#include "univ.i"
#include "dict0dict.h"
#include "data0data.h"
#include "mtr0mtr.h"
#include "page0cur.h"
#include "btr0cur.h"
#include "btr0btr.h"
#include "btr0types.h"
#include "btr0pcur.ic"

Include dependency graph for btr0pcur.h:

This graph shows which files directly or indirectly include this file:

Go to the source code of this file.

Data Structures
struct	btr_pcur_t

Macros
#define	BTR_PCUR_ON 1
#define	BTR_PCUR_BEFORE 2
#define	BTR_PCUR_AFTER 3
#define	BTR_PCUR_BEFORE_FIRST_IN_TREE 4 /* in an empty tree */
#define	BTR_PCUR_AFTER_LAST_IN_TREE 5 /* in an empty tree */
#define	btr_pcur_open(i, t, md, l, c, m) btr_pcur_open_low(i,0,t,md,l,c,__FILE__,__LINE__,m)
#define	btr_pcur_open_with_no_init(ix, t, md, l, cur, has, m) btr_pcur_open_with_no_init_func(ix,t,md,l,cur,has,__FILE__,__LINE__,m)
#define	btr_pcur_open_on_user_rec(i, t, md, l, c, m) btr_pcur_open_on_user_rec_func(i,t,md,l,c,__FILE__,__LINE__,m)
#define	btr_pcur_open_at_rnd_pos(i, l, c, m) btr_pcur_open_at_rnd_pos_func(i,l,c,__FILE__,__LINE__,m)
#define	btr_pcur_restore_position(l, cur, mtr) btr_pcur_restore_position_func(l,cur,__FILE__,__LINE__,mtr)
#define	BTR_PCUR_OLD_STORED 908467085
#define	BTR_PCUR_OLD_NOT_STORED 122766467

Enumerations
enum	pcur_pos_t { BTR_PCUR_NOT_POSITIONED = 0, BTR_PCUR_WAS_POSITIONED, BTR_PCUR_IS_POSITIONED_OPTIMISTIC, BTR_PCUR_IS_POSITIONED }

