Red Black Trees
(C) 1999 Andrea Arcangeli <andrea@suse.de>
(C) 2002 David Woodhouse <dwmw2@infradead.org>
-
+ (C) 2012 Michel Lespinasse <walken@google.com>
+
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
linux/lib/rbtree.c
*/
-#include "rbtree.h"
-
-static void __rb_rotate_left(struct rb_node *node, struct rb_root *root)
-{
- struct rb_node *right = node->rb_right;
- struct rb_node *parent = rb_parent(node);
+#include "rbtree_augmented.h"
- if ((node->rb_right = right->rb_left))
- rb_set_parent(right->rb_left, node);
- right->rb_left = node;
-
- rb_set_parent(right, parent);
+/*
+ * red-black trees properties: http://en.wikipedia.org/wiki/Rbtree
+ *
+ * 1) A node is either red or black
+ * 2) The root is black
+ * 3) All leaves (NULL) are black
+ * 4) Both children of every red node are black
+ * 5) Every simple path from root to leaves contains the same number
+ * of black nodes.
+ *
+ * 4 and 5 give the O(log n) guarantee, since 4 implies you cannot have two
+ * consecutive red nodes in a path and every red node is therefore followed by
+ * a black. So if B is the number of black nodes on every simple path (as per
+ * 5), then the longest possible path due to 4 is 2B.
+ *
+ * We shall indicate color with case, where black nodes are uppercase and red
+ * nodes will be lowercase. Unknown color nodes shall be drawn as red within
+ * parentheses and have some accompanying text comment.
+ */
- if (parent)
- {
- if (node == parent->rb_left)
- parent->rb_left = right;
- else
- parent->rb_right = right;
- }
- else
- root->rb_node = right;
- rb_set_parent(node, right);
+static inline void rb_set_black(struct rb_node *rb)
+{
+ rb->__rb_parent_color |= RB_BLACK;
}
-static void __rb_rotate_right(struct rb_node *node, struct rb_root *root)
+static inline struct rb_node *rb_red_parent(struct rb_node *red)
{
- struct rb_node *left = node->rb_left;
- struct rb_node *parent = rb_parent(node);
-
- if ((node->rb_left = left->rb_right))
- rb_set_parent(left->rb_right, node);
- left->rb_right = node;
-
- rb_set_parent(left, parent);
+ return (struct rb_node *)red->__rb_parent_color;
+}
- if (parent)
- {
- if (node == parent->rb_right)
- parent->rb_right = left;
- else
- parent->rb_left = left;
- }
- else
- root->rb_node = left;
- rb_set_parent(node, left);
+/*
+ * Helper function for rotations:
+ * - old's parent and color get assigned to new
+ * - old gets assigned new as a parent and 'color' as a color.
+ */
+static inline void
+__rb_rotate_set_parents(struct rb_node *old, struct rb_node *new,
+ struct rb_root *root, int color)
+{
+ struct rb_node *parent = rb_parent(old);
+ new->__rb_parent_color = old->__rb_parent_color;
+ rb_set_parent_color(old, new, color);
+ __rb_change_child(old, new, parent, root);
}
-void rb_insert_color(struct rb_node *node, struct rb_root *root)
+static __always_inline void
+__rb_insert(struct rb_node *node, struct rb_root *root,
+ void (*augment_rotate)(struct rb_node *old, struct rb_node *new))
{
- struct rb_node *parent, *gparent;
-
- while ((parent = rb_parent(node)) && rb_is_red(parent))
- {
- gparent = rb_parent(parent);
-
- if (parent == gparent->rb_left)
- {
- {
- register struct rb_node *uncle = gparent->rb_right;
- if (uncle && rb_is_red(uncle))
- {
- rb_set_black(uncle);
- rb_set_black(parent);
- rb_set_red(gparent);
- node = gparent;
- continue;
- }
+ struct rb_node *parent = rb_red_parent(node), *gparent, *tmp;
+
+ while (true) {
+ /*
+ * Loop invariant: node is red
+ *
+ * If there is a black parent, we are done.
+ * Otherwise, take some corrective action as we don't
+ * want a red root or two consecutive red nodes.
+ */
+ if (!parent) {
+ rb_set_parent_color(node, NULL, RB_BLACK);
+ break;
+ } else if (rb_is_black(parent))
+ break;
+
+ gparent = rb_red_parent(parent);
+
+ tmp = gparent->rb_right;
+ if (parent != tmp) { /* parent == gparent->rb_left */
+ if (tmp && rb_is_red(tmp)) {
+ /*
+ * Case 1 - color flips
+ *
+ * G g
+ * / \ / \
+ * p u --> P U
+ * / /
+ * n n
+ *
+ * However, since g's parent might be red, and
+ * 4) does not allow this, we need to recurse
+ * at g.
