一、學習筆記
1. rbtree 簡介
rbtree，全稱是 Red-Black Tree，又稱為“紅黑樹”，它一種特殊的二叉查找樹。紅黑樹的每個節點上都有存儲位表示節點的顔色，可以是紅(Red)或黑(Black)。
紅黑樹的特性:
(1) 每個節點或者是黑色，或者是紅色。
(2) 根節點是黑色。
(3) 每個葉子節點（NIL）是黑色。 [注意：這裡葉子節點，是指為空(NIL 或 NULL)的葉子節點！]
(4) 如果一個節點是紅色的，則它的子節點必須是黑色的。
(5) 從一個節點到該節點的子孫節點的所有路徑上包含相同數目的黑節點。此特性確定沒有一條路徑會比其他路徑長出兩倍，因而，紅黑樹是相對是接近平衡的二叉樹。
對紅黑樹的所有操作都要保持紅黑樹的特性不變，紅黑樹的應用比較廣泛，主要是用它來存儲有序的資料，它的時間複雜度是O(lgn)，效率非常之高。cfs_rq就是使用紅黑樹存儲任務的。
2. 紅黑樹的基本操作
(1) 左旋
左旋示例圖(以x為節點進行左旋)：
z
x /
/ \ --(左旋)--> x
y z /
y 對 x 進行左旋，意味着，将 “x的右孩子” 設為 “x的父親節點”，即，将x變成了一個左節點(x成了為z的左孩子)。 是以，左旋中的 “左”，意味着 “被旋轉的節點将變成一個左節點”。
(2) 右旋
右旋示例圖(以x為節點進行右旋)：
y
x \
/ \ --(右旋)--> x
y z \
z 對 x 進行右旋，意味着，将 “x的左孩子” 設為 “x的父親節點”，即，将x變成了一個右節點(x成了為y的右孩子)，是以，右旋中的 “右”，意味着 “被旋轉的節點将變成一個右節點”。
(3) 添加
将一個節點插入到紅黑樹中，首先，将紅黑樹當作一顆二叉查找樹，将節點插入；然後，将節點着色為紅色；最後，通過旋轉和重新着色等方法來修正該樹，使之重新成為一顆紅黑樹。
(4) 删除
将紅黑樹内的某一個節點删除。需要執行的操作依次是：首先，将紅黑樹當作一顆二叉查找樹，将該節點從二叉查找樹中删除；然後，通過"旋轉和重新着色"等一系列來修正該樹，使之重新成為一棵紅黑樹。
二、移植測試
1. 移植 linux/include/linux/rbtree.h
/* SPDX-License-Identifier: GPL-2.0-or-later */
/*
linux/include/linux/rbtree.h
*/
#ifndef _LINUX_RBTREE_H
#define _LINUX_RBTREE_H
//#include <linux/kernel.h>
//#include <linux/stddef.h>
//#include <linux/rcupdate.h>
/*------------------------- I add -------------------------*/
#include <stdlib.h>
#define NULL ((void *)0)
#define RB_RED 0
#define RB_BLACK 1
#define WRITE_ONCE(p, v) (p)=(v)
#define unlikely(x) x
#define rcu_assign_pointer(p, v) (p)=(v)
typedef enum _bool {
false = 0,
true = 1,
} bool;
#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)
#define offsetof(TYPE, MEMBER) ((size_t) &((TYPE *)0)->MEMBER)
#define container_of(ptr, type, member) ({ \
const typeof( ((type *)0)->member ) *__mptr = (ptr); \
(type *)( (char *)__mptr - offsetof(type,member) );})
/*------------------ end ----------------------------*/
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_node *rb_node;
};
#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) (READ_ONCE((root)->rb_node) == NULL)
/* 'empty' nodes are nodes that are known not to be inserted in an rbtree */
#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(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);
/*
* 傳參(&node->rb, parent, new) node是使用者資料結構中的rb_node成員，rb_link是在紅黑樹上周遊出來的位置，要麼為
* parent的rb_left，要麼為rb_right
*/
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_left = node->rb_right = NULL;
*rb_link = node;
}
static inline void rb_link_node_rcu(struct rb_node *node, struct rb_node *parent, struct rb_node **rb_link)
{
node->__rb_parent_color = (unsigned long)parent;
node->rb_left = node->rb_right = NULL;
rcu_assign_pointer(*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 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) \
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)
/*
* Leftmost-cached rbtrees.
