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/*
* 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_destoy().
*
* 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.
*/
/*
* 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:
* stuct 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 */
```

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