+++ /dev/null
-/*
- * 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.
- */
-
-/*
- * AVL - generic AVL tree implementation for kernel use
- *
- * A complete description of AVL trees can be found in many CS textbooks.
- *
- * Here is a very brief overview. An AVL tree is a binary search tree that is
- * almost perfectly balanced. By "almost" perfectly balanced, we mean that at
- * any given node, the left and right subtrees are allowed to differ in height
- * by at most 1 level.
- *
- * This relaxation from a perfectly balanced binary tree allows doing
- * insertion and deletion relatively efficiently. Searching the tree is
- * still a fast operation, roughly O(log(N)).
- *
- * The key to insertion and deletion is a set of tree manipulations called
- * rotations, which bring unbalanced subtrees back into the semi-balanced state.
- *
- * This implementation of AVL trees has the following peculiarities:
- *
- * - The AVL specific data structures are physically embedded as fields
- * in the "using" data structures. To maintain generality the code
- * must constantly translate between "avl_node_t *" and containing
- * data structure "void *"s by adding/subtracting the avl_offset.
- *
- * - Since the AVL data is always embedded in other structures, there is
- * no locking or memory allocation in the AVL routines. This must be
- * provided for by the enclosing data structure's semantics. Typically,
- * avl_insert()/_add()/_remove()/avl_insert_here() require some kind of
- * exclusive write lock. Other operations require a read lock.
- *
- * - The implementation uses iteration instead of explicit recursion,
- * since it is intended to run on limited size kernel stacks. Since
- * there is no recursion stack present to move "up" in the tree,
- * there is an explicit "parent" link in the avl_node_t.
- *
- * - The left/right children pointers of a node are in an array.
- * In the code, variables (instead of constants) are used to represent
- * left and right indices. The implementation is written as if it only
- * dealt with left handed manipulations. By changing the value assigned
- * to "left", the code also works for right handed trees. The
- * following variables/terms are frequently used:
- *
- * int left; // 0 when dealing with left children,
- * // 1 for dealing with right children
- *
- * int left_heavy; // -1 when left subtree is taller at some node,
- * // +1 when right subtree is taller
- *
- * int right; // will be the opposite of left (0 or 1)
- * int right_heavy;// will be the opposite of left_heavy (-1 or 1)
- *
- * int direction; // 0 for "<" (ie. left child); 1 for ">" (right)
- *
- * Though it is a little more confusing to read the code, the approach
- * allows using half as much code (and hence cache footprint) for tree
- * manipulations and eliminates many conditional branches.
- *
- * - The avl_index_t is an opaque "cookie" used to find nodes at or
- * adjacent to where a new value would be inserted in the tree. The value
- * is a modified "avl_node_t *". The bottom bit (normally 0 for a
- * pointer) is set to indicate if that the new node has a value greater
- * than the value of the indicated "avl_node_t *".
- *
- * Note - in addition to userland (e.g. libavl and libutil) and the kernel
- * (e.g. genunix), avl.c is compiled into ld.so and kmdb's genunix module,
- * which each have their own compilation environments and subsequent
- * requirements. Each of these environments must be considered when adding
- * dependencies from avl.c.
- */
-
-#include <sys/types.h>
-#include <sys/param.h>
-#include <sys/debug.h>
-#include <sys/avl.h>
-#include <sys/cmn_err.h>
-
-/*
- * Small arrays to translate between balance (or diff) values and child indices.
- *
- * Code that deals with binary tree data structures will randomly use
- * left and right children when examining a tree. C "if()" statements
- * which evaluate randomly suffer from very poor hardware branch prediction.
- * In this code we avoid some of the branch mispredictions by using the
- * following translation arrays. They replace random branches with an
- * additional memory reference. Since the translation arrays are both very
- * small the data should remain efficiently in cache.
