/*
* returns 1 if @node is empty after pruning, 0 otherwise
*/
static int
radix_tree_prune_branch(radix_tree_t *tree,
radix_tree_node_t *node, uint32_t now)
{
int i, empty;
radix_tree_link_t *link;
empty = 1;
if (!node)
return empty;
for (i = 0; i < RADIX_TREE_NODE_SIZE; i++) {
link = node->links + i;
if (now - link->time < BLOCK_CACHE_PAGE_IDLETIME) {
if (radix_tree_node_contains_leaves(tree, node)) {
empty = 0;
continue;
}
if (radix_tree_prune_branch(tree, link->u.next, now))
radix_tree_clear_link(link);
else
empty = 0;
continue;
}
if (radix_tree_node_contains_leaves(tree, node))
radix_tree_remove_page(tree, link->u.leaf.page);
else
radix_tree_delete_branch(tree, link->u.next);
radix_tree_clear_link(link);
}
if (empty && !radix_tree_node_is_root(tree, node))
radix_tree_free_node(tree, node);
return empty;
}
static void
radix_tree_delete_branch(radix_tree_t *tree, radix_tree_node_t *node)
{
int i;
radix_tree_link_t *link;
if (!node)
return;
for (i = 0; i < RADIX_TREE_NODE_SIZE; i++) {
link = node->links + i;
if (radix_tree_node_contains_leaves(tree, node))
radix_tree_remove_page(tree, link->u.leaf.page);
else
radix_tree_delete_branch(tree, link->u.next);
radix_tree_clear_link(link);
}
radix_tree_free_node(tree, node);
}
void *
radix_tree_remove_node(struct radix_tree *t, uint64_t idx)
{
struct radix_tree_path path;
void **vpp;
void *oldp;
int i;
vpp = radix_tree_lookup_ptr(t, idx, &path, false, 0);
KASSERT(vpp != NULL);
oldp = *vpp;
KASSERT(oldp != NULL);
KASSERT(path.p_lastidx == t->t_height);
KASSERT(vpp == path_pptr(t, &path, path.p_lastidx));
*vpp = NULL;
for (i = t->t_height - 1; i >= 0; i--) {
void *entry;
struct radix_tree_node ** const pptr =
(struct radix_tree_node **)path_pptr(t, &path, i);
struct radix_tree_node *n;
KASSERT(pptr != NULL);
entry = *pptr;
n = entry_ptr(entry);
KASSERT(n != NULL);
KASSERT(n->n_nptrs > 0);
n->n_nptrs--;
if (n->n_nptrs > 0) {
break;
}
radix_tree_free_node(n);
*pptr = NULL;
}
/*
* fix up height
*/
if (i < 0) {
KASSERT(t->t_root == NULL);
t->t_height = 0;
}
/*
* update tags
*/
for (; i >= 0; i--) {
void *entry;
struct radix_tree_node ** const pptr =
(struct radix_tree_node **)path_pptr(t, &path, i);
struct radix_tree_node *n;
unsigned int newmask;
KASSERT(pptr != NULL);
entry = *pptr;
n = entry_ptr(entry);
KASSERT(n != NULL);
KASSERT(n->n_nptrs > 0);
newmask = any_children_tagmask(n);
if (newmask == entry_tagmask(entry)) {
break;
}
*pptr = entry_compose(n, newmask);
}
/*
* XXX is it worth to try to reduce height?
* if we do that, make radix_tree_grow rollback its change as well.
*/
return entry_ptr(oldp);
}
