Introduce red-black trees utility
Signed-off-by: Robert Baldyga <robert.baldyga@intel.com>
This commit is contained in:
Robert Baldyga
parent
86d7212217
commit
935df23c74
411
src/utils/utils_rbtree.c
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411
src/utils/utils_rbtree.c
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@ -0,0 +1,411 @@
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/*
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* Copyright(c) 2020 Intel Corporation
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* SPDX-License-Identifier: BSD-3-Clause-Clear
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*/
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#include "utils_rbtree.h"
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void ocf_rb_tree_init(struct ocf_rb_tree *tree, ocf_rb_tree_node_cmp_cb cmp)
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{
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tree->root = NULL;
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tree->cmp = cmp;
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}
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static void ocf_rb_tree_update_parent(struct ocf_rb_tree *tree,
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struct ocf_rb_node *node, struct ocf_rb_node *old_node,
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struct ocf_rb_node *new_node)
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{
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if (!node->parent)
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tree->root = new_node;
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else if (old_node == node->parent->left)
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node->parent->left = new_node;
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else if (old_node == node->parent->right)
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node->parent->right = new_node;
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}
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static void ocf_rb_tree_update_children(struct ocf_rb_node *node)
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{
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if (node->left)
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node->left->parent = node;
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if (node->right)
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node->right->parent = node;
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}
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static void ocf_rb_tree_rotate_left(struct ocf_rb_tree *tree,
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struct ocf_rb_node *node)
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{
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struct ocf_rb_node *right = node->right;
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node->right = right->left;
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if (node->right)
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node->right->parent = node;
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right->parent = node->parent;
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ocf_rb_tree_update_parent(tree, node, node, right);
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right->left = node;
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node->parent = right;
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}
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static void ocf_rb_tree_rotate_right(struct ocf_rb_tree *tree,
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struct ocf_rb_node *node)
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{
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struct ocf_rb_node *left = node->left;
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node->left = left->right;
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if (node->left)
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node->left->parent = node;
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left->parent = node->parent;
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ocf_rb_tree_update_parent(tree, node, node, left);
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left->right = node;
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node->parent = left;
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}
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static void ocf_rb_tree_fix_violation(struct ocf_rb_tree *tree,
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struct ocf_rb_node *node)
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{
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struct ocf_rb_node *parent, *grandparent, *uncle;
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int tmp;
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while (node->red && node->parent && node->parent->red) {
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parent = node->parent;
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grandparent = parent->parent;
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if (!grandparent)
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break;
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if (parent == grandparent->left) {
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/* Parent is left child */
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uncle = grandparent->right;
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if (uncle && uncle->red) {
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/* Uncle is red -> recolor */
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grandparent->red = true;
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parent->red = false;
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uncle->red = false;
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node = grandparent; /* Recheck grandparent */
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} else if (node == parent->right) {
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/* Node is right child -> rot left */
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ocf_rb_tree_rotate_left(tree, parent);
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node = parent;
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parent = node->parent;
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} else {
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/* Node is left child -> rot right + recolor */
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ocf_rb_tree_rotate_right(tree, grandparent);
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tmp = parent->red;
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parent->red = grandparent->red;
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grandparent->red = tmp;
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node = parent;
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}
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} else {
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/* Parent is right child */
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uncle = grandparent->left;
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if (uncle && uncle->red) {
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/* Uncle is red -> recolor */
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grandparent->red = true;
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parent->red = false;
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uncle->red = false;
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node = grandparent; /* Recheck grandparent */
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} else if (node == parent->left) {
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/* Node is left child -> rot right */
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ocf_rb_tree_rotate_right(tree, parent);
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node = parent;
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parent = node->parent;
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} else {
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/* Node is left child -> rot left + recolor */
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ocf_rb_tree_rotate_left(tree, grandparent);
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tmp = parent->red;
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parent->red = grandparent->red;
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grandparent->red = tmp;
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node = parent;
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}
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}
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}
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/* Final recolor */
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tree->root->red = false;
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}
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void ocf_rb_tree_insert(struct ocf_rb_tree *tree, struct ocf_rb_node *node)
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{
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struct ocf_rb_node *iter, *new_iter;
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int cmp;
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node->left = NULL;
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node->right = NULL;
