Exemple #1
0
/*
 * __cursor_var_append_prev --
 *	Return the previous variable-length entry on the append list.
 */
static inline int
__cursor_var_append_prev(WT_CURSOR_BTREE *cbt, bool newpage)
{
	WT_ITEM *val;
	WT_SESSION_IMPL *session;
	WT_UPDATE *upd;

	session = (WT_SESSION_IMPL *)cbt->iface.session;
	val = &cbt->iface.value;

	if (newpage) {
		cbt->ins = WT_SKIP_LAST(cbt->ins_head);
		goto new_page;
	}

	for (;;) {
		WT_RET(__cursor_skip_prev(cbt));
new_page:	if (cbt->ins == NULL)
			return (WT_NOTFOUND);

		__cursor_set_recno(cbt, WT_INSERT_RECNO(cbt->ins));
		if ((upd = __wt_txn_read(session, cbt->ins->upd)) == NULL)
			continue;
		if (WT_UPDATE_DELETED_ISSET(upd)) {
			if (__wt_txn_visible_all(session, upd->txnid))
				++cbt->page_deleted_count;
			continue;
		}
		val->data = WT_UPDATE_DATA(upd);
		val->size = upd->size;
		return (0);
	}
	/* NOTREACHED */
}
Exemple #2
0
/*
 * __cursor_var_append_next --
 *	Return the next variable-length entry on the append list.
 */
static inline int
__cursor_var_append_next(WT_CURSOR_BTREE *cbt, bool newpage)
{
	WT_SESSION_IMPL *session;
	WT_UPDATE *upd;

	session = (WT_SESSION_IMPL *)cbt->iface.session;

	if (newpage) {
		cbt->ins = WT_SKIP_FIRST(cbt->ins_head);
		goto new_page;
	}

	for (;;) {
		cbt->ins = WT_SKIP_NEXT(cbt->ins);
new_page:	if (cbt->ins == NULL)
			return (WT_NOTFOUND);

		__cursor_set_recno(cbt, WT_INSERT_RECNO(cbt->ins));
		if ((upd = __wt_txn_read(session, cbt->ins->upd)) == NULL)
			continue;
		if (upd->type == WT_UPDATE_DELETED) {
			if (__wt_txn_upd_visible_all(session, upd))
				++cbt->page_deleted_count;
			continue;
		}
		return (__wt_value_return(session, cbt, upd));
	}
	/* NOTREACHED */
}
/*
 * __cursor_var_append_prev --
 *	Return the previous variable-length entry on the append list.
 */
static inline int
__cursor_var_append_prev(WT_CURSOR_BTREE *cbt, int newpage)
{
	WT_ITEM *val;
	WT_SESSION_IMPL *session;
	WT_UPDATE *upd;

	session = (WT_SESSION_IMPL *)cbt->iface.session;
	val = &cbt->iface.value;

	if (newpage) {
		cbt->ins = WT_SKIP_LAST(cbt->ins_head);
		goto new_page;
	}

	for (;;) {
		WT_RET(__cursor_skip_prev(cbt));
new_page:	if (cbt->ins == NULL)
			return (WT_NOTFOUND);

		__cursor_set_recno(cbt, WT_INSERT_RECNO(cbt->ins));
		if ((upd = __wt_txn_read(session, cbt->ins->upd)) == NULL ||
		    WT_UPDATE_DELETED_ISSET(upd))
			continue;
		val->data = WT_UPDATE_DATA(upd);
		val->size = upd->size;
		break;
	}
	return (0);
}
Exemple #4
0
/*
 * __cursor_invalid --
 *	Return if the cursor references an invalid K/V pair (either the pair
 * doesn't exist at all because the tree is empty, or the pair was deleted).
 */
static inline int
__cursor_invalid(WT_CURSOR_BTREE *cbt)
{
	WT_BTREE *btree;
	WT_CELL *cell;
	WT_CELL_UNPACK unpack;
	WT_COL *cip;
	WT_INSERT *ins;
	WT_PAGE *page;
	WT_SESSION_IMPL *session;
	WT_UPDATE *upd;

	btree = cbt->btree;
	ins = cbt->ins;
	page = cbt->page;
	session = (WT_SESSION_IMPL *)cbt->iface.session;

	/* If we found an item on an insert list, check there. */
	if (ins != NULL && (upd = __wt_txn_read(session, ins->upd)) != NULL)
		return (WT_UPDATE_DELETED_ISSET(upd) ? 1 : 0);

	/* The page may be empty, the search routine doesn't check. */
	if (page->entries == 0)
		return (1);

	/* Otherwise, check for an update in the page's slots. */
	switch (btree->type) {
	case BTREE_COL_FIX:
		break;
	case BTREE_COL_VAR:
		cip = &page->u.col_var.d[cbt->slot];
		if ((cell = WT_COL_PTR(page, cip)) == NULL)
			return (WT_NOTFOUND);
		__wt_cell_unpack(cell, &unpack);
		if (unpack.type == WT_CELL_DEL)
			return (1);
		break;
	case BTREE_ROW:
		if (page->u.row.upd != NULL && (upd = __wt_txn_read(session,
		    page->u.row.upd[cbt->slot])) != NULL &&
		    WT_UPDATE_DELETED_ISSET(upd))
			return (1);
		break;
	}
	return (0);
}
Exemple #5
0
/*btree cursor移向下一个记录,仅仅在append list上移动*/
static inline int __cursor_fix_append_next(WT_CURSOR_BTREE* cbt, int newpage)
{
	WT_ITEM *val;
	WT_SESSION_IMPL *session;
	WT_UPDATE *upd;

	session = (WT_SESSION_IMPL *)cbt->iface.session;
	val = &cbt->iface.value;

	/*新载入的page,判断ins_head是否为空,如果为空表示没有append的记录*/
	if (newpage){
		if ((cbt->ins = WT_SKIP_FIRST(cbt->ins_head)) == NULL)
			return (WT_NOTFOUND);
	}
	else{
		/*已经到append list的最后一条记录了,后面没有记录*/
		if (cbt->recno >= WT_INSERT_RECNO(cbt->ins) && (cbt->ins = WT_SKIP_NEXT(cbt->ins)) == NULL)
			return (WT_NOTFOUND);
	}
	/*
	* This code looks different from the cursor-previous code.  The append
	* list appears on the last page of the tree, but it may be preceded by
	* other rows, which means the cursor's recno will be set to a value and
	* we simply want to increment it.  If the cursor's recno is NOT set,
	* we're starting our iteration in a tree that has only appended items.
	* In that case, recno will be 0 and happily enough the increment will
	* set it to 1, which is correct.
	*/
	__cursor_set_recno(cbt, cbt->recno + 1);

	/*
	* Fixed-width column store appends are inherently non-transactional.
	* Even a non-visible update by a concurrent or aborted transaction
	* changes the effective end of the data.  The effect is subtle because
	* of the blurring between deleted and empty values, but ideally we
	* would skip all uncommitted changes at the end of the data.  This
	* doesn't apply to variable-width column stores because the implicitly
	* created records written by reconciliation are deleted and so can be
	* never seen by a read.
	*
	* The problem is that we don't know at this point whether there may be
	* multiple uncommitted changes at the end of the data, and it would be
	* expensive to check every time we hit an aborted update.  If an
	* insert is aborted, we simply return zero (empty), regardless of
	* whether we are at the end of the data.
	*/
	if (cbt->recno < WT_INSERT_RECNO(cbt->ins) || (upd = __wt_txn_read(session, cbt->ins->upd)) == NULL){ /*没有可见的记录值,直接返回0*/
		cbt->v = 0;
		val->data = &cbt->v;
	}
	else
		val->data = WT_UPDATE_DATA(upd);
	val->size = 1;
	return 0;
}
Exemple #6
0
/*
 * __cursor_fix_prev --
 *	Move to the previous, fixed-length column-store item.
 */
static inline int
__cursor_fix_prev(WT_CURSOR_BTREE *cbt, int newpage)
{
	WT_BTREE *btree;
	WT_ITEM *val;
	WT_SESSION_IMPL *session;
	WT_UPDATE *upd;

	session = (WT_SESSION_IMPL *)cbt->iface.session;
	btree = session->btree;
	val = &cbt->iface.value;

