avl.h revision 269845
1/* 2 * CDDL HEADER START 3 * 4 * The contents of this file are subject to the terms of the 5 * Common Development and Distribution License (the "License"). 6 * You may not use this file except in compliance with the License. 7 * 8 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE 9 * or http://www.opensolaris.org/os/licensing. 10 * See the License for the specific language governing permissions 11 * and limitations under the License. 12 * 13 * When distributing Covered Code, include this CDDL HEADER in each 14 * file and include the License file at usr/src/OPENSOLARIS.LICENSE. 15 * If applicable, add the following below this CDDL HEADER, with the 16 * fields enclosed by brackets "[]" replaced with your own identifying 17 * information: Portions Copyright [yyyy] [name of copyright owner] 18 * 19 * CDDL HEADER END 20 */ 21/* 22 * Copyright 2009 Sun Microsystems, Inc. All rights reserved. 23 * Use is subject to license terms. 24 */ 25 26/* 27 * Copyright (c) 2014 by Delphix. All rights reserved. 28 */ 29 30#ifndef _AVL_H 31#define _AVL_H 32 33/* 34 * This is a private header file. Applications should not directly include 35 * this file. 36 */ 37 38#ifdef __cplusplus 39extern "C" { 40#endif 41 42#include <sys/types.h> 43#include <sys/avl_impl.h> 44 45/* 46 * This is a generic implementation of AVL trees for use in the Solaris kernel. 47 * The interfaces provide an efficient way of implementing an ordered set of 48 * data structures. 49 * 50 * AVL trees provide an alternative to using an ordered linked list. Using AVL 51 * trees will usually be faster, however they requires more storage. An ordered 52 * linked list in general requires 2 pointers in each data structure. The 53 * AVL tree implementation uses 3 pointers. The following chart gives the 54 * approximate performance of operations with the different approaches: 55 * 56 * Operation Link List AVL tree 57 * --------- -------- -------- 58 * lookup O(n) O(log(n)) 59 * 60 * insert 1 node constant constant 61 * 62 * delete 1 node constant between constant and O(log(n)) 63 * 64 * delete all nodes O(n) O(n) 65 * 66 * visit the next 67 * or prev node constant between constant and O(log(n)) 68 * 69 * 70 * The data structure nodes are anchored at an "avl_tree_t" (the equivalent 71 * of a list header) and the individual nodes will have a field of 72 * type "avl_node_t" (corresponding to list pointers). 73 * 74 * The type "avl_index_t" is used to indicate a position in the list for 75 * certain calls. 76 * 77 * The usage scenario is generally: 78 * 79 * 1. Create the list/tree with: avl_create() 80 * 81 * followed by any mixture of: 82 * 83 * 2a. Insert nodes with: avl_add(), or avl_find() and avl_insert() 84 * 85 * 2b. Visited elements with: 86 * avl_first() - returns the lowest valued node 87 * avl_last() - returns the highest valued node 88 * AVL_NEXT() - given a node go to next higher one 89 * AVL_PREV() - given a node go to previous lower one 90 * 91 * 2c. Find the node with the closest value either less than or greater 92 * than a given value with avl_nearest(). 93 * 94 * 2d. Remove individual nodes from the list/tree with avl_remove(). 95 * 96 * and finally when the list is being destroyed 97 * 98 * 3. Use avl_destroy_nodes() to quickly process/free up any remaining nodes. 99 * Note that once you use avl_destroy_nodes(), you can no longer 100 * use any routine except avl_destroy_nodes() and avl_destoy(). 101 * 102 * 4. Use avl_destroy() to destroy the AVL tree itself. 103 * 104 * Any locking for multiple thread access is up to the user to provide, just 105 * as is needed for any linked list implementation. 106 */ 107 108 109/* 110 * Type used for the root of the AVL tree. 111 */ 112typedef struct avl_tree avl_tree_t; 113 114/* 115 * The data nodes in the AVL tree must have a field of this type. 116 */ 117typedef struct avl_node avl_node_t; 118 119/* 120 * An opaque type used to locate a position in the tree where a node 121 * would be inserted. 122 */ 123typedef uintptr_t avl_index_t; 124 125 126/* 127 * Direction constants used for avl_nearest(). 128 */ 129#define AVL_BEFORE (0) 130#define AVL_AFTER (1) 131 132 133/* 134 * Prototypes 135 * 136 * Where not otherwise mentioned, "void *" arguments are a pointer to the 137 * user data structure which must contain a field of type avl_node_t. 138 * 139 * Also assume the user data structures looks like: 140 * stuct my_type { 141 * ... 142 * avl_node_t my_link; 143 * ... 144 * }; 145 */ 146 147/* 148 * Initialize an AVL tree. Arguments are: 149 * 150 * tree - the tree to be initialized 151 * compar - function to compare two nodes, it must return exactly: -1, 0, or +1 152 * -1 for <, 0 for ==, and +1 for > 153 * size - the value of sizeof(struct my_type) 154 * offset - the value of OFFSETOF(struct my_type, my_link) 155 */ 156extern void avl_create(avl_tree_t *tree, 157 int (*compar) (const void *, const void *), size_t size, size_t offset); 158 159 160/* 161 * Find a node with a matching value in the tree. Returns the matching node 162 * found. If not found, it returns NULL and then if "where" is not NULL it sets 163 * "where" for use with avl_insert() or avl_nearest(). 