/***************************************************************************** Copyright (c) 1996, 2010, 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/btr0pcur.h The index tree persistent cursor Created 2/23/1996 Heikki Tuuri *******************************************************/ #ifndef btr0pcur_h #define btr0pcur_h #include "univ.i" #include "dict0dict.h" #include "data0data.h" #include "mtr0mtr.h" #include "page0cur.h" #include "btr0cur.h" #include "btr0btr.h" #include "btr0types.h" /* Relative positions for a stored cursor position */ #define BTR_PCUR_ON 1 #define BTR_PCUR_BEFORE 2 #define BTR_PCUR_AFTER 3 /* Note that if the tree is not empty, btr_pcur_store_position does not use the following, but only uses the above three alternatives, where the position is stored relative to a specific record: this makes implementation of a scroll cursor easier */ #define BTR_PCUR_BEFORE_FIRST_IN_TREE 4 /* in an empty tree */ #define BTR_PCUR_AFTER_LAST_IN_TREE 5 /* in an empty tree */ /**************************************************************//** Allocates memory for a persistent cursor object and initializes the cursor. @return own: persistent cursor */ UNIV_INTERN btr_pcur_t* btr_pcur_create_for_mysql(void); /*============================*/ /**************************************************************//** Frees the memory for a persistent cursor object. */ UNIV_INTERN void btr_pcur_free_for_mysql( /*====================*/ btr_pcur_t* cursor); /*!< in, own: persistent cursor */ /**************************************************************//** Copies the stored position of a pcur to another pcur. */ UNIV_INTERN void btr_pcur_copy_stored_position( /*==========================*/ btr_pcur_t* pcur_receive, /*!< in: pcur which will receive the position info */ btr_pcur_t* pcur_donate); /*!< in: pcur from which the info is copied */ /**************************************************************//** Sets the old_rec_buf field to NULL. */ UNIV_INLINE void btr_pcur_init( /*==========*/ btr_pcur_t* pcur); /*!< in: persistent cursor */ /**************************************************************//** Initializes and opens a persistent cursor to an index tree. It should be closed with btr_pcur_close. */ UNIV_INLINE void btr_pcur_open_func( /*===============*/ dict_index_t* index, /*!< in: index */ const dtuple_t* tuple, /*!< in: tuple on which search done */ ulint 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! */ ulint latch_mode,/*!< in: BTR_SEARCH_LEAF, ... */ btr_pcur_t* cursor, /*!< in: memory buffer for persistent cursor */ const char* file, /*!< in: file name */ ulint line, /*!< in: line where called */ mtr_t* mtr); /*!< in: mtr */ #define btr_pcur_open(i,t,md,l,c,m) \ btr_pcur_open_func(i,t,md,l,c,__FILE__,__LINE__,m) /**************************************************************//** Opens an persistent cursor to an index tree without initializing the cursor. */ UNIV_INLINE void btr_pcur_open_with_no_init_func( /*============================*/ dict_index_t* index, /*!< in: index */ const dtuple_t* tuple, /*!< in: tuple on which search done */ ulint 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! */ ulint 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! */ btr_pcur_t* cursor, /*!< in: memory buffer for persistent cursor */ ulint has_search_latch,/*!< in: latch mode the caller currently has on btr_search_latch: RW_S_LATCH, or 0 */ const char* file, /*!< in: file name */ ulint line, /*!< in: line where called */ mtr_t* mtr); /*!< in: mtr */ #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) /*****************************************************************//** Opens a persistent cursor at either end of an index. */ UNIV_INLINE void btr_pcur_open_at_index_side( /*========================*/ ibool from_left, /*!< in: TRUE if open to the low end, FALSE if to the high end */ dict_index_t* index, /*!< in: index */ ulint latch_mode, /*!< in: latch mode */ btr_pcur_t* pcur, /*!< in: cursor */ ibool do_init, /*!< in: TRUE if should be initialized */ mtr_t* mtr); /*!