Functions
UNIV_INTERN btr_pcur_t *	btr_pcur_create_for_mysql (void)
UNIV_INTERN void	btr_pcur_reset (btr_pcur_t *cursor)
UNIV_INTERN void	btr_pcur_free_for_mysql (btr_pcur_t *cursor)
UNIV_INTERN void	btr_pcur_copy_stored_position (btr_pcur_t pcur_receive, btr_pcur_t pcur_donate)
UNIV_INLINE void	btr_pcur_init (btr_pcur_t *pcur)
UNIV_INLINE void	btr_pcur_open_low (dict_index_t index, ulint level, const dtuple_t tuple, ulint mode, ulint latch_mode, btr_pcur_t cursor, const char file, ulint line, mtr_t *mtr)
UNIV_INLINE void	btr_pcur_open_with_no_init_func (dict_index_t index, const dtuple_t tuple, ulint mode, ulint latch_mode, btr_pcur_t cursor, ulint has_search_latch, const char file, ulint line, mtr_t *mtr)
UNIV_INLINE void	btr_pcur_open_at_index_side (bool from_left, dict_index_t index, ulint latch_mode, btr_pcur_t pcur, bool init_pcur, ulint level, mtr_t *mtr))
UNIV_INLINE ulint	btr_pcur_get_up_match (const btr_pcur_t *cursor)
UNIV_INLINE ulint	btr_pcur_get_low_match (const btr_pcur_t *cursor)
UNIV_INTERN void	btr_pcur_open_on_user_rec_func (dict_index_t index, const dtuple_t tuple, ulint mode, ulint latch_mode, btr_pcur_t cursor, const char file, ulint line, mtr_t *mtr)
UNIV_INLINE void	btr_pcur_open_at_rnd_pos_func (dict_index_t index, ulint latch_mode, btr_pcur_t cursor, const char file, ulint line, mtr_t mtr)
UNIV_INLINE void	btr_pcur_close (btr_pcur_t *cursor)
UNIV_INTERN void	btr_pcur_store_position (btr_pcur_t cursor, mtr_t mtr)
UNIV_INTERN ibool	btr_pcur_restore_position_func (ulint latch_mode, btr_pcur_t cursor, const char file, ulint line, mtr_t *mtr)
UNIV_INLINE ulint	btr_pcur_get_rel_pos (const btr_pcur_t *cursor)
UNIV_INLINE void	btr_pcur_commit_specify_mtr (btr_pcur_t pcur, mtr_t mtr)
UNIV_INLINE ibool	btr_pcur_move_to_next (btr_pcur_t cursor, mtr_t mtr)
UNIV_INTERN ibool	btr_pcur_move_to_prev (btr_pcur_t cursor, mtr_t mtr)
UNIV_INLINE void	btr_pcur_move_to_last_on_page (btr_pcur_t cursor, mtr_t mtr)
UNIV_INLINE ibool	btr_pcur_move_to_next_user_rec (btr_pcur_t cursor, mtr_t mtr)
UNIV_INTERN void	btr_pcur_move_to_next_page (btr_pcur_t cursor, mtr_t mtr)
UNIV_INTERN void	btr_pcur_move_backward_from_page (btr_pcur_t cursor, mtr_t mtr)
UNIV_INLINE btr_cur_t *	btr_pcur_get_btr_cur (const btr_pcur_t *cursor)
UNIV_INLINE page_cur_t *	btr_pcur_get_page_cur (const btr_pcur_t *cursor)
UNIV_INLINE page_t *	btr_pcur_get_page (const btr_pcur_t *cursor)
UNIV_INLINE buf_block_t *	btr_pcur_get_block (const btr_pcur_t *cursor)
UNIV_INLINE rec_t *	btr_pcur_get_rec (const btr_pcur_t *cursor)
UNIV_INLINE ibool	btr_pcur_is_on_user_rec (const btr_pcur_t *cursor)
UNIV_INLINE ibool	btr_pcur_is_after_last_on_page (const btr_pcur_t *cursor)
UNIV_INLINE ibool	btr_pcur_is_before_first_on_page (const btr_pcur_t *cursor)
UNIV_INLINE ibool	btr_pcur_is_before_first_in_tree (btr_pcur_t cursor, mtr_t mtr)
UNIV_INLINE ibool	btr_pcur_is_after_last_in_tree (btr_pcur_t cursor, mtr_t mtr)
UNIV_INLINE void	btr_pcur_move_to_next_on_page (btr_pcur_t *cursor)
UNIV_INLINE void	btr_pcur_move_to_prev_on_page (btr_pcur_t *cursor)
UNIV_INLINE void	btr_pcur_move_before_first_on_page (btr_pcur_t *cursor)

Detailed Description

The index tree persistent cursor

Created 2/23/1996 Heikki Tuuri

Enumeration Type Documentation

enum pcur_pos_t

Position state of persistent B-tree cursor.

Enumerator:

BTR_PCUR_NOT_POSITIONED	The persistent cursor is not positioned.
BTR_PCUR_WAS_POSITIONED	The persistent cursor was previously positioned. TODO: currently, the state can be BTR_PCUR_IS_POSITIONED, though it really should be BTR_PCUR_WAS_POSITIONED, because we have no obligation to commit the cursor with mtr; similarly latch_mode may be out of date. This can lead to problems if btr_pcur is not used the right way; all current code should be ok.
BTR_PCUR_IS_POSITIONED_OPTIMISTIC	The persistent cursor is positioned by optimistic get to the same record as it was positioned at. Not used for rel_pos == BTR_PCUR_ON. It may need adjustment depending on previous/current search direction and rel_pos.
BTR_PCUR_IS_POSITIONED	The persistent cursor is positioned by index search. Or optimistic get for rel_pos == BTR_PCUR_ON.