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if (!tree->root) {
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node->red = false;
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node->parent = NULL;
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tree->root = node;
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return;
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}
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for (new_iter = tree->root; new_iter;) {
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iter = new_iter;
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cmp = tree->cmp(node, iter);
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new_iter = (cmp < 0) ? iter->left : iter->right;
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}
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node->red = true;
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node->parent = iter;
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if (cmp < 0)
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iter->left = node;
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else
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iter->right = node;
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ocf_rb_tree_fix_violation(tree, node);
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}
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static void ocf_rb_tree_swap(struct ocf_rb_tree *tree,
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struct ocf_rb_node *node1, struct ocf_rb_node *node2)
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{
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struct ocf_rb_node tmp;
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if (node1->left == node2)
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node1->left = node1;
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else if (node1->right == node2)
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node1->right = node1;
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else if (node1->parent == node2)
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node1->parent = node1;
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if (node2->left == node1)
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node2->left = node2;
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else if (node2->right == node1)
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node2->right = node2;
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else if (node2->parent == node1)
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node2->parent = node2;
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tmp = *node1;
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*node1 = *node2;
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*node2 = tmp;
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ocf_rb_tree_update_parent(tree, node1, node2, node1);
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ocf_rb_tree_update_parent(tree, node2, node1, node2);
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ocf_rb_tree_update_children(node1);
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ocf_rb_tree_update_children(node2);
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}
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static struct ocf_rb_node *ocf_rb_tree_successor(struct ocf_rb_node *node)
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{
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struct ocf_rb_node *succ;
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if (!node->right)
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return NULL;
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for (succ = node->right; succ->left;)
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succ = succ->left;
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return succ;
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}
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static struct ocf_rb_node *ocf_rb_tree_predecessor(struct ocf_rb_node *node)
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{
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struct ocf_rb_node *pred;
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if (!node->left)
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return NULL;
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for (pred = node->left; pred->right;)
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pred = pred->right;
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return pred;
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}
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static struct ocf_rb_node *ocf_rb_tree_bst_replacement(struct ocf_rb_node *node)
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{
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if (node->left && node->right)
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return ocf_rb_tree_successor(node);
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if (node->left)
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return node->left;
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if (node->right)
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return node->right;
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return NULL;
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}
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static struct ocf_rb_node *ocf_rb_tree_sibling(struct ocf_rb_node *node)
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{
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if (!node->parent)
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return NULL;
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return (node == node->parent->left) ?
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node->parent->right : node->parent->left;
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}
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void ocf_rb_tree_fix_double_black(struct ocf_rb_tree *tree,
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struct ocf_rb_node *node)
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{
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struct ocf_rb_node *sibling;
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while (true) {
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if (!node->parent) {
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/* Reached root -> end */
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break;
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}
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sibling = ocf_rb_tree_sibling(node);
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if (!sibling) {
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/* No sibling -> move up */
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node = node->parent;
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continue;
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}
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if (sibling->red) {
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/* Sibling is red -> recolor, rot and repeat */
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node->parent->red = true;
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sibling->red = false;
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if (sibling == node->parent->left)
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ocf_rb_tree_rotate_right(tree, node->parent);
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else
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ocf_rb_tree_rotate_left(tree, node->parent);
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continue;
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}
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if (sibling->left && sibling->left->red) {
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/* Sibling has left red child -> recolor and rot */
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if (sibling == node->parent->left) {
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sibling->left->red = sibling->red;
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sibling->red = node->parent->red;
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ocf_rb_tree_rotate_right(tree, node->parent);
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} else {
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sibling->left->red = node->parent->red;
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ocf_rb_tree_rotate_right(tree, sibling);
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ocf_rb_tree_rotate_left(tree, node->parent);
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}
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node->parent->red = false;
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break;
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} else if (sibling->right && sibling->right->red) {
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/* Sibling has right red child -> recolor and rot */
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if (sibling == node->parent->left) {
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sibling->right->red = node->parent->red;
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ocf_rb_tree_rotate_left(tree, sibling);
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ocf_rb_tree_rotate_right(tree, node->parent);
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} else {