+ */
+ rb_set_parent_color(tmp, gparent, RB_BLACK);
+ rb_set_parent_color(parent, gparent, RB_BLACK);
+ node = gparent;
+ parent = rb_parent(node);
+ rb_set_parent_color(node, parent, RB_RED);
+ continue;
}
- if (parent->rb_right == node)
- {
- register struct rb_node *tmp;
- __rb_rotate_left(parent, root);
- tmp = parent;
+ tmp = parent->rb_right;
+ if (node == tmp) {
+ /*
+ * Case 2 - left rotate at parent
+ *
+ * G G
+ * / \ / \
+ * p U --> n U
+ * \ /
+ * n p
+ *
+ * This still leaves us in violation of 4), the
+ * continuation into Case 3 will fix that.
+ */
+ parent->rb_right = tmp = node->rb_left;
+ node->rb_left = parent;
+ if (tmp)
+ rb_set_parent_color(tmp, parent,
+ RB_BLACK);
+ rb_set_parent_color(parent, node, RB_RED);
+ augment_rotate(parent, node);
parent = node;
- node = tmp;
+ tmp = node->rb_right;
}
- rb_set_black(parent);
- rb_set_red(gparent);
- __rb_rotate_right(gparent, root);
+ /*
+ * Case 3 - right rotate at gparent
+ *
+ * G P
+ * / \ / \
+ * p U --> n g
+ * / \
+ * n U
+ */
+ gparent->rb_left = tmp; /* == parent->rb_right */
+ parent->rb_right = gparent;
+ if (tmp)
+ rb_set_parent_color(tmp, gparent, RB_BLACK);
+ __rb_rotate_set_parents(gparent, parent, root, RB_RED);
+ augment_rotate(gparent, parent);
+ break;
} else {
- {
- register struct rb_node *uncle = gparent->rb_left;
- if (uncle && rb_is_red(uncle))
- {
- rb_set_black(uncle);
- rb_set_black(parent);
- rb_set_red(gparent);
- node = gparent;
- continue;
- }
+ tmp = gparent->rb_left;
+ if (tmp && rb_is_red(tmp)) {
+ /* Case 1 - color flips */
+ rb_set_parent_color(tmp, gparent, RB_BLACK);
+ rb_set_parent_color(parent, gparent, RB_BLACK);
+ node = gparent;
+ parent = rb_parent(node);
+ rb_set_parent_color(node, parent, RB_RED);
+ continue;
}
- if (parent->rb_left == node)
- {
- register struct rb_node *tmp;
- __rb_rotate_right(parent, root);
- tmp = parent;
+ tmp = parent->rb_left;
+ if (node == tmp) {
+ /* Case 2 - right rotate at parent */
+ parent->rb_left = tmp = node->rb_right;
+ node->rb_right = parent;
+ if (tmp)
+ rb_set_parent_color(tmp, parent,
+ RB_BLACK);
+ rb_set_parent_color(parent, node, RB_RED);
+ augment_rotate(parent, node);
parent = node;
- node = tmp;
+ tmp = node->rb_left;
}
- rb_set_black(parent);
- rb_set_red(gparent);
- __rb_rotate_left(gparent, root);
+ /* Case 3 - left rotate at gparent */
+ gparent->rb_right = tmp; /* == parent->rb_left */
+ parent->rb_left = gparent;
+ if (tmp)
+ rb_set_parent_color(tmp, gparent, RB_BLACK);
+ __rb_rotate_set_parents(gparent, parent, root, RB_RED);
+ augment_rotate(gparent, parent);
+ break;
}
}
-
- rb_set_black(root->rb_node);
}
-static void __rb_erase_color(struct rb_node *node, struct rb_node *parent,
- struct rb_root *root)
+/*
+ * Inline version for rb_erase() use - we want to be able to inline
+ * and eliminate the dummy_rotate callback there
+ */
+static __always_inline void
+____rb_erase_color(struct rb_node *parent, struct rb_root *root,
+ void (*augment_rotate)(struct rb_node *old, struct rb_node *new))
{
- struct rb_node *other;
-
- while ((!node || rb_is_black(node)) && node != root->rb_node)
- {
- if (parent->rb_left == node)
- {
- other = parent->rb_right;
- if (rb_is_red(other))
- {
- rb_set_black(other);
- rb_set_red(parent);
- __rb_rotate_left(parent, root);
- other = parent->rb_right;
- }
- if ((!other->rb_left || rb_is_black(other->rb_left)) &&
- (!other->rb_right || rb_is_black(other->rb_right)))
- {
- rb_set_red(other);
- node = parent;
- parent = rb_parent(node);
+ struct rb_node *node = NULL, *sibling, *tmp1, *tmp2;
+
+ while (true) {
+ /*
+ * Loop invariants:
+ * - node is black (or NULL on first iteration)
+ * - node is not the root (parent is not NULL)
+ * - All leaf paths going through parent and node have a
+ * black node count that is 1 lower than other leaf paths.