*
* We do not cache the rightmost node based on footprint
* size vs number of potential users that could benefit
* from O(1) rb_last(). Just not worth it, users that want
* this feature can always implement the logic explicitly.
* Furthermore, users that want to cache both pointers may
* find it a bit asymmetric, but that's ok.
*/
struct rb_root_cached {
struct rb_root rb_root;
struct rb_node *rb_leftmost;
};
#define RB_ROOT_CACHED (struct rb_root_cached) { {NULL, }, NULL }
/* Same as rb_first(), but O(1) */
#define rb_first_cached(root) (root)->rb_leftmost
static inline void rb_insert_color_cached(struct rb_node *node, struct rb_root_cached *root, bool leftmost)
{
if (leftmost)
root->rb_leftmost = node;
rb_insert_color(node, &root->rb_root);
}
static inline void rb_erase_cached(struct rb_node *node, struct rb_root_cached *root)
{
if (root->rb_leftmost == node)
root->rb_leftmost = rb_next(node);
rb_erase(node, &root->rb_root);
}
static inline void rb_replace_node_cached(struct rb_node *victim, struct rb_node *new, struct rb_root_cached *root)
{
if (root->rb_leftmost == victim)
root->rb_leftmost = new;
rb_replace_node(victim, new, &root->rb_root);
}
#endif /* _LINUX_RBTREE_H */ 2. 移植 linux/lib/rbtree.c
/*
linux/lib/rbtree.c
*/
//#include <linux/rbtree_augmented.h>
//#include <linux/export.h>
/*------------------------------------- I add ----------------------------------------------*/
#include "rbtree.h" //linux/rbtree.h
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);
};
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)
WRITE_ONCE(parent->rb_left, new);
else
WRITE_ONCE(parent->rb_right, new);
} else
WRITE_ONCE(root->rb_node, new);
}
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 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;
struct rb_node *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);
child2 = successor->rb_right;
WRITE_ONCE(parent->rb_left, child2);
WRITE_ONCE(successor->rb_right, child);
rb_set_parent(child, successor);
augment->copy(node, successor);
augment->propagate(parent, successor);
}
tmp = node->rb_left;
WRITE_ONCE(successor->rb_left, tmp);
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 inline void __rb_change_child_rcu(struct rb_node *old, struct rb_node *new, struct rb_node *parent, struct rb_root *root)
{
if (parent) {
if (parent->rb_left == old)
rcu_assign_pointer(parent->rb_left, new);
else
rcu_assign_pointer(parent->rb_right, new);
} else
rcu_assign_pointer(root->rb_node, new);
}
/*--------------------------------------- end ------------------------------------------------*/
static inline void rb_set_black(struct rb_node *rb)
{
rb->__rb_parent_color |= RB_BLACK;
}
static inline struct rb_node *rb_red_parent(struct rb_node *red)
{
return (struct rb_node *)red->__rb_parent_color;
}
/*
* 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);
}
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 = rb_red_parent(node), *gparent, *tmp;
while (true) {
/*
* Loop invariant: node is red.
*/
if (unlikely(!parent)) {
/*
* The inserted node is root. Either this is the
* first node, or we recursed at Case 1 below and
* are no longer violating 4).
*/
rb_set_parent_color(node, NULL, RB_BLACK);
break;
}
/*
* If there is a black parent, we are done.
* Otherwise, take some corrective action as,
* per 4), we don't want a red root or two
* consecutive red nodes.
*/
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 - node's uncle is red (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;
}
tmp = parent->rb_right;
if (node == tmp) {
/*
* Case 2 - node's uncle is black and node is
* the parent's right child (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.