- */
-static const int avl_child2balance[2] = {-1, 1};
-static const int avl_balance2child[] = {0, 0, 1};
-
-
-/*
- * Walk from one node to the previous valued node (ie. an infix walk
- * towards the left). At any given node we do one of 2 things:
- *
- * - If there is a left child, go to it, then to it's rightmost descendant.
- *
- * - otherwise we return through parent nodes until we've come from a right
- * child.
- *
- * Return Value:
- * NULL - if at the end of the nodes
- * otherwise next node
- */
-void *
-avl_walk(avl_tree_t *tree, void *oldnode, int left)
-{
- size_t off = tree->avl_offset;
- avl_node_t *node = AVL_DATA2NODE(oldnode, off);
- int right = 1 - left;
- int was_child;
-
-
- /*
- * nowhere to walk to if tree is empty
- */
- if (node == NULL)
- return (NULL);
-
- /*
- * Visit the previous valued node. There are two possibilities:
- *
- * If this node has a left child, go down one left, then all
- * the way right.
- */
- if (node->avl_child[left] != NULL) {
- for (node = node->avl_child[left];
- node->avl_child[right] != NULL;
- node = node->avl_child[right])
- ;
- /*
- * Otherwise, return thru left children as far as we can.
- */
- } else {
- for (;;) {
- was_child = AVL_XCHILD(node);
- node = AVL_XPARENT(node);
- if (node == NULL)
- return (NULL);
- if (was_child == right)
- break;
- }
- }
-
- return (AVL_NODE2DATA(node, off));
-}
-
-/*
- * Return the lowest valued node in a tree or NULL.
- * (leftmost child from root of tree)
- */
-void *
-avl_first(avl_tree_t *tree)
-{
- avl_node_t *node;
- avl_node_t *prev = NULL;
- size_t off = tree->avl_offset;
-
- for (node = tree->avl_root; node != NULL; node = node->avl_child[0])
- prev = node;
-
- if (prev != NULL)
- return (AVL_NODE2DATA(prev, off));
- return (NULL);
-}
-
-/*
- * Return the highest valued node in a tree or NULL.
- * (rightmost child from root of tree)
- */
-void *
-avl_last(avl_tree_t *tree)
-{
- avl_node_t *node;
- avl_node_t *prev = NULL;
- size_t off = tree->avl_offset;
-
- for (node = tree->avl_root; node != NULL; node = node->avl_child[1])
- prev = node;
-
- if (prev != NULL)
- return (AVL_NODE2DATA(prev, off));
- return (NULL);
-}
-
-/*
- * Access the node immediately before or after an insertion point.
- *
- * "avl_index_t" is a (avl_node_t *) with the bottom bit indicating a child
- *
- * Return value:
- * NULL: no node in the given direction
- * "void *" of the found tree node
- */
-void *
-avl_nearest(avl_tree_t *tree, avl_index_t where, int direction)
-{
- int child = AVL_INDEX2CHILD(where);
- avl_node_t *node = AVL_INDEX2NODE(where);
- void *data;
- size_t off = tree->avl_offset;
-
- if (node == NULL) {
- ASSERT(tree->avl_root == NULL);
- return (NULL);
- }
- data = AVL_NODE2DATA(node, off);
- if (child != direction)
- return (data);
-
- return (avl_walk(tree, data, direction));
-}
-
-
-/*
- * Search for the node which contains "value". The algorithm is a
- * simple binary tree search.
- *
- * return value:
- * NULL: the value is not in the AVL tree
- * *where (if not NULL) is set to indicate the insertion point
- * "void *" of the found tree node
- */
-void *
-avl_find(avl_tree_t *tree, const void *value, avl_index_t *where)
-{
- avl_node_t *node;
- avl_node_t *prev = NULL;
- int child = 0;
- int diff;
- size_t off = tree->avl_offset;
-
- for (node = tree->avl_root; node != NULL;
- node = node->avl_child[child]) {
-
- prev = node;
-
- diff = tree->avl_compar(value, AVL_NODE2DATA(node, off));
- ASSERT(-1 <= diff && diff <= 1);
- if (diff == 0) {
-#ifdef DEBUG
- if (where != NULL)
- *where = 0;
-#endif
- return (AVL_NODE2DATA(node, off));
- }
- child = avl_balance2child[1 + diff];
-
- }
-
- if (where != NULL)
- *where = AVL_MKINDEX(prev, child);
-
- return (NULL);
-}
-
-
-/*
- * Perform a rotation to restore balance at the subtree given by depth.
