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