*/
tmp = node->rb_left;
WRITE_ONCE(parent->rb_right, tmp);
WRITE_ONCE(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;
tmp = node->rb_right;
}
/*
* Case 3 - node's uncle is black and node is
* the parent's left child (right rotate at gparent).
*
* G P
* / \ / \
* p U --> n g
* / \
* n U
*/
WRITE_ONCE(gparent->rb_left, tmp); /* == parent->rb_right */
WRITE_ONCE(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 {
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;
}
tmp = parent->rb_left;
if (node == tmp) {
/* Case 2 - right rotate at parent */
tmp = node->rb_right;
WRITE_ONCE(parent->rb_left, tmp);
WRITE_ONCE(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;
tmp = node->rb_left;
}
/* Case 3 - left rotate at gparent */
WRITE_ONCE(gparent->rb_right, tmp); /* == parent->rb_left */
WRITE_ONCE(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;
}
}
}
/*
* 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 *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
*/
tmp1 = sibling->rb_left;
WRITE_ONCE(parent->rb_right, tmp1);
WRITE_ONCE(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;
}
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;
}
/*
* Case 3 - right rotate at sibling
* (p could be either color here)
*
* (p) (p)
* / \ / \
* N S --> N sl
* / \ \
* sl Sr S
* \
* Sr
*
* Note: p might be red, and then both
* p and sl are red after rotation(which
* breaks property 4). This is fixed in
* Case 4 (in __rb_rotate_set_parents()
* which set sl the color of p
* and set p RB_BLACK)
*
* (p) (sl)
* / \ / \
* N sl --> P S
* \ / \
* S N Sr
* \
* Sr
*/
tmp1 = tmp2->rb_right;
WRITE_ONCE(sibling->rb_left, tmp1);
WRITE_ONCE(tmp2->rb_right, sibling);
WRITE_ONCE(parent->rb_right, 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
* (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)
*/
tmp2 = sibling->rb_left;
WRITE_ONCE(parent->rb_right, tmp2);
WRITE_ONCE(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 */
tmp1 = sibling->rb_right;
WRITE_ONCE(parent->rb_left, tmp1);
WRITE_ONCE(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;
}
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;
}
/* Case 3 - left rotate at sibling */
tmp1 = tmp2->rb_left;
WRITE_ONCE(sibling->rb_right, tmp1);
WRITE_ONCE(tmp2->rb_left, sibling);
WRITE_ONCE(parent->rb_left, tmp2);
if (tmp1)
rb_set_parent_color(tmp1, sibling,
RB_BLACK);
augment_rotate(sibling, tmp2);
tmp1 = sibling;
sibling = tmp2;
}
/* Case 4 - right rotate at parent + color flips */
tmp2 = sibling->rb_right;
WRITE_ONCE(parent->rb_left, tmp2);
WRITE_ONCE(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;
}
}
}
/* 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);
}
//EXPORT_SYMBOL(__rb_erase_color);
/*
* 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 = {
.propagate = dummy_propagate,
.copy = dummy_copy,
.rotate = dummy_rotate
};
void rb_insert_color(struct rb_node *node, struct rb_root *root)
{
__rb_insert(node, root, dummy_rotate);
}
//EXPORT_SYMBOL(rb_insert_color);
void rb_erase(struct rb_node *node, struct rb_root *root)
{
struct rb_node *rebalance;
rebalance = __rb_erase_augmented(node, root, &dummy_callbacks);
if (rebalance)
____rb_erase_color(rebalance, root, dummy_rotate);
}
//EXPORT_SYMBOL(rb_erase);
/*
* Augmented rbtree manipulation functions.
*
* This instantiates the same __always_inline functions as in the non-augmented
* case, but this time with user-defined callbacks.
*/
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);
}
//EXPORT_SYMBOL(__rb_insert_augmented);
/*
* This function returns the first node (in sort order) of the tree.