< in: mtr */ /**************************************************************//** Gets the up_match value for a pcur after a search. @return number of matched fields at the cursor or to the right if search mode was PAGE_CUR_GE, otherwise undefined */ UNIV_INLINE ulint btr_pcur_get_up_match( /*==================*/ const btr_pcur_t* cursor); /*!< in: persistent cursor */ /**************************************************************//** Gets the low_match value for a pcur after a search. @return number of matched fields at the cursor or to the right if search mode was PAGE_CUR_LE, otherwise undefined */ UNIV_INLINE ulint btr_pcur_get_low_match( /*===================*/ const btr_pcur_t* cursor); /*!< in: persistent cursor */ /**************************************************************//** 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. */ UNIV_INTERN void btr_pcur_open_on_user_rec_func( /*===========================*/ dict_index_t* index, /*!< in: index */ const dtuple_t* tuple, /*!< in: tuple on which search done */ ulint mode, /*!< in: PAGE_CUR_L, ... */ ulint latch_mode, /*!< in: BTR_SEARCH_LEAF or BTR_MODIFY_LEAF */ btr_pcur_t* cursor, /*!< in: memory buffer for persistent cursor */ const char* file, /*!< in: file name */ ulint line, /*!< in: line where called */ mtr_t* mtr); /*!< in: mtr */ #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) /**********************************************************************//** Positions a cursor at a randomly chosen position within a B-tree. */ UNIV_INLINE void btr_pcur_open_at_rnd_pos_func( /*==========================*/ dict_index_t* index, /*!< in: index */ ulint latch_mode, /*!< in: BTR_SEARCH_LEAF, ... */ btr_pcur_t* cursor, /*!< in/out: B-tree pcur */ const char* file, /*!< in: file name */ ulint line, /*!< in: line where called */ mtr_t* mtr); /*!< in: mtr */ #define btr_pcur_open_at_rnd_pos(i,l,c,m) \ btr_pcur_open_at_rnd_pos_func(i,l,c,__FILE__,__LINE__,m) /**************************************************************//** Frees the possible old_rec_buf buffer of a persistent cursor and sets the latch mode of the persistent cursor to BTR_NO_LATCHES. */ UNIV_INLINE void btr_pcur_close( /*===========*/ btr_pcur_t* cursor); /*!< in: persistent cursor */ /**************************************************************//** 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! */ UNIV_INTERN void btr_pcur_store_position( /*====================*/ btr_pcur_t* cursor, /*!< in: persistent cursor */ mtr_t* mtr); /*!< in: 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. @return 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 */ UNIV_INTERN ibool btr_pcur_restore_position_func( /*===========================*/ ulint latch_mode, /*!< in: BTR_SEARCH_LEAF, ... */ btr_pcur_t* cursor, /*!< in: detached persistent cursor */ const char* file, /*!< in: file name */ ulint line, /*!< in: line where called */ mtr_t* mtr); /*!< in: mtr */ #define btr_pcur_restore_position(l,cur,mtr) \ btr_pcur_restore_position_func(l,cur,__FILE__,__LINE__,mtr) /**************************************************************//** If the latch mode of the cursor is BTR_LEAF_SEARCH or BTR_LEAF_MODIFY, releases the page latch and bufferfix reserved by the cursor. NOTE! In the case of BTR_LEAF_MODIFY, there should not exist changes made by the current mini-transaction to the data protected by the cursor latch, as then the latch must not be released until mtr_commit. */ UNIV_INTERN void btr_pcur_release_leaf( /*==================*/ btr_pcur_t* cursor, /*!< in: persistent cursor */ mtr_t* mtr); /*!< in: mtr */ /*********************************************************//** Gets the rel_pos field for a cursor whose position has been stored. @return BTR_PCUR_ON, ... */ UNIV_INLINE ulint btr_pcur_get_rel_pos( /*=================*/ const btr_pcur_t* cursor);/*!< in: persistent cursor */ /**************************************************************//** Commits the mtr and sets the pcur latch mode to BTR_NO_LATCHES, that is, the cursor becomes detached. If there have been modifications to the page where pcur is positioned, this can be used instead of btr_pcur_release_leaf. Function btr_pcur_store_position should be used before calling this, if restoration of cursor is wanted later. */ UNIV_INLINE void btr_pcur_commit_specify_mtr( /*========================*/ btr_pcur_t* pcur, /*!