	/* Initialize for each new page. */
	if (newpage) {
		cbt->last_standard_recno = __col_last_recno(cbt->page);
		if (cbt->last_standard_recno == 0)
			return (WT_NOTFOUND);
		__cursor_set_recno(cbt, cbt->last_standard_recno);
		goto new_page;
	}

	/* Move to the previous entry and return the item. */
	for (;;) {
		if (cbt->recno == cbt->page->u.col_fix.recno)
			return (WT_NOTFOUND);
		__cursor_set_recno(cbt, cbt->recno - 1);

new_page:	/* Check any insert list for a matching record. */
		cbt->ins_head = WT_COL_UPDATE_SINGLE(cbt->page);
		cbt->ins = __col_insert_search(
		    cbt->ins_head, cbt->ins_stack, cbt->next_stack, cbt->recno);
		if (cbt->ins != NULL &&
		    cbt->recno != WT_INSERT_RECNO(cbt->ins))
			cbt->ins = NULL;
		upd = cbt->ins == NULL ?
		    NULL : __wt_txn_read(session, cbt->ins->upd);
		if (upd != NULL) {
			val->data = WT_UPDATE_DATA(upd);
			val->size = 1;
			return (0);
		}

		cbt->v = __bit_getv_recno(cbt->page, cbt->recno, btree->bitcnt);
		val->data = &cbt->v;
		val->size = 1;
		return (0);
	}
	/* NOTREACHED */
}
Exemple #7
0
/*
 * __cursor_fix_prev --
 *	Move to the previous, fixed-length column-store item.
 */
static inline int
__cursor_fix_prev(WT_CURSOR_BTREE *cbt, int newpage)
{
	WT_BTREE *btree;
	WT_INSERT *ins;
	WT_ITEM *val;
	WT_SESSION_IMPL *session;
	WT_UPDATE *upd;
	uint64_t *recnop;

	session = (WT_SESSION_IMPL *)cbt->iface.session;
	btree = session->btree;

	recnop = &cbt->iface.recno;
	val = &cbt->iface.value;

	/* Initialize for each new page. */
	if (newpage) {
		cbt->last_standard_recno = __col_last_recno(cbt->page);
		if (cbt->last_standard_recno == 0)
			return (WT_NOTFOUND);
		cbt->recno = cbt->last_standard_recno;
		goto new_page;
	}

	/* Move to the previous entry and return the item. */
	for (;;) {
		if (cbt->recno == cbt->page->u.col_fix.recno)
			return (WT_NOTFOUND);
		--cbt->recno;
new_page:	*recnop = cbt->recno;

		/* Check any insert list for a matching record. */
		if ((ins = cbt->ins = __col_insert_search_match(
		    WT_COL_UPDATE_SINGLE(cbt->page), cbt->recno)) != NULL &&
		    (upd = __wt_txn_read(session, ins->upd)) != NULL) {
			val->data = WT_UPDATE_DATA(upd);
			val->size = 1;
			return (0);
		}

		cbt->v = __bit_getv_recno(cbt->page, cbt->recno, btree->bitcnt);
		val->data = &cbt->v;
		val->size = 1;
		return (0);
	}
	/* NOTREACHED */
}
Exemple #8
0
/*btree cursor移向下一个记录(fix col方式存储),在btree树空间上移动*/
static inline int __cursor_fix_next(WT_CURSOR_BTREE* cbt, int newpage)
{
	WT_BTREE *btree;
	WT_ITEM *val;
	WT_PAGE *page;
	WT_SESSION_IMPL *session;
	WT_UPDATE *upd;

	session = (WT_SESSION_IMPL *)cbt->iface.session;
	btree = S2BT(session);
	page = cbt->ref->page;
	val = &cbt->iface.value;

	/*切换到新的page上做next操作*/
	if (newpage){
		cbt->last_standard_recno = __col_fix_last_recno(page);
		if (cbt->last_standard_recno == 0)
			return (WT_NOTFOUND);

		__cursor_set_recno(cbt, page->pg_fix_recno);
		goto new_page;
	}

	/*记录序号超出最后一个序号,到末尾了*/
	if (cbt->recno >= cbt->last_standard_recno)
		return WT_NOTFOUND;
	__cursor_set_recno(cbt, cbt->recno + 1);

new_page:
	/*获得第一个修改列表*/
	cbt->ins_head = WT_COL_UPDATE_SINGLE(page);
	/*定位recno所在的修改条目*/
	cbt->ins = __col_insert_search(cbt->ins_head, cbt->ins_stack, cbt->next_stack, cbt->recno);
	if (cbt->ins != NULL && cbt->recno != WT_INSERT_RECNO(cbt->ins)) /*不正确的修改定位,将ins设置为NULL表示定位失败*/
		cbt->ins = NULL;
	
	/*做事务隔离读取记录版本*/
	upd = cbt->ins == NULL ? NULL : __wt_txn_read(session, cbt->ins->upd);
	if (upd == NULL){
		cbt->v = __bit_getv_recno(page, cbt->recno, btree->bitcnt); /*V赋值*/
		val->data = &cbt->v;
	}
	else
		val->data = WT_UPDATE_DATA(upd);
	val->size = 1;

	return 0;
}
Exemple #9
0
/*
 * __cursor_fix_next --
 *	Move to the next, fixed-length column-store item.
 */
static inline int
__cursor_fix_next(WT_CURSOR_BTREE *cbt, bool newpage)
{
	WT_BTREE *btree;
	WT_PAGE *page;
	WT_SESSION_IMPL *session;
	WT_UPDATE *upd;

	session = (WT_SESSION_IMPL *)cbt->iface.session;
	btree = S2BT(session);
	page = cbt->ref->page;

	/* Initialize for each new page. */
	if (newpage) {
		cbt->last_standard_recno = __col_fix_last_recno(cbt->ref);
		if (cbt->last_standard_recno == 0)
			return (WT_NOTFOUND);
		__cursor_set_recno(cbt, cbt->ref->ref_recno);
		goto new_page;
	}

