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9c079add ML |
1 | /* |
2 | Red Black Trees | |
3 | (C) 1999 Andrea Arcangeli <andrea@suse.de> | |
4 | (C) 2002 David Woodhouse <dwmw2@infradead.org> | |
5 | (C) 2012 Michel Lespinasse <walken@google.com> | |
6 | ||
7 | This program is free software; you can redistribute it and/or modify | |
8 | it under the terms of the GNU General Public License as published by | |
9 | the Free Software Foundation; either version 2 of the License, or | |
10 | (at your option) any later version. | |
11 | ||
12 | This program is distributed in the hope that it will be useful, | |
13 | but WITHOUT ANY WARRANTY; without even the implied warranty of | |
14 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
15 | GNU General Public License for more details. | |
16 | ||
17 | You should have received a copy of the GNU General Public License | |
18 | along with this program; if not, write to the Free Software | |
19 | Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA | |
20 | ||
21 | linux/include/linux/rbtree_augmented.h | |
22 | */ | |
23 | ||
24 | #ifndef _LINUX_RBTREE_AUGMENTED_H | |
25 | #define _LINUX_RBTREE_AUGMENTED_H | |
26 | ||
29fc7c5a | 27 | #include <linux/compiler.h> |
9c079add ML |
28 | #include <linux/rbtree.h> |
29 | ||
30 | /* | |
31 | * Please note - only struct rb_augment_callbacks and the prototypes for | |
32 | * rb_insert_augmented() and rb_erase_augmented() are intended to be public. | |
33 | * The rest are implementation details you are not expected to depend on. | |
34 | * | |
35 | * See Documentation/rbtree.txt for documentation and samples. | |
36 | */ | |
37 | ||
38 | struct rb_augment_callbacks { | |
39 | void (*propagate)(struct rb_node *node, struct rb_node *stop); | |
40 | void (*copy)(struct rb_node *old, struct rb_node *new); | |
41 | void (*rotate)(struct rb_node *old, struct rb_node *new); | |
42 | }; | |
43 | ||
44 | extern void __rb_insert_augmented(struct rb_node *node, struct rb_root *root, | |
45 | void (*augment_rotate)(struct rb_node *old, struct rb_node *new)); | |
a841b659 LJ |
46 | /* |
47 | * Fixup the rbtree and update the augmented information when rebalancing. | |
48 | * | |
49 | * On insertion, the user must update the augmented information on the path | |
50 | * leading to the inserted node, then call rb_link_node() as usual and | |
51 | * rb_augment_inserted() instead of the usual rb_insert_color() call. | |
52 | * If rb_augment_inserted() rebalances the rbtree, it will callback into | |
53 | * a user provided function to update the augmented information on the | |
54 | * affected subtrees. | |
55 | */ | |
9c079add ML |
56 | static inline void |
57 | rb_insert_augmented(struct rb_node *node, struct rb_root *root, | |
58 | const struct rb_augment_callbacks *augment) | |
59 | { | |
60 | __rb_insert_augmented(node, root, augment->rotate); | |
61 | } | |
62 | ||
63 | #define RB_DECLARE_CALLBACKS(rbstatic, rbname, rbstruct, rbfield, \ | |
64 | rbtype, rbaugmented, rbcompute) \ | |
65 | static inline void \ | |
66 | rbname ## _propagate(struct rb_node *rb, struct rb_node *stop) \ | |
67 | { \ | |
68 | while (rb != stop) { \ | |
69 | rbstruct *node = rb_entry(rb, rbstruct, rbfield); \ | |
70 | rbtype augmented = rbcompute(node); \ | |
71 | if (node->rbaugmented == augmented) \ | |
72 | break; \ | |
73 | node->rbaugmented = augmented; \ | |
74 | rb = rb_parent(&node->rbfield); \ | |