< in: persistent cursor */ mtr_t* mtr); /*!< in: mtr to commit */ /**************************************************************//** Tests if a cursor is detached: that is the latch mode is BTR_NO_LATCHES. @return TRUE if detached */ UNIV_INLINE ibool btr_pcur_is_detached( /*=================*/ btr_pcur_t* pcur); /*!< in: persistent cursor */ /*********************************************************//** Moves the persistent cursor to the next record in the tree. If no records are left, the cursor stays 'after last in tree'. @return TRUE if the cursor was not after last in tree */ UNIV_INLINE ibool btr_pcur_move_to_next( /*==================*/ btr_pcur_t* cursor, /*!< in: persistent cursor; NOTE that the function may release the page latch */ mtr_t* mtr); /*!< in: mtr */ /*********************************************************//** Moves the persistent cursor to the previous record in the tree. If no records are left, the cursor stays 'before first in tree'. @return TRUE if the cursor was not before first in tree */ UNIV_INTERN ibool btr_pcur_move_to_prev( /*==================*/ btr_pcur_t* cursor, /*!< in: persistent cursor; NOTE that the function may release the page latch */ mtr_t* mtr); /*!< in: mtr */ /*********************************************************//** Moves the persistent cursor to the last record on the same page. */ UNIV_INLINE void btr_pcur_move_to_last_on_page( /*==========================*/ btr_pcur_t* cursor, /*!< in: persistent cursor */ mtr_t* mtr); /*!< 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'. @return TRUE if the cursor moved forward, ending on a user record */ UNIV_INLINE ibool btr_pcur_move_to_next_user_rec( /*===========================*/ btr_pcur_t* cursor, /*!< in: persistent cursor; NOTE that the function may release the page latch */ mtr_t* mtr); /*!< in: 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. */ UNIV_INTERN void btr_pcur_move_to_next_page( /*=======================*/ btr_pcur_t* cursor, /*!< in: persistent cursor; must be on the last record of the current page */ mtr_t* mtr); /*!< in: 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. */ UNIV_INTERN void btr_pcur_move_backward_from_page( /*=============================*/ btr_pcur_t* cursor, /*!< in: persistent cursor, must be on the first record of the current page */ mtr_t* mtr); /*!< in: mtr */ #ifdef UNIV_DEBUG /*********************************************************//** Returns the btr cursor component of a persistent cursor. @return pointer to btr cursor component */ UNIV_INLINE btr_cur_t* btr_pcur_get_btr_cur( /*=================*/ const btr_pcur_t* cursor); /*!< in: persistent cursor */ /*********************************************************//** Returns the page cursor component of a persistent cursor. @return pointer to page cursor component */ UNIV_INLINE page_cur_t* btr_pcur_get_page_cur( /*==================*/ const btr_pcur_t* cursor); /*!< in: persistent cursor */ /*********************************************************//** Returns the page of a persistent cursor. @return pointer to the page */ UNIV_INLINE page_t* btr_pcur_get_page( /*==============*/ const btr_pcur_t* cursor);/*!< in: persistent cursor */ /*********************************************************//** Returns the buffer block of a persistent cursor. @return pointer to the block */ UNIV_INLINE buf_block_t* btr_pcur_get_block( /*===============*/ const btr_pcur_t* cursor);/*!< in: persistent cursor */ /*********************************************************//** Returns the record of a persistent cursor. @return pointer to the record */ UNIV_INLINE rec_t* btr_pcur_get_rec( /*=============*/ const btr_pcur_t* cursor);/*!< in: persistent cursor */ #else /* UNIV_DEBUG */ # define btr_pcur_get_btr_cur(cursor) (&(cursor)->btr_cur) # define btr_pcur_get_page_cur(cursor) (&(cursor)->btr_cur.page_cur) # define btr_pcur_get_page(cursor) ((cursor)->btr_cur.page_cur.block->frame) # define btr_pcur_get_block(cursor) ((cursor)->btr_cur.page_cur.block) # define btr_pcur_get_rec(cursor) ((cursor)->btr_cur.page_cur.rec) #endif /* UNIV_DEBUG */ /*********************************************************//** Checks if the persistent cursor is on a user record. */ UNIV_INLINE ibool btr_pcur_is_on_user_rec( /*====================*/ const btr_pcur_t* cursor);/*!