	/* Move to the next entry and return the item. */
	if (cbt->recno >= cbt->last_standard_recno)
		return (WT_NOTFOUND);
	__cursor_set_recno(cbt, cbt->recno + 1);

new_page:
	/* Check any insert list for a matching record. */
	cbt->ins_head = WT_COL_UPDATE_SINGLE(page);
	cbt->ins = __col_insert_search(
	    cbt->ins_head, cbt->ins_stack, cbt->next_stack, cbt->recno);
	if (cbt->ins != NULL && cbt->recno != WT_INSERT_RECNO(cbt->ins))
		cbt->ins = NULL;
	upd = cbt->ins == NULL ? NULL : __wt_txn_read(session, cbt->ins->upd);
	if (upd == NULL) {
		cbt->v = __bit_getv_recno(cbt->ref, cbt->recno, btree->bitcnt);
		cbt->iface.value.data = &cbt->v;
	} else
		cbt->iface.value.data = upd->data;
	cbt->iface.value.size = 1;
	return (0);
}
Exemple #10
0
/*
 * __cursor_fix_append_prev --
 *	Return the previous fixed-length entry on the append list.
 */
static inline int
__cursor_fix_append_prev(WT_CURSOR_BTREE *cbt, int newpage)
{
	WT_ITEM *val;
	WT_SESSION_IMPL *session;
	WT_UPDATE *upd;

	session = (WT_SESSION_IMPL *)cbt->iface.session;
	val = &cbt->iface.value;

	if (newpage) {
		if ((cbt->ins = WT_SKIP_LAST(cbt->ins_head)) == NULL)
			return (WT_NOTFOUND);
		cbt->recno = WT_INSERT_RECNO(cbt->ins);
	} else {
		if (cbt->recno == WT_INSERT_RECNO(cbt->ins)) {
			__cursor_skip_prev(cbt);
			if (cbt->ins == NULL)
				return (WT_NOTFOUND);
		}
		--cbt->recno;
	}

	/*
	 * Column store appends are inherently non-transactional.
	 *
	 * Even a non-visible update by a concurrent or aborted transaction
	 * changes the effective end of the data.  The effect is subtle because
	 * of the blurring between deleted and empty values, but ideally we
	 * would skip all uncommitted changes at the end of the data.
	 */
	cbt->iface.recno = cbt->recno;
	if (cbt->recno > WT_INSERT_RECNO(cbt->ins) ||
	    (upd = __wt_txn_read(session, cbt->ins->upd)) == NULL) {
		cbt->v = 0;
		val->data = &cbt->v;
	} else
		val->data = WT_UPDATE_DATA(upd);
	val->size = 1;
	return (0);
}
Exemple #11
0
/*在append list上移动variable-length类型的btree cursor*/
static inline int __cursor_var_append_next(WT_CURSOR_BTREE* cbt, int newpage)
{
	WT_ITEM *val;
	WT_SESSION_IMPL *session;
	WT_UPDATE *upd;

	session = (WT_SESSION_IMPL *)cbt->iface.session;
	val = &cbt->iface.value;

	if (newpage){
		cbt->ins = WT_SKIP_FIRST(cbt->ins_head);
		goto new_page;
	}

	for (;;){
		cbt->ins = WT_SKIP_NEXT(cbt->ins);
new_page:
		if (cbt->ins == NULL)
			return (WT_NOTFOUND);

		__cursor_set_recno(cbt, WT_INSERT_RECNO(cbt->ins));
		/*事务隔离读,对本事务不可见,继续向前*/
		if ((upd = __wt_txn_read(session, cbt->ins->upd)) == NULL)
			continue;
		/*删除集合,不做指向这条记录,继续向下移动*/
		if (WT_UPDATE_DELETED_ISSET(upd)) {
			++cbt->page_deleted_count;
			continue;
		}
		/*赋值value*/
		val->data = WT_UPDATE_DATA(upd);
		val->size = upd->size;

		return 0;
	}
}
Exemple #12
0
/*
 * __cursor_row_next --
 *	Move to the next row-store item.
 */
static inline int
__cursor_row_next(WT_CURSOR_BTREE *cbt, bool newpage)
{
	WT_INSERT *ins;
	WT_ITEM *key;
	WT_PAGE *page;
	WT_ROW *rip;
	WT_SESSION_IMPL *session;
	WT_UPDATE *upd;

	session = (WT_SESSION_IMPL *)cbt->iface.session;
	page = cbt->ref->page;
	key = &cbt->iface.key;

	/*
	 * For row-store pages, we need a single item that tells us the part
	 * of the page we're walking (otherwise switching from next to prev
	 * and vice-versa is just too complicated), so we map the WT_ROW and
	 * WT_INSERT_HEAD insert array slots into a single name space: slot 1
	 * is the "smallest key insert list", slot 2 is WT_ROW[0], slot 3 is
	 * WT_INSERT_HEAD[0], and so on.  This means WT_INSERT lists are
	 * odd-numbered slots, and WT_ROW array slots are even-numbered slots.
	 *
	 * Initialize for each new page.
	 */
	if (newpage) {
		cbt->ins_head = WT_ROW_INSERT_SMALLEST(page);
		cbt->ins = WT_SKIP_FIRST(cbt->ins_head);
		cbt->row_iteration_slot = 1;
		cbt->rip_saved = NULL;
		goto new_insert;
	}

	/* Move to the next entry and return the item. */
	for (;;) {
		/*
		 * Continue traversing any insert list; maintain the insert list
		 * head reference and entry count in case we switch to a cursor
		 * previous movement.
		 */
		if (cbt->ins != NULL)
			cbt->ins = WT_SKIP_NEXT(cbt->ins);

new_insert:	if ((ins = cbt->ins) != NULL) {
			if ((upd = __wt_txn_read(session, ins->upd)) == NULL)
				continue;
			if (upd->type == WT_UPDATE_DELETED) {
				if (__wt_txn_upd_visible_all(session, upd))
					++cbt->page_deleted_count;
				continue;
			}
			key->data = WT_INSERT_KEY(ins);
			key->size = WT_INSERT_KEY_SIZE(ins);
			return (__wt_value_return(session, cbt, upd));
		}

		/* Check for the end of the page. */
		if (cbt->row_iteration_slot >= page->entries * 2 + 1)
			return (WT_NOTFOUND);
		++cbt->row_iteration_slot;

		/*
		 * Odd-numbered slots configure as WT_INSERT_HEAD entries,
		 * even-numbered slots configure as WT_ROW entries.
		 */
		if (cbt->row_iteration_slot & 0x01) {
			cbt->ins_head = WT_ROW_INSERT_SLOT(
			    page, cbt->row_iteration_slot / 2 - 1);
			cbt->ins = WT_SKIP_FIRST(cbt->ins_head);
			goto new_insert;
		}
		cbt->ins_head = NULL;
		cbt->ins = NULL;

		cbt->slot = cbt->row_iteration_slot / 2 - 1;
		rip = &page->pg_row[cbt->slot];
		upd = __wt_txn_read(session, WT_ROW_UPDATE(page, rip));
		if (upd != NULL && upd->type == WT_UPDATE_DELETED) {
			if (__wt_txn_upd_visible_all(session, upd))
				++cbt->page_deleted_count;
			continue;
		}
		return (__cursor_row_slot_return(cbt, rip, upd));
	}
	/* NOTREACHED */
}
Exemple #13
0
/*
 * __cursor_var_prev --
 *	Move to the previous, variable-length column-store item.
 */
static inline int
__cursor_var_prev(WT_CURSOR_BTREE *cbt, int newpage)
{
	WT_CELL *cell;
	WT_CELL_UNPACK unpack;
	WT_COL *cip;
	WT_INSERT *ins;
	WT_ITEM *val;
	WT_SESSION_IMPL *session;
	WT_UPDATE *upd;
	uint64_t *recnop;

	session = (WT_SESSION_IMPL *)cbt->iface.session;
	recnop = &cbt->iface.recno;
	val = &cbt->iface.value;

	/* Initialize for each new page. */
	if (newpage) {
		cbt->last_standard_recno = __col_last_recno(cbt->page);
		if (cbt->last_standard_recno == 0)
			return (WT_NOTFOUND);
		cbt->recno = cbt->last_standard_recno;
		goto new_page;
	}

	/* Move to the previous entry and return the item. */
	for (;;) {
		--cbt->recno;
new_page:	*recnop = cbt->recno;
		if (cbt->recno < cbt->page->u.col_var.recno)
			return (WT_NOTFOUND);