75 | } \ | |
76 | } \ | |
77 | static inline void \ | |
78 | rbname ## _copy(struct rb_node *rb_old, struct rb_node *rb_new) \ | |
79 | { \ | |
80 | rbstruct *old = rb_entry(rb_old, rbstruct, rbfield); \ | |
81 | rbstruct *new = rb_entry(rb_new, rbstruct, rbfield); \ | |
82 | new->rbaugmented = old->rbaugmented; \ | |
83 | } \ | |
84 | static void \ | |
85 | rbname ## _rotate(struct rb_node *rb_old, struct rb_node *rb_new) \ | |
86 | { \ | |
87 | rbstruct *old = rb_entry(rb_old, rbstruct, rbfield); \ | |
88 | rbstruct *new = rb_entry(rb_new, rbstruct, rbfield); \ | |
89 | new->rbaugmented = old->rbaugmented; \ | |
90 | old->rbaugmented = rbcompute(old); \ | |
91 | } \ | |
92 | rbstatic const struct rb_augment_callbacks rbname = { \ | |
f231aebf KC |
93 | .propagate = rbname ## _propagate, \ |
94 | .copy = rbname ## _copy, \ | |
95 | .rotate = rbname ## _rotate \ | |
9c079add ML |
96 | }; |
97 | ||
98 | ||
99 | #define RB_RED 0 | |
100 | #define RB_BLACK 1 | |
101 | ||
102 | #define __rb_parent(pc) ((struct rb_node *)(pc & ~3)) | |
103 | ||
104 | #define __rb_color(pc) ((pc) & 1) | |
105 | #define __rb_is_black(pc) __rb_color(pc) | |
106 | #define __rb_is_red(pc) (!__rb_color(pc)) | |
107 | #define rb_color(rb) __rb_color((rb)->__rb_parent_color) | |
108 | #define rb_is_red(rb) __rb_is_red((rb)->__rb_parent_color) | |
109 | #define rb_is_black(rb) __rb_is_black((rb)->__rb_parent_color) | |
110 | ||
111 | static inline void rb_set_parent(struct rb_node *rb, struct rb_node *p) | |
112 | { | |
113 | rb->__rb_parent_color = rb_color(rb) | (unsigned long)p; | |
114 | } | |
115 | ||
116 | static inline void rb_set_parent_color(struct rb_node *rb, | |
117 | struct rb_node *p, int color) | |
118 | { | |
119 | rb->__rb_parent_color = (unsigned long)p | color; | |
120 | } | |
121 | ||
122 | static inline void | |
123 | __rb_change_child(struct rb_node *old, struct rb_node *new, | |
124 | struct rb_node *parent, struct rb_root *root) | |
125 | { | |
126 | if (parent) { | |
127 | if (parent->rb_left == old) | |
d72da4a4 | 128 | WRITE_ONCE(parent->rb_left, new); |
9c079add | 129 | else |
d72da4a4 | 130 | WRITE_ONCE(parent->rb_right, new); |
9c079add | 131 | } else |
d72da4a4 | 132 | WRITE_ONCE(root->rb_node, new); |
9c079add ML |
133 | } |
134 | ||
c1adf200 DH |
135 | static inline void |
136 | __rb_change_child_rcu(struct rb_node *old, struct rb_node *new, | |
137 | struct rb_node *parent, struct rb_root *root) | |
138 | { | |
139 | if (parent) { | |
140 | if (parent->rb_left == old) | |
141 | rcu_assign_pointer(parent->rb_left, new); | |
142 | else | |
143 | rcu_assign_pointer(parent->rb_right, new); | |
144 | } else | |
145 | rcu_assign_pointer(root->rb_node, new); | |
146 | } | |
147 | ||
9c079add ML |
148 | extern void __rb_erase_color(struct rb_node *parent, struct rb_root *root, |
149 | void (*augment_rotate)(struct rb_node *old, struct rb_node *new)); | |
150 | ||
3cb7a563 ML |
151 | static __always_inline struct rb_node * |
152 | __rb_erase_augmented(struct rb_node *node, struct rb_root *root, | |
153 | const struct rb_augment_callbacks *augment) | |
9c079add | 154 | { |
d72da4a4 PZ |
155 | struct rb_node *child = node->rb_right; |
156 | struct rb_node *tmp = node->rb_left; | |
9c079add ML |
157 | struct rb_node *parent, *rebalance; |
158 | unsigned long pc; | |
159 | ||
160 | if (!tmp) { | |
161 | /* | |
162 | * Case 1: node to erase has no more than 1 child (easy!) | |