< in: persistent cursor */ /*********************************************************//** Checks if the persistent cursor is after the last user record on a page. */ UNIV_INLINE ibool btr_pcur_is_after_last_on_page( /*===========================*/ const btr_pcur_t* cursor);/*!< in: persistent cursor */ /*********************************************************//** Checks if the persistent cursor is before the first user record on a page. */ UNIV_INLINE ibool btr_pcur_is_before_first_on_page( /*=============================*/ const btr_pcur_t* cursor);/*!< in: persistent cursor */ /*********************************************************//** Checks if the persistent cursor is before the first user record in the index tree. */ UNIV_INLINE ibool btr_pcur_is_before_first_in_tree( /*=============================*/ btr_pcur_t* cursor, /*!< in: persistent cursor */ mtr_t* mtr); /*!< in: mtr */ /*********************************************************//** Checks if the persistent cursor is after the last user record in the index tree. */ UNIV_INLINE ibool btr_pcur_is_after_last_in_tree( /*===========================*/ btr_pcur_t* cursor, /*!< in: persistent cursor */ mtr_t* mtr); /*!< in: mtr */ /*********************************************************//** Moves the persistent cursor to the next record on the same page. */ UNIV_INLINE void btr_pcur_move_to_next_on_page( /*==========================*/ btr_pcur_t* cursor);/*!< in/out: persistent cursor */ /*********************************************************//** Moves the persistent cursor to the previous record on the same page. */ UNIV_INLINE void btr_pcur_move_to_prev_on_page( /*==========================*/ btr_pcur_t* cursor);/*!< in/out: persistent cursor */ /* The persistent B-tree cursor structure. This is used mainly for SQL selects, updates, and deletes. */ struct btr_pcur_struct{ btr_cur_t btr_cur; /*!< a B-tree cursor */ ulint latch_mode; /*!< see TODO note below! BTR_SEARCH_LEAF, BTR_MODIFY_LEAF, BTR_MODIFY_TREE, or BTR_NO_LATCHES, depending on the latching state of the page and tree where the cursor is positioned; the last value means that the cursor is not currently positioned: we say then that the cursor is detached; it can be restored to attached if the old position was stored in old_rec */ ulint old_stored; /*!< BTR_PCUR_OLD_STORED or BTR_PCUR_OLD_NOT_STORED */ rec_t* old_rec; /*!< if cursor position is stored, contains an initial segment of the latest record cursor was positioned either on, before, or after */ ulint old_n_fields; /*!< number of fields in old_rec */ ulint rel_pos; /*!< BTR_PCUR_ON, BTR_PCUR_BEFORE, or BTR_PCUR_AFTER, depending on whether cursor was on, before, or after the old_rec record */ buf_block_t* block_when_stored;/* buffer block when the position was stored */ ib_uint64_t modify_clock; /*!< the modify clock value of the buffer block when the cursor position was stored */ ulint pos_state; /*!< see TODO note below! BTR_PCUR_IS_POSITIONED, BTR_PCUR_WAS_POSITIONED, BTR_PCUR_NOT_POSITIONED */ ulint search_mode; /*!< PAGE_CUR_G, ... */ trx_t* trx_if_known; /*!< the transaction, if we know it; otherwise this field is not defined; can ONLY BE USED in error prints in fatal assertion failures! */ /*-----------------------------*/ /* NOTE that the following fields may possess dynamically allocated memory which should be freed if not needed anymore! */ byte* old_rec_buf; /*!< NULL, or a dynamically allocated buffer for old_rec */ ulint buf_size; /*!< old_rec_buf size if old_rec_buf is not NULL */ }; #define BTR_PCUR_IS_POSITIONED 1997660512 /* 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. */ #define BTR_PCUR_WAS_POSITIONED 1187549791 #define BTR_PCUR_NOT_POSITIONED 1328997689 #define BTR_PCUR_OLD_STORED 908467085 #define BTR_PCUR_OLD_NOT_STORED 122766467 #ifndef UNIV_NONINL #include "btr0pcur.ic" #endif #endif