/*
* __wt_delete_page_skip --
* If iterating a cursor, skip deleted pages that are visible to us.
*/
bool
__wt_delete_page_skip(WT_SESSION_IMPL *session, WT_REF *ref)
{
bool skip;
/*
* Deleted pages come from two sources: either it's a fast-delete as
* described above, or the page has been emptied by other operations
* and eviction deleted it.
*
* In both cases, the WT_REF state will be WT_REF_DELETED. In the case
* of a fast-delete page, there will be a WT_PAGE_DELETED structure with
* the transaction ID of the transaction that deleted the page, and the
* page is visible if that transaction ID is visible. In the case of an
* empty page, there will be no WT_PAGE_DELETED structure and the delete
* is by definition visible, eviction could not have deleted the page if
* there were changes on it that were not globally visible.
*
* We're here because we found a WT_REF state set to WT_REF_DELETED. It
* is possible the page is being read into memory right now, though, and
* the page could switch to an in-memory state at any time. Lock down
* the structure, just to be safe.
*/
if (ref->page_del == NULL)
return (true);
if (!__wt_atomic_casv32(&ref->state, WT_REF_DELETED, WT_REF_LOCKED))
return (false);
skip = (ref->page_del == NULL ||
__wt_txn_visible(session, ref->page_del->txnid));
WT_PUBLISH(ref->state, WT_REF_DELETED);
return (skip);
}
/*
* __wt_ext_transaction_visible --
* Return if the current transaction can see the given transaction ID.
*/
int
__wt_ext_transaction_visible(WT_EXTENSION_API *wt_api,
WT_SESSION *wt_session, uint64_t transaction_id)
{
(void)wt_api; /* Unused parameters */
return (__wt_txn_visible(
(WT_SESSION_IMPL *)wt_session, transaction_id));
}
/*
* __wt_delete_page_skip --
* If iterating a cursor, skip deleted pages that are either visible to
* us or globally visible.
*/
bool
__wt_delete_page_skip(WT_SESSION_IMPL *session, WT_REF *ref, bool visible_all)
{
bool skip;
/*
* Deleted pages come from two sources: either it's a fast-delete as
* described above, or the page has been emptied by other operations
* and eviction deleted it.
*
* In both cases, the WT_REF state will be WT_REF_DELETED. In the case
* of a fast-delete page, there will be a WT_PAGE_DELETED structure with
* the transaction ID of the transaction that deleted the page, and the
* page is visible if that transaction ID is visible. In the case of an
* empty page, there will be no WT_PAGE_DELETED structure and the delete
* is by definition visible, eviction could not have deleted the page if
* there were changes on it that were not globally visible.
*
* We're here because we found a WT_REF state set to WT_REF_DELETED. It
* is possible the page is being read into memory right now, though, and
* the page could switch to an in-memory state at any time. Lock down
* the structure, just to be safe.
*/
if (ref->page_del == NULL)
return (true);
if (!__wt_atomic_casv32(&ref->state, WT_REF_DELETED, WT_REF_LOCKED))
return (false);
skip = ref->page_del == NULL || (visible_all ?
__wt_txn_visible_all(session, ref->page_del->txnid,
WT_TIMESTAMP_NULL(&ref->page_del->timestamp)):
__wt_txn_visible(session, ref->page_del->txnid,
WT_TIMESTAMP_NULL(&ref->page_del->timestamp)));
/*
* The page_del structure can be freed as soon as the delete is stable:
* it is only read when the ref state is WT_REF_DELETED. It is worth
* checking every time we come through because once this is freed, we
* no longer need synchronization to check the ref.
*/
if (skip && ref->page_del != NULL && (visible_all ||
__wt_txn_visible_all(session, ref->page_del->txnid,
WT_TIMESTAMP_NULL(&ref->page_del->timestamp)))) {
__wt_free(session, ref->page_del->update_list);
__wt_free(session, ref->page_del);
}
WT_PUBLISH(ref->state, WT_REF_DELETED);
return (skip);
}
