/*
* __wt_btcur_equals --
* Return an equality comparison between two cursors.
*/
int
__wt_btcur_equals(WT_CURSOR_BTREE *a_arg, WT_CURSOR_BTREE *b_arg, int *equalp)
{
WT_CURSOR *a, *b;
WT_SESSION_IMPL *session;
int cmp;
a = (WT_CURSOR *)a_arg;
b = (WT_CURSOR *)b_arg;
cmp = 0;
session = (WT_SESSION_IMPL *)a->session;
/* Confirm both cursors reference the same object. */
if (a_arg->btree != b_arg->btree)
WT_RET_MSG(
session, EINVAL, "Cursors must reference the same object");
/*
* The reason for an equals method is because we can avoid doing
* a full key comparison in some cases. If both cursors point into the
* tree, take the fast path, otherwise fall back to the slower compare
* method; in both cases, return 1 if the cursors are equal, 0 if they
* are not.
*/
if (F_ISSET(a, WT_CURSTD_KEY_INT) && F_ISSET(b, WT_CURSTD_KEY_INT))
*equalp = __cursor_equals(a_arg, b_arg);
else {
WT_RET(__wt_btcur_compare(a_arg, b_arg, &cmp));
*equalp = (cmp == 0) ? 1 : 0;
}
return (0);
}
/*
* __cursor_truncate_fix --
* Discard a cursor range from fixed-width column-store tree.
*/
static int
__cursor_truncate_fix(WT_SESSION_IMPL *session,
WT_CURSOR_BTREE *start, WT_CURSOR_BTREE *stop,
int (*rmfunc)(WT_SESSION_IMPL *, WT_CURSOR_BTREE *, int))
{
WT_DECL_RET;
uint8_t *value;
/*
* Handle fixed-length column-store objects separately: for row-store
* and variable-length column-store objects we have "deleted" values
* and so returned objects actually exist: fixed-length column-store
* objects are filled-in if they don't exist, that is, if you create
* record 37, records 1-36 magically appear. Those records can't be
* deleted, which means we have to ignore already "deleted" records.
*
* First, call the standard cursor remove method to do a full search and
* re-position the cursor because we don't have a saved copy of the
* page's write generation information, which we need to remove records.
* Once that's done, we can delete records without a full search, unless
* we encounter a restart error because the page was modified by some
* other thread of control; in that case, repeat the full search to
* refresh the page's modification information.
*/
if (start == NULL) {
do {
WT_RET(__wt_btcur_remove(stop));
for (;;) {
if ((ret = __wt_btcur_prev(stop, 1)) != 0)
break;
stop->compare = 0; /* Exact match */
value = (uint8_t *)stop->iface.value.data;
if (*value != 0 &&
(ret = rmfunc(session, stop, 1)) != 0)
break;
}
} while (ret == WT_RESTART);
} else {
do {
WT_RET(__wt_btcur_remove(start));
for (;;) {
if (stop != NULL &&
__cursor_equals(start, stop))
break;
if ((ret = __wt_btcur_next(start, 1)) != 0)
break;
start->compare = 0; /* Exact match */
value = (uint8_t *)start->iface.value.data;
if (*value != 0 &&
(ret = rmfunc(session, start, 1)) != 0)
break;
}
} while (ret == WT_RESTART);
}
WT_RET_NOTFOUND_OK(ret);
return (0);
}
/*
* __cursor_truncate --
* Discard a cursor range from row-store or variable-width column-store
* tree.
*/
static int
__cursor_truncate(WT_SESSION_IMPL *session,
WT_CURSOR_BTREE *start, WT_CURSOR_BTREE *stop,
int (*rmfunc)(WT_SESSION_IMPL *, WT_CURSOR_BTREE *, int))
{
WT_DECL_RET;
/*
* First, call the standard cursor remove method to do a full search and
* re-position the cursor because we don't have a saved copy of the
* page's write generation information, which we need to remove records.
* Once that's done, we can delete records without a full search, unless
* we encounter a restart error because the page was modified by some
* other thread of control; in that case, repeat the full search to
* refresh the page's modification information.
*
* If this is a row-store, we delete leaf pages having no overflow items
* without reading them; for that to work, we have to ensure we read the
* page referenced by the ending cursor, since we may be deleting only a
* partial page at the end of the truncation. Our caller already fully
* instantiated the end cursor, so we know that page is pinned in memory
* and we can proceed without concern.
*/
if (start == NULL) {
do {
WT_RET(__wt_btcur_remove(stop));
for (;;) {
if ((ret = __wt_btcur_prev(stop, 1)) != 0)
break;
stop->compare = 0; /* Exact match */
if ((ret = rmfunc(session, stop, 1)) != 0)
break;
}
} while (ret == WT_RESTART);
} else {
do {
WT_RET(__wt_btcur_remove(start));
/*
* Reset ret each time through so that we don't loop
* forever in the cursor equals case.
*/
for (ret = 0;;) {
if (stop != NULL &&
__cursor_equals(start, stop))
break;
if ((ret = __wt_btcur_next(start, 1)) != 0)
break;
start->compare = 0; /* Exact match */
if ((ret = rmfunc(session, start, 1)) != 0)
break;
}
} while (ret == WT_RESTART);
}
WT_RET_NOTFOUND_OK(ret);
return (0);
}