		/* Find the matching WT_COL slot. */
		if ((cip = __col_var_search(cbt->page, cbt->recno)) == NULL)
			return (WT_NOTFOUND);

		/* Check any insert list for a matching record. */
		if ((ins = __col_insert_search_match(
		    WT_COL_UPDATE(cbt->page, cip), cbt->recno)) != NULL &&
		    (upd = __wt_txn_read(session, ins->upd)) != NULL) {
			if (WT_UPDATE_DELETED_ISSET(upd))
				continue;
			cbt->ins = ins;
			val->data = WT_UPDATE_DATA(upd);
			val->size = upd->size;
			return (0);
		}

		/*
		 * If we're at the same slot as the last reference and there's
		 * no matching insert list item, re-use the return information
		 * (so encoded items with large repeat counts aren't repeatedly
		 * decoded).  Otherwise, unpack the cell and build the return
		 * information.
		 */
		if (cbt->cip_saved != cip) {
			if ((cell = WT_COL_PTR(cbt->page, cip)) == NULL)
				continue;
			__wt_cell_unpack(cell, &unpack);
			switch (unpack.type) {
			case WT_CELL_DEL:
				continue;
			case WT_CELL_VALUE:
				if (session->btree->huffman_value == NULL) {
					cbt->tmp.data = unpack.data;
					cbt->tmp.size = unpack.size;
					break;
				}
				/* FALLTHROUGH */
			default:
				WT_RET(__wt_cell_unpack_copy(
				    session, &unpack, &cbt->tmp));
			}
			cbt->cip_saved = cip;
		}
		val->data = cbt->tmp.data;
		val->size = cbt->tmp.size;
		return (0);
	}
	/* NOTREACHED */
}
Exemple #14
0
/*
 * __cursor_var_prev --
 *	Move to the previous, variable-length column-store item.
 */
static inline int
__cursor_var_prev(WT_CURSOR_BTREE *cbt, int newpage)
{
	WT_CELL *cell;
	WT_CELL_UNPACK unpack;
	WT_COL *cip;
	WT_ITEM *val;
	WT_PAGE *page;
	WT_SESSION_IMPL *session;
	WT_UPDATE *upd;

	session = (WT_SESSION_IMPL *)cbt->iface.session;
	page = cbt->ref->page;
	val = &cbt->iface.value;

	/* Initialize for each new page. */
	if (newpage) {
		cbt->last_standard_recno = __col_var_last_recno(page);
		if (cbt->last_standard_recno == 0)
			return (WT_NOTFOUND);
		__cursor_set_recno(cbt, cbt->last_standard_recno);
		goto new_page;
	}

	/* Move to the previous entry and return the item. */
	for (;;) {
		__cursor_set_recno(cbt, cbt->recno - 1);

new_page:	if (cbt->recno < page->pg_var_recno)
			return (WT_NOTFOUND);

		/* Find the matching WT_COL slot. */
		if ((cip = __col_var_search(page, cbt->recno)) == NULL)
			return (WT_NOTFOUND);
		cbt->slot = WT_COL_SLOT(page, cip);

		/* Check any insert list for a matching record. */
		cbt->ins_head = WT_COL_UPDATE_SLOT(page, cbt->slot);
		cbt->ins = __col_insert_search_match(cbt->ins_head, cbt->recno);
		upd = cbt->ins == NULL ?
		    NULL : __wt_txn_read(session, cbt->ins->upd);
		if (upd != NULL) {
			if (WT_UPDATE_DELETED_ISSET(upd)) {
				++cbt->page_deleted_count;
				continue;
			}

			val->data = WT_UPDATE_DATA(upd);
			val->size = upd->size;
			return (0);
		}

		/*
		 * If we're at the same slot as the last reference and there's
		 * no matching insert list item, re-use the return information
		 * (so encoded items with large repeat counts aren't repeatedly
		 * decoded).  Otherwise, unpack the cell and build the return
		 * information.
		 */
		if (cbt->cip_saved != cip) {
			if ((cell = WT_COL_PTR(page, cip)) == NULL)
				continue;
			__wt_cell_unpack(cell, &unpack);
			if (unpack.type == WT_CELL_DEL)
				continue;
			WT_RET(__wt_page_cell_data_ref(
			    session, page, &unpack, &cbt->tmp));

			cbt->cip_saved = cip;
		}
		val->data = cbt->tmp.data;
		val->size = cbt->tmp.size;
		return (0);
	}
	/* NOTREACHED */
}
Exemple #15
0
/*
 * __cursor_var_prev --
 *	Move to the previous, variable-length column-store item.
 */
static inline int
__cursor_var_prev(WT_CURSOR_BTREE *cbt, int newpage)
{
	WT_CELL *cell;
	WT_CELL_UNPACK unpack;
	WT_COL *cip;
	WT_DECL_RET;
	WT_ITEM *val;
	WT_SESSION_IMPL *session;
	WT_UPDATE *upd;

	session = (WT_SESSION_IMPL *)cbt->iface.session;
	val = &cbt->iface.value;

	/* Initialize for each new page. */
	if (newpage) {
		cbt->last_standard_recno = __col_last_recno(cbt->page);
		if (cbt->last_standard_recno == 0)
			return (WT_NOTFOUND);
		__cursor_set_recno(cbt, cbt->last_standard_recno);
		goto new_page;
	}

	/* Move to the previous entry and return the item. */
	for (;;) {
		__cursor_set_recno(cbt, cbt->recno - 1);

new_page:	if (cbt->recno < cbt->page->u.col_var.recno)
			return (WT_NOTFOUND);

		/* Find the matching WT_COL slot. */
		if ((cip = __col_var_search(cbt->page, cbt->recno)) == NULL)
			return (WT_NOTFOUND);
		cbt->slot = WT_COL_SLOT(cbt->page, cip);

		/* Check any insert list for a matching record. */
		cbt->ins_head = WT_COL_UPDATE_SLOT(cbt->page, cbt->slot);
		cbt->ins = __col_insert_search_match(cbt->ins_head, cbt->recno);
		upd = cbt->ins == NULL ?
		    NULL : __wt_txn_read(session, cbt->ins->upd);
		if (upd != NULL) {
			if (WT_UPDATE_DELETED_ISSET(upd))
				continue;

			val->data = WT_UPDATE_DATA(upd);
			val->size = upd->size;
			return (0);
		}

		/*
		 * If we're at the same slot as the last reference and there's
		 * no matching insert list item, re-use the return information
		 * (so encoded items with large repeat counts aren't repeatedly
		 * decoded).  Otherwise, unpack the cell and build the return
		 * information.
		 */
		if (cbt->cip_saved != cip) {
			if ((cell = WT_COL_PTR(cbt->page, cip)) == NULL)
				continue;
			__wt_cell_unpack(cell, &unpack);
			if (unpack.type == WT_CELL_DEL)
				continue;

