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Introduce red-black trees utility

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Signed-off-by: Robert Baldyga <robert.baldyga@intel.com>
This commit is contained in:
Robert Baldyga 2020-03-17 20:19:20 +01:00
parent 86d7212217
commit 935df23c74
2 changed files with 449 additions and 0 deletions
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411
src/utils/utils_rbtree.c Normal file
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/*
* Copyright(c) 2020 Intel Corporation
* SPDX-License-Identifier: BSD-3-Clause-Clear
*/
#include "utils_rbtree.h"
void ocf_rb_tree_init(struct ocf_rb_tree *tree, ocf_rb_tree_node_cmp_cb cmp)
{
tree->root = NULL;
tree->cmp = cmp;
}
static void ocf_rb_tree_update_parent(struct ocf_rb_tree *tree,
struct ocf_rb_node *node, struct ocf_rb_node *old_node,
struct ocf_rb_node *new_node)
{
if (!node->parent)
tree->root = new_node;
else if (old_node == node->parent->left)
node->parent->left = new_node;
else if (old_node == node->parent->right)
node->parent->right = new_node;
}
static void ocf_rb_tree_update_children(struct ocf_rb_node *node)
{
if (node->left)
node->left->parent = node;
if (node->right)
node->right->parent = node;
}
static void ocf_rb_tree_rotate_left(struct ocf_rb_tree *tree,
struct ocf_rb_node *node)
{
struct ocf_rb_node *right = node->right;
node->right = right->left;
if (node->right)
node->right->parent = node;
right->parent = node->parent;
ocf_rb_tree_update_parent(tree, node, node, right);
right->left = node;
node->parent = right;
}
static void ocf_rb_tree_rotate_right(struct ocf_rb_tree *tree,
struct ocf_rb_node *node)
{
struct ocf_rb_node *left = node->left;
node->left = left->right;
if (node->left)
node->left->parent = node;
left->parent = node->parent;
ocf_rb_tree_update_parent(tree, node, node, left);
left->right = node;
node->parent = left;
}
static void ocf_rb_tree_fix_violation(struct ocf_rb_tree *tree,
struct ocf_rb_node *node)
{
struct ocf_rb_node *parent, *grandparent, *uncle;
int tmp;
while (node->red && node->parent && node->parent->red) {
parent = node->parent;
grandparent = parent->parent;
if (!grandparent)
break;
if (parent == grandparent->left) {
/* Parent is left child */
uncle = grandparent->right;
if (uncle && uncle->red) {
/* Uncle is red -> recolor */
grandparent->red = true;
parent->red = false;
uncle->red = false;
node = grandparent; /* Recheck grandparent */
} else if (node == parent->right) {
/* Node is right child -> rot left */
ocf_rb_tree_rotate_left(tree, parent);
node = parent;
parent = node->parent;
} else {
/* Node is left child -> rot right + recolor */
ocf_rb_tree_rotate_right(tree, grandparent);
tmp = parent->red;
parent->red = grandparent->red;
grandparent->red = tmp;
node = parent;
}
} else {
/* Parent is right child */
uncle = grandparent->left;
if (uncle && uncle->red) {
/* Uncle is red -> recolor */
grandparent->red = true;
parent->red = false;
uncle->red = false;
node = grandparent; /* Recheck grandparent */
} else if (node == parent->left) {
/* Node is left child -> rot right */
ocf_rb_tree_rotate_right(tree, parent);
node = parent;
parent = node->parent;
} else {
/* Node is left child -> rot left + recolor */
ocf_rb_tree_rotate_left(tree, grandparent);
