/*
* Extend a priority search tree so that it can store a node with heap_index
* max_heap_index. In the worst case, this algorithm takes O((log n)^2).
* However, this function is used rarely and the common case performance is
* not bad.
*/
static struct prio_tree_node *prio_tree_expand(struct prio_tree_root *root,
struct prio_tree_node *node, unsigned long max_heap_index)
{
struct prio_tree_node *prev;
if (max_heap_index > prio_tree_maxindex(root->index_bits))
root->index_bits++;
prev = node;
INIT_PRIO_TREE_NODE(node);
while (max_heap_index > prio_tree_maxindex(root->index_bits)) {
struct prio_tree_node *tmp = root->prio_tree_node;
root->index_bits++;
if (prio_tree_empty(root))
continue;
prio_tree_remove(root, root->prio_tree_node);
INIT_PRIO_TREE_NODE(tmp);
prio_set_parent(prev, tmp, true);
prev = tmp;
}
if (!prio_tree_empty(root))
prio_set_parent(prev, root->prio_tree_node, true);
root->prio_tree_node = node;
return node;
}
/*
* 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;
}
/*
* Extend a priority search tree so that it can store a node with heap_index
* max_heap_index. In the worst case, this algorithm takes O((log n)^2).
* However, this function is used rarely and the common case performance is
* not bad.
*/
static struct prio_tree_node *prio_tree_expand(struct prio_tree_root *root,
struct prio_tree_node *node, unsigned long max_heap_index)
{
struct prio_tree_node *first = NULL, *prev, *last = NULL;
if (max_heap_index > prio_tree_maxindex(root->index_bits))
root->index_bits++;
while (max_heap_index > prio_tree_maxindex(root->index_bits)) {
root->index_bits++;
if (prio_tree_empty(root))
continue;
if (first == NULL) {
first = root->prio_tree_node;
prio_tree_remove(root, root->prio_tree_node);
INIT_PRIO_TREE_NODE(first);
last = first;
} else {
prev = last;
last = root->prio_tree_node;
prio_tree_remove(root, root->prio_tree_node);
INIT_PRIO_TREE_NODE(last);
prev->left = last;
last->parent = prev;
}
}
INIT_PRIO_TREE_NODE(node);
if (first) {
node->left = first;
first->parent = node;
} else
last = node;
if (!prio_tree_empty(root)) {
last->left = root->prio_tree_node;
last->left->parent = last;
}
root->prio_tree_node = node;
return node;
}
/*
* 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;
}
/*
* Insert a prio_tree_node @node into a radix priority search tree @root. The
* algorithm typically takes O(log n) time where 'log n' is the number of bits
* required to represent the maximum heap_index. In the worst case, the algo
* can take O((log n)^2) - check prio_tree_expand.
*
* If a prior node with same radix_index and heap_index is already found in
* the tree, then returns the address of the prior node. Otherwise, inserts
* @node into the tree and returns @node.
*/
struct prio_tree_node *prio_tree_insert(struct prio_tree_root *root,
struct prio_tree_node *node)
{
struct prio_tree_node *cur, *res = node;
unsigned long radix_index, heap_index;
unsigned long r_index, h_index, index, mask;
int size_flag = 0;
get_index(node, &radix_index, &heap_index);
if (prio_tree_empty(root) ||
heap_index > prio_tree_maxindex(root->index_bits))
return prio_tree_expand(root, node, heap_index);
cur = root->prio_tree_node;
mask = 1UL << (root->index_bits - 1);
while (mask) {
get_index(cur, &r_index, &h_index);
if (r_index == radix_index && h_index == heap_index)
return cur;
if (h_index < heap_index ||
(h_index == heap_index && r_index > radix_index)) {
struct prio_tree_node *tmp = node;
node = prio_tree_replace(root, cur, node);
cur = tmp;
/* swap indices */
index = r_index;
r_index = radix_index;
radix_index = index;
index = h_index;
h_index = heap_index;
heap_index = index;
}
if (size_flag)
index = heap_index - radix_index;
else
index = radix_index;
if (index & mask) {
if (prio_tree_right_empty(cur)) {
INIT_PRIO_TREE_NODE(node);
cur->right = node;
node->parent = cur;
return res;
} else
cur = cur->right;
} else {
if (prio_tree_left_empty(cur)) {
INIT_PRIO_TREE_NODE(node);
cur->left = node;
node->parent = cur;
return res;
} else
cur = cur->left;
}
mask >>= 1;
if (!mask) {
mask = 1UL << (BITS_PER_LONG - 1);
size_flag = 1;
}
}
/* Should not reach here */
assert(0);
return NULL;
}