Function Documentation

UNIV_INLINE void btr_pcur_close ( btr_pcur_t * cursor )

Frees the possible memory heap of a persistent cursor and sets the latch mode of the persistent cursor to BTR_NO_LATCHES. WARNING: this function does not release the latch on the page where the cursor is currently positioned. The latch is acquired by the "move to next/previous" family of functions. Since recursive shared locks are not allowed, you must take care (if using the cursor in S-mode) to manually release the latch by either calling btr_leaf_page_release(btr_pcur_get_block(&pcur), pcur.latch_mode, mtr) or by committing the mini-transaction right after btr_pcur_close(). A subsequent attempt to crawl the same page in the same mtr would cause an assertion failure. in: persistent cursor

Frees the possible memory heap of a persistent cursor and sets the latch mode of the persistent cursor to BTR_NO_LATCHES. WARNING: this function does not release the latch on the page where the cursor is currently positioned. The latch is acquired by the "move to next/previous" family of functions. Since recursive shared locks are not allowed, you must take care (if using the cursor in S-mode) to manually release the latch by either calling btr_leaf_page_release(btr_pcur_get_block(&pcur), pcur.latch_mode, mtr) or by committing the mini-transaction right after btr_pcur_close(). A subsequent attempt to crawl the same page in the same mtr would cause an assertion failure.

Parameters

cursor in: persistent cursor

UNIV_INLINE void btr_pcur_commit_specify_mtr	(	btr_pcur_t *	pcur,
		mtr_t *	mtr
	)

Commits the mtr and sets the pcur latch mode to BTR_NO_LATCHES, that is, the cursor becomes detached. Function btr_pcur_store_position should be used before calling this, if restoration of cursor is wanted later. in: mtr to commit

Commits the mtr and sets the pcur latch mode to BTR_NO_LATCHES, that is, the cursor becomes detached. Function btr_pcur_store_position should be used before calling this, if restoration of cursor is wanted later.

Parameters

pcur	in: persistent cursor
mtr	in: mtr to commit

UNIV_INTERN void btr_pcur_copy_stored_position	(	btr_pcur_t *	pcur_receive,
		btr_pcur_t *	pcur_donate
	)

Copies the stored position of a pcur to another pcur. in: pcur from which the info is copied

Parameters

pcur_receive in: pcur which will receive the position info

UNIV_INTERN btr_pcur_t* btr_pcur_create_for_mysql ( void )

Allocates memory for a persistent cursor object and initializes the cursor.

Returns: own: persistent cursor

UNIV_INTERN void btr_pcur_free_for_mysql ( btr_pcur_t * cursor )

Frees the memory for a persistent cursor object. in, own: persistent cursor

UNIV_INLINE buf_block_t* btr_pcur_get_block ( const btr_pcur_t * cursor )

Returns the buffer block of a persistent cursor.

Returns: pointer to the block in: persistent cursor

Returns the buffer block of a persistent cursor.

Returns: pointer to the block

Parameters

cursor in: persistent cursor

UNIV_INLINE btr_cur_t* btr_pcur_get_btr_cur ( const btr_pcur_t * cursor )

Returns the btr cursor component of a persistent cursor.

Returns: pointer to btr cursor component in: persistent cursor

Returns the btr cursor component of a persistent cursor.

Returns: pointer to btr cursor component

Parameters

cursor in: persistent cursor

UNIV_INLINE ulint btr_pcur_get_low_match ( const btr_pcur_t * cursor )

Gets the low_match value for a pcur after a search.

Returns: number of matched fields at the cursor or to the right if search mode was PAGE_CUR_LE, otherwise undefined in: persistent cursor

Gets the low_match value for a pcur after a search.

Returns: number of matched fields at the cursor or to the right if search mode was PAGE_CUR_LE, otherwise undefined

Parameters

cursor in: persistent cursor

UNIV_INLINE page_t* btr_pcur_get_page ( const btr_pcur_t * cursor )

Returns the page of a persistent cursor.

Returns: pointer to the page in: persistent cursor

Returns the page of a persistent cursor.

Returns: pointer to the page

Parameters

cursor in: persistent cursor

UNIV_INLINE page_cur_t* btr_pcur_get_page_cur ( const btr_pcur_t * cursor )

Returns the page cursor component of a persistent cursor.

Returns: pointer to page cursor component in: persistent cursor

Returns the page cursor component of a persistent cursor.

Returns: pointer to page cursor component

Parameters

cursor in: persistent cursor

UNIV_INLINE rec_t* btr_pcur_get_rec ( const btr_pcur_t * cursor )

Returns the record of a persistent cursor.

Returns: pointer to the record in: persistent cursor

Returns the record of a persistent cursor.

Returns: pointer to the record

Parameters

cursor in: persistent cursor

UNIV_INLINE ulint btr_pcur_get_rel_pos ( const btr_pcur_t * cursor )

Gets the rel_pos field for a cursor whose position has been stored.