			/*
			 * Restart for a variable-length column-store.  We could
			 * catch restart higher up the call-stack but there's no
			 * point to it: unlike row-store (where a normal search
			 * path finds cached overflow values), we have to access
			 * the page's reconciliation structures, and that's as
			 * easy here as higher up the stack.
			 */
			if ((ret = __wt_cell_unpack_ref(
			    session, &unpack, &cbt->tmp)) == WT_RESTART)
				ret = __wt_ovfl_cache_col_restart(
				    session, cbt->page, &unpack, &cbt->tmp);
			WT_RET(ret);

			cbt->cip_saved = cip;
		}
		val->data = cbt->tmp.data;
		val->size = cbt->tmp.size;
		return (0);
	}
	/* NOTREACHED */
}
Exemple #16
0
/*
 * __cursor_row_prev --
 *	Move to the previous row-store item.
 */
static inline int
__cursor_row_prev(WT_CURSOR_BTREE *cbt, bool newpage)
{
	WT_INSERT *ins;
	WT_ITEM *key, *val;
	WT_PAGE *page;
	WT_ROW *rip;
	WT_SESSION_IMPL *session;
	WT_UPDATE *upd;

	session = (WT_SESSION_IMPL *)cbt->iface.session;
	page = cbt->ref->page;
	key = &cbt->iface.key;
	val = &cbt->iface.value;

	/*
	 * For row-store pages, we need a single item that tells us the part
	 * of the page we're walking (otherwise switching from next to prev
	 * and vice-versa is just too complicated), so we map the WT_ROW and
	 * WT_INSERT_HEAD insert array slots into a single name space: slot 1
	 * is the "smallest key insert list", slot 2 is WT_ROW[0], slot 3 is
	 * WT_INSERT_HEAD[0], and so on.  This means WT_INSERT lists are
	 * odd-numbered slots, and WT_ROW array slots are even-numbered slots.
	 *
	 * New page configuration.
	 */
	if (newpage) {
		/*
		 * If we haven't instantiated keys on this page, do so, else it
		 * is a very, very slow traversal.
		 */
		if (!F_ISSET_ATOMIC(page, WT_PAGE_BUILD_KEYS))
			WT_RET(__wt_row_leaf_keys(session, page));

		if (page->pg_row_entries == 0)
			cbt->ins_head = WT_ROW_INSERT_SMALLEST(page);
		else
			cbt->ins_head =
			    WT_ROW_INSERT_SLOT(page, page->pg_row_entries - 1);
		cbt->ins = WT_SKIP_LAST(cbt->ins_head);
		cbt->row_iteration_slot = page->pg_row_entries * 2 + 1;
		goto new_insert;
	}

	/* Move to the previous entry and return the item. */
	for (;;) {
		/*
		 * Continue traversing any insert list.  Maintain the reference
		 * to the current insert element in case we switch to a cursor
		 * next movement.
		 */
		if (cbt->ins != NULL)
			WT_RET(__cursor_skip_prev(cbt));

new_insert:	if ((ins = cbt->ins) != NULL) {
			if ((upd = __wt_txn_read(session, ins->upd)) == NULL)
				continue;
			if (WT_UPDATE_DELETED_ISSET(upd)) {
				if (__wt_txn_visible_all(session, upd->txnid))
					++cbt->page_deleted_count;
				continue;
			}
			key->data = WT_INSERT_KEY(ins);
			key->size = WT_INSERT_KEY_SIZE(ins);
			val->data = WT_UPDATE_DATA(upd);
			val->size = upd->size;
			return (0);
		}

		/* Check for the beginning of the page. */
		if (cbt->row_iteration_slot == 1)
			return (WT_NOTFOUND);
		--cbt->row_iteration_slot;

		/*
		 * Odd-numbered slots configure as WT_INSERT_HEAD entries,
		 * even-numbered slots configure as WT_ROW entries.
		 */
		if (cbt->row_iteration_slot & 0x01) {
			cbt->ins_head = cbt->row_iteration_slot == 1 ?
			    WT_ROW_INSERT_SMALLEST(page) :
			    WT_ROW_INSERT_SLOT(
				page, cbt->row_iteration_slot / 2 - 1);
			cbt->ins = WT_SKIP_LAST(cbt->ins_head);
			goto new_insert;
		}
		cbt->ins_head = NULL;
		cbt->ins = NULL;

		cbt->slot = cbt->row_iteration_slot / 2 - 1;
		rip = &page->pg_row_d[cbt->slot];
		upd = __wt_txn_read(session, WT_ROW_UPDATE(page, rip));
		if (upd != NULL && WT_UPDATE_DELETED_ISSET(upd)) {
			if (__wt_txn_visible_all(session, upd->txnid))
				++cbt->page_deleted_count;
			continue;
		}

		return (__cursor_row_slot_return(cbt, rip, upd));
	}
	/* NOTREACHED */
}
Exemple #17
0
/*
 * __wt_kv_return --
 *	Return a page referenced key/value pair to the application.
 */
int
__wt_kv_return(WT_SESSION_IMPL *session, WT_CURSOR_BTREE *cbt)
{
    WT_BTREE *btree;
    WT_CELL *cell;
    WT_CELL_UNPACK unpack;
    WT_CURSOR *cursor;
    WT_DECL_RET;
    WT_PAGE *page;
    WT_ROW *rip;
    WT_UPDATE *upd;
    uint8_t v;

    btree = S2BT(session);

    page = cbt->page;
    cursor = &cbt->iface;

    switch (page->type) {
    case WT_PAGE_COL_FIX:
        /*
         * The interface cursor's record has usually been set, but that
         * isn't universally true, specifically, cursor.search_near may
         * call here without first setting the interface cursor.
         */
        cursor->recno = cbt->recno;

        /*
         * If the cursor references a WT_INSERT item, take the related
         * WT_UPDATE item.
         */
        if (cbt->ins != NULL &&
                (upd = __wt_txn_read(session, cbt->ins->upd)) != NULL) {
            cursor->value.data = WT_UPDATE_DATA(upd);
            cursor->value.size = upd->size;
            return (0);
        }
        v = __bit_getv_recno(page, cbt->iface.recno, btree->bitcnt);
        return (__wt_buf_set(session, &cursor->value, &v, 1));
    case WT_PAGE_COL_VAR:
        /*
         * The interface cursor's record has usually been set, but that
         * isn't universally true, specifically, cursor.search_near may
         * call here without first setting the interface cursor.
         */
        cursor->recno = cbt->recno;

        /*
         * If the cursor references a WT_INSERT item, take the related
         * WT_UPDATE item.
         */
        if (cbt->ins != NULL &&
                (upd = __wt_txn_read(session, cbt->ins->upd)) != NULL) {
            cursor->value.data = WT_UPDATE_DATA(upd);
            cursor->value.size = upd->size;
            return (0);
        }
        cell = WT_COL_PTR(page, &page->u.col_var.d[cbt->slot]);
        break;
    case WT_PAGE_ROW_LEAF:
        rip = &page->u.row.d[cbt->slot];

        /*
         * If the cursor references a WT_INSERT item, take the key and
         * related WT_UPDATE item.   Otherwise, take the key from the
         * original page, and the value from any related WT_UPDATE item,
         * or the page if the key was never updated.
         */
        if (cbt->ins != NULL &&
                (upd = __wt_txn_read(session, cbt->ins->upd)) != NULL) {
            cursor->key.data = WT_INSERT_KEY(cbt->ins);
            cursor->key.size = WT_INSERT_KEY_SIZE(cbt->ins);
        } else {
            WT_RET(
                __wt_row_key(session, page, rip, &cursor->key, 0));
            upd = __wt_txn_read(session, WT_ROW_UPDATE(page, rip));
        }
        if (upd != NULL) {
            cursor->value.data = WT_UPDATE_DATA(upd);
            cursor->value.size = upd->size;
            return (0);
        }

        /* Take the original cell (which may be empty). */
        if ((cell = __wt_row_value(page, rip)) == NULL) {
            cursor->value.size = 0;
            return (0);
        }
        break;
        WT_ILLEGAL_VALUE(session);
    }

    /* The value is an on-page cell, unpack and expand it as necessary. */
    __wt_cell_unpack(cell, &unpack);
    ret = __wt_cell_unpack_ref(session, &unpack, &cursor->value);

