uwsgi/lib/rbtree.c

/*

  *** uWSGI, stripped down version of Linux rbtree ***


  Red Black Trees
  (C) 1999  Andrea Arcangeli <andrea@suse.de>
  (C) 2002  David Woodhouse <dwmw2@infradead.org>
  
  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., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301  USA

*/

#include "../uwsgi.h"

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;
}


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);

	if ((node->rb_right = right->rb_left))
		rb_set_parent(right->rb_left, node);
	right->rb_left = node;

	rb_set_parent(right, parent);

	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 void __rb_rotate_right(struct rb_node *node, struct rb_root *root)
{
	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);

	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);
}

void rb_insert_color(struct rb_node *node, struct rb_root *root)
{
	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;
				}
			}

			if (parent->rb_right == node)
			{
				register struct rb_node *tmp;
				__rb_rotate_left(parent, root);
				tmp = parent;
				parent = node;
				node = tmp;
			}

			rb_set_black(parent);
			rb_set_red(gparent);
			__rb_rotate_right(gparent, root);
		} 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;
				}
			}

			if (parent->rb_left == node)
			{
				register struct rb_node *tmp;
				__rb_rotate_right(parent, root);
				tmp = parent;
				parent = node;
				node = tmp;
			}

			rb_set_black(parent);
			rb_set_red(gparent);
			__rb_rotate_left(gparent, root);
		}
	}

	rb_set_black(root->rb_node);
}

static void __rb_erase_color(struct rb_node *node, struct rb_node *parent,
			     struct rb_root *root)
{
	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);
			}
			else
			{
				if (!other->rb_right || rb_is_black(other->rb_right))
				{
					rb_set_black(other->rb_left);
					rb_set_red(other);
					__rb_rotate_right(other, root);
					other = parent->rb_right;
				}
				rb_set_color(other, rb_color(parent));
				rb_set_black(parent);
				rb_set_black(other->rb_right);
				__rb_rotate_left(parent, root);
				node = root->rb_node;
				break;
			}
		}
		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);
			}
			else
			{
				if (!other->rb_left || rb_is_black(other->rb_left))
				{
					rb_set_black(other->rb_right);
					rb_set_red(other);
					__rb_rotate_left(other, root);
					other = parent->rb_left;
				}
				rb_set_color(other, rb_color(parent));
				rb_set_black(parent);
				rb_set_black(other->rb_left);
				__rb_rotate_right(parent, root);
				node = root->rb_node;
				break;
			}
		}
	}
	if (node)
		rb_set_black(node);
}

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;

		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;

		child = node->rb_right;
		parent = rb_parent(node);
		color = rb_color(node);

		if (parent == old) {
			parent = node;
		} else {
			if (child)
				rb_set_parent(child, parent);
			parent->rb_left = child;

			node->rb_right = old->rb_right;
			rb_set_parent(old->rb_right, node);
		}

		node->rb_parent_color = old->rb_parent_color;
		node->rb_left = old->rb_left;
		rb_set_parent(old->rb_left, node);

		goto color;
	}

	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;

 color:
	if (color == RB_BLACK)
		__rb_erase_color(child, parent, root);
}

#ifdef __clang__
void rb_link_node(struct rb_node * node, struct rb_node * parent,
                                struct rb_node ** rb_link)
#else
inline void rb_link_node(struct rb_node * node, struct rb_node * parent,
                                struct rb_node ** rb_link)
#endif
{
        node->rb_parent_color = (unsigned long )parent;
        node->rb_left = node->rb_right = NULL;

        *rb_link = node;
}