- *
- * This routine is used by both insertion and deletion. The return value
- * indicates:
- * 0 : subtree did not change height
- * !0 : subtree was reduced in height
- *
- * The code is written as if handling left rotations, right rotations are
- * symmetric and handled by swapping values of variables right/left[_heavy]
- *
- * On input balance is the "new" balance at "node". This value is either
- * -2 or +2.
- */
-static int
-avl_rotation(avl_tree_t *tree, avl_node_t *node, int balance)
-{
- int left = !(balance < 0); /* when balance = -2, left will be 0 */
- int right = 1 - left;
- int left_heavy = balance >> 1;
- int right_heavy = -left_heavy;
- avl_node_t *parent = AVL_XPARENT(node);
- avl_node_t *child = node->avl_child[left];
- avl_node_t *cright;
- avl_node_t *gchild;
- avl_node_t *gright;
- avl_node_t *gleft;
- int which_child = AVL_XCHILD(node);
- int child_bal = AVL_XBALANCE(child);
-
- /* BEGIN CSTYLED */
- /*
- * case 1 : node is overly left heavy, the left child is balanced or
- * also left heavy. This requires the following rotation.
- *
- * (node bal:-2)
- * / \
- * / \
- * (child bal:0 or -1)
- * / \
- * / \
- * cright
- *
- * becomes:
- *
- * (child bal:1 or 0)
- * / \
- * / \
- * (node bal:-1 or 0)
- * / \
- * / \
- * cright
- *
- * we detect this situation by noting that child's balance is not
- * right_heavy.
- */
- /* END CSTYLED */
- if (child_bal != right_heavy) {
-
- /*
- * compute new balance of nodes
- *
- * If child used to be left heavy (now balanced) we reduced
- * the height of this sub-tree -- used in "return...;" below
- */
- child_bal += right_heavy; /* adjust towards right */
-
- /*
- * move "cright" to be node's left child
- */
- cright = child->avl_child[right];
- node->avl_child[left] = cright;
- if (cright != NULL) {
- AVL_SETPARENT(cright, node);
- AVL_SETCHILD(cright, left);
- }
-
- /*
- * move node to be child's right child
- */
- child->avl_child[right] = node;
- AVL_SETBALANCE(node, -child_bal);
- AVL_SETCHILD(node, right);
- AVL_SETPARENT(node, child);
-
- /*
- * update the pointer into this subtree
- */
- AVL_SETBALANCE(child, child_bal);
- AVL_SETCHILD(child, which_child);
- AVL_SETPARENT(child, parent);
- if (parent != NULL)
- parent->avl_child[which_child] = child;
- else
- tree->avl_root = child;
-
- return (child_bal == 0);
- }
-
- /* BEGIN CSTYLED */
- /*
- * case 2 : When node is left heavy, but child is right heavy we use
- * a different rotation.
- *
- * (node b:-2)
- * / \
- * / \
- * / \
- * (child b:+1)
- * / \
- * / \
- * (gchild b: != 0)
- * / \
- * / \
- * gleft gright
- *
- * becomes:
- *
- * (gchild b:0)
- * / \
- * / \
- * / \
- * (child b:?) (node b:?)
