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