+ */
+ sibling = parent->rb_right;
+ if (node != sibling) { /* node == parent->rb_left */
+ if (rb_is_red(sibling)) {
+ /*
+ * Case 1 - left rotate at parent
+ *
+ * P S
+ * / \ / \
+ * N s --> p Sr
+ * / \ / \
+ * Sl Sr N Sl
+ */
+ parent->rb_right = tmp1 = sibling->rb_left;
+ sibling->rb_left = parent;
+ rb_set_parent_color(tmp1, parent, RB_BLACK);
+ __rb_rotate_set_parents(parent, sibling, root,
+ RB_RED);
+ augment_rotate(parent, sibling);
+ sibling = tmp1;
}
- else
- {
- if (!other->rb_right || rb_is_black(other->rb_right))
- {
- struct rb_node *o_left;
- if ((o_left = other->rb_left))
- rb_set_black(o_left);
- rb_set_red(other);
- __rb_rotate_right(other, root);
- other = parent->rb_right;
+ tmp1 = sibling->rb_right;
+ if (!tmp1 || rb_is_black(tmp1)) {
+ tmp2 = sibling->rb_left;
+ if (!tmp2 || rb_is_black(tmp2)) {
+ /*
+ * Case 2 - sibling color flip
+ * (p could be either color here)
+ *
+ * (p) (p)
+ * / \ / \
+ * N S --> N s
+ * / \ / \
+ * Sl Sr Sl Sr
+ *
+ * This leaves us violating 5) which
+ * can be fixed by flipping p to black
+ * if it was red, or by recursing at p.
+ * p is red when coming from Case 1.
+ */
+ rb_set_parent_color(sibling, parent,
+ RB_RED);
+ if (rb_is_red(parent))
+ rb_set_black(parent);
+ else {
+ node = parent;
+ parent = rb_parent(node);
+ if (parent)
+ continue;
+ }
+ break;
}
- rb_set_color(other, rb_color(parent));
- rb_set_black(parent);
- if (other->rb_right)
- rb_set_black(other->rb_right);
- __rb_rotate_left(parent, root);
- node = root->rb_node;
- break;
+ /*
+ * Case 3 - right rotate at sibling
+ * (p could be either color here)
+ *
+ * (p) (p)
+ * / \ / \
+ * N S --> N Sl
+ * / \ \
+ * sl Sr s
+ * \
+ * Sr
+ */
+ sibling->rb_left = tmp1 = tmp2->rb_right;
+ tmp2->rb_right = sibling;
+ parent->rb_right = tmp2;
+ if (tmp1)
+ rb_set_parent_color(tmp1, sibling,
+ RB_BLACK);
+ augment_rotate(sibling, tmp2);
+ tmp1 = sibling;
+ sibling = tmp2;
}
- }
- else
- {
- other = parent->rb_left;
- if (rb_is_red(other))
- {
- rb_set_black(other);
- rb_set_red(parent);
- __rb_rotate_right(parent, root);
- other = parent->rb_left;
- }
- if ((!other->rb_left || rb_is_black(other->rb_left)) &&
- (!other->rb_right || rb_is_black(other->rb_right)))
- {
- rb_set_red(other);
- node = parent;
- parent = rb_parent(node);
+ /*
+ * Case 4 - left rotate at parent + color flips
+ * (p and sl could be either color here.
+ * After rotation, p becomes black, s acquires
+ * p's color, and sl keeps its color)
+ *
+ * (p) (s)
+ * / \ / \
+ * N S --> P Sr
+ * / \ / \
+ * (sl) sr N (sl)
+ */
+ parent->rb_right = tmp2 = sibling->rb_left;
+ sibling->rb_left = parent;
+ rb_set_parent_color(tmp1, sibling, RB_BLACK);
+ if (tmp2)
+ rb_set_parent(tmp2, parent);
+ __rb_rotate_set_parents(parent, sibling, root,
+ RB_BLACK);
+ augment_rotate(parent, sibling);
+ break;
+ } else {
+ sibling = parent->rb_left;
+ if (rb_is_red(sibling)) {
+ /* Case 1 - right rotate at parent */
+ parent->rb_left = tmp1 = sibling->rb_right;
+ sibling->rb_right = parent;
+ rb_set_parent_color(tmp1, parent, RB_BLACK);
+ __rb_rotate_set_parents(parent, sibling, root,
+ RB_RED);
+ augment_rotate(parent, sibling);
+ sibling = tmp1;
}
- else
- {
- if (!other->rb_left || rb_is_black(other->rb_left))
- {
- register struct rb_node *o_right;
- if ((o_right = other->rb_right))
- rb_set_black(o_right);
- rb_set_red(other);
- __rb_rotate_left(other, root);
- other = parent->rb_left;
+ tmp1 = sibling->rb_left;
+ if (!tmp1 || rb_is_black(tmp1)) {
+ tmp2 = sibling->rb_right;
+ if (!tmp2 || rb_is_black(tmp2)) {
+ /* Case 2 - sibling color flip */
+ rb_set_parent_color(sibling, parent,
+ RB_RED);
+ if (rb_is_red(parent))
+ rb_set_black(parent);
+ else {
+ node = parent;
+ parent = rb_parent(node);