163 | * | |
164 | * Note that if there is one child it must be red due to 5) | |
165 | * and node must be black due to 4). We adjust colors locally | |
166 | * so as to bypass __rb_erase_color() later on. | |
167 | */ | |
168 | pc = node->__rb_parent_color; | |
169 | parent = __rb_parent(pc); | |
170 | __rb_change_child(node, child, parent, root); | |
171 | if (child) { | |
172 | child->__rb_parent_color = pc; | |
173 | rebalance = NULL; | |
174 | } else | |
175 | rebalance = __rb_is_black(pc) ? parent : NULL; | |
176 | tmp = parent; | |
177 | } else if (!child) { | |
178 | /* Still case 1, but this time the child is node->rb_left */ | |
179 | tmp->__rb_parent_color = pc = node->__rb_parent_color; | |
180 | parent = __rb_parent(pc); | |
181 | __rb_change_child(node, tmp, parent, root); | |
182 | rebalance = NULL; | |
183 | tmp = parent; | |
184 | } else { | |
185 | struct rb_node *successor = child, *child2; | |
d72da4a4 | 186 | |
9c079add ML |
187 | tmp = child->rb_left; |
188 | if (!tmp) { | |
189 | /* | |
190 | * Case 2: node's successor is its right child | |
191 | * | |
192 | * (n) (s) | |
193 | * / \ / \ | |
194 | * (x) (s) -> (x) (c) | |
195 | * \ | |
196 | * (c) | |
197 | */ | |
198 | parent = successor; | |
199 | child2 = successor->rb_right; | |
d72da4a4 | 200 | |
9c079add ML |
201 | augment->copy(node, successor); |
202 | } else { | |
203 | /* | |
204 | * Case 3: node's successor is leftmost under | |
205 | * node's right child subtree | |
206 | * | |
207 | * (n) (s) | |
208 | * / \ / \ | |
209 | * (x) (y) -> (x) (y) | |
210 | * / / | |
211 | * (p) (p) | |
212 | * / / | |
213 | * (s) (c) | |
214 | * \ | |
215 | * (c) | |
216 | */ | |
217 | do { | |
218 | parent = successor; | |
219 | successor = tmp; | |
220 | tmp = tmp->rb_left; | |
221 | } while (tmp); | |
d72da4a4 PZ |
222 | child2 = successor->rb_right; |
223 | WRITE_ONCE(parent->rb_left, child2); | |
224 | WRITE_ONCE(successor->rb_right, child); | |
9c079add | 225 | rb_set_parent(child, successor); |
d72da4a4 | 226 | |
9c079add ML |
227 | augment->copy(node, successor); |
228 | augment->propagate(parent, successor); | |
229 | } | |
230 | ||
d72da4a4 PZ |
231 | tmp = node->rb_left; |
232 | WRITE_ONCE(successor->rb_left, tmp); | |
9c079add ML |
233 | rb_set_parent(tmp, successor); |
234 | ||
235 | pc = node->__rb_parent_color; | |
236 | tmp = __rb_parent(pc); | |
237 | __rb_change_child(node, successor, tmp, root); | |
d72da4a4 | 238 | |
9c079add ML |
239 | if (child2) { |
240 | successor->__rb_parent_color = pc; | |
241 | rb_set_parent_color(child2, parent, RB_BLACK); | |
242 | rebalance = NULL; | |
243 | } else { | |
244 | unsigned long pc2 = successor->__rb_parent_color; | |
245 | successor->__rb_parent_color = pc; | |
246 | rebalance = __rb_is_black(pc2) ? parent : NULL; | |
247 | } | |
248 | tmp = successor; | |
249 | } | |
250 | ||
251 | augment->propagate(tmp, NULL); | |
3cb7a563 ML |
252 | return rebalance; |
253 | } | |
254 | ||
255 | static __always_inline void | |
256 | rb_erase_augmented(struct rb_node *node, struct rb_root *root, | |
257 | const struct rb_augment_callbacks *augment) | |
258 | { | |
259 | struct rb_node *rebalance = __rb_erase_augmented(node, root, augment); | |
9c079add ML |
260 | if (rebalance) |
261 | __rb_erase_color(rebalance, root, augment->rotate); | |
262 | } | |
263 | ||
264 | #endif /* _LINUX_RBTREE_AUGMENTED_H */ |