Exemple #1
0
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;
}
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;

	switch (cursor->rel_pos) {
	case BTR_PCUR_ON:
		mode = PAGE_CUR_LE;
		break;
	case BTR_PCUR_AFTER:
		mode = PAGE_CUR_G;
		break;
	case BTR_PCUR_BEFORE:
		mode = PAGE_CUR_L;
		break;
	default:
		ut_error;
		mode = 0; /* silence a warning */
	}

	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 (btr_pcur_is_on_user_rec(cursor, mtr)) {
		switch (cursor->rel_pos) {
		case BTR_PCUR_ON:
			if (!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);
			}

			break;
		case BTR_PCUR_BEFORE:
			page_cur_move_to_next(btr_pcur_get_page_cur(cursor));
			break;
		case BTR_PCUR_AFTER:
			page_cur_move_to_prev(btr_pcur_get_page_cur(cursor));
			break;
#ifdef UNIV_DEBUG
		default:
			ut_error;
#endif /* UNIV_DEBUG */
		}
	}

	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);
}