+ if (parent)
+ continue;
+ }
+ break;
}
- rb_set_color(other, rb_color(parent));
- rb_set_black(parent);
- if (other->rb_left)
- rb_set_black(other->rb_left);
- __rb_rotate_right(parent, root);
- node = root->rb_node;
- break;
+ /* Case 3 - right rotate at sibling */
+ sibling->rb_right = tmp1 = tmp2->rb_left;
+ tmp2->rb_left = sibling;
+ parent->rb_left = tmp2;
+ if (tmp1)
+ rb_set_parent_color(tmp1, sibling,
+ RB_BLACK);
+ augment_rotate(sibling, tmp2);
+ tmp1 = sibling;
+ sibling = tmp2;
}
+ /* Case 4 - left rotate at parent + color flips */
+ parent->rb_left = tmp2 = sibling->rb_right;
+ sibling->rb_right = parent;
+ rb_set_parent_color(tmp1, sibling, RB_BLACK);
+ if (tmp2)
+ rb_set_parent(tmp2, parent);
+ __rb_rotate_set_parents(parent, sibling, root,
+ RB_BLACK);
+ augment_rotate(parent, sibling);
+ break;
}
}
- if (node)
- rb_set_black(node);
+}
+
+/* Non-inline version for rb_erase_augmented() use */
+void __rb_erase_color(struct rb_node *parent, struct rb_root *root,
+ void (*augment_rotate)(struct rb_node *old, struct rb_node *new))
+{
+ ____rb_erase_color(parent, root, augment_rotate);
+}
+
+/*
+ * Non-augmented rbtree manipulation functions.
+ *
+ * We use dummy augmented callbacks here, and have the compiler optimize them
+ * out of the rb_insert_color() and rb_erase() function definitions.
+ */
+
+static inline void dummy_propagate(struct rb_node *node, struct rb_node *stop) {}
+static inline void dummy_copy(struct rb_node *old, struct rb_node *new) {}
+static inline void dummy_rotate(struct rb_node *old, struct rb_node *new) {}
+
+static const struct rb_augment_callbacks dummy_callbacks = {
+ dummy_propagate, dummy_copy, dummy_rotate
+};
+
+void rb_insert_color(struct rb_node *node, struct rb_root *root)
+{
+ __rb_insert(node, root, dummy_rotate);
}
void rb_erase(struct rb_node *node, struct rb_root *root)
{
- struct rb_node *child, *parent;
- int color;
-
- if (!node->rb_left)
- child = node->rb_right;
- else if (!node->rb_right)
- child = node->rb_left;
- else
- {
- struct rb_node *old = node, *left;
-
- node = node->rb_right;
- while ((left = node->rb_left) != NULL)
- node = left;
- child = node->rb_right;
- parent = rb_parent(node);
- color = rb_color(node);
-
- if (child)
- rb_set_parent(child, parent);
- if (parent == old) {
- parent->rb_right = child;
- parent = node;
- } else
- parent->rb_left = child;
-
- node->rb_parent_color = old->rb_parent_color;
- node->rb_right = old->rb_right;
- node->rb_left = old->rb_left;
-
- if (rb_parent(old))
- {
- if (rb_parent(old)->rb_left == old)
- rb_parent(old)->rb_left = node;
- else
- rb_parent(old)->rb_right = node;
- } else
- root->rb_node = node;
-
- rb_set_parent(old->rb_left, node);
- if (old->rb_right)
- rb_set_parent(old->rb_right, node);
- goto color;
- }
+ struct rb_node *rebalance;
+ rebalance = __rb_erase_augmented(node, root, &dummy_callbacks);
+ if (rebalance)
+ ____rb_erase_color(rebalance, root, dummy_rotate);
+}
- parent = rb_parent(node);
- color = rb_color(node);
-
- if (child)
- rb_set_parent(child, parent);
- if (parent)
- {
- if (parent->rb_left == node)
- parent->rb_left = child;
- else
- parent->rb_right = child;
- }
- else
- root->rb_node = child;
+/*
+ * Augmented rbtree manipulation functions.
+ *
+ * This instantiates the same __always_inline functions as in the non-augmented
+ * case, but this time with user-defined callbacks.
+ */
- color:
- if (color == RB_BLACK)
- __rb_erase_color(child, parent, root);
+void __rb_insert_augmented(struct rb_node *node, struct rb_root *root,
+ void (*augment_rotate)(struct rb_node *old, struct rb_node *new))
+{
+ __rb_insert(node, root, augment_rotate);
}
/*
* This function returns the first node (in sort order) of the tree.