- * / \ / \
- * / \ / \
- * gleft gright
- *
- * computing the new balances is more complicated. As an example:
- * if gchild was right_heavy, then child is now left heavy
- * else it is balanced
- */
- /* END CSTYLED */
- gchild = child->avl_child[right];
- gleft = gchild->avl_child[left];
- gright = gchild->avl_child[right];
-
- /*
- * move gright to left child of node and
- *
- * move gleft to right child of node
- */
- node->avl_child[left] = gright;
- if (gright != NULL) {
- AVL_SETPARENT(gright, node);
- AVL_SETCHILD(gright, left);
- }
-
- child->avl_child[right] = gleft;
- if (gleft != NULL) {
- AVL_SETPARENT(gleft, child);
- AVL_SETCHILD(gleft, right);
- }
-
- /*
- * move child to left child of gchild and
- *
- * move node to right child of gchild and
- *
- * fixup parent of all this to point to gchild
- */
- balance = AVL_XBALANCE(gchild);
- gchild->avl_child[left] = child;
- AVL_SETBALANCE(child, (balance == right_heavy ? left_heavy : 0));
- AVL_SETPARENT(child, gchild);
- AVL_SETCHILD(child, left);
-
- gchild->avl_child[right] = node;
- AVL_SETBALANCE(node, (balance == left_heavy ? right_heavy : 0));
- AVL_SETPARENT(node, gchild);
- AVL_SETCHILD(node, right);
-
- AVL_SETBALANCE(gchild, 0);
- AVL_SETPARENT(gchild, parent);
- AVL_SETCHILD(gchild, which_child);
- if (parent != NULL)
- parent->avl_child[which_child] = gchild;
- else
- tree->avl_root = gchild;
-
- return (1); /* the new tree is always shorter */
-}
-
-
-/*
- * Insert a new node into an AVL tree at the specified (from avl_find()) place.
- *
- * Newly inserted nodes are always leaf nodes in the tree, since avl_find()
- * searches out to the leaf positions. The avl_index_t indicates the node
- * which will be the parent of the new node.
- *
- * After the node is inserted, a single rotation further up the tree may
- * be necessary to maintain an acceptable AVL balance.
- */
-void
-avl_insert(avl_tree_t *tree, void *new_data, avl_index_t where)
-{
- avl_node_t *node;
- avl_node_t *parent = AVL_INDEX2NODE(where);
- int old_balance;
- int new_balance;
- int which_child = AVL_INDEX2CHILD(where);
- size_t off = tree->avl_offset;
-
- ASSERT(tree);
-#ifdef _LP64
- ASSERT(((uintptr_t)new_data & 0x7) == 0);
-#endif
-
- node = AVL_DATA2NODE(new_data, off);
-
- /*
- * First, add the node to the tree at the indicated position.
- */
- ++tree->avl_numnodes;
-
- node->avl_child[0] = NULL;
- node->avl_child[1] = NULL;
-
- AVL_SETCHILD(node, which_child);
- AVL_SETBALANCE(node, 0);
- AVL_SETPARENT(node, parent);
- if (parent != NULL) {
- ASSERT(parent->avl_child[which_child] == NULL);
- parent->avl_child[which_child] = node;
- } else {
- ASSERT(tree->avl_root == NULL);
- tree->avl_root = node;
- }
- /*
- * Now, back up the tree modifying the balance of all nodes above the
- * insertion point. If we get to a highly unbalanced ancestor, we
- * need to do a rotation. If we back out of the tree we are done.
- * If we brought any subtree into perfect balance (0), we are also done.
- */
- for (;;) {
- node = parent;
- if (node == NULL)
- return;
-
- /*
- * Compute the new balance
- */
- old_balance = AVL_XBALANCE(node);
- new_balance = old_balance + avl_child2balance[which_child];
-
- /*
- * If we introduced equal balance, then we are done immediately
- */
- if (new_balance == 0) {
- AVL_SETBALANCE(node, 0);
- return;
- }
-
- /*
- * If both old and new are not zero we went
- * from -1 to -2 balance, do a rotation.
