/****************************************************** The index tree persistent cursor (c) 1996 Innobase Oy Created 2/23/1996 Heikki Tuuri *******************************************************/ #include "btr0pcur.h" #ifdef UNIV_NONINL #include "btr0pcur.ic" #endif #include "ut0byte.h" #include "rem0cmp.h" #include "trx0trx.h" /****************************************************************** Allocates memory for a persistent cursor object and initializes the cursor. */ btr_pcur_t* btr_pcur_create_for_mysql(void) /*============================*/ /* out, own: persistent cursor */ { btr_pcur_t* pcur; pcur = mem_alloc(sizeof(btr_pcur_t)); pcur->btr_cur.index = NULL; btr_pcur_init(pcur); return(pcur); } /****************************************************************** Frees the memory for a persistent cursor object. */ void btr_pcur_free_for_mysql( /*====================*/ btr_pcur_t* cursor) /* in, own: persistent cursor */ { if (cursor->old_rec_buf != NULL) { mem_free(cursor->old_rec_buf); cursor->old_rec_buf = NULL; } cursor->btr_cur.page_cur.rec = NULL; cursor->old_rec = NULL; cursor->old_n_fields = 0; cursor->old_stored = BTR_PCUR_OLD_NOT_STORED; cursor->latch_mode = BTR_NO_LATCHES; cursor->pos_state = BTR_PCUR_NOT_POSITIONED; mem_free(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! */ void btr_pcur_store_position( /*====================*/ btr_pcur_t* cursor, /* in: persistent cursor */ mtr_t* mtr) /* in: mtr */ { page_cur_t* page_cursor; rec_t* rec; dict_index_t* index; page_t* page; ulint offs; ut_a(cursor->pos_state == BTR_PCUR_IS_POSITIONED); ut_ad(cursor->latch_mode != BTR_NO_LATCHES); index = btr_cur_get_index(btr_pcur_get_btr_cur(cursor)); page_cursor = btr_pcur_get_page_cur(cursor); rec = page_cur_get_rec(page_cursor); page = page_align(rec); offs = page_offset(rec); ut_ad(mtr_memo_contains(mtr, buf_block_align(page), MTR_MEMO_PAGE_S_FIX) || mtr_memo_contains(mtr, buf_block_align(page), MTR_MEMO_PAGE_X_FIX)); ut_a(cursor->latch_mode != BTR_NO_LATCHES); if (UNIV_UNLIKELY(page_get_n_recs(page) == 0)) { /* It must be an empty index tree; NOTE that in this case we do not store the modify_clock, but always do a search if we restore the cursor position */ ut_a(btr_page_get_next(page, mtr) == FIL_NULL); ut_a(btr_page_get_prev(page, mtr) == FIL_NULL); cursor->old_stored = BTR_PCUR_OLD_STORED; if (page_rec_is_supremum_low(offs)) { cursor->rel_pos = BTR_PCUR_AFTER_LAST_IN_TREE; } else { cursor->rel_pos = BTR_PCUR_BEFORE_FIRST_IN_TREE; } return; } if (page_rec_is_supremum_low(offs)) { rec = page_rec_get_prev(rec); cursor->rel_pos = BTR_PCUR_AFTER; } else if (page_rec_is_infimum_low(offs)) { rec = page_rec_get_next(rec); cursor->rel_pos = BTR_PCUR_BEFORE; } else { cursor->rel_pos = BTR_PCUR_ON; } cursor->old_stored = BTR_PCUR_OLD_STORED; cursor->old_rec = dict_index_copy_rec_order_prefix( index, rec, &cursor->old_n_fields, &cursor->old_rec_buf, &cursor->buf_size); cursor->block_when_stored = buf_block_align(page); cursor->modify_clock = buf_block_get_modify_clock( cursor->block_when_stored); } /****************************************************************** Copies the stored position of a pcur to another pcur. */ 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 */ { if (pcur_receive->old_rec_buf) { mem_free(pcur_receive->old_rec_buf); } ut_memcpy(pcur_receive, pcur_donate, sizeof(btr_pcur_t)); if (pcur_donate->old_rec_buf) { pcur_receive->old_rec_buf = mem_alloc(pcur_donate->buf_size); ut_memcpy(pcur_receive->old_rec_buf, pcur_donate->old_rec_buf, pcur_donate->buf_size); pcur_receive->old_rec = pcur_receive->old_rec_buf + (pcur_donate->old_rec - pcur_donate->old_rec_buf); } pcur_receive->old_n_fields = pcur_donate->old_n_fields; } /****************************************************************** 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. */ ibool btr_pcur_restore_position( /*======================*/ /* out: 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 */ ulint latch_mode, /* in: BTR_SEARCH_LEAF, ... */ btr_pcur_t* cursor, /* in: detached persistent cursor */ mtr_t* mtr) /* in: mtr */ { dict_index_t* index; page_t* page; dtuple_t* tuple; ulint