/*********************************************************//**
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 */
{
ulint next_page_no;
ulint space;
ulint zip_size;
page_t* page;
buf_block_t* next_block;
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));
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_block_get_space(btr_pcur_get_block(cursor));
zip_size = buf_block_get_zip_size(btr_pcur_get_block(cursor));
ut_ad(next_page_no != FIL_NULL);
next_block = btr_block_get(space, zip_size, next_page_no,
cursor->latch_mode,
btr_pcur_get_btr_cur(cursor)->index, mtr);
next_page = buf_block_get_frame(next_block);
if (srv_pass_corrupt_table && !next_page) {
btr_leaf_page_release(btr_pcur_get_block(cursor),
cursor->latch_mode, mtr);
btr_pcur_get_page_cur(cursor)->block = 0;
btr_pcur_get_page_cur(cursor)->rec = 0;
return;
}
ut_a(next_page);
#ifdef UNIV_BTR_DEBUG
ut_a(page_is_comp(next_page) == page_is_comp(page));
ut_a(btr_page_get_prev(next_page, mtr)
== buf_block_get_page_no(btr_pcur_get_block(cursor)));
#endif /* UNIV_BTR_DEBUG */
next_block->check_index_page_at_flush = TRUE;
btr_leaf_page_release(btr_pcur_get_block(cursor),
cursor->latch_mode, mtr);
page_cur_set_before_first(next_block, 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. */
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 */
{
ulint prev_page_no;
ulint space;
page_t* page;
buf_block_t* prev_block;
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));
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_block_get_space(btr_pcur_get_block(cursor));
if (prev_page_no == FIL_NULL) {
} else if (btr_pcur_is_before_first_on_page(cursor)) {
prev_block = btr_pcur_get_btr_cur(cursor)->left_block;
btr_leaf_page_release(btr_pcur_get_block(cursor),
latch_mode, mtr);
page_cur_set_after_last(prev_block,
btr_pcur_get_page_cur(cursor));
} else {
/* 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_block = btr_pcur_get_btr_cur(cursor)->left_block;
btr_leaf_page_release(prev_block, latch_mode, mtr);
}
cursor->latch_mode = latch_mode;
cursor->old_stored = BTR_PCUR_OLD_NOT_STORED;
}