*/
-struct rb_node *rb_first(struct rb_root *root)
+struct rb_node *rb_first(const struct rb_root *root)
{
struct rb_node *n;
return n;
}
-struct rb_node *rb_last(struct rb_root *root)
+struct rb_node *rb_last(const struct rb_root *root)
{
struct rb_node *n;
return n;
}
-struct rb_node *rb_next(struct rb_node *node)
+struct rb_node *rb_next(const struct rb_node *node)
{
struct rb_node *parent;
- if (rb_parent(node) == node)
+ if (RB_EMPTY_NODE(node))
return NULL;
- /* If we have a right-hand child, go down and then left as far
- as we can. */
+ /*
+ * If we have a right-hand child, go down and then left as far
+ * as we can.
+ */
if (node->rb_right) {
node = node->rb_right;
while (node->rb_left)
node=node->rb_left;
- return node;
+ return (struct rb_node *)node;
}
- /* No right-hand children. Everything down and left is
- smaller than us, so any 'next' node must be in the general
- direction of our parent. Go up the tree; any time the
- ancestor is a right-hand child of its parent, keep going
- up. First time it's a left-hand child of its parent, said
- parent is our 'next' node. */
+ /*
+ * No right-hand children. Everything down and left is smaller than us,
+ * so any 'next' node must be in the general direction of our parent.
+ * Go up the tree; any time the ancestor is a right-hand child of its
+ * parent, keep going up. First time it's a left-hand child of its
+ * parent, said parent is our 'next' node.
+ */
while ((parent = rb_parent(node)) && node == parent->rb_right)
node = parent;
return parent;
}
-struct rb_node *rb_prev(struct rb_node *node)
+struct rb_node *rb_prev(const struct rb_node *node)
{
struct rb_node *parent;
- if (rb_parent(node) == node)
+ if (RB_EMPTY_NODE(node))
return NULL;
- /* If we have a left-hand child, go down and then right as far
- as we can. */
+ /*
+ * If we have a left-hand child, go down and then right as far
+ * as we can.
+ */
if (node->rb_left) {
node = node->rb_left;
while (node->rb_right)
node=node->rb_right;
- return node;
+ return (struct rb_node *)node;
}
- /* No left-hand children. Go up till we find an ancestor which
- is a right-hand child of its parent */
+ /*
+ * No left-hand children. Go up till we find an ancestor which
+ * is a right-hand child of its parent.
+ */
while ((parent = rb_parent(node)) && node == parent->rb_left)
node = parent;
struct rb_node *parent = rb_parent(victim);
/* Set the surrounding nodes to point to the replacement */
- if (parent) {
- if (victim == parent->rb_left)
- parent->rb_left = new;
- else
- parent->rb_right = new;
- } else {
- root->rb_node = new;
- }
+ __rb_change_child(victim, new, parent, root);
if (victim->rb_left)
rb_set_parent(victim->rb_left, new);
if (victim->rb_right)
/* Copy the pointers/colour from the victim to the replacement */
*new = *victim;
}
+
+static struct rb_node *rb_left_deepest_node(const struct rb_node *node)
+{
+ for (;;) {
+ if (node->rb_left)
+ node = node->rb_left;
+ else if (node->rb_right)
+ node = node->rb_right;
+ else
+ return (struct rb_node *)node;
+ }
+}
+
+struct rb_node *rb_next_postorder(const struct rb_node *node)
+{
+ const struct rb_node *parent;
+ if (!node)
+ return NULL;
+ parent = rb_parent(node);
+
+ /* If we're sitting on node, we've already seen our children */
+ if (parent && node == parent->rb_left && parent->rb_right) {
+ /* If we are the parent's left node, go to the parent's right
+ * node then all the way down to the left */
+ return rb_left_deepest_node(parent->rb_right);
+ } else
+ /* Otherwise we are the parent's right node, and the parent
+ * should be next */
+ return (struct rb_node *)parent;
+}
+
+struct rb_node *rb_first_postorder(const struct rb_root *root)
+{
+ if (!root->rb_node)
+ return NULL;
+
+ return rb_left_deepest_node(root->rb_node);
+}
I know it's not the cleaner way, but in C (not in C++) to get
performances and genericity...
- Some example of insert and search follows here. The search is a plain
- normal search over an ordered tree. The insert instead must be implemented
- int two steps: as first thing the code must insert the element in
- order as a red leaf in the tree, then the support library function
- rb_insert_color() must be called. Such function will do the
- not trivial work to rebalance the rbtree if necessary.
