external/cddl/osnet/dist/uts/common/sys/avl.h

   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 2008 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 #pragma ident   "%Z%%M% %I%     %E% SMI"
  30
  31 /*
  32  * This is a private header file.  Applications should not directly include
  33  * this file.
  34  */
  35
  36 #ifdef  __cplusplus
  37 extern "C" {
  38 #endif
  39
  40 #include <sys/types.h>
  41 #include <sys/avl_impl.h>
  42
  43 /*
  44  * This is a generic implemenatation of AVL trees for use in the Solaris kernel.
  45  * The interfaces provide an efficient way of implementing an ordered set of
  46  * data structures.
  47  *
  48  * AVL trees provide an alternative to using an ordered linked list. Using AVL
  49  * trees will usually be faster, however they requires more storage. An ordered
  50  * linked list in general requires 2 pointers in each data structure. The
  51  * AVL tree implementation uses 3 pointers. The following chart gives the
  52  * approximate performance of operations with the different approaches:
  53  *
  54  *      Operation        Link List      AVL tree
  55  *      ---------        --------       --------
  56  *      lookup             O(n)         O(log(n))
  57  *
  58  *      insert 1 node    constant       constant
  59  *
  60  *      delete 1 node    constant       between constant and O(log(n))
  61  *
  62  *      delete all nodes   O(n)         O(n)
  63  *
  64  *      visit the next
  65  *      or prev node     constant       between constant and O(log(n))
  66  *
  67  *
  68  * The data structure nodes are anchored at an "avl_tree_t" (the equivalent
  69  * of a list header) and the individual nodes will have a field of
  70  * type "avl_node_t" (corresponding to list pointers).
  71  *
  72  * The type "avl_index_t" is used to indicate a position in the list for
  73  * certain calls.
  74  *
  75  * The usage scenario is generally:
  76  *
  77  * 1. Create the list/tree with: avl_create()
  78  *
  79  * followed by any mixture of:
  80  *
  81  * 2a. Insert nodes with: avl_add(), or avl_find() and avl_insert()
  82  *
  83  * 2b. Visited elements with:
  84  *       avl_first() - returns the lowest valued node
  85  *       avl_last() - returns the highest valued node
  86  *       AVL_NEXT() - given a node go to next higher one
  87  *       AVL_PREV() - given a node go to previous lower one
  88  *
  89  * 2c.  Find the node with the closest value either less than or greater
  90  *      than a given value with avl_nearest().
  91  *
  92  * 2d. Remove individual nodes from the list/tree with avl_remove().
  93  *
  94  * and finally when the list is being destroyed
  95  *
  96  * 3. Use avl_destroy_nodes() to quickly process/free up any remaining nodes.
  97  *    Note that once you use avl_destroy_nodes(), you can no longer
  98  *    use any routine except avl_destroy_nodes() and avl_destoy().
  99  *
 100  * 4. Use avl_destroy() to destroy the AVL tree itself.
 101  *
 102  * Any locking for multiple thread access is up to the user to provide, just
 103  * as is needed for any linked list implementation.
 104  */
 105
 106
 107 /*
 108  * Type used for the root of the AVL tree.
 109  */
 110 typedef struct avl_tree avl_tree_t;
 111
 112 /*
 113  * The data nodes in the AVL tree must have a field of this type.
 114  */
 115 typedef struct avl_node avl_node_t;
 116
 117 /*
 118  * An opaque type used to locate a position in the tree where a node
 119  * would be inserted.
 120  */
 121 typedef uintptr_t avl_index_t;
 122
 123
 124 /*
 125  * Direction constants used for avl_nearest().
 126  */
 127 #define AVL_BEFORE      (0)
 128 #define AVL_AFTER       (1)
 129
 130
 131 /*
 132  * Prototypes
 133  *
 134  * Where not otherwise mentioned, "void *" arguments are a pointer to the
 135  * user data structure which must contain a field of type avl_node_t.
 136  *
 137  * Also assume the user data structures looks like:
 138  *      stuct my_type {
 139  *              ...
 140  *              avl_node_t      my_link;
 141  *              ...
 142  *      };
 143  */
 144
 145 /*
 146  * Initialize an AVL tree. Arguments are:
 147  *
 148  * tree   - the tree to be initialized
 149  * compar - function to compare two nodes, it must return exactly: -1, 0, or +1
 150  *          -1 for <, 0 for ==, and +1 for >
 151  * size   - the value of sizeof(struct my_type)
 152  * offset - the value of OFFSETOF(struct my_type, my_link)
 153  */
 154 extern void avl_create(avl_tree_t *tree,
 155         int (*compar) (const void *, const void *), size_t size, size_t offset);
 156
 157
 158 /*
 159  * Find a node with a matching value in the tree. Returns the matching node
 160  * found. If not found, it returns NULL and then if "where" is not NULL it sets
 161  * "where" for use with avl_insert() or avl_nearest().
 162  *
 163  * node   - node that has the value being looked for
 164  * where  - position for use with avl_nearest() or avl_insert(), may be NULL
 165  */
 166 extern void *avl_find(avl_tree_t *tree, void *node, avl_index_t *where);
 167
 168 /*
 169  * Insert a node into the tree.