- */
- if (old_balance != 0)
- break;
-
- AVL_SETBALANCE(node, new_balance);
- parent = AVL_XPARENT(node);
- which_child = AVL_XCHILD(node);
- }
-
- /*
- * perform a rotation to fix the tree and return
- */
- (void) avl_rotation(tree, node, new_balance);
-}
-
-/*
- * Insert "new_data" in "tree" in the given "direction" either after or
- * before (AVL_AFTER, AVL_BEFORE) the data "here".
- *
- * Insertions can only be done at empty leaf points in the tree, therefore
- * if the given child of the node is already present we move to either
- * the AVL_PREV or AVL_NEXT and reverse the insertion direction. Since
- * every other node in the tree is a leaf, this always works.
- *
- * To help developers using this interface, we assert that the new node
- * is correctly ordered at every step of the way in DEBUG kernels.
- */
-void
-avl_insert_here(
- avl_tree_t *tree,
- void *new_data,
- void *here,
- int direction)
-{
- avl_node_t *node;
- int child = direction; /* rely on AVL_BEFORE == 0, AVL_AFTER == 1 */
-#ifdef DEBUG
- int diff;
-#endif
-
- ASSERT(tree != NULL);
- ASSERT(new_data != NULL);
- ASSERT(here != NULL);
- ASSERT(direction == AVL_BEFORE || direction == AVL_AFTER);
-
- /*
- * If corresponding child of node is not NULL, go to the neighboring
- * node and reverse the insertion direction.
- */
- node = AVL_DATA2NODE(here, tree->avl_offset);
-
-#ifdef DEBUG
- diff = tree->avl_compar(new_data, here);
- ASSERT(-1 <= diff && diff <= 1);
- ASSERT(diff != 0);
- ASSERT(diff > 0 ? child == 1 : child == 0);
-#endif
-
- if (node->avl_child[child] != NULL) {
- node = node->avl_child[child];
- child = 1 - child;
- while (node->avl_child[child] != NULL) {
-#ifdef DEBUG
- diff = tree->avl_compar(new_data,
- AVL_NODE2DATA(node, tree->avl_offset));
- ASSERT(-1 <= diff && diff <= 1);
- ASSERT(diff != 0);
- ASSERT(diff > 0 ? child == 1 : child == 0);
-#endif
- node = node->avl_child[child];
- }
-#ifdef DEBUG
- diff = tree->avl_compar(new_data,
- AVL_NODE2DATA(node, tree->avl_offset));
- ASSERT(-1 <= diff && diff <= 1);
- ASSERT(diff != 0);
- ASSERT(diff > 0 ? child == 1 : child == 0);
-#endif
- }
- ASSERT(node->avl_child[child] == NULL);
-
- avl_insert(tree, new_data, AVL_MKINDEX(node, child));
-}
-
-/*
- * Add a new node to an AVL tree.
- */
-void
-avl_add(avl_tree_t *tree, void *new_node)
-{
- avl_index_t where;
-
- /*
- * This is unfortunate. We want to call panic() here, even for
- * non-DEBUG kernels. In userland, however, we can't depend on anything
- * in libc or else the rtld build process gets confused. So, all we can
- * do in userland is resort to a normal ASSERT().
- */
- if (avl_find(tree, new_node, &where) != NULL)
-#ifdef _KERNEL
- panic("avl_find() succeeded inside avl_add()");
-#else
- ASSERT(0);
-#endif
- avl_insert(tree, new_node, where);
-}
-
-/*
- * Delete a node from the AVL tree. Deletion is similar to insertion, but
- * with 2 complications.
- *
- * First, we may be deleting an interior node. Consider the following subtree:
- *
- * d c c
- * / \ / \ / \
- * b e b e b e
- * / \ / \ /
- * a c a a
- *
- * When we are deleting node (d), we find and bring up an adjacent valued leaf
- * node, say (c), to take the interior node's place. In the code this is
- * handled by temporarily swapping (d) and (c) in the tree and then using
- * common code to delete (d) from the leaf position.