-
------------------------------------------------------------------------
-static inline struct page * rb_search_page_cache(struct inode * inode,
- unsigned long offset)
-{
- struct rb_node * n = inode->i_rb_page_cache.rb_node;
- struct page * page;
-
- while (n)
- {
- page = rb_entry(n, struct page, rb_page_cache);
-
- if (offset < page->offset)
- n = n->rb_left;
- else if (offset > page->offset)
- n = n->rb_right;
- else
- return page;
- }
- return NULL;
-}
-
-static inline struct page * __rb_insert_page_cache(struct inode * inode,
- unsigned long offset,
- struct rb_node * node)
-{
- struct rb_node ** p = &inode->i_rb_page_cache.rb_node;
- struct rb_node * parent = NULL;
- struct page * page;
-
- while (*p)
- {
- parent = *p;
- page = rb_entry(parent, struct page, rb_page_cache);
-
- if (offset < page->offset)
- p = &(*p)->rb_left;
- else if (offset > page->offset)
- p = &(*p)->rb_right;
- else
- return page;
- }
-
- rb_link_node(node, parent, p);
-
- return NULL;
-}
-
-static inline struct page * rb_insert_page_cache(struct inode * inode,
- unsigned long offset,
- struct rb_node * node)
-{
- struct page * ret;
- if ((ret = __rb_insert_page_cache(inode, offset, node)))
- goto out;
- rb_insert_color(node, &inode->i_rb_page_cache);
- out:
- return ret;
-}
------------------------------------------------------------------------
+ See Documentation/rbtree.txt for documentation and samples.
*/
#ifndef _LINUX_RBTREE_H
#else
#include <btrfs/kerncompat.h>
#endif /* BTRFS_FLAT_INCLUDES */
-struct rb_node
-{
- unsigned long rb_parent_color;
-#define RB_RED 0
-#define RB_BLACK 1
+
+struct rb_node {
+ unsigned long __rb_parent_color;
struct rb_node *rb_right;
struct rb_node *rb_left;
} __attribute__((aligned(sizeof(long))));
/* The alignment might seem pointless, but allegedly CRIS needs it */
-struct rb_root
-{
+struct rb_root {
struct rb_node *rb_node;
};
-#define rb_parent(r) ((struct rb_node *)((r)->rb_parent_color & ~3))
-#define rb_color(r) ((r)->rb_parent_color & 1)
-#define rb_is_red(r) (!rb_color(r))
-#define rb_is_black(r) rb_color(r)
-#define rb_set_red(r) do { (r)->rb_parent_color &= ~1; } while (0)
-#define rb_set_black(r) do { (r)->rb_parent_color |= 1; } while (0)
-static inline void rb_set_parent(struct rb_node *rb, struct rb_node *p)
-{
- rb->rb_parent_color = (rb->rb_parent_color & 3) | (unsigned long)p;
-}
-static inline void rb_set_color(struct rb_node *rb, int color)
-{
- rb->rb_parent_color = (rb->rb_parent_color & ~1) | color;
-}
+#define rb_parent(r) ((struct rb_node *)((r)->__rb_parent_color & ~3))
#define RB_ROOT (struct rb_root) { NULL, }
#define rb_entry(ptr, type, member) container_of(ptr, type, member)
-#define RB_EMPTY_ROOT(root) ((root)->rb_node == NULL)
-#define RB_EMPTY_NODE(node) (rb_parent(node) == node)
-#define RB_CLEAR_NODE(node) (rb_set_parent(node, node))
+#define RB_EMPTY_ROOT(root) ((root)->rb_node == NULL)
+
+/* 'empty' nodes are nodes that are known not to be inserted in an rbree */
+#define RB_EMPTY_NODE(node) \
+ ((node)->__rb_parent_color == (unsigned long)(node))
+#define RB_CLEAR_NODE(node) \
+ ((node)->__rb_parent_color = (unsigned long)(node))
+
extern void rb_insert_color(struct rb_node *, struct rb_root *);
extern void rb_erase(struct rb_node *, struct rb_root *);
+
/* Find logical next and previous nodes in a tree */
-extern struct rb_node *rb_next(struct rb_node *);
-extern struct rb_node *rb_prev(struct rb_node *);
-extern struct rb_node *rb_first(struct rb_root *);
-extern struct rb_node *rb_last(struct rb_root *);
+extern struct rb_node *rb_next(const struct rb_node *);
+extern struct rb_node *rb_prev(const struct rb_node *);
+extern struct rb_node *rb_first(const struct rb_root *);
+extern struct rb_node *rb_last(const struct rb_root *);
+
+/* Postorder iteration - always visit the parent after its children */
+extern struct rb_node *rb_first_postorder(const struct rb_root *);
+extern struct rb_node *rb_next_postorder(const struct rb_node *);
/* Fast replacement of a single node without remove/rebalance/add/rebalance */
-extern void rb_replace_node(struct rb_node *victim, struct rb_node *xnew,
+extern void rb_replace_node(struct rb_node *victim, struct rb_node *new,
struct rb_root *root);
static inline void rb_link_node(struct rb_node * node, struct rb_node * parent,
struct rb_node ** rb_link)
{
- node->rb_parent_color = (unsigned long )parent;
+ node->__rb_parent_color = (unsigned long)parent;
node->rb_left = node->rb_right = NULL;
*rb_link = node;
}
+
+#define rb_entry_safe(ptr, type, member) \
+ ({ typeof(ptr) ____ptr = (ptr); \
+ ____ptr ? rb_entry(____ptr, type, member) : NULL; \
+ })
+
+/**
+ * rbtree_postorder_for_each_entry_safe - iterate over rb_root in post order of
+ * given type safe against removal of rb_node entry
+ *
+ * @pos: the 'type *' to use as a loop cursor.