Returns: BTR_PCUR_ON, ... in: persistent cursor

Gets the rel_pos field for a cursor whose position has been stored.

Returns: BTR_PCUR_ON, ...

Parameters

cursor in: persistent cursor

UNIV_INLINE ulint btr_pcur_get_up_match ( const btr_pcur_t * cursor )

Gets the up_match value for a pcur after a search.

Returns: number of matched fields at the cursor or to the right if search mode was PAGE_CUR_GE, otherwise undefined in: persistent cursor

Gets the up_match value for a pcur after a search.

Returns: number of matched fields at the cursor or to the right if search mode was PAGE_CUR_GE, otherwise undefined

Parameters

cursor in: persistent cursor

UNIV_INLINE void btr_pcur_init ( btr_pcur_t * pcur )

Sets the old_rec_buf field to NULL. in: persistent cursor

Sets the old_rec_buf field to NULL.

Parameters

pcur	in: persistent cursor

UNIV_INLINE ibool btr_pcur_is_after_last_in_tree	(	btr_pcur_t *	cursor,
		mtr_t *	mtr
	)

Checks if the persistent cursor is after the last user record in the index tree. in: mtr

Checks if the persistent cursor is after the last user record in the index tree.

Parameters

cursor	in: persistent cursor
mtr	in: mtr

UNIV_INLINE ibool btr_pcur_is_after_last_on_page ( const btr_pcur_t * cursor )

Checks if the persistent cursor is after the last user record on a page. in: persistent cursor

Checks if the persistent cursor is after the last user record on a page.

Parameters

cursor in: persistent cursor

UNIV_INLINE ibool btr_pcur_is_before_first_in_tree	(	btr_pcur_t *	cursor,
		mtr_t *	mtr
	)

Checks if the persistent cursor is before the first user record in the index tree. in: mtr

Checks if the persistent cursor is before the first user record in the index tree.

Parameters

cursor	in: persistent cursor
mtr	in: mtr

UNIV_INLINE ibool btr_pcur_is_before_first_on_page ( const btr_pcur_t * cursor )

Checks if the persistent cursor is before the first user record on a page. in: persistent cursor

Checks if the persistent cursor is before the first user record on a page.

Parameters

cursor in: persistent cursor

UNIV_INLINE ibool btr_pcur_is_on_user_rec ( const btr_pcur_t * cursor )

Checks if the persistent cursor is on a user record. in: persistent cursor

Checks if the persistent cursor is on a user record.

Parameters

cursor in: persistent cursor

UNIV_INTERN void btr_pcur_move_backward_from_page	(	btr_pcur_t *	cursor,
		mtr_t *	mtr
	)

Moves the persistent cursor backward if it is on the first record of the page. Releases the latch on the current page, and bufferunfixes it. Note that to prevent a possible deadlock, the operation first stores the position of the cursor, releases the leaf latch, acquires necessary latches and restores the cursor position again before returning. The alphabetical position of the cursor is guaranteed to be sensible on return, but it may happen that the cursor is not positioned on the last record of any page, because the structure of the tree may have changed while the cursor had no latches. in: mtr

Parameters

cursor in: persistent cursor, must be on the first record of the current page

UNIV_INLINE void btr_pcur_move_before_first_on_page ( btr_pcur_t * cursor )

Moves the persistent cursor to the infimum record on the same page. in/out: persistent cursor

Moves the persistent cursor to the infimum record on the same page.

Parameters

cursor in/out: persistent cursor

UNIV_INLINE void btr_pcur_move_to_last_on_page	(	btr_pcur_t *	cursor,
		mtr_t *	mtr
	)

Moves the persistent cursor to the last record on the same page. in: mtr

Moves the persistent cursor to the last record on the same page.

Parameters

cursor	in: persistent cursor
mtr	in: mtr

UNIV_INLINE ibool btr_pcur_move_to_next	(	btr_pcur_t *	cursor,
		mtr_t *	mtr
	)

Moves the persistent cursor to the next record in the tree. If no records are left, the cursor stays 'after last in tree'.

Returns: TRUE if the cursor was not after last in tree in: mtr

Moves the persistent cursor to the next record in the tree. If no records are left, the cursor stays 'after last in tree'.