- *
- * Secondly, an interior deletion from a deep tree may require more than one
- * rotation to fix the balance. This is handled by moving up the tree through
- * parents and applying rotations as needed. The return value from
- * avl_rotation() is used to detect when a subtree did not change overall
- * height due to a rotation.
- */
-void
-avl_remove(avl_tree_t *tree, void *data)
-{
- avl_node_t *delete;
- avl_node_t *parent;
- avl_node_t *node;
- avl_node_t tmp;
- int old_balance;
- int new_balance;
- int left;
- int right;
- int which_child;
- size_t off = tree->avl_offset;
-
- ASSERT(tree);
-
- delete = AVL_DATA2NODE(data, off);
-
- /*
- * Deletion is easiest with a node that has at most 1 child.
- * We swap a node with 2 children with a sequentially valued
- * neighbor node. That node will have at most 1 child. Note this
- * has no effect on the ordering of the remaining nodes.
- *
- * As an optimization, we choose the greater neighbor if the tree
- * is right heavy, otherwise the left neighbor. This reduces the
- * number of rotations needed.
- */
- if (delete->avl_child[0] != NULL && delete->avl_child[1] != NULL) {
-
- /*
- * choose node to swap from whichever side is taller
- */
- old_balance = AVL_XBALANCE(delete);
- left = avl_balance2child[old_balance + 1];
- right = 1 - left;
-
- /*
- * get to the previous value'd node
- * (down 1 left, as far as possible right)
- */
- for (node = delete->avl_child[left];
- node->avl_child[right] != NULL;
- node = node->avl_child[right])
- ;
-
- /*
- * create a temp placeholder for 'node'
- * move 'node' to delete's spot in the tree
- */
- tmp = *node;
-
- *node = *delete;
- if (node->avl_child[left] == node)
- node->avl_child[left] = &tmp;
-
- parent = AVL_XPARENT(node);
- if (parent != NULL)
- parent->avl_child[AVL_XCHILD(node)] = node;
- else
- tree->avl_root = node;
- AVL_SETPARENT(node->avl_child[left], node);
- AVL_SETPARENT(node->avl_child[right], node);
-
- /*
- * Put tmp where node used to be (just temporary).
- * It always has a parent and at most 1 child.
- */
- delete = &tmp;
- parent = AVL_XPARENT(delete);
- parent->avl_child[AVL_XCHILD(delete)] = delete;
- which_child = (delete->avl_child[1] != 0);
- if (delete->avl_child[which_child] != NULL)
- AVL_SETPARENT(delete->avl_child[which_child], delete);
- }
-
-
- /*
- * Here we know "delete" is at least partially a leaf node. It can
- * be easily removed from the tree.
- */
- ASSERT(tree->avl_numnodes > 0);
- --tree->avl_numnodes;
- parent = AVL_XPARENT(delete);
- which_child = AVL_XCHILD(delete);
- if (delete->avl_child[0] != NULL)
- node = delete->avl_child[0];
- else
- node = delete->avl_child[1];
-
- /*
- * Connect parent directly to node (leaving out delete).
- */
- if (node != NULL) {
- AVL_SETPARENT(node, parent);
- AVL_SETCHILD(node, which_child);
- }
- if (parent == NULL) {
- tree->avl_root = node;
- return;
- }
- parent->avl_child[which_child] = node;
-
-
- /*
- * Since the subtree is now shorter, begin adjusting parent balances
- * and performing any needed rotations.
- */
- do {
-
- /*
- * Move up the tree and adjust the balance
- *
- * Capture the parent and which_child values for the next
- * iteration before any rotations occur.
- */
- node = parent;
- old_balance = AVL_XBALANCE(node);
- new_balance = old_balance - avl_child2balance[which_child];
- parent = AVL_XPARENT(node);
- which_child = AVL_XCHILD(node);
-
- /*
- * If a node was in perfect balance but isn't anymore then
- * we can stop, since the height didn't change above this point
- * due to a deletion.