*/
struct rb_node *rb_first(const struct rb_root *root)
{
struct rb_node *n;
n = root->rb_node;
if (!n)
return NULL;
while (n->rb_left)
n = n->rb_left;
return n;
}
//EXPORT_SYMBOL(rb_first);
struct rb_node *rb_last(const struct rb_root *root)
{
struct rb_node *n;
n = root->rb_node;
if (!n)
return NULL;
while (n->rb_right)
n = n->rb_right;
return n;
}
//EXPORT_SYMBOL(rb_last);
struct rb_node *rb_next(const struct rb_node *node)
{
struct rb_node *parent;
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 (node->rb_right) {
node = node->rb_right;
while (node->rb_left)
node=node->rb_left;
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.
*/
while ((parent = rb_parent(node)) && node == parent->rb_right)
node = parent;
return parent;
}
//EXPORT_SYMBOL(rb_next);
struct rb_node *rb_prev(const struct rb_node *node)
{
struct rb_node *parent;
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 (node->rb_left) {
node = node->rb_left;
while (node->rb_right)
node=node->rb_right;
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.
*/
while ((parent = rb_parent(node)) && node == parent->rb_left)
node = parent;
return parent;
}
//EXPORT_SYMBOL(rb_prev);
void rb_replace_node(struct rb_node *victim, struct rb_node *new, struct rb_root *root)
{
struct rb_node *parent = rb_parent(victim);
/* Copy the pointers/colour from the victim to the replacement */
*new = *victim;
/* Set the surrounding nodes to point to the replacement */
if (victim->rb_left)
rb_set_parent(victim->rb_left, new);
if (victim->rb_right)
rb_set_parent(victim->rb_right, new);
__rb_change_child(victim, new, parent, root);
}
//EXPORT_SYMBOL(rb_replace_node);
void rb_replace_node_rcu(struct rb_node *victim, struct rb_node *new, struct rb_root *root)
{
struct rb_node *parent = rb_parent(victim);
/* Copy the pointers/colour from the victim to the replacement */
*new = *victim;
/* Set the surrounding nodes to point to the replacement */
if (victim->rb_left)
rb_set_parent(victim->rb_left, new);
if (victim->rb_right)
rb_set_parent(victim->rb_right, new);
/* Set the parent's pointer to the new node last after an RCU barrier
* so that the pointers onwards are seen to be set correctly when doing
* an RCU walk over the tree.
*/
__rb_change_child_rcu(victim, new, parent, root);
}
//EXPORT_SYMBOL(rb_replace_node_rcu);
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;
}
//EXPORT_SYMBOL(rb_next_postorder);
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);
}
//EXPORT_SYMBOL(rb_first_postorder); 3. 測試檔案
/*
* 使用 kernel 中的 rbtree_test.c 進行測試更好，其産生随機資料，并記錄查找時間
*/
#include <stdio.h>
#include <stdlib.h>
#include "rbtree.h"
struct test_node {
int key;
struct rb_node rb;
int val;
};
static struct rb_root_cached rbtree_root = RB_ROOT_CACHED;
static struct test_node *nodes = NULL;
static void insert_cached(struct test_node *node, struct rb_root_cached *root)
{
struct rb_node **new = &root->rb_root.rb_node, *parent = NULL;
int key = node->key;
bool leftmost = true;
while (*new) {
parent = *new;
if (key < rb_entry(parent, struct test_node, rb)->key) {
new = &parent->rb_left;
} else {
new = &parent->rb_right;
leftmost = false; //隻要一次往右找了，新節點node就不可能是leftmost節點了
}
}
rb_link_node(&node->rb, parent, new);
rb_insert_color_cached(&node->rb, root, leftmost);
}
struct test_node *search_cached(struct rb_root_cached *root, int key) {
struct test_node *node_target = NULL;
struct rb_node **new = &root->rb_root.rb_node, *parent = NULL;
while (*new) {
parent = *new;
node_target = rb_entry(parent, struct test_node, rb);