+ * @n: another 'type *' to use as temporary storage
+ * @root: 'rb_root *' of the rbtree.
+ * @field: the name of the rb_node field within 'type'.
+ */
+#define rbtree_postorder_for_each_entry_safe(pos, n, root, field) \
+ for (pos = rb_entry_safe(rb_first_postorder(root), typeof(*pos), field); \
+ pos && ({ n = rb_entry_safe(rb_next_postorder(&pos->field), \
+ typeof(*pos), field); 1; }); \
+ pos = n)
+
#endif /* _LINUX_RBTREE_H */
--- /dev/null
+/*
+ Red Black Trees
+ (C) 1999 Andrea Arcangeli <andrea@suse.de>
+ (C) 2002 David Woodhouse <dwmw2@infradead.org>
+ (C) 2012 Michel Lespinasse <walken@google.com>
+
+ This program is free software; you can redistribute it and/or modify
+ it under the terms of the GNU General Public License as published by
+ the Free Software Foundation; either version 2 of the License, or
+ (at your option) any later version.
+
+ This program is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ GNU General Public License for more details.
+
+ You should have received a copy of the GNU General Public License
+ along with this program; if not, write to the Free Software
+ Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+
+ linux/include/linux/rbtree_augmented.h
+*/
+
+#ifndef _LINUX_RBTREE_AUGMENTED_H
+#define _LINUX_RBTREE_AUGMENTED_H
+
+#include "rbtree.h"
+
+/*
+ * Please note - only struct rb_augment_callbacks and the prototypes for
+ * rb_insert_augmented() and rb_erase_augmented() are intended to be public.
+ * The rest are implementation details you are not expected to depend on.
+ *
+ * See Documentation/rbtree.txt for documentation and samples.
+ */
+
+struct rb_augment_callbacks {
+ void (*propagate)(struct rb_node *node, struct rb_node *stop);
+ void (*copy)(struct rb_node *old, struct rb_node *new);
+ void (*rotate)(struct rb_node *old, struct rb_node *new);
+};
+
+extern void __rb_insert_augmented(struct rb_node *node, struct rb_root *root,
+ void (*augment_rotate)(struct rb_node *old, struct rb_node *new));
+static inline void
+rb_insert_augmented(struct rb_node *node, struct rb_root *root,
+ const struct rb_augment_callbacks *augment)
+{
+ __rb_insert_augmented(node, root, augment->rotate);
+}
+
+#define RB_DECLARE_CALLBACKS(rbstatic, rbname, rbstruct, rbfield, \
+ rbtype, rbaugmented, rbcompute) \
+static inline void \
+rbname ## _propagate(struct rb_node *rb, struct rb_node *stop) \
+{ \
+ while (rb != stop) { \
+ rbstruct *node = rb_entry(rb, rbstruct, rbfield); \
+ rbtype augmented = rbcompute(node); \
+ if (node->rbaugmented == augmented) \
+ break; \
+ node->rbaugmented = augmented; \
+ rb = rb_parent(&node->rbfield); \
+ } \
+} \
+static inline void \
+rbname ## _copy(struct rb_node *rb_old, struct rb_node *rb_new) \
+{ \
+ rbstruct *old = rb_entry(rb_old, rbstruct, rbfield); \
+ rbstruct *new = rb_entry(rb_new, rbstruct, rbfield); \
+ new->rbaugmented = old->rbaugmented; \
+} \
+static void \
+rbname ## _rotate(struct rb_node *rb_old, struct rb_node *rb_new) \
+{ \
+ rbstruct *old = rb_entry(rb_old, rbstruct, rbfield); \
+ rbstruct *new = rb_entry(rb_new, rbstruct, rbfield); \
+ new->rbaugmented = old->rbaugmented; \
+ old->rbaugmented = rbcompute(old); \
+} \
+rbstatic const struct rb_augment_callbacks rbname = { \
+ rbname ## _propagate, rbname ## _copy, rbname ## _rotate \
+};
+
+
+#define RB_RED 0
+#define RB_BLACK 1
+
+#define __rb_parent(pc) ((struct rb_node *)(pc & ~3))
+
+#define __rb_color(pc) ((pc) & 1)
+#define __rb_is_black(pc) __rb_color(pc)
+#define __rb_is_red(pc) (!__rb_color(pc))
+#define rb_color(rb) __rb_color((rb)->__rb_parent_color)