- */
- if (old_balance == 0) {
- AVL_SETBALANCE(node, new_balance);
- break;
- }
-
- /*
- * If the new balance is zero, we don't need to rotate
- * else
- * need a rotation to fix the balance.
- * If the rotation doesn't change the height
- * of the sub-tree we have finished adjusting.
- */
- if (new_balance == 0)
- AVL_SETBALANCE(node, new_balance);
- else if (!avl_rotation(tree, node, new_balance))
- break;
- } while (parent != NULL);
-}
-
-#define AVL_REINSERT(tree, obj) \
- avl_remove((tree), (obj)); \
- avl_add((tree), (obj))
-
-boolean_t
-avl_update_lt(avl_tree_t *t, void *obj)
-{
- void *neighbor;
-
- ASSERT(((neighbor = AVL_NEXT(t, obj)) == NULL) ||
- (t->avl_compar(obj, neighbor) <= 0));
-
- neighbor = AVL_PREV(t, obj);
- if ((neighbor != NULL) && (t->avl_compar(obj, neighbor) < 0)) {
- AVL_REINSERT(t, obj);
- return (B_TRUE);
- }
-
- return (B_FALSE);
-}
-
-boolean_t
-avl_update_gt(avl_tree_t *t, void *obj)
-{
- void *neighbor;
-
- ASSERT(((neighbor = AVL_PREV(t, obj)) == NULL) ||
- (t->avl_compar(obj, neighbor) >= 0));
-
- neighbor = AVL_NEXT(t, obj);
- if ((neighbor != NULL) && (t->avl_compar(obj, neighbor) > 0)) {
- AVL_REINSERT(t, obj);
- return (B_TRUE);
- }
-
- return (B_FALSE);
-}
-
-boolean_t
-avl_update(avl_tree_t *t, void *obj)
-{
- void *neighbor;
-
- neighbor = AVL_PREV(t, obj);
- if ((neighbor != NULL) && (t->avl_compar(obj, neighbor) < 0)) {
- AVL_REINSERT(t, obj);
- return (B_TRUE);
- }
-
- neighbor = AVL_NEXT(t, obj);
- if ((neighbor != NULL) && (t->avl_compar(obj, neighbor) > 0)) {
- AVL_REINSERT(t, obj);
- return (B_TRUE);
- }
-
- return (B_FALSE);
-}
-
-void
-avl_swap(avl_tree_t *tree1, avl_tree_t *tree2)
-{
- avl_node_t *temp_node;
- ulong_t temp_numnodes;
-
- ASSERT3P(tree1->avl_compar, ==, tree2->avl_compar);
- ASSERT3U(tree1->avl_offset, ==, tree2->avl_offset);
- ASSERT3U(tree1->avl_size, ==, tree2->avl_size);
-
- temp_node = tree1->avl_root;
- temp_numnodes = tree1->avl_numnodes;
- tree1->avl_root = tree2->avl_root;
- tree1->avl_numnodes = tree2->avl_numnodes;
- tree2->avl_root = temp_node;
- tree2->avl_numnodes = temp_numnodes;
-}
-
-/*
- * initialize a new AVL tree
- */
-void
-avl_create(avl_tree_t *tree, int (*compar) (const void *, const void *),
- size_t size, size_t offset)
-{
- ASSERT(tree);
- ASSERT(compar);
- ASSERT(size > 0);
- ASSERT(size >= offset + sizeof (avl_node_t));
-#ifdef _LP64
- ASSERT((offset & 0x7) == 0);
-#endif
-
- tree->avl_compar = compar;
- tree->avl_root = NULL;
- tree->avl_numnodes = 0;
- tree->avl_size = size;
- tree->avl_offset = offset;
-}
-
-/*
- * Delete a tree.