 170  *
 171  * node   - the node to insert
 172  * where  - position as returned from avl_find()
 173  */
 174 extern void avl_insert(avl_tree_t *tree, void *node, avl_index_t where);
 175
 176 /*
 177  * Insert "new_data" in "tree" in the given "direction" either after
 178  * or before the data "here".
 179  *
 180  * This might be usefull for avl clients caching recently accessed
 181  * data to avoid doing avl_find() again for insertion.
 182  *
 183  * new_data     - new data to insert
 184  * here         - existing node in "tree"
 185  * direction    - either AVL_AFTER or AVL_BEFORE the data "here".
 186  */
 187 extern void avl_insert_here(avl_tree_t *tree, void *new_data, void *here,
 188     int direction);
 189
 190
 191 /*
 192  * Return the first or last valued node in the tree. Will return NULL
 193  * if the tree is empty.
 194  *
 195  */
 196 extern void *avl_first(avl_tree_t *tree);
 197 extern void *avl_last(avl_tree_t *tree);
 198
 199
 200 /*
 201  * Return the next or previous valued node in the tree.
 202  * AVL_NEXT() will return NULL if at the last node.
 203  * AVL_PREV() will return NULL if at the first node.
 204  *
 205  * node   - the node from which the next or previous node is found
 206  */
 207 #define AVL_NEXT(tree, node)    avl_walk(tree, node, AVL_AFTER)
 208 #define AVL_PREV(tree, node)    avl_walk(tree, node, AVL_BEFORE)
 209
 210
 211 /*
 212  * Find the node with the nearest value either greater or less than
 213  * the value from a previous avl_find(). Returns the node or NULL if
 214  * there isn't a matching one.
 215  *
 216  * where     - position as returned from avl_find()
 217  * direction - either AVL_BEFORE or AVL_AFTER
 218  *
 219  * EXAMPLE get the greatest node that is less than a given value:
 220  *
 221  *      avl_tree_t *tree;
 222  *      struct my_data look_for_value = {....};
 223  *      struct my_data *node;
 224  *      struct my_data *less;
 225  *      avl_index_t where;
 226  *
 227  *      node = avl_find(tree, &look_for_value, &where);
 228  *      if (node != NULL)
 229  *              less = AVL_PREV(tree, node);
 230  *      else
 231  *              less = avl_nearest(tree, where, AVL_BEFORE);
 232  */
 233 extern void *avl_nearest(avl_tree_t *tree, avl_index_t where, int direction);
 234
 235
 236 /*
 237  * Add a single node to the tree.
 238  * The node must not be in the tree, and it must not
 239  * compare equal to any other node already in the tree.
 240  *
 241  * node   - the node to add
 242  */
 243 extern void avl_add(avl_tree_t *tree, void *node);
 244
 245
 246 /*
 247  * Remove a single node from the tree.  The node must be in the tree.
 248  *
 249  * node   - the node to remove
 250  */
 251 extern void avl_remove(avl_tree_t *tree, void *node);
 252
 253 /*
 254  * Reinsert a node only if its order has changed relative to its nearest
 255  * neighbors. To optimize performance avl_update_lt() checks only the previous
 256  * node and avl_update_gt() checks only the next node. Use avl_update_lt() and
 257  * avl_update_gt() only if you know the direction in which the order of the
 258  * node may change.
 259  */
 260 extern boolean_t avl_update(avl_tree_t *, void *);
 261 extern boolean_t avl_update_lt(avl_tree_t *, void *);
 262 extern boolean_t avl_update_gt(avl_tree_t *, void *);
 263
 264 /*
 265  * Return the number of nodes in the tree
 266  */
 267 extern ulong_t avl_numnodes(avl_tree_t *tree);
 268
 269 /*
 270  * Return B_TRUE if there are zero nodes in the tree, B_FALSE otherwise.
 271  */
 272 extern boolean_t avl_is_empty(avl_tree_t *tree);
 273
 274 /*
 275  * Used to destroy any remaining nodes in a tree. The cookie argument should
 276  * be initialized to NULL before the first call. Returns a node that has been
 277  * removed from the tree and may be free()'d. Returns NULL when the tree is
 278  * empty.
 279  *
 280  * Once you call avl_destroy_nodes(), you can only continuing calling it and
 281  * finally avl_destroy(). No other AVL routines will be valid.
 282  *
 283  * cookie - a "void *" used to save state between calls to avl_destroy_nodes()
 284  *
 285  * EXAMPLE:
 286  *      avl_tree_t *tree;
 287  *      struct my_data *node;
 288  *      void *cookie;
 289  *
 290  *      cookie = NULL;
 291  *      while ((node = avl_destroy_nodes(tree, &cookie)) != NULL)
 292  *              free(node);
 293  *      avl_destroy(tree);
 294  */
 295 extern void *avl_destroy_nodes(avl_tree_t *tree, void **cookie);
 296
 297
 298 /*
 299  * Final destroy of an AVL tree. Arguments are:
 300  *
 301  * tree   - the empty tree to destroy
 302  */
 303 extern void avl_destroy(avl_tree_t *tree);
 304
 305
 306
 307 #ifdef  __cplusplus
 308 }
 309 #endif
 310
 311 #endif  /* _AVL_H */