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author | Andriy Gapon <avg@FreeBSD.org> | 2015-09-28 12:23:10 +0000 |
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committer | Andriy Gapon <avg@FreeBSD.org> | 2015-09-28 12:23:10 +0000 |

commit | 65b71c48d226f3ef3eb1c4452dccc678a7d2ac96 (patch) | |

tree | a7de80990b9bdf771dc666e6c9be6f08d41a58ce /cddl | |

parent | 2f2f522b5de618d24c7ce477bc54ec945124122c (diff) | |

download | src-65b71c48d226f3ef3eb1c4452dccc678a7d2ac96.tar.gz src-65b71c48d226f3ef3eb1c4452dccc678a7d2ac96.zip |

remove an extra copy of avl.c from illumos contrib code

MFC after: 20 days

Notes

Notes:
svn path=/head/; revision=288337

Diffstat (limited to 'cddl')

-rw-r--r-- | cddl/contrib/opensolaris/common/avl/avl.c | 1059 |

1 files changed, 0 insertions, 1059 deletions

diff --git a/cddl/contrib/opensolaris/common/avl/avl.c b/cddl/contrib/opensolaris/common/avl/avl.c deleted file mode 100644 index 4223da49915c..000000000000 --- a/cddl/contrib/opensolaris/common/avl/avl.c +++ /dev/null @@ -1,1059 +0,0 @@ -/* - * 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)); -} |