- */
-/* ARGSUSED */
-void
-avl_destroy(avl_tree_t *tree)
-{
- ASSERT(tree);
- ASSERT(tree->avl_numnodes == 0);
- ASSERT(tree->avl_root == NULL);
-}
-
-
-/*
- * Return the number of nodes in an AVL tree.
- */
-ulong_t
-avl_numnodes(avl_tree_t *tree)
-{
- ASSERT(tree);
- return (tree->avl_numnodes);
-}
-
-boolean_t
-avl_is_empty(avl_tree_t *tree)
-{
- ASSERT(tree);
- return (tree->avl_numnodes == 0);
-}
-
-#define CHILDBIT (1L)
-
-/*
- * Post-order tree walk used to visit all tree nodes and destroy the tree
- * in post order. This is used for destroying a tree without paying any cost
- * for rebalancing it.
- *
- * example:
- *
- * void *cookie = NULL;
- * my_data_t *node;
- *
- * while ((node = avl_destroy_nodes(tree, &cookie)) != NULL)
- * free(node);
- * avl_destroy(tree);
- *
- * The cookie is really an avl_node_t to the current node's parent and
- * an indication of which child you looked at last.
- *
- * On input, a cookie value of CHILDBIT indicates the tree is done.
- */
-void *
-avl_destroy_nodes(avl_tree_t *tree, void **cookie)
-{
- avl_node_t *node;
- avl_node_t *parent;
- int child;
- void *first;
- size_t off = tree->avl_offset;
-
- /*
- * Initial calls go to the first node or it's right descendant.
- */
- if (*cookie == NULL) {
- first = avl_first(tree);
-
- /*
- * deal with an empty tree
- */
- if (first == NULL) {
- *cookie = (void *)CHILDBIT;
- return (NULL);
- }
-
- node = AVL_DATA2NODE(first, off);
- parent = AVL_XPARENT(node);
- goto check_right_side;
- }
-
- /*
- * If there is no parent to return to we are done.
- */
- parent = (avl_node_t *)((uintptr_t)(*cookie) & ~CHILDBIT);
- if (parent == NULL) {
- if (tree->avl_root != NULL) {
- ASSERT(tree->avl_numnodes == 1);
- tree->avl_root = NULL;
- tree->avl_numnodes = 0;
- }
- return (NULL);
- }
-
- /*
- * Remove the child pointer we just visited from the parent and tree.
- */
- child = (uintptr_t)(*cookie) & CHILDBIT;
- parent->avl_child[child] = NULL;
- ASSERT(tree->avl_numnodes > 1);
- --tree->avl_numnodes;
-
- /*
- * If we just did a right child or there isn't one, go up to parent.
- */
- if (child == 1 || parent->avl_child[1] == NULL) {
- node = parent;
- parent = AVL_XPARENT(parent);
- goto done;
- }
-
- /*
- * Do parent's right child, then leftmost descendent.
- */
- node = parent->avl_child[1];
- while (node->avl_child[0] != NULL) {
- parent = node;
- node = node->avl_child[0];
- }
-
- /*
- * If here, we moved to a left child. It may have one
- * child on the right (when balance == +1).
- */
-check_right_side:
- if (node->avl_child[1] != NULL) {
- ASSERT(AVL_XBALANCE(node) == 1);
- parent = node;
- node = node->avl_child[1];
- ASSERT(node->avl_child[0] == NULL &&
- node->avl_child[1] == NULL);
- } else {
- ASSERT(AVL_XBALANCE(node) <= 0);
- }
-
-done:
- if (parent == NULL) {
- *cookie = (void *)CHILDBIT;
- ASSERT(node == tree->avl_root);
- } else {
- *cookie = (void *)((uintptr_t)parent | AVL_XCHILD(node));
- }
-
- return (AVL_NODE2DATA(node, off));
-}
projects / people / julieng / freebsd.git / commitdiff