Returns: TRUE if the cursor was not after last in tree

Parameters

cursor	in: persistent cursor; NOTE that the function may release the page latch
mtr	in: mtr

UNIV_INLINE void btr_pcur_move_to_next_on_page ( btr_pcur_t * cursor )

Moves the persistent cursor to the next record on the same page. in/out: persistent cursor

Moves the persistent cursor to the next record on the same page.

Parameters

cursor in/out: persistent cursor

UNIV_INTERN void btr_pcur_move_to_next_page	(	btr_pcur_t *	cursor,
		mtr_t *	mtr
	)

Moves the persistent cursor to the first record on the next page. Releases the latch on the current page, and bufferunfixes it. Note that there must not be modifications on the current page, as then the x-latch can be released only in mtr_commit. in: mtr

Parameters

cursor in: persistent cursor; must be on the last record of the current page

UNIV_INLINE ibool btr_pcur_move_to_next_user_rec	(	btr_pcur_t *	cursor,
		mtr_t *	mtr
	)

Moves the persistent cursor to the next user record in the tree. If no user records are left, the cursor ends up 'after last in tree'.

Returns: TRUE if the cursor moved forward, ending on a user record in: mtr

Moves the persistent cursor to the next user record in the tree. If no user records are left, the cursor ends up 'after last in tree'.

Returns: TRUE if the cursor moved forward, ending on a user record

Parameters

cursor	in: persistent cursor; NOTE that the function may release the page latch
mtr	in: mtr

UNIV_INTERN ibool btr_pcur_move_to_prev	(	btr_pcur_t *	cursor,
		mtr_t *	mtr
	)

Moves the persistent cursor to the previous record in the tree. If no records are left, the cursor stays 'before first in tree'.

Returns: TRUE if the cursor was not before first in tree in: mtr

Parameters

cursor in: persistent cursor; NOTE that the function may release the page latch

UNIV_INLINE void btr_pcur_move_to_prev_on_page ( btr_pcur_t * cursor )

Moves the persistent cursor to the previous record on the same page. in/out: persistent cursor

Moves the persistent cursor to the previous record on the same page.

Parameters

cursor in/out: persistent cursor

UNIV_INLINE void btr_pcur_open_at_index_side	(	bool	from_left,
		dict_index_t *	index,
		ulint	latch_mode,
		btr_pcur_t *	pcur,
		bool	init_pcur,
		ulint	level,
		mtr_t *	mtr
	)

Opens a persistent cursor at either end of an index.

Parameters

from_left	in: true if open to the low end, false if to the high end
index	in: index
latch_mode	in: latch mode
pcur	in/out: cursor
init_pcur	in: whether to initialize pcur
level	in: level to search for (0=leaf)
mtr	in/out: mini-transaction

UNIV_INLINE void btr_pcur_open_at_rnd_pos_func	(	dict_index_t *	index,
		ulint	latch_mode,
		btr_pcur_t *	cursor,
		const char *	file,
		ulint	line,
		mtr_t *	mtr
	)

Positions a cursor at a randomly chosen position within a B-tree. in: mtr

Positions a cursor at a randomly chosen position within a B-tree.

Parameters

index	in: index
latch_mode	in: BTR_SEARCH_LEAF, ...
cursor	in/out: B-tree pcur
file	in: file name
line	in: line where called
mtr	in: mtr

UNIV_INLINE void btr_pcur_open_low	(	dict_index_t *	index,
		ulint	level,
		const dtuple_t *	tuple,
		ulint	mode,
		ulint	latch_mode,
		btr_pcur_t *	cursor,
		const char *	file,
		ulint	line,
		mtr_t *	mtr
	)

Initializes and opens a persistent cursor to an index tree. It should be closed with btr_pcur_close. in: mtr

Initializes and opens a persistent cursor to an index tree. It should be closed with btr_pcur_close.

