rc_t bt_cursor_t::_check_page_update(btree_page_h &p)
{
// was the page changed?
if (_pid != p.pid() || p.get_page_lsn() != _lsn) {
// check if the page still contains the key we are based on
bool found = false;
if (p.fence_contains(_key)) {
// it still contains. just re-locate _slot
p.search(_key, found, _slot);
} else {
// we have to re-locate the page
W_DO( btree_impl::_ux_traverse(_store, _key, btree_impl::t_fence_contain, LATCH_SH, p));
p.search(_key, found, _slot);
}
w_assert1(found || !_needs_lock
|| (!_forward && !_upper_inclusive && !_dont_move_next)); // see _locate_first
_set_current_page(p);
}
return RCOK;
}
rc_t
btree_impl::_ux_lock_range(const StoreID& stid,
btree_page_h& leaf,
const void* keystr,
size_t keylen,
slotid_t slot,
latch_mode_t latch_mode,
const okvl_mode& exact_hit_lock_mode,
const okvl_mode& miss_lock_mode,
bool check_only) {
w_assert1(slot >= -1 && slot <= leaf.nrecs());
w_assert1(exact_hit_lock_mode.get_gap_mode() == okvl_mode::N);
w_assert1(miss_lock_mode.is_keylock_empty());
if (slot == -1) { // this means we should search it again
bool found;
leaf.search((const char *) keystr, keylen, found, slot);
w_assert1(!found); // precondition
}
w_assert1(slot >= 0 && slot <= leaf.nrecs());
#if W_DEBUG_LEVEL > 1
w_keystr_t key, key_at_slot;
key.construct_from_keystr(keystr, keylen);
if (slot<leaf.nrecs()) {
leaf.get_key(slot, key_at_slot);
w_assert1(key_at_slot.compare(key)>0);
}
#endif // W_DEBUG_LEVEL > 1
slot--; // want range lock from previous key
if (slot == -1 &&
w_keystr_t::compare_bin_str(keystr, keylen,
leaf.get_fence_low_key(), leaf.get_fence_low_length()) == 0) {
// We were searching for the low-fence key! then, we take key lock on it and
// subsequent structural modification (e.g., merge) will add the low-fence as
// ghost record to be aware of the lock.
W_DO (_ux_lock_key(stid, leaf,
leaf.get_fence_low_key(), leaf.get_fence_low_length(),
latch_mode, exact_hit_lock_mode, check_only));
} else {
w_keystr_t prevkey;
if (slot == -1) {
leaf.copy_fence_low_key(prevkey);
} else {
leaf.get_key(slot, prevkey);
}
#if W_DEBUG_LEVEL > 1
w_assert1(prevkey.compare(key) < 0);
#endif // W_DEBUG_LEVEL > 1
W_DO (_ux_lock_key(stid, leaf, prevkey, latch_mode, miss_lock_mode, check_only));
}
return RCOK;
}
