*	rec);	/* in: the inserted record */
/*****************************************************************
Updates the lock table when a record is removed. */

void
lock_update_delete(
/*===============*/
	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(
/*===========================*/
	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(
/*===============================*/
	rec_t*	rec,	/* in: record whose lock state is restored */
	page_t*	page);	/* 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. */

ibool
lock_rec_expl_exist_on_page(
/*========================*/
			/* out: TRUE if there are explicit record locks on
			the 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. */

ulint
lock_rec_insert_check_and_lock(
/*===========================*/
				/* out: DB_SUCCESS, DB_LOCK_WAIT,
				DB_DEADLOCK, or DB_QUE_THR_SUSPENDED */
	ulint		flags,	/* in: if BTR_NO_LOCKING_FLAG bit is set,
				does nothing */
	rec_t*		rec,	/* in: record after which to insert */
	dict_index_t*	index,	/* in: index */
	que_thr_t*	thr,	/* in: query thread */
	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. */

ulint
lock_clust_rec_modify_check_and_lock(
/*=================================*/
				/* out: DB_SUCCESS, DB_LOCK_WAIT,
				DB_DEADLOCK, or DB_QUE_THR_SUSPENDED */
	ulint		flags,	/* in: if BTR_NO_LOCKING_FLAG bit is set,
				does nothing */
	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. */

ulint
lock_sec_rec_modify_check_and_lock(
/*===============================*/
				/* out: DB_SUCCESS, DB_LOCK_WAIT,
				DB_DEADLOCK, or DB_QUE_THR_SUSPENDED */
	ulint		flags,	/* in: if BTR_NO_LOCKING_FLAG bit is set,
				does nothing */
	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 */
/*************************************************************************
Like the counterpart for a clustered index below, but now we read a
secondary index record. */

ulint
lock_sec_rec_read_check_and_lock(
/*=============================*/
				/* out: DB_SUCCESS, DB_LOCK_WAIT,
				DB_DEADLOCK, or DB_QUE_THR_SUSPENDED */
	ulint		flags,	/* in: if BTR_NO_LOCKING_FLAG bit is set,
				does nothing */
	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) */
	ulint		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. */

ulint
lock_clust_rec_read_check_and_lock(
/*===============================*/
				/* out: DB_SUCCESS, DB_LOCK_WAIT,
				DB_DEADLOCK, or DB_QUE_THR_SUSPENDED */
	ulint		flags,	/* in: if BTR_NO_LOCKING_FLAG bit is set,
				does nothing */
	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) */
	ulint		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. */

ibool
lock_clust_rec_cons_read_sees(
/*==========================*/
				/* out: TRUE if sees, or FALSE if an earlier
				version of the record should be retrieved */
	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. */

ulint
lock_sec_rec_cons_read_sees(
/*========================*/
				/* out: TRUE if certainly sees, or FALSE if an
				earlier version of the clustered index record
				might be needed: 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 */
	rec_t*		rec,	/* in: user record which should be read or
				passed over by a read cursor */
	dict_index_t*	index,	/* in: non-clustered index */
	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. */

ulint
lock_table(
/*=======*/
				/* out: DB_SUCCESS, DB_LOCK_WAIT,
				DB_DEADLOCK, or DB_QUE_THR_SUSPENDED */
	ulint		flags,	/* in: if BTR_NO_LOCKING_FLAG bit is set,
				does nothing;
				if LOCK_TABLE_EXP bits are set,
				creates an explicit table lock */
	dict_table_t*	table,	/* in: database table in dictionary cache */
	ulint		mode,	/* in: lock mode */
	que_thr_t*	thr);	/* in: query thread */
/*************************************************************************
Checks if there are any locks set on the table. */

ibool
lock_is_on_table(
/*=============*/
				/* out: TRUE if there are lock(s) */
	dict_table_t*	table);	/* in: database table in dictionary cache */
/*************************************************************************
Releases a table lock.
Releases possible other transactions waiting for this lock. */

void
lock_table_unlock(
/*==============*/
	lock_t*	lock);	/* in: lock */
/*************************************************************************
Releases an auto-inc lock a transaction possibly has on a table.
Releases possible other transactions waiting for this lock. */

void
lock_table_unlock_auto_inc(
/*=======================*/
	trx_t*	trx);	/* in: transaction */
/*************************************************************************
Releases transaction locks, and releases possible other transactions waiting
because of these locks. */

void
lock_release_off_kernel(
/*====================*/
	trx_t*	trx);	/* in: transaction */
/*************************************************************************
Releases table locks explicitly requested with LOCK TABLES (indicated by
lock type LOCK_TABLE_EXP), and releases possible other transactions waiting
because of these locks. */

void
lock_release_tables_off_kernel(
/*===========================*/
	trx_t*	trx);	/* in: transaction */
/*************************************************************************
Cancels a waiting lock request and releases possible other transactions
waiting behind it. */