+#define rb_is_red(rb) __rb_is_red((rb)->__rb_parent_color)
+#define rb_is_black(rb) __rb_is_black((rb)->__rb_parent_color)
+
+static inline void rb_set_parent(struct rb_node *rb, struct rb_node *p)
+{
+ rb->__rb_parent_color = rb_color(rb) | (unsigned long)p;
+}
+
+static inline void rb_set_parent_color(struct rb_node *rb,
+ struct rb_node *p, int color)
+{
+ rb->__rb_parent_color = (unsigned long)p | color;
+}
+
+static inline void
+__rb_change_child(struct rb_node *old, struct rb_node *new,
+ struct rb_node *parent, struct rb_root *root)
+{
+ if (parent) {
+ if (parent->rb_left == old)
+ parent->rb_left = new;
+ else
+ parent->rb_right = new;
+ } else
+ root->rb_node = new;
+}
+
+extern void __rb_erase_color(struct rb_node *parent, struct rb_root *root,
+ void (*augment_rotate)(struct rb_node *old, struct rb_node *new));
+
+static __always_inline struct rb_node *
+__rb_erase_augmented(struct rb_node *node, struct rb_root *root,
+ const struct rb_augment_callbacks *augment)
+{
+ struct rb_node *child = node->rb_right, *tmp = node->rb_left;
+ struct rb_node *parent, *rebalance;
+ unsigned long pc;
+
+ if (!tmp) {
+ /*
+ * Case 1: node to erase has no more than 1 child (easy!)
+ *
+ * Note that if there is one child it must be red due to 5)
+ * and node must be black due to 4). We adjust colors locally
+ * so as to bypass __rb_erase_color() later on.
+ */
+ pc = node->__rb_parent_color;
+ parent = __rb_parent(pc);
+ __rb_change_child(node, child, parent, root);
+ if (child) {
+ child->__rb_parent_color = pc;
+ rebalance = NULL;
+ } else
+ rebalance = __rb_is_black(pc) ? parent : NULL;
+ tmp = parent;
+ } else if (!child) {
+ /* Still case 1, but this time the child is node->rb_left */
+ tmp->__rb_parent_color = pc = node->__rb_parent_color;
+ parent = __rb_parent(pc);
+ __rb_change_child(node, tmp, parent, root);
+ rebalance = NULL;
+ tmp = parent;
+ } else {
+ struct rb_node *successor = child, *child2;
+ tmp = child->rb_left;
+ if (!tmp) {
+ /*
+ * Case 2: node's successor is its right child
+ *
+ * (n) (s)
+ * / \ / \
+ * (x) (s) -> (x) (c)
+ * \
+ * (c)
+ */
+ parent = successor;
+ child2 = successor->rb_right;
+ augment->copy(node, successor);
+ } else {
+ /*
+ * Case 3: node's successor is leftmost under
+ * node's right child subtree
+ *
+ * (n) (s)
+ * / \ / \
+ * (x) (y) -> (x) (y)
+ * / /
+ * (p) (p)
+ * / /
+ * (s) (c)
+ * \
+ * (c)
+ */
+ do {
+ parent = successor;
+ successor = tmp;
+ tmp = tmp->rb_left;
+ } while (tmp);
+ parent->rb_left = child2 = successor->rb_right;
+ successor->rb_right = child;
+ rb_set_parent(child, successor);
+ augment->copy(node, successor);
+ augment->propagate(parent, successor);
+ }
+
+ successor->rb_left = tmp = node->rb_left;
+ rb_set_parent(tmp, successor);
+
+ pc = node->__rb_parent_color;
+ tmp = __rb_parent(pc);
+ __rb_change_child(node, successor, tmp, root);
+ if (child2) {
+ successor->__rb_parent_color = pc;
+ rb_set_parent_color(child2, parent, RB_BLACK);
+ rebalance = NULL;
+ } else {
+ unsigned long pc2 = successor->__rb_parent_color;
+ successor->__rb_parent_color = pc;
+ rebalance = __rb_is_black(pc2) ? parent : NULL;
+ }
+ tmp = successor;
+ }
+
+ augment->propagate(tmp, NULL);
+ return rebalance;
+}
+
+static __always_inline void
+rb_erase_augmented(struct rb_node *node, struct rb_root *root,
+ const struct rb_augment_callbacks *augment)
+{
+ struct rb_node *rebalance = __rb_erase_augmented(node, root, augment);
+ if (rebalance)
+ __rb_erase_color(rebalance, root, augment->rotate);
+}
+
+#endif /* _LINUX_RBTREE_AUGMENTED_H */
projects / platform / upstream / btrfs-progs.git / commitdiff