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Diffstat (limited to 'include/sys/avl.h')
| -rw-r--r-- | include/sys/avl.h | 325 |
1 files changed, 325 insertions, 0 deletions
diff --git a/include/sys/avl.h b/include/sys/avl.h new file mode 100644 index 000000000000..ed3c6f86a568 --- /dev/null +++ b/include/sys/avl.h @@ -0,0 +1,325 @@ +/* + * CDDL HEADER START + * + * The contents of this file are subject to the terms of the + * Common Development and Distribution License (the "License"). + * You may not use this file except in compliance with the License. + * + * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE + * or http://www.opensolaris.org/os/licensing. + * See the License for the specific language governing permissions + * and limitations under the License. + * + * When distributing Covered Code, include this CDDL HEADER in each + * file and include the License file at usr/src/OPENSOLARIS.LICENSE. + * If applicable, add the following below this CDDL HEADER, with the + * fields enclosed by brackets "[]" replaced with your own identifying + * information: Portions Copyright [yyyy] [name of copyright owner] + * + * CDDL HEADER END + */ +/* + * Copyright 2009 Sun Microsystems, Inc. All rights reserved. + * Use is subject to license terms. + */ + +/* + * Copyright (c) 2014 by Delphix. All rights reserved. + */ + +#ifndef _AVL_H +#define _AVL_H + +/* + * This is a private header file. Applications should not directly include + * this file. + */ + +#ifdef __cplusplus +extern "C" { +#endif + +#include <sys/types.h> +#include <sys/avl_impl.h> + +/* + * This is a generic implementation of AVL trees for use in the Solaris kernel. + * The interfaces provide an efficient way of implementing an ordered set of + * data structures. + * + * AVL trees provide an alternative to using an ordered linked list. Using AVL + * trees will usually be faster, however they requires more storage. An ordered + * linked list in general requires 2 pointers in each data structure. The + * AVL tree implementation uses 3 pointers. The following chart gives the + * approximate performance of operations with the different approaches: + * + * Operation Link List AVL tree + * --------- -------- -------- + * lookup O(n) O(log(n)) + * + * insert 1 node constant constant + * + * delete 1 node constant between constant and O(log(n)) + * + * delete all nodes O(n) O(n) + * + * visit the next + * or prev node constant between constant and O(log(n)) + * + * + * The data structure nodes are anchored at an "avl_tree_t" (the equivalent + * of a list header) and the individual nodes will have a field of + * type "avl_node_t" (corresponding to list pointers). + * + * The type "avl_index_t" is used to indicate a position in the list for + * certain calls. + * + * The usage scenario is generally: + * + * 1. Create the list/tree with: avl_create() + * + * followed by any mixture of: + * + * 2a. Insert nodes with: avl_add(), or avl_find() and avl_insert() + * + * 2b. Visited elements with: + * avl_first() - returns the lowest valued node + * avl_last() - returns the highest valued node + * AVL_NEXT() - given a node go to next higher one + * AVL_PREV() - given a node go to previous lower one + * + * 2c. Find the node with the closest value either less than or greater + * than a given value with avl_nearest(). + * + * 2d. Remove individual nodes from the list/tree with avl_remove(). + * + * and finally when the list is being destroyed + * + * 3. Use avl_destroy_nodes() to quickly process/free up any remaining nodes. + * Note that once you use avl_destroy_nodes(), you can no longer + * use any routine except avl_destroy_nodes() and avl_destroy(). + * + * 4. Use avl_destroy() to destroy the AVL tree itself. + * + * Any locking for multiple thread access is up to the user to provide, just + * as is needed for any linked list implementation. + */ + +/* + * AVL comparator helpers + */ +#define TREE_ISIGN(a) (((a) > 0) - ((a) < 0)) +#define TREE_CMP(a, b) (((a) > (b)) - ((a) < (b))) +#define TREE_PCMP(a, b) \ + (((uintptr_t)(a) > (uintptr_t)(b)) - ((uintptr_t)(a) < (uintptr_t)(b))) + +/* + * Type used for the root of the AVL tree. + */ +typedef struct avl_tree avl_tree_t; + +/* + * The data nodes in the AVL tree must have a field of this type. + */ +typedef struct avl_node avl_node_t; + +/* + * An opaque type used to locate a position in the tree where a node + * would be inserted. + */ +typedef uintptr_t avl_index_t; + + +/* + * Direction constants used for avl_nearest(). + */ +#define AVL_BEFORE (0) +#define AVL_AFTER (1) + + +/* + * Prototypes + * + * Where not otherwise mentioned, "void *" arguments are a pointer to the + * user data structure which must contain a field of type avl_node_t. + * + * Also assume the user data structures looks like: + * struct my_type { + * ... + * avl_node_t my_link; + * ... + * }; + */ + +/* + * Initialize an AVL tree. Arguments are: + * + * tree - the tree to be initialized + * compar - function to