    /*
     * Restart for a variable-length column-store.  We could catch restart
     * higher up the call-stack but there's no point to it: unlike row-store
     * (where a normal search path finds cached overflow values), we have to
     * access the page's reconciliation structures, and that's as easy here
     * as higher up the stack.
     */
    if (ret == WT_RESTART && page->type == WT_PAGE_COL_VAR)
        ret = __wt_ovfl_cache_col_restart(
                  session, page, &unpack, &cursor->value);
    return (ret);
}
Exemple #18
0
/*
 * __cursor_fix_append_prev --
 *	Return the previous fixed-length entry on the append list.
 */
static inline int
__cursor_fix_append_prev(WT_CURSOR_BTREE *cbt, bool newpage)
{
	WT_ITEM *val;
	WT_PAGE *page;
	WT_SESSION_IMPL *session;
	WT_UPDATE *upd;

	session = (WT_SESSION_IMPL *)cbt->iface.session;
	page = cbt->ref->page;
	val = &cbt->iface.value;

	if (newpage) {
		if ((cbt->ins = WT_SKIP_LAST(cbt->ins_head)) == NULL)
			return (WT_NOTFOUND);
	} else {
		/*
		 * Handle the special case of leading implicit records, that is,
		 * there aren't any records in the tree not on the append list,
		 * and the first record on the append list isn't record 1.
		 *
		 * The "right" place to handle this is probably in our caller.
		 * The high-level cursor-previous routine would:
		 *    -- call this routine to walk the append list
		 *    -- call the routine to walk the standard page items
		 *    -- call the tree walk routine looking for a previous page
		 * Each of them returns WT_NOTFOUND, at which point our caller
		 * checks the cursor record number, and if it's larger than 1,
		 * returns the implicit records.  Instead, I'm trying to detect
		 * the case here, mostly because I don't want to put that code
		 * into our caller.  Anyway, if this code breaks for any reason,
		 * that's the way I'd go.
		 *
		 * If we're not pointing to a WT_INSERT entry, or we can't find
		 * a WT_INSERT record that precedes our record name-space, check
		 * if there are any records on the page.  If there aren't, then
		 * we're in the magic zone, keep going until we get to a record
		 * number of 1.
		 */
		if (cbt->ins != NULL &&
		    cbt->recno <= WT_INSERT_RECNO(cbt->ins))
			WT_RET(__cursor_skip_prev(cbt));
		if (cbt->ins == NULL &&
		    (cbt->recno == 1 || __col_fix_last_recno(page) != 0))
			return (WT_NOTFOUND);
	}

	/*
	 * This code looks different from the cursor-next code.  The append
	 * list appears on the last page of the tree and contains the last
	 * records in the tree.  If we're iterating through the tree, starting
	 * at the last record in the tree, by definition we're starting a new
	 * iteration and we set the record number to the last record found in
	 * the tree.  Otherwise, decrement the record.
	 */
	if (newpage)
		__cursor_set_recno(cbt, WT_INSERT_RECNO(cbt->ins));
	else
		__cursor_set_recno(cbt, cbt->recno - 1);

	/*
	 * Fixed-width column store appends are inherently non-transactional.
	 * Even a non-visible update by a concurrent or aborted transaction
	 * changes the effective end of the data.  The effect is subtle because
	 * of the blurring between deleted and empty values, but ideally we
	 * would skip all uncommitted changes at the end of the data.  This
	 * doesn't apply to variable-width column stores because the implicitly
	 * created records written by reconciliation are deleted and so can be
	 * never seen by a read.
	 */
	if (cbt->ins == NULL ||
	    cbt->recno > WT_INSERT_RECNO(cbt->ins) ||
	    (upd = __wt_txn_read(session, cbt->ins->upd)) == NULL) {
		cbt->v = 0;
		val->data = &cbt->v;
	} else
		val->data = WT_UPDATE_DATA(upd);
	val->size = 1;
	return (0);
}
Exemple #19
0
/*移向下条variable-length column-store 记录*/
static inline int __cursor_var_next(WT_CURSOR_BTREE* cbt, int newpage)
{
	WT_CELL *cell;
	WT_CELL_UNPACK unpack;
	WT_COL *cip;
	WT_ITEM *val;
	WT_INSERT *ins;
	WT_PAGE *page;
	WT_SESSION_IMPL *session;
	WT_UPDATE *upd;
	uint64_t rle, rle_start;

	session = (WT_SESSION_IMPL *)cbt->iface.session;
	page = cbt->ref->page;
	val = &cbt->iface.value;

	rle_start = 0;			/* -Werror=maybe-uninitialized */

	if (newpage){
		cbt->last_standard_recno = __col_var_last_recno(page);
		if (cbt->last_standard_recno == 0)
			return (WT_NOTFOUND);
		__cursor_set_recno(cbt, page->pg_var_recno);
		goto new_page;
	}

	for (;;){
		if (cbt->recno >= cbt->last_standard_recno)
			return (WT_NOTFOUND);
		__cursor_set_recno(cbt, cbt->recno + 1);

	new_page:
		/*定位到recno对应的WT_COL slot*/
		if ((cip = __col_var_search(page, cbt->recno, &rle_start)) == NULL)
			return (WT_NOTFOUND);
		cbt->slot = WT_COL_SLOT(page, cip);

		/*读取内容值*/
		cbt->ins_head = WT_COL_UPDATE_SLOT(page, cbt->slot);
		cbt->ins = __col_insert_search_match(cbt->ins_head, cbt->recno);
		upd = cbt->ins == NULL ? NULL : __wt_txn_read(session, cbt->ins->upd);
		if (upd != NULL) {
			if (WT_UPDATE_DELETED_ISSET(upd)) {
				++cbt->page_deleted_count;
				continue;
			}

			val->data = WT_UPDATE_DATA(upd);
			val->size = upd->size;
			return (0);
		}

		/*
		* If we're at the same slot as the last reference and there's
		* no matching insert list item, re-use the return information
		* (so encoded items with large repeat counts aren't repeatedly
		* decoded).  Otherwise, unpack the cell and build the return
		* information.
		* upd == NULL, 记录可能被删除放入到了insert列表中,slot可能被重用了,那么需要进行cell unpack取值
		*/

		if (cbt->cip_saved != cip) {
			if ((cell = WT_COL_PTR(page, cip)) == NULL)
				continue;
			__wt_cell_unpack(cell, &unpack);
			if (unpack.type == WT_CELL_DEL) {
				if ((rle = __wt_cell_rle(&unpack)) == 1)
					continue;

				/*定位到修改列表中的记录*/
				ins = __col_insert_search_gt(cbt->ins_head, cbt->recno);
				cbt->recno = rle_start + rle;
				if (ins != NULL && WT_INSERT_RECNO(ins) < cbt->recno)
					cbt->recno = WT_INSERT_RECNO(ins);