tmp = parent->red;
parent->red = grandparent->red;
grandparent->red = tmp;
node = parent;
}
}
}
/* Final recolor */
tree->root->red = false;
}
void ocf_rb_tree_insert(struct ocf_rb_tree *tree, struct ocf_rb_node *node)
{
struct ocf_rb_node *iter, *new_iter;
int cmp;
node->left = NULL;
node->right = NULL;
if (!tree->root) {
node->red = false;
node->parent = NULL;
tree->root = node;
return;
}
for (new_iter = tree->root; new_iter;) {
iter = new_iter;
cmp = tree->cmp(node, iter);
new_iter = (cmp < 0) ? iter->left : iter->right;
}
node->red = true;
node->parent = iter;
if (cmp < 0)
iter->left = node;
else
iter->right = node;
ocf_rb_tree_fix_violation(tree, node);
}
static void ocf_rb_tree_swap(struct ocf_rb_tree *tree,
struct ocf_rb_node *node1, struct ocf_rb_node *node2)
{
struct ocf_rb_node tmp;
if (node1->left == node2)
node1->left = node1;
else if (node1->right == node2)
node1->right = node1;
else if (node1->parent == node2)
node1->parent = node1;
if (node2->left == node1)
node2->left = node2;
else if (node2->right == node1)
node2->right = node2;
else if (node2->parent == node1)
node2->parent = node2;
tmp = *node1;
*node1 = *node2;
*node2 = tmp;
ocf_rb_tree_update_parent(tree, node1, node2, node1);
ocf_rb_tree_update_parent(tree, node2, node1, node2);
ocf_rb_tree_update_children(node1);
ocf_rb_tree_update_children(node2);
}
static struct ocf_rb_node *ocf_rb_tree_successor(struct ocf_rb_node *node)
{
struct ocf_rb_node *succ;
if (!node->right)
return NULL;
for (succ = node->right; succ->left;)
succ = succ->left;
return succ;
}
static struct ocf_rb_node *ocf_rb_tree_predecessor(struct ocf_rb_node *node)
{
struct ocf_rb_node *pred;
if (!node->left)
return NULL;
for (pred = node->left; pred->right;)
pred = pred->right;
return pred;
}
static struct ocf_rb_node *ocf_rb_tree_bst_replacement(struct ocf_rb_node *node)
{
if (node->left && node->right)
return ocf_rb_tree_successor(node);
if (node->left)
return node->left;
if (node->right)
return node->right;
return NULL;
}
static struct ocf_rb_node *ocf_rb_tree_sibling(struct ocf_rb_node *node)
{
if (!node->parent)
return NULL;
return (node == node->parent->left) ?
node->parent->right : node->parent->left;
}
void ocf_rb_tree_fix_double_black(struct ocf_rb_tree *tree,
struct ocf_rb_node *node)
{
struct ocf_rb_node *sibling;
while (true) {
if (!node->parent) {
/* Reached root -> end */
break;
}
sibling = ocf_rb_tree_sibling(node);
if (!sibling) {
/* No sibling -> move up */
node = node->parent;
continue;
}
if (sibling->red) {
/* Sibling is red -> recolor, rot and repeat */
node->parent->red = true;
sibling->red = false;
if (sibling == node->parent->left)
ocf_rb_tree_rotate_right(tree, node->parent);
else
ocf_rb_tree_rotate_left(tree, node->parent);
continue;
}
if (sibling->left && sibling->left->red) {
/* Sibling has left red child -> recolor and rot */
if (sibling == node->parent->left) {
sibling->left->red = sibling->red;
sibling->red = node->parent->red;
ocf_rb_tree_rotate_right(tree, node->parent);
} else {
sibling->left->red = node->parent->red;
ocf_rb_tree_rotate_right(tree, sibling);
ocf_rb_tree_rotate_left(tree, node->parent);
}
node->parent->red = false;
break;
} else if (sibling->right && sibling->right->red) {