compare two nodes, it must return exactly: -1, 0, or +1 + * -1 for <, 0 for ==, and +1 for > + * size - the value of sizeof(struct my_type) + * offset - the value of OFFSETOF(struct my_type, my_link) + */ +extern void avl_create(avl_tree_t *tree, + int (*compar) (const void *, const void *), size_t size, size_t offset); + + +/* + * Find a node with a matching value in the tree. Returns the matching node + * found. If not found, it returns NULL and then if "where" is not NULL it sets + * "where" for use with avl_insert() or avl_nearest(). + * + * node - node that has the value being looked for + * where - position for use with avl_nearest() or avl_insert(), may be NULL + */ +extern void *avl_find(avl_tree_t *tree, const void *node, avl_index_t *where); + +/* + * Insert a node into the tree. + * + * node - the node to insert + * where - position as returned from avl_find() + */ +extern void avl_insert(avl_tree_t *tree, void *node, avl_index_t where); + +/* + * Insert "new_data" in "tree" in the given "direction" either after + * or before the data "here". + * + * This might be useful for avl clients caching recently accessed + * data to avoid doing avl_find() again for insertion. + * + * new_data - new data to insert + * here - existing node in "tree" + * direction - either AVL_AFTER or AVL_BEFORE the data "here". + */ +extern void avl_insert_here(avl_tree_t *tree, void *new_data, void *here, + int direction); + + +/* + * Return the first or last valued node in the tree. Will return NULL + * if the tree is empty. + * + */ +extern void *avl_first(avl_tree_t *tree); +extern void *avl_last(avl_tree_t *tree); + + +/* + * Return the next or previous valued node in the tree. + * AVL_NEXT() will return NULL if at the last node. + * AVL_PREV() will return NULL if at the first node. + * + * node - the node from which the next or previous node is found + */ +#define AVL_NEXT(tree, node) avl_walk(tree, node, AVL_AFTER) +#define AVL_PREV(tree, node) avl_walk(tree, node, AVL_BEFORE) + + +/* + * Find the node with the nearest value either greater or less than + * the value from a previous avl_find(). Returns the node or NULL if + * there isn't a matching one. + * + * where - position as returned from avl_find() + * direction - either AVL_BEFORE or AVL_AFTER + * + * EXAMPLE get the greatest node that is less than a given value: + * + * avl_tree_t *tree; + * struct my_data look_for_value = {....}; + * struct my_data *node; + * struct my_data *less; + * avl_index_t where; + * + * node = avl_find(tree, &look_for_value, &where); + * if (node != NULL) + * less = AVL_PREV(tree, node); + * else + * less = avl_nearest(tree, where, AVL_BEFORE); + */ +extern void *avl_nearest(avl_tree_t *tree, avl_index_t where, int direction); + + +/* + * Add a single node to the tree. + * The node must not be in the tree, and it must not + * compare equal to any other node already in the tree. + * + * node - the node to add + */ +extern void avl_add(avl_tree_t *tree, void *node); + + +/* + * Remove a single node from the tree. The node must be in the tree. + * + * node - the node to remove + */ +extern void avl_remove(avl_tree_t *tree, void *node); + +/* + * Reinsert a node only if its order has changed relative to its nearest + * neighbors. To optimize performance avl_update_lt() checks only the previous + * node and avl_update_gt() checks only the next node. Use avl_update_lt() and + * avl_update_gt() only if you know the direction in which the order of the + * node may change. + */ +extern boolean_t avl_update(avl_tree_t *, void *); +extern boolean_t avl_update_lt(avl_tree_t *, void *); +extern boolean_t avl_update_gt(avl_tree_t *, void *); + +/* + * Swaps the contents of the two trees. + */ +extern void avl_swap(avl_tree_t *tree1, avl_tree_t *tree2); + +/* + * Return the number of nodes in the tree + */ +extern ulong_t avl_numnodes(avl_tree_t *tree); + +/* + * Return B_TRUE if there are zero nodes in the tree, B_FALSE otherwise. + */ +extern boolean_t avl_is_empty(avl_tree_t *tree); + +/* + * Used to destroy any remaining nodes in a tree. The cookie argument should + * be initialized to NULL before the first call. Returns a node that has been + * removed from the tree and may be free()'d. Returns NULL when the tree is + * empty. + * + * Once you call avl_destroy_nodes(), you can only continuing calling it and + * finally avl_destroy(). No other AVL routines will be valid. + * + * cookie - a "void *" used to save state between calls to avl_destroy_nodes() + * + * EXAMPLE: + * avl_tree_t *tree; + * struct my_data *node; + * void *cookie; + * + * cookie = NULL; + * while ((node = avl_destroy_nodes(tree, &cookie)) != NULL) + * free(node); + * avl_destroy(tree); + */ +extern void *avl_destroy_nodes(avl_tree_t *tree, void **cookie); + + +/* + * Final destroy of an AVL tree. Arguments are: + * + * tree - the empty tree to destroy + */ +extern void avl_destroy(avl_tree_t *tree); + + + +#ifdef __cplusplus +} +#endif + +#endif /* _AVL_H */ |