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sibling->right->red = sibling->red;
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sibling->red = node->parent->red;
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ocf_rb_tree_rotate_left(tree, node->parent);
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}
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node->parent->red = false;
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break;
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} else {
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/* Sibling has both black children */
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sibling->red = true;
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if (!node->parent->red) {
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/* Parent is black -> move up */
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node = node->parent;
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continue;
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}
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/* Parent is red -> recolor */
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node->parent->red = false;
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break;
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}
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}
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}
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void ocf_rb_tree_remove(struct ocf_rb_tree *tree, struct ocf_rb_node *node)
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{
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struct ocf_rb_node *sibling, *rep;
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while (true) {
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sibling = ocf_rb_tree_sibling(node);
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rep = ocf_rb_tree_bst_replacement(node);
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if (!rep) {
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/* Node has no children -> remove */
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if (node == tree->root) {
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tree->root = NULL;
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} else {
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if (!node->red)
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ocf_rb_tree_fix_double_black(tree, node);
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else if (sibling)
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sibling->red = true;
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ocf_rb_tree_update_parent(tree, node, node, NULL);
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}
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break;
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}
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if (!rep->left & !rep->right) {
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/* BST replacement is leaf -> swap and remove */
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ocf_rb_tree_swap(tree, node, rep);
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if (!node->red)
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ocf_rb_tree_fix_double_black(tree, node);
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ocf_rb_tree_update_parent(tree, node, node, NULL);
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break;
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}
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/* BST replacement has children -> swap and repeat */
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ocf_rb_tree_swap(tree, node, rep);
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}
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}
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bool ocf_rb_tree_can_update(struct ocf_rb_tree *tree,
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struct ocf_rb_node *node, struct ocf_rb_node *new_node)
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{
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struct ocf_rb_node *iter = tree->root;
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int cmp = 0;
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while (iter) {
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if (iter == node)
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break;
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cmp = tree->cmp(new_node, iter);
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iter = (cmp < 0) ? iter->left : iter->right;
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}
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if (!iter)
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return false;
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cmp = tree->cmp(new_node, iter);
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if (cmp < 0) {
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iter = ocf_rb_tree_predecessor(iter);
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if (!iter)
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return true;
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cmp = tree->cmp(new_node, iter);
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return (cmp > 0);
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}
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if (cmp > 0) {
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iter = ocf_rb_tree_successor(iter);
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if (!iter)
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return true;
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cmp = tree->cmp(new_node, iter);
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return (cmp < 0);
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}
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return true;
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}
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struct ocf_rb_node *ocf_rb_tree_find(struct ocf_rb_tree *tree,
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struct ocf_rb_node *node)
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{
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struct ocf_rb_node *iter = tree->root;
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int cmp = 0;
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while (iter) {
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cmp = tree->cmp(node, iter);
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if (!cmp)
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break;
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iter = (cmp < 0) ? iter->left : iter->right;
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}
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return iter;
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}
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38
src/utils/utils_rbtree.h
Normal file
38
src/utils/utils_rbtree.h
Normal file
@ -0,0 +1,38 @@
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/*
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* Copyright(c) 2020 Intel Corporation
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* SPDX-License-Identifier: BSD-3-Clause-Clear
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*/
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#ifndef __UTILS_RBTREE_H__
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#define __UTILS_RBTREE_H__
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#include "ocf/ocf.h"
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struct ocf_rb_node {
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bool red;
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struct ocf_rb_node *left;
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struct ocf_rb_node *right;
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struct ocf_rb_node *parent;
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};
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typedef int (*ocf_rb_tree_node_cmp_cb)(struct ocf_rb_node *n1,
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struct ocf_rb_node *n2);
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struct ocf_rb_tree {
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struct ocf_rb_node *root;
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ocf_rb_tree_node_cmp_cb cmp;
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};
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void ocf_rb_tree_init(struct ocf_rb_tree *tree, ocf_rb_tree_node_cmp_cb cmp);
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void ocf_rb_tree_insert(struct ocf_rb_tree *tree, struct ocf_rb_node *node);
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void ocf_rb_tree_remove(struct ocf_rb_tree *tree, struct ocf_rb_node *node);
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bool ocf_rb_tree_can_update(struct ocf_rb_tree *tree,
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struct ocf_rb_node *node, struct ocf_rb_node *new_node);
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struct ocf_rb_node *ocf_rb_tree_find(struct ocf_rb_tree *tree,
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struct ocf_rb_node *node);
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#endif /* __UTILS_RBTREE_H__ */
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Block a user