void
lock_cancel_waiting_and_release(
/*============================*/
	lock_t*	lock);	/* in: waiting lock request */
/*************************************************************************
Resets all locks, both table and record locks, on a table to be dropped.
No lock is allowed to be a wait lock. */

void
lock_reset_all_on_table(
/*====================*/
	dict_table_t*	table);	/* in: table to be dropped */
/*************************************************************************
Calculates the fold value of a page file address: used in inserting or
searching for a lock in the hash table. */
UNIV_INLINE
ulint
lock_rec_fold(
/*===========*/
			/* out: folded value */
	ulint	space,	/* in: space */
	ulint	page_no);/* in: page number */
/*************************************************************************
Calculates the hash value of a page file address: used in inserting or
searching for a lock in the hash table. */
UNIV_INLINE
ulint
lock_rec_hash(
/*==========*/
			/* out: hashed value */
	ulint	space,	/* in: space */
	ulint	page_no);/* in: page number */
/*************************************************************************
Gets the source table of an ALTER TABLE transaction.  The table must be
covered by an IX or IS table lock. */

dict_table_t*
lock_get_src_table(
/*===============*/
				/* out: 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 */
	trx_t*		trx,	/* in: transaction */
	dict_table_t*	dest,	/* in: destination of ALTER TABLE */
	ulint*		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. */

ibool
lock_is_table_exclusive(
/*====================*/
				/* out: TRUE if table is only locked by trx,
				with LOCK_IX, and possibly LOCK_AUTO_INC */
	dict_table_t*	table,	/* in: table */
	trx_t*		trx);	/* in: transaction */
/*************************************************************************
Checks that a transaction id is sensible, i.e., not in the future. */

ibool
lock_check_trx_id_sanity(
/*=====================*/
					/* out: TRUE if ok */
	dulint		trx_id,		/* in: trx id */
	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 */
/*************************************************************************
Validates the lock queue on a single record. */

ibool
lock_rec_queue_validate(
/*====================*/
				/* out: TRUE if ok */
	rec_t*		rec,	/* in: record to look at */
	dict_index_t*	index,	/* in: index, or NULL if not known */
	const ulint*	offsets);/* in: rec_get_offsets(rec, index) */
/*************************************************************************
Prints info of a table lock. */

void
lock_table_print(
/*=============*/
	FILE*	file,	/* in: file where to print */
	lock_t*	lock);	/* in: table type lock */
/*************************************************************************
Prints info of a record lock. */

void
lock_rec_print(
/*===========*/
	FILE*	file,	/* in: file where to print */
	lock_t*	lock);	/* in: record type lock */
/*************************************************************************
Prints info of locks for all transactions. */

void
lock_print_info(
/*============*/
	FILE*	file);	/* in: file where to print */
/*************************************************************************
Validates the lock queue on a table. */

ibool
lock_table_queue_validate(
/*======================*/
				/* out: TRUE if ok */
	dict_table_t*	table);	/* in: table */
/*************************************************************************
Validates the record lock queues on a page. */

ibool
lock_rec_validate_page(
/*===================*/
			/* out: TRUE if ok */
	ulint	space,	/* in: space id */
	ulint	page_no);/* in: page number */
/*************************************************************************
Validates the lock system. */

ibool
lock_validate(void);
/*===============*/
			/* out: TRUE if ok */

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

/* Lock modes and types */
/* Basic modes */
#define	LOCK_NONE	0	/* this flag is used elsewhere to note
				consistent read */
#define	LOCK_IS		2	/* intention shared */
#define	LOCK_IX		3	/* intention exclusive */
#define	LOCK_S		4	/* shared */
#define	LOCK_X		5	/* exclusive */
#define	LOCK_AUTO_INC	6	/* locks the auto-inc counter of a table
				in an exclusive mode */
#define LOCK_MODE_MASK	0xFUL	/* mask used to extract mode from the
				type_mode field in a lock */
/* Lock types */
#define LOCK_TABLE	16	/* these type values should be so high that */
#define	LOCK_REC	32	/* they can be ORed to the lock mode */
#define LOCK_TABLE_EXP	80	/* explicit table lock (80 = 16 + 64) */
#define LOCK_TYPE_MASK	0xF0UL	/* mask used to extract lock type from the
				type_mode field in a lock */
/* Waiting lock flag */
#define LOCK_WAIT	256	/* this wait bit should be so high that
				it can be ORed to the lock mode and type;
				when this bit is 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	/* this gap bit should be so high that
				it can be ORed to the other flags;
				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 */
				
/* When lock bits are reset, the following flags are available: */
#define LOCK_RELEASE_WAIT	1
#define LOCK_NOT_RELEASE_WAIT	2

/* Lock operation struct */
typedef struct lock_op_struct	lock_op_t;
struct lock_op_struct{
	dict_table_t*	table;	/* table to be locked */
	ulint		mode;	/* lock mode */
};

#define LOCK_OP_START		1
#define LOCK_OP_COMPLETE	2

/* 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