164 * 165 * node - node that has the value being looked for 166 * where - position for use with avl_nearest() or avl_insert(), may be NULL 167 */ 168extern void *avl_find(avl_tree_t *tree, const void *node, avl_index_t *where); 169 170/* 171 * Insert a node into the tree. 172 * 173 * node - the node to insert 174 * where - position as returned from avl_find() 175 */ 176extern void avl_insert(avl_tree_t *tree, void *node, avl_index_t where); 177 178/* 179 * Insert "new_data" in "tree" in the given "direction" either after 180 * or before the data "here". 181 * 182 * This might be useful for avl clients caching recently accessed 183 * data to avoid doing avl_find() again for insertion. 184 * 185 * new_data - new data to insert 186 * here - existing node in "tree" 187 * direction - either AVL_AFTER or AVL_BEFORE the data "here". 188 */ 189extern void avl_insert_here(avl_tree_t *tree, void *new_data, void *here, 190 int direction); 191 192 193/* 194 * Return the first or last valued node in the tree. Will return NULL 195 * if the tree is empty. 196 * 197 */ 198extern void *avl_first(avl_tree_t *tree); 199extern void *avl_last(avl_tree_t *tree); 200 201 202/* 203 * Return the next or previous valued node in the tree. 204 * AVL_NEXT() will return NULL if at the last node. 205 * AVL_PREV() will return NULL if at the first node. 206 * 207 * node - the node from which the next or previous node is found 208 */ 209#define AVL_NEXT(tree, node) avl_walk(tree, node, AVL_AFTER) 210#define AVL_PREV(tree, node) avl_walk(tree, node, AVL_BEFORE) 211 212 213/* 214 * Find the node with the nearest value either greater or less than 215 * the value from a previous avl_find(). Returns the node or NULL if 216 * there isn't a matching one. 217 * 218 * where - position as returned from avl_find() 219 * direction - either AVL_BEFORE or AVL_AFTER 220 * 221 * EXAMPLE get the greatest node that is less than a given value: 222 * 223 * avl_tree_t *tree; 224 * struct my_data look_for_value = {....}; 225 * struct my_data *node; 226 * struct my_data *less; 227 * avl_index_t where; 228 * 229 * node = avl_find(tree, &look_for_value, &where); 230 * if (node != NULL) 231 * less = AVL_PREV(tree, node); 232 * else 233 * less = avl_nearest(tree, where, AVL_BEFORE); 234 */ 235extern void *avl_nearest(avl_tree_t *tree, avl_index_t where, int direction); 236 237 238/* 239 * Add a single node to the tree. 240 * The node must not be in the tree, and it must not 241 * compare equal to any other node already in the tree. 242 * 243 * node - the node to add 244 */ 245extern void avl_add(avl_tree_t *tree, void *node); 246 247 248/* 249 * Remove a single node from the tree. The node must be in the tree. 250 * 251 * node - the node to remove 252 */ 253extern void avl_remove(avl_tree_t *tree, void *node); 254 255/* 256 * Reinsert a node only if its order has changed relative to its nearest 257 * neighbors. To optimize performance avl_update_lt() checks only the previous 258 * node and avl_update_gt() checks only the next node. Use avl_update_lt() and 259 * avl_update_gt() only if you know the direction in which the order of the 260 * node may change. 261 */ 262extern boolean_t avl_update(avl_tree_t *, void *); 263extern boolean_t avl_update_lt(avl_tree_t *, void *); 264extern boolean_t avl_update_gt(avl_tree_t *, void *); 265 266/* 267 * Swaps the contents of the two trees. 268 */ 269extern void avl_swap(avl_tree_t *tree1, avl_tree_t *tree2); 270 271/* 272 * Return the number of nodes in the tree 273 */ 274extern ulong_t avl_numnodes(avl_tree_t *tree); 275 276/* 277 * Return B_TRUE if there are zero nodes in the tree, B_FALSE otherwise. 278 */ 279extern boolean_t avl_is_empty(avl_tree_t *tree); 280 281/* 282 * Used to destroy any remaining nodes in a tree. The cookie argument should 283 * be initialized to NULL before the first call. Returns a node that has been 284 * removed from the tree and may be free()'d. Returns NULL when the tree is 285 * empty. 286 * 287 * Once you call avl_destroy_nodes(), you can only continuing calling it and 288 * finally avl_destroy(). No other AVL routines will be valid. 289 * 290 * cookie - a "void *" used to save state between calls to avl_destroy_nodes() 291 * 292 * EXAMPLE: 293 * avl_tree_t *tree; 294 * struct my_data *node; 295 * void *cookie; 296 * 297 * cookie = NULL; 298 * while ((node = avl_destroy_nodes(tree, &cookie)) != NULL) 299 * free(node); 300 * avl_destroy(tree); 301 */ 302extern void *avl_destroy_nodes(avl_tree_t *tree, void **cookie); 303 304 305/* 306 * Final destroy of an AVL tree. Arguments are: 307 * 308 * tree - the empty tree to destroy 309 */ 310extern void avl_destroy(avl_tree_t *tree); 311 312 313 314#ifdef __cplusplus 315} 316#endif 317 318#endif /* _AVL_H */ 319