mode; ulint old_mode; mem_heap_t* heap; index = btr_cur_get_index(btr_pcur_get_btr_cur(cursor)); if (UNIV_UNLIKELY(cursor->old_stored != BTR_PCUR_OLD_STORED) || UNIV_UNLIKELY(cursor->pos_state != BTR_PCUR_WAS_POSITIONED && cursor->pos_state != BTR_PCUR_IS_POSITIONED)) { ut_print_buf(stderr, cursor, sizeof(btr_pcur_t)); if (cursor->trx_if_known) { trx_print(stderr, cursor->trx_if_known, 0); } ut_error; } if (UNIV_UNLIKELY( cursor->rel_pos == BTR_PCUR_AFTER_LAST_IN_TREE || cursor->rel_pos == BTR_PCUR_BEFORE_FIRST_IN_TREE)) { /* In these cases we do not try an optimistic restoration, but always do a search */ btr_cur_open_at_index_side( cursor->rel_pos == BTR_PCUR_BEFORE_FIRST_IN_TREE, index, latch_mode, btr_pcur_get_btr_cur(cursor), mtr); cursor->block_when_stored = buf_block_align(btr_pcur_get_page(cursor)); return(FALSE); } ut_a(cursor->old_rec); ut_a(cursor->old_n_fields); page = btr_cur_get_page(btr_pcur_get_btr_cur(cursor)); if (UNIV_LIKELY(latch_mode == BTR_SEARCH_LEAF) || UNIV_LIKELY(latch_mode == BTR_MODIFY_LEAF)) { /* Try optimistic restoration */ if (UNIV_LIKELY(buf_page_optimistic_get( latch_mode, cursor->block_when_stored, page, cursor->modify_clock, mtr))) { cursor->pos_state = BTR_PCUR_IS_POSITIONED; #ifdef UNIV_SYNC_DEBUG buf_page_dbg_add_level(page, SYNC_TREE_NODE); #endif /* UNIV_SYNC_DEBUG */ if (cursor->rel_pos == BTR_PCUR_ON) { #ifdef UNIV_DEBUG rec_t* rec; ulint* offsets1; ulint* offsets2; #endif /* UNIV_DEBUG */ cursor->latch_mode = latch_mode; #ifdef UNIV_DEBUG rec = btr_pcur_get_rec(cursor); heap = mem_heap_create(256); offsets1 = rec_get_offsets( cursor->old_rec, index, NULL, cursor->old_n_fields, &heap); offsets2 = rec_get_offsets( rec, index, NULL, cursor->old_n_fields, &heap); ut_ad(!cmp_rec_rec(cursor->old_rec, rec, offsets1, offsets2, index)); mem_heap_free(heap); #endif /* UNIV_DEBUG */ return(TRUE); } return(FALSE); } } /* If optimistic restoration did not succeed, open the cursor anew */ heap = mem_heap_create(256); tuple = dict_index_build_data_tuple(index, cursor->old_rec, cursor->old_n_fields, heap); /* Save the old search mode of the cursor */ old_mode = cursor->search_mode; if (UNIV_LIKELY(cursor->rel_pos == BTR_PCUR_ON)) { mode = PAGE_CUR_LE; } else if (cursor->rel_pos == BTR_PCUR_AFTER) { mode = PAGE_CUR_G; } else { ut_ad(cursor->rel_pos == BTR_PCUR_BEFORE); mode = PAGE_CUR_L; } btr_pcur_open_with_no_init(index, tuple, mode, latch_mode, cursor, 0, mtr); /* Restore the old search mode */ cursor->search_mode = old_mode; if (cursor->rel_pos == BTR_PCUR_ON && btr_pcur_is_on_user_rec(cursor, mtr) && 0 == cmp_dtuple_rec(tuple, btr_pcur_get_rec(cursor), rec_get_offsets( btr_pcur_get_rec(cursor), index, NULL, ULINT_UNDEFINED, &heap))) { /* We have to store the NEW value for the modify clock, since the cursor can now be on a different page! But we can retain the value of old_rec */ cursor->block_when_stored = buf_block_align( btr_pcur_get_page(cursor)); cursor->modify_clock = buf_block_get_modify_clock( cursor->block_when_stored); cursor->old_stored = BTR_PCUR_OLD_STORED; mem_heap_free(heap); return(TRUE); } mem_heap_free(heap); /* We have to store new position information, modify_clock etc., to the cursor because it can now be on a different page, the record under it may have been removed, etc. */ btr_pcur_store_position(cursor, mtr); return(FALSE); } /****************************************************************** 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. */ void btr_pcur_release_leaf( /*==================*/ btr_pcur_t* cursor, /* in: persistent cursor */ mtr_t* mtr) /* in: mtr */ { page_t* page; ut_a(cursor->pos_state == BTR_PCUR_IS_POSITIONED); ut_ad(cursor->latch_mode != BTR_NO_LATCHES); page = btr_cur_get_page(btr_pcur_get_btr_cur(cursor)); btr_leaf_page_release(page, cursor->latch_mode, mtr); cursor->latch_mode = BTR_NO_LATCHES; cursor->pos_state = BTR_PCUR_WAS_POSITIONED; } /************************************************************* 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. */ 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 */ { ulint next_page_no; ulint space; page_t* page; page_t* next_page; ut_a(cursor->pos_state == BTR_PCUR_IS_POSITIONED); ut_ad(cursor->latch_mode != BTR_NO_LATCHES); ut_ad(btr_pcur_is_after_last_on_page(cursor, mtr)); cursor->old_stored = BTR_PCUR_OLD_NOT_STORED; page = btr_pcur_get_page(cursor); next_page_no = btr_page_get_next(page, mtr); space = buf_frame_get_space_id(page); ut_ad(next_page_no != FIL_NULL); next_page = btr_page_get(space, next_page_no, cursor->latch_mode, mtr); #ifdef UNIV_BTR_DEBUG ut_a(btr_page_get_prev(next_page, mtr) == buf_frame_get_page_no(page)); #endif /* UNIV_BTR_DEBUG */ ut_a(page_is_comp(next_page) == page_is_comp(page)); buf_block_align(next_page)->check_index_page_at_flush = TRUE; btr_leaf_page_release(page, cursor->latch_mode, mtr); page_cur_set_before_first(next_page, btr_pcur_get_page_cur(cursor)); page_check_dir(next_page); } /************************************************************* Moves the persistent cursor backward if it is on the first record of the page. Commits mtr. Note that to prevent a possible deadlock, the operation first stores the position of the cursor, commits mtr, acquires the 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 during the time when the cursor had no latches. */ 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 */ { ulint prev_page_no; ulint space; page_t* page; page_t* prev_page; ulint latch_mode; ulint latch_mode2; ut_a(cursor->pos_state == BTR_PCUR_IS_POSITIONED); ut_ad(cursor->latch_mode != BTR_NO_LATCHES); ut_ad(btr_pcur_is_before_first_on_page(cursor, mtr)); ut_ad(!btr_pcur_is_before_first_in_tree(cursor, mtr)); latch_mode = cursor->latch_mode; if (latch_mode == BTR_SEARCH_LEAF) { latch_mode2 = BTR_SEARCH_PREV; } else if (latch_mode == BTR_MODIFY_LEAF) { latch_mode2 = BTR_MODIFY_PREV; } else { latch_mode2 = 0; /* To eliminate compiler warning */ ut_error; } btr_pcur_store_position(cursor, mtr); mtr_commit(mtr); mtr_start(mtr); btr_pcur_restore_position(latch_mode2, cursor, mtr); page = btr_pcur_get_page(cursor); prev_page_no = btr_page_get_prev(page, mtr); space = buf_frame_get_space_id(page); if (btr_pcur_is_before_first_on_page(cursor, mtr) && (prev_page_no != FIL_NULL)) { prev_page = btr_pcur_get_btr_cur(cursor)->left_page; btr_leaf_page_release(page, latch_mode, mtr); page_cur_set_after_last(prev_page, btr_pcur_get_page_cur(cursor)); } else if (prev_page_no != FIL_NULL) { /* The repositioned cursor did not end on an infimum record on a page. Cursor repositioning acquired a latch also on the previous page, but we do not need the latch: release it. */ prev_page = btr_pcur_get_btr_cur(cursor)->left_page; btr_leaf_page_release(prev_page, latch_mode, mtr); } cursor->latch_mode = latch_mode; cursor->old_stored = BTR_PCUR_OLD_NOT_STORED; } /************************************************************* Moves the persistent cursor to the previous record in the tree. If no records are left, the cursor stays 'before first in tree'. */ ibool btr_pcur_move_to_prev( /*==================*/ /* out: TRUE if the cursor was not before first in tree */ btr_pcur_t* cursor, /* in: persistent cursor; NOTE that the function may release the page latch */ mtr_t* mtr) /* in: mtr */ { ut_ad(cursor->pos_state == BTR_PCUR_IS_POSITIONED); ut_ad(cursor->latch_mode != BTR_NO_LATCHES); cursor->old_stored = BTR_PCUR_OLD_NOT_STORED; if (btr_pcur_is_before_first_on_page(cursor, mtr)) { if (btr_pcur_is_before_first_in_tree(cursor, mtr)) { return(FALSE); } btr_pcur_move_backward_from_page(cursor, mtr); return(TRUE); } btr_pcur_move_to_prev_on_page(cursor, mtr); return(TRUE); } /****************************************************************** 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. */ void btr_pcur_open_on_user_rec( /*======================*/ dict_index_t* index, /* in: index */ 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 */ mtr_t* mtr) /* in: mtr */ { btr_pcur_open(index, tuple, mode, latch_mode, cursor, mtr); if ((mode == PAGE_CUR_GE) || (mode == PAGE_CUR_G)) { if (btr_pcur_is_after_last_on_page(cursor, mtr)) { btr_pcur_move_to_next_user_rec(cursor, mtr); } } else { ut_ad((mode == PAGE_CUR_LE) || (mode == PAGE_CUR_L)); /* Not implemented yet */ ut_error; } }