				/* Adjust for the outer loop increment. */
				--cbt->recno;
				continue;
			}

			/*取出cell中的值到tmp中*/
			WT_RET(__wt_page_cell_data_ref(session, page, &unpack, &cbt->tmp));
			cbt->cip_saved = cip;
		}
		val->data = cbt->tmp.data;
		val->size = cbt->tmp.size;
		return 0;
	}
}
Exemple #20
0
/*
 * __cursor_var_prev --
 *	Move to the previous, variable-length column-store item.
 */
static inline int
__cursor_var_prev(WT_CURSOR_BTREE *cbt, bool newpage)
{
	WT_CELL *cell;
	WT_CELL_UNPACK unpack;
	WT_COL *cip;
	WT_INSERT *ins;
	WT_ITEM *val;
	WT_PAGE *page;
	WT_SESSION_IMPL *session;
	WT_UPDATE *upd;
	uint64_t rle_start;

	session = (WT_SESSION_IMPL *)cbt->iface.session;
	page = cbt->ref->page;
	val = &cbt->iface.value;

	rle_start = 0;			/* -Werror=maybe-uninitialized */

	/* Initialize for each new page. */
	if (newpage) {
		cbt->last_standard_recno = __col_var_last_recno(page);
		if (cbt->last_standard_recno == 0)
			return (WT_NOTFOUND);
		__cursor_set_recno(cbt, cbt->last_standard_recno);
		goto new_page;
	}

	/* Move to the previous entry and return the item. */
	for (;;) {
		__cursor_set_recno(cbt, cbt->recno - 1);

new_page:	if (cbt->recno < page->pg_var_recno)
			return (WT_NOTFOUND);

		/* Find the matching WT_COL slot. */
		if ((cip =
		    __col_var_search(page, cbt->recno, &rle_start)) == NULL)
			return (WT_NOTFOUND);
		cbt->slot = WT_COL_SLOT(page, cip);

		/* Check any insert list for a matching record. */
		cbt->ins_head = WT_COL_UPDATE_SLOT(page, cbt->slot);
		cbt->ins = __col_insert_search_match(cbt->ins_head, cbt->recno);
		upd = cbt->ins == NULL ?
		    NULL : __wt_txn_read(session, cbt->ins->upd);
		if (upd != NULL) {
			if (WT_UPDATE_DELETED_ISSET(upd)) {
				if (__wt_txn_visible_all(session, upd->txnid))
					++cbt->page_deleted_count;
				continue;
			}

			val->data = WT_UPDATE_DATA(upd);
			val->size = upd->size;
			return (0);
		}

		/*
		 * If we're at the same slot as the last reference and there's
		 * no matching insert list item, re-use the return information
		 * (so encoded items with large repeat counts aren't repeatedly
		 * decoded).  Otherwise, unpack the cell and build the return
		 * information.
		 */
		if (cbt->cip_saved != cip) {
			if ((cell = WT_COL_PTR(page, cip)) == NULL)
				continue;
			__wt_cell_unpack(cell, &unpack);
			if (unpack.type == WT_CELL_DEL) {
				if (__wt_cell_rle(&unpack) == 1)
					continue;
				/*
				 * There can be huge gaps in the variable-length
				 * column-store name space appearing as deleted
				 * records. If more than one deleted record, do
				 * the work of finding the next record to return
				 * instead of looping through the records.
				 *
				 * First, find the largest record in the update
				 * list that's smaller than the current record.
				 */
				ins = __col_insert_search_lt(
				    cbt->ins_head, cbt->recno);

				/*
				 * Second, for records with RLEs greater than 1,
				 * the above call to __col_var_search located
				 * this record in the page's list of repeating
				 * records, and returned the starting record.
				 * The starting record - 1 is the record to
				 * which we could skip, if there was no larger
				 * record in the update list.
				 */
				cbt->recno = rle_start - 1;
				if (ins != NULL &&
				    WT_INSERT_RECNO(ins) > cbt->recno)
					cbt->recno = WT_INSERT_RECNO(ins);

				/* Adjust for the outer loop decrement. */
				++cbt->recno;
				continue;
			}
			WT_RET(__wt_page_cell_data_ref(
			    session, page, &unpack, cbt->tmp));

			cbt->cip_saved = cip;
		}
		val->data = cbt->tmp->data;
		val->size = cbt->tmp->size;
		return (0);
	}
	/* NOTREACHED */
}
Exemple #21
0
/*移向行存储的下一个行对象*/
static inline int __cursor_row_next(WT_CURSOR_BTREE* cbt, int newpage)
{
	WT_INSERT *ins;
	WT_ITEM *key, *val;
	WT_PAGE *page;
	WT_ROW *rip;
	WT_SESSION_IMPL *session;
	WT_UPDATE *upd;

	session = (WT_SESSION_IMPL *)cbt->iface.session;
	page = cbt->ref->page;
	key = &cbt->iface.key;
	val = &cbt->iface.value;

	/*假如是newpage,定位到insert修改队列的头位置*/
	if (newpage){
		cbt->ins_head = WT_ROW_INSERT_SMALLEST(page);
		cbt->ins = WT_SKIP_FIRST(cbt->ins_head);
		cbt->row_iteration_slot = 1;
		goto new_insert;
	}

	for (;;){
		if (cbt->ins != NULL)
			cbt->ins = WT_SKIP_NEXT(cbt->ins);

new_insert:
		if ((ins = cbt->ins) != NULL) {
			/*事务可见数据读取*/
			if ((upd = __wt_txn_read(session, ins->upd)) == NULL)
				continue;
			/*判断是否删除,如果删除,跳过被删除的对象*/
			if (WT_UPDATE_DELETED_ISSET(upd)) {
				++cbt->page_deleted_count;
				continue;
			}

			key->data = WT_INSERT_KEY(ins);
			key->size = WT_INSERT_KEY_SIZE(ins);
			val->data = WT_UPDATE_DATA(upd);
			val->size = upd->size;
			return 0;
		}

		/*检索page row entires数组, 到了page的末尾*/
		if (cbt->row_iteration_slot >= page->pg_row_entries * 2 + 1)
			return (WT_NOTFOUND);
		++cbt->row_iteration_slot;

		/*
		* Odd-numbered slots configure as WT_INSERT_HEAD entries,
		* even-numbered slots configure as WT_ROW entries.
		*/
		if (cbt->row_iteration_slot & 0x01) {
			cbt->ins_head = WT_ROW_INSERT_SLOT(page, cbt->row_iteration_slot / 2 - 1);
			cbt->ins = WT_SKIP_FIRST(cbt->ins_head);
			goto new_insert;
		}

		cbt->ins_head = NULL;
		cbt->ins = NULL;

		/*计算定位slot*/
		cbt->slot = cbt->row_iteration_slot / 2 - 1;
		rip = &page->pg_row_d[cbt->slot];

		upd = __wt_txn_read(session, WT_ROW_UPDATE(page, rip));
		if (upd != NULL && WT_UPDATE_DELETED_ISSET(upd)) {
			++cbt->page_deleted_count;
			continue;
		}

		return __cursor_row_slot_return(cbt, rip, upd);
	}
}
Exemple #22
0
/*
 * __cursor_valid --
 *	Return if the cursor references an valid key/value pair.
 */
static inline bool
__cursor_valid(WT_CURSOR_BTREE *cbt, WT_UPDATE **updp)
{
	WT_BTREE *btree;
	WT_CELL *cell;
	WT_COL *cip;
	WT_PAGE *page;
	WT_SESSION_IMPL *session;
	WT_UPDATE *upd;

	btree = cbt->btree;
	page = cbt->ref->page;
	session = (WT_SESSION_IMPL *)cbt->iface.session;
	if (updp != NULL)
		*updp = NULL;