Parameters

index	in: index
level	in: level in the btree
tuple	in: tuple on which search done
mode	in: PAGE_CUR_L, ...; NOTE that if the search is made using a unique prefix of a record, mode should be PAGE_CUR_LE, not PAGE_CUR_GE, as the latter may end up on the previous page from the record!
latch_mode	in: BTR_SEARCH_LEAF, ...
cursor	in: memory buffer for persistent cursor
file	in: file name
line	in: line where called
mtr	in: mtr

UNIV_INTERN void btr_pcur_open_on_user_rec_func	(	dict_index_t *	index,
		const dtuple_t *	tuple,
		ulint	mode,
		ulint	latch_mode,
		btr_pcur_t *	cursor,
		const char *	file,
		ulint	line,
		mtr_t *	mtr
	)

If mode is PAGE_CUR_G or PAGE_CUR_GE, opens a persistent cursor on the first user record satisfying the search condition, in the case PAGE_CUR_L or PAGE_CUR_LE, on the last user record. If no such user record exists, then in the first case sets the cursor after last in tree, and in the latter case before first in tree. The latching mode must be BTR_SEARCH_LEAF or BTR_MODIFY_LEAF. in: mtr

Parameters

index	in: index
tuple	in: tuple on which search done
mode	in: PAGE_CUR_L, ...
latch_mode	in: BTR_SEARCH_LEAF or BTR_MODIFY_LEAF
cursor	in: memory buffer for persistent cursor
file	in: file name
line	in: line where called

UNIV_INLINE void btr_pcur_open_with_no_init_func	(	dict_index_t *	index,
		const dtuple_t *	tuple,
		ulint	mode,
		ulint	latch_mode,
		btr_pcur_t *	cursor,
		ulint	has_search_latch,
		const char *	file,
		ulint	line,
		mtr_t *	mtr
	)

Opens an persistent cursor to an index tree without initializing the cursor. in: mtr

Opens an persistent cursor to an index tree without initializing the cursor.

Parameters

index	in: index
tuple	in: tuple on which search done
mode	in: PAGE_CUR_L, ...; NOTE that if the search is made using a unique prefix of a record, mode should be PAGE_CUR_LE, not PAGE_CUR_GE, as the latter may end up on the previous page of the record!
latch_mode	in: BTR_SEARCH_LEAF, ...; NOTE that if has_search_latch != 0 then we maybe do not acquire a latch on the cursor page, but assume that the caller uses his btr search latch to protect the record!
cursor	in: memory buffer for persistent cursor
has_search_latch	in: latch mode the caller currently has on btr_search_latch: RW_S_LATCH, or 0
file	in: file name
line	in: line where called
mtr	in: mtr

UNIV_INTERN void btr_pcur_reset ( btr_pcur_t * cursor )

Resets a persistent cursor object, freeing ::old_rec_buf if it is allocated and resetting the other members to their initial values. in, out: persistent cursor

UNIV_INTERN ibool btr_pcur_restore_position_func	(	ulint	latch_mode,
		btr_pcur_t *	cursor,
		const char *	file,
		ulint	line,
		mtr_t *	mtr
	)

Restores the stored position of a persistent cursor bufferfixing the page and obtaining the specified latches. If the cursor position was saved when the (1) cursor was positioned on a user record: this function restores the position to the last record LESS OR EQUAL to the stored record; (2) cursor was positioned on a page infimum record: restores the position to the last record LESS than the user record which was the successor of the page infimum; (3) cursor was positioned on the page supremum: restores to the first record GREATER than the user record which was the predecessor of the supremum. (4) cursor was positioned before the first or after the last in an empty tree: restores to before first or after the last in the tree.

Returns: TRUE if the cursor position was stored when it was on a user record and it can be restored on a user record whose ordering fields are identical to the ones of the original user record in: mtr

Parameters

latch_mode	in: BTR_SEARCH_LEAF, ...
cursor	in: detached persistent cursor
file	in: file name
line	in: line where called

UNIV_INTERN void btr_pcur_store_position	(	btr_pcur_t *	cursor,
		mtr_t *	mtr
	)

The position of the cursor is stored by taking an initial segment of the record the cursor is positioned on, before, or after, and copying it to the cursor data structure, or just setting a flag if the cursor id before the first in an EMPTY tree, or after the last in an EMPTY tree. NOTE that the page where the cursor is positioned must not be empty if the index tree is not totally empty! in: mtr

Parameters

cursor in: persistent cursor

Data Structures

Macros

Enumerations

Functions

Detailed Description

Enumeration Type Documentation

Function Documentation