linux/include/linux/rbtree.h

/* SPDX-License-Identifier: GPL-2.0-or-later */
/*
  Red Black Trees
  (C) 1999  Andrea Arcangeli <[email protected]>
  

  linux/include/linux/rbtree.h

  To use rbtrees you'll have to implement your own insert and search cores.
  This will avoid us to use callbacks and to drop drammatically performances.
  I know it's not the cleaner way,  but in C (not in C++) to get
  performances and genericity...

  See Documentation/core-api/rbtree.rst for documentation and samples.
*/

#ifndef	_LINUX_RBTREE_H
#define _LINUX_RBTREE_H

#include <linux/container_of.h>
#include <linux/rbtree_types.h>

#include <linux/stddef.h>
#include <linux/rcupdate.h>

#define rb_parent(r) …

#define rb_entry(ptr, type, member) …

#define RB_EMPTY_ROOT(root) …

/* 'empty' nodes are nodes that are known not to be inserted in an rbtree */
#define RB_EMPTY_NODE(node) …
#define RB_CLEAR_NODE(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(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 *new,
			    struct rb_root *root);
extern void rb_replace_node_rcu(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)
{ … }

static inline void rb_link_node_rcu(struct rb_node *node, struct rb_node *parent,
				    struct rb_node **rb_link)
{ … }

#define rb_entry_safe(ptr, type, member) …

/**
 * rbtree_postorder_for_each_entry_safe - iterate in post-order over rb_root of
 * given type allowing the backing memory of @pos to be invalidated
 *
 * @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'.
 *
 * rbtree_postorder_for_each_entry_safe() provides a similar guarantee as
 * list_for_each_entry_safe() and allows the iteration to continue independent
 * of changes to @pos by the body of the loop.
 *
 * Note, however, that it cannot handle other modifications that re-order the
 * rbtree it is iterating over. This includes calling rb_erase() on @pos, as
 * rb_erase() may rebalance the tree, causing us to miss some nodes.
 */
#define rbtree_postorder_for_each_entry_safe(pos, n, root, field) …

/* Same as rb_first(), but O(1) */
#define rb_first_cached(root) …

static inline void rb_insert_color_cached(struct rb_node *node,
					  struct rb_root_cached *root,
					  bool leftmost)
{ … }


static inline struct rb_node *
rb_erase_cached(struct rb_node *node, struct rb_root_cached *root)
{ … }

static inline void rb_replace_node_cached(struct rb_node *victim,
					  struct rb_node *new,
					  struct rb_root_cached *root)
{ … }

/*
 * The below helper functions use 2 operators with 3 different
 * calling conventions. The operators are related like:
 *
 *	comp(a->key,b) < 0  := less(a,b)
 *	comp(a->key,b) > 0  := less(b,a)
 *	comp(a->key,b) == 0 := !less(a,b) && !less(b,a)
 *
 * If these operators define a partial order on the elements we make no
 * guarantee on which of the elements matching the key is found. See
 * rb_find().
 *
 * The reason for this is to allow the find() interface without requiring an
 * on-stack dummy object, which might not be feasible due to object size.
 */

/**
 * rb_add_cached() - insert @node into the leftmost cached tree @tree
 * @node: node to insert
 * @tree: leftmost cached tree to insert @node into
 * @less: operator defining the (partial) node order
 *
 * Returns @node when it is the new leftmost, or NULL.
 */
static __always_inline struct rb_node *
rb_add_cached(struct rb_node *node, struct rb_root_cached *tree,
	      bool (*less)(struct rb_node *, const struct rb_node *))
{ … }

/**
 * rb_add() - insert @node into @tree
 * @node: node to insert
 * @tree: tree to insert @node into
 * @less: operator defining the (partial) node order
 */
static __always_inline void
rb_add(struct rb_node *node, struct rb_root *tree,
       bool (*less)(struct rb_node *, const struct rb_node *))
{ … }

/**
 * rb_find_add() - find equivalent @node in @tree, or add @node
 * @node: node to look-for / insert
 * @tree: tree to search / modify
 * @cmp: operator defining the node order
 *
 * Returns the rb_node matching @node, or NULL when no match is found and @node
 * is inserted.
 */
static __always_inline struct rb_node *
rb_find_add(struct rb_node *node, struct rb_root *tree,
	    int (*cmp)(struct rb_node *, const struct rb_node *))
{ … }

/**
 * rb_find_add_rcu() - find equivalent @node in @tree, or add @node
 * @node: node to look-for / insert
 * @tree: tree to search / modify
 * @cmp: operator defining the node order
 *
 * Adds a Store-Release for link_node.
 *
 * Returns the rb_node matching @node, or NULL when no match is found and @node
 * is inserted.
 */
static __always_inline struct rb_node *
rb_find_add_rcu(struct rb_node *node, struct rb_root *tree,
		int (*cmp)(struct rb_node *, const struct rb_node *))
{ … }

/**
 * rb_find() - find @key in tree @tree
 * @key: key to match
 * @tree: tree to search
 * @cmp: operator defining the node order
 *
 * Returns the rb_node matching @key or NULL.
 */
static __always_inline struct rb_node *
rb_find(const void *key, const struct rb_root *tree,
	int (*cmp)(const void *key, const struct rb_node *))
{ … }

/**
 * rb_find_rcu() - find @key in tree @tree
 * @key: key to match
 * @tree: tree to search
 * @cmp: operator defining the node order
 *
 * Notably, tree descent vs concurrent tree rotations is unsound and can result
 * in false-negatives.
 *
 * Returns the rb_node matching @key or NULL.
 */
static __always_inline struct rb_node *
rb_find_rcu(const void *key, const struct rb_root *tree,
	    int (*cmp)(const void *key, const struct rb_node *))
{ … }

/**
 * rb_find_first() - find the first @key in @tree
 * @key: key to match
 * @tree: tree to search
 * @cmp: operator defining node order
 *
 * Returns the leftmost node matching @key, or NULL.
 */
static __always_inline struct rb_node *
rb_find_first(const void *key, const struct rb_root *tree,
	      int (*cmp)(const void *key, const struct rb_node *))
{ … }

/**
 * rb_next_match() - find the next @key in @tree
 * @key: key to match
 * @tree: tree to search
 * @cmp: operator defining node order
 *
 * Returns the next node matching @key, or NULL.
 */
static __always_inline struct rb_node *
rb_next_match(const void *key, struct rb_node *node,
	      int (*cmp)(const void *key, const struct rb_node *))
{ … }

/**
 * rb_for_each() - iterates a subtree matching @key
 * @node: iterator
 * @key: key to match
 * @tree: tree to search
 * @cmp: operator defining node order
 */
#define rb_for_each(node, key, tree, cmp) …

#endif	/* _LINUX_RBTREE_H */