	/*
	 * We may be pointing to an insert object, and we may have a page with
	 * existing entries.  Insert objects always have associated update
	 * objects (the value).  Any update object may be deleted, or invisible
	 * to us.  In the case of an on-page entry, there is by definition a
	 * value that is visible to us, the original page cell.
	 *
	 * If we find a visible update structure, return our caller a reference
	 * to it because we don't want to repeatedly search for the update, it
	 * might suddenly become invisible (imagine a read-uncommitted session
	 * with another session's aborted insert), and we don't want to handle
	 * that potential error every time we look at the value.
	 *
	 * Unfortunately, the objects we might have and their relationships are
	 * different for the underlying page types.
	 *
	 * In the case of row-store, an insert object implies ignoring any page
	 * objects, no insert object can have the same key as an on-page object.
	 * For row-store:
	 *	if there's an insert object:
	 *		if there's a visible update:
	 *			exact match
	 *		else
	 *			no exact match
	 *	else
	 *		use the on-page object (which may have an associated
	 *		update object that may or may not be visible to us).
	 *
	 * Column-store is more complicated because an insert object can have
	 * the same key as an on-page object: updates to column-store rows
	 * are insert/object pairs, and an invisible update isn't the end as
	 * there may be an on-page object that is visible.  This changes the
	 * logic to:
	 *	if there's an insert object:
	 *		if there's a visible update:
	 *			exact match
	 *		else if the on-page object's key matches the insert key
	 *			use the on-page object
	 *	else
	 *		use the on-page object
	 *
	 * First, check for an insert object with a visible update (a visible
	 * update that's been deleted is not a valid key/value pair).
	 */
	if (cbt->ins != NULL &&
	    (upd = __wt_txn_read(session, cbt->ins->upd)) != NULL) {
		if (WT_UPDATE_DELETED_ISSET(upd))
			return (false);
		if (updp != NULL)
			*updp = upd;
		return (true);
	}

	/*
	 * If we don't have an insert object, or in the case of column-store,
	 * there's an insert object but no update was visible to us and the key
	 * on the page is the same as the insert object's key, and the slot as
	 * set by the search function is valid, we can use the original page
	 * information.
	 */
	switch (btree->type) {
	case BTREE_COL_FIX:
		/*
		 * If search returned an insert object, there may or may not be
		 * a matching on-page object, we have to check.  Fixed-length
		 * column-store pages don't have slots, but map one-to-one to
		 * keys, check for retrieval past the end of the page.
		 */
		if (cbt->recno >= cbt->ref->ref_recno + page->pg_fix_entries)
			return (false);

		/*
		 * An update would have appeared as an "insert" object; no
		 * further checks to do.
		 */
		break;
	case BTREE_COL_VAR:
		/* The search function doesn't check for empty pages. */
		if (page->pg_var_entries == 0)
			return (false);
		WT_ASSERT(session, cbt->slot < page->pg_var_entries);

		/*
		 * Column-store updates are stored as "insert" objects. If
		 * search returned an insert object we can't return, the
		 * returned on-page object must be checked for a match.
		 */
		if (cbt->ins != NULL && !F_ISSET(cbt, WT_CBT_VAR_ONPAGE_MATCH))
			return (false);

		/*
		 * Although updates would have appeared as an "insert" objects,
		 * variable-length column store deletes are written into the
		 * backing store; check the cell for a record already deleted
		 * when read.
		 */
		cip = &page->pg_var_d[cbt->slot];
		if ((cell = WT_COL_PTR(page, cip)) == NULL ||
		    __wt_cell_type(cell) == WT_CELL_DEL)
			return (false);
		break;
	case BTREE_ROW:
		/* The search function doesn't check for empty pages. */
		if (page->pg_row_entries == 0)
			return (false);
		WT_ASSERT(session, cbt->slot < page->pg_row_entries);

		/*
		 * See above: for row-store, no insert object can have the same
		 * key as an on-page object, we're done.
		 */
		if (cbt->ins != NULL)
			return (false);

		/* Check for an update. */
		if (page->modify != NULL &&
		    page->modify->mod_row_update != NULL &&
		    (upd = __wt_txn_read(session,
		    page->modify->mod_row_update[cbt->slot])) != NULL) {
			if (WT_UPDATE_DELETED_ISSET(upd))
				return (false);
			if (updp != NULL)
				*updp = upd;
		}
		break;
	}
	return (true);
}
Exemple #23
0
/*
 * __cursor_fix_append_prev --
 *	Return the previous fixed-length entry on the append list.
 */
static inline int
__cursor_fix_append_prev(WT_CURSOR_BTREE *cbt, bool newpage)
{
	WT_SESSION_IMPL *session;
	WT_UPDATE *upd;

	session = (WT_SESSION_IMPL *)cbt->iface.session;

	if (newpage) {
		if ((cbt->ins = WT_SKIP_LAST(cbt->ins_head)) == NULL)
			return (WT_NOTFOUND);
	} else {
		/* Move to the previous record in the append list, if any. */
		if (cbt->ins != NULL &&
		    cbt->recno <= WT_INSERT_RECNO(cbt->ins))
			WT_RET(__cursor_skip_prev(cbt));

		/*
		 * Handle the special case of leading implicit records, that is,
		 * there aren't any records in the page not on the append list,
		 * and the append list's first record isn't the first record on
		 * the page. (Although implemented as a test of the page values,
		 * this is really a test for a tree where the first inserted
		 * record wasn't record 1, any other page with only an append
		 * list will have a first page record number matching the first
		 * record in the append list.)
		 *
		 * The "right" place to handle this is probably in our caller.
		 * The high-level cursor-previous routine would:
		 *    -- call this routine to walk the append list
		 *    -- call the routine to walk the standard page items
		 *    -- call the tree walk routine looking for a previous page
		 * Each of them returns WT_NOTFOUND, at which point our caller
		 * checks the cursor record number, and if it's larger than 1,
		 * returns the implicit records.  Instead, I'm trying to detect
		 * the case here, mostly because I don't want to put that code
		 * into our caller.  Anyway, if this code breaks for any reason,
		 * that's the way I'd go.
		 *
		 * If we're not pointing to a WT_INSERT entry (we didn't find a
		 * WT_INSERT record preceding our record name-space), check if
		 * we've reached the beginning of this page, a possibility if a
		 * page had a large number of items appended, and then split.
		 * If not, check if there are any records on the page. If there
		 * aren't, then we're in the magic zone, keep going until we get
		 * to a record number matching the first record on the page.
		 */
		if (cbt->ins == NULL &&
		    (cbt->recno == cbt->ref->ref_recno ||
		    __col_fix_last_recno(cbt->ref) != 0))
			return (WT_NOTFOUND);
	}

	/*
	 * This code looks different from the cursor-next code. The append list
	 * may be preceded by other rows. If we're iterating through the tree,
	 * starting at the last record in the tree, by definition we're starting
	 * a new iteration and we set the record number to the last record found
	 * on the page. Otherwise, decrement the record.
	 */
	if (newpage)
		__cursor_set_recno(cbt, WT_INSERT_RECNO(cbt->ins));
	else
		__cursor_set_recno(cbt, cbt->recno - 1);

	/*
	 * Fixed-width column store appends are inherently non-transactional.
	 * Even a non-visible update by a concurrent or aborted transaction
	 * changes the effective end of the data.  The effect is subtle because
	 * of the blurring between deleted and empty values, but ideally we
	 * would skip all uncommitted changes at the end of the data.  This
	 * doesn't apply to variable-width column stores because the implicitly
	 * created records written by reconciliation are deleted and so can be
	 * never seen by a read.
	 */
	if (cbt->ins == NULL ||
	    cbt->recno > WT_INSERT_RECNO(cbt->ins) ||
	    (upd = __wt_txn_read(session, cbt->ins->upd)) == NULL) {
		cbt->v = 0;
		cbt->iface.value.data = &cbt->v;
	} else
		cbt->iface.value.data = upd->data;
	cbt->iface.value.size = 1;
	return (0);
}