if (key < node_target->key) {
new = &parent->rb_left;
} else if (key > node_target->key) {
new = &parent->rb_right;
} else {
return node_target;
}
}
return NULL;
}
static void erase_cached(struct test_node *node, struct rb_root_cached *root)
{
rb_erase_cached(&node->rb, root);
}
static void test_init(struct rb_root_cached *root, int num) {
int i, key, val;
nodes = (struct test_node *)calloc(num, sizeof(struct test_node));
if (!nodes) {
exit(-1);
}
printf("insert:\n");
for (i = 0; i < num; i++) {
key = rand() % (num * 100);
val = rand() % (num * 100);
nodes[i].key = key;
nodes[i].val = val;
insert_cached(&nodes[i], root);
printf("key=%d, val=%d\n", key, val);
}
}
static void test_interator(struct rb_root_cached *root) {
struct test_node *pos, *n;
printf("\ninterator:\n");
rbtree_postorder_for_each_entry_safe(pos, n, &root->rb_root, rb) {
printf("key=%d, val=%d\n", pos->key, pos->val);
}
pos = container_of(root->rb_leftmost, struct test_node, rb);
printf("leftmost->key=%d, leftmost->val=%d\n", pos->key, pos->val);
}
static void test_interator_self_define(struct rb_root_cached *root) {
struct rb_node *rn;
struct test_node *pos;
printf("\nspecial_pos:\n");
rn = rb_first(&root->rb_root);
pos = container_of(rn, struct test_node, rb);
printf("first: key=%d, val=%d\n", pos->key, pos->val);
rn = rb_next(rn);
pos = container_of(rn, struct test_node, rb);
printf("next: key=%d, val=%d\n", pos->key, pos->val);
rn = rb_last(&root->rb_root);
pos = container_of(rn, struct test_node, rb);
printf("last: key=%d, val=%d\n", pos->key, pos->val);
rn = rb_prev(rn);
pos = container_of(rn, struct test_node, rb);
printf("prev: key=%d, val=%d\n", pos->key, pos->val);
printf("\ninterator_self:\n");
rn = rb_first(&root->rb_root);
while(rn) {
rn = rb_next(rn);
if (rn) {
pos = container_of(rn, struct test_node, rb);
printf("key=%d, val=%d\n", pos->key, pos->val);
}
}
}
static void test_search_erase(struct rb_root_cached *root, int num)
{
int i;
struct test_node *node;
//删除key值落在前50%的節點
printf("\ndelete:\n");
for (i = 0; i < num * 100 / 2; i++) {
node = search_cached(root, i);
if (node) {
printf("key=%d, val=%d\n", node->key, node->val);
erase_cached(node, root);
}
}
}
int main(int argc, char *argv[])
{
int num = 100;
if (argc == 2) {
num = atoi(argv[1]);
}
test_init(&rbtree_root, num);
test_interator(&rbtree_root);
test_interator_self_define(&rbtree_root);
test_search_erase(&rbtree_root, num);
test_interator(&rbtree_root);
free(nodes);
return 0;
} 實驗結果：
/*
$ ./pp 10
insert:
key=383, val=886
key=777, val=915
key=793, val=335
key=386, val=492
key=649, val=421
key=362, val=27
key=690, val=59
key=763, val=926
key=540, val=426
key=172, val=736
interator:
key=172, val=736
key=383, val=886
key=362, val=27
key=540, val=426
key=649, val=421
key=386, val=492
key=763, val=926
key=793, val=335
key=777, val=915
key=690, val=59
leftmost->key=172, leftmost->val=736
special_pos:
first: key=172, val=736
next: key=362, val=27
last: key=793, val=335
prev: key=777, val=915
interator_self:
key=362, val=27
key=383, val=886
key=386, val=492
key=540, val=426
key=649, val=421
key=690, val=59
key=763, val=926
key=777, val=915
key=793, val=335
delete:
key=172, val=736
key=362, val=27
key=383, val=886
key=386, val=492
interator:
key=649, val=421
key=540, val=426
key=763, val=926
key=793, val=335
key=777, val=915
key=690, val=59
leftmost->key=540, leftmost->val=426
*/ ![linux-svn解除安裝與安裝[圖]](data:image/gif;base64,R0lGODlhAQABAIAAAP///wAAACwAAAAAAQABAAACAkQBADs=)