/* Sibling has right red child -> recolor and rot */
if (sibling == node->parent->left) {
sibling->right->red = node->parent->red;
ocf_rb_tree_rotate_left(tree, sibling);
ocf_rb_tree_rotate_right(tree, node->parent);
} else {
sibling->right->red = sibling->red;
sibling->red = node->parent->red;
ocf_rb_tree_rotate_left(tree, node->parent);
}
node->parent->red = false;
break;
} else {
/* Sibling has both black children */
sibling->red = true;
if (!node->parent->red) {
/* Parent is black -> move up */
node = node->parent;
continue;
}
/* Parent is red -> recolor */
node->parent->red = false;
break;
}
}
}
void ocf_rb_tree_remove(struct ocf_rb_tree *tree, struct ocf_rb_node *node)
{
struct ocf_rb_node *sibling, *rep;
while (true) {
sibling = ocf_rb_tree_sibling(node);
rep = ocf_rb_tree_bst_replacement(node);
if (!rep) {
/* Node has no children -> remove */
if (node == tree->root) {
tree->root = NULL;
} else {
if (!node->red)
ocf_rb_tree_fix_double_black(tree, node);
else if (sibling)
sibling->red = true;
ocf_rb_tree_update_parent(tree, node, node, NULL);
}
break;
}
if (!rep->left & !rep->right) {
/* BST replacement is leaf -> swap and remove */
ocf_rb_tree_swap(tree, node, rep);
if (!node->red)
ocf_rb_tree_fix_double_black(tree, node);
ocf_rb_tree_update_parent(tree, node, node, NULL);
break;
}
/* BST replacement has children -> swap and repeat */
ocf_rb_tree_swap(tree, node, rep);
}
}
bool ocf_rb_tree_can_update(struct ocf_rb_tree *tree,
struct ocf_rb_node *node, struct ocf_rb_node *new_node)
{
struct ocf_rb_node *iter = tree->root;
int cmp = 0;
while (iter) {
if (iter == node)
break;
cmp = tree->cmp(new_node, iter);
iter = (cmp < 0) ? iter->left : iter->right;
}
if (!iter)
return false;
cmp = tree->cmp(new_node, iter);
if (cmp < 0) {
iter = ocf_rb_tree_predecessor(iter);
if (!iter)
return true;
cmp = tree->cmp(new_node, iter);
return (cmp > 0);
}
if (cmp > 0) {
iter = ocf_rb_tree_successor(iter);
if (!iter)
return true;
cmp = tree->cmp(new_node, iter);
return (cmp < 0);
}
return true;
}
struct ocf_rb_node *ocf_rb_tree_find(struct ocf_rb_tree *tree,
struct ocf_rb_node *node)
{
struct ocf_rb_node *iter = tree->root;
int cmp = 0;
while (iter) {
cmp = tree->cmp(node, iter);
if (!cmp)
break;
iter = (cmp < 0) ? iter->left : iter->right;
}
return iter;
}

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/*
* Copyright(c) 2020 Intel Corporation
* SPDX-License-Identifier: BSD-3-Clause-Clear
*/
#ifndef __UTILS_RBTREE_H__
#define __UTILS_RBTREE_H__
#include "ocf/ocf.h"
struct ocf_rb_node {
bool red;
struct ocf_rb_node *left;
struct ocf_rb_node *right;
struct ocf_rb_node *parent;
};
typedef int (*ocf_rb_tree_node_cmp_cb)(struct ocf_rb_node *n1,
struct ocf_rb_node *n2);
struct ocf_rb_tree {
struct ocf_rb_node *root;
ocf_rb_tree_node_cmp_cb cmp;
};
void ocf_rb_tree_init(struct ocf_rb_tree *tree, ocf_rb_tree_node_cmp_cb cmp);
void ocf_rb_tree_insert(struct ocf_rb_tree *tree, struct ocf_rb_node *node);
void ocf_rb_tree_remove(struct ocf_rb_tree *tree, struct ocf_rb_node *node);
bool ocf_rb_tree_can_update(struct ocf_rb_tree *tree,
struct ocf_rb_node *node, struct ocf_rb_node *new_node);
struct ocf_rb_node *ocf_rb_tree_find(struct ocf_rb_tree *tree,
struct ocf_rb_node *node);
#endif /* __UTILS_RBTREE_H__ */