/*
* Replace a prio_tree_node with a new node and return the old node
*/
struct prio_tree_node *prio_tree_replace(struct prio_tree_root *root,
struct prio_tree_node *old, struct prio_tree_node *node)
{
INIT_PRIO_TREE_NODE(node);
if (prio_tree_root(old)) {
assert(root->prio_tree_node == old);
/*
* We can reduce root->index_bits here. However, it is complex
* and does not help much to improve performance (IMO).
*/
node->parent = node;
root->prio_tree_node = node;
} else {
node->parent = old->parent;
if (old->parent->left == old)
old->parent->left = node;
else
old->parent->right = node;
}
if (!prio_tree_left_empty(old)) {
node->left = old->left;
old->left->parent = node;
}
if (!prio_tree_right_empty(old)) {
node->right = old->right;
old->right->parent = node;
}
return old;
}
/*
* Remove a prio_tree_node @node from a radix priority search tree @root. The
* algorithm takes O(log n) time where 'log n' is the number of bits required
* to represent the maximum heap_index.
*/
void prio_tree_remove(struct prio_tree_root *root, struct prio_tree_node *node)
{
struct prio_tree_node *cur;
unsigned long r_index, h_index_right, h_index_left;
cur = node;
while (!prio_tree_left_empty(cur) || !prio_tree_right_empty(cur)) {
if (!prio_tree_left_empty(cur))
get_index(cur->left, &r_index, &h_index_left);
else {
cur = cur->right;
continue;
}
if (!prio_tree_right_empty(cur))
get_index(cur->right, &r_index, &h_index_right);
else {
cur = cur->left;
continue;
}
/* both h_index_left and h_index_right cannot be 0 */
if (h_index_left >= h_index_right)
cur = cur->left;
else
cur = cur->right;
}
if (prio_tree_root(cur)) {
assert(root->prio_tree_node == cur);
INIT_PRIO_TREE_ROOT(root);
return;
}
if (cur->parent->right == cur)
cur->parent->right = cur->parent;
else
cur->parent->left = cur->parent;
while (cur != node)
cur = prio_tree_replace(root, cur->parent, cur);
}
/*
* Replace a prio_tree_node with a new node and return the old node
*/
struct prio_tree_node *prio_tree_replace(struct prio_tree_root *root,
struct prio_tree_node *old, struct prio_tree_node *node)
{
INIT_PRIO_TREE_NODE(node);
if (prio_tree_root(old)) {
BUG_ON(root->prio_tree_node != old);
/*
* We can reduce root->index_bits here. However, it is complex
* and does not help much to improve performance (IMO).
*/
root->prio_tree_node = node;
} else
prio_set_parent(old->parent, node, old->parent->left == old);
if (!prio_tree_left_empty(old))
prio_set_parent(node, old->left, true);
if (!prio_tree_right_empty(old))
prio_set_parent(node, old->right, false);
return old;
}
