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 27 #include <linux/compiler.h> 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)); 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 */ 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 = { \ 93 rbname ## _propagate, rbname ## _copy, rbname ## _rotate \ 94 }; 95 96 97 #define RB_RED 0 98 #define RB_BLACK 1 99 100 #define __rb_parent(pc) ((struct rb_node *)(pc & ~3)) 101 102 #define __rb_color(pc) ((pc) & 1) 103 #define __rb_is_black(pc) __rb_color(pc) 104 #define __rb_is_red(pc) (!__rb_color(pc)) 105 #define rb_color(rb) __rb_color((rb)->__rb_parent_color) 106 #define rb_is_red(rb) __rb_is_red((rb)->__rb_parent_color) 107 #define rb_is_black(rb) __rb_is_black((rb)->__rb_parent_color) 108 109 static inline void rb_set_parent(struct rb_node *rb, struct rb_node *p) 110 { 111 rb->__rb_parent_color = rb_color(rb) | (unsigned long)p; 112 } 113 114 static inline void rb_set_parent_color(struct rb_node *rb, 115 struct rb_node *p, int color) 116 { 117 rb->__rb_parent_color = (unsigned long)p | color; 118 } 119 120 static inline void 121 __rb_change_child(struct rb_node *old, struct rb_node *new, 122 struct rb_node *parent, struct rb_root *root) 123 { 124 if (parent) { 125 if (parent->rb_left == old) 126 WRITE_ONCE(parent->rb_left, new); 127 else 128 WRITE_ONCE(parent->rb_right, new); 129 } else 130 WRITE_ONCE(root->rb_node, new); 131 } 132 133 extern void __rb_erase_color(struct rb_node *parent, struct rb_root *root, 134 void (*augment_rotate)(struct rb_node *old, struct rb_node *new)); 135 136 static __always_inline struct rb_node * 137 __rb_erase_augmented(struct rb_node *node, struct rb_root *root, 138 const struct rb_augment_callbacks *augment) 139 { 140 struct rb_node *child = node->rb_right; 141 struct rb_node *tmp = node->rb_left; 142 struct rb_node *parent, *rebalance; 143 unsigned long pc; 144 145 if (!tmp) { 146 /* 147 * Case 1: node to erase has no more than 1 child (easy!) 148 * 149 * Note that if there is one child it must be red due to 5) 150 * and node must be black due to 4). We adjust colors locally 151 * so as to bypass __rb_erase_color() later on. 152 */ 153 pc = node->__rb_parent_color; 154 parent = __rb_parent(pc); 155 __rb_change_child(node, child, parent, root); 156 if (child) { 157 child->__rb_parent_color = pc; 158 rebalance = NULL; 159 } else 160 rebalance = __rb_is_black(pc) ? parent : NULL; 161 tmp = parent; 162 } else if (!child) { 163 /* Still case 1, but this time the child is node->rb_left */ 164 tmp->__rb_parent_color = pc = node->__rb_parent_color; 165 parent = __rb_parent(pc); 166 __rb_change_child(node, tmp, parent, root); 167 rebalance = NULL; 168 tmp = parent; 169 } else { 170 struct rb_node *successor = child, *child2; 171 172 tmp = child->rb_left; 173 if (!tmp) { 174 /* 175 * Case 2: node's successor is its right child 176 * 177 * (n) (s) 178 * / \ / \ 179 * (x) (s) -> (x) (c) 180 * \ 181 * (c) 182 */ 183 parent = successor; 184 child2 = successor->rb_right; 185 186 augment->copy(node, successor); 187 } else { 188 /* 189 * Case 3: node's successor is leftmost under 190 * node's right child subtree 191 * 192 * (n) (s) 193 * / \ / \ 194 * (x) (y) -> (x) (y) 195 * / / 196 * (p) (p) 197 * / / 198 * (s) (c) 199 * \ 200 * (c) 201 */ 202 do { 203 parent = successor; 204 successor = tmp; 205 tmp = tmp->rb_left; 206 } while (tmp); 207 child2 = successor->rb_right; 208 WRITE_ONCE(parent->rb_left, child2); 209 WRITE_ONCE(successor->rb_right, child); 210 rb_set_parent(child, successor); 211 212 augment->copy(node, successor); 213 augment->propagate(parent, successor); 214 } 215 216 tmp = node->rb_left; 217 WRITE_ONCE(successor->rb_left, tmp); 218 rb_set_parent(tmp, successor); 219 220 pc = node->__rb_parent_color; 221 tmp = __rb_parent(pc); 222 __rb_change_child(node, successor, tmp, root); 223 224 if (child2) { 225 successor->__rb_parent_color = pc; 226 rb_set_parent_color(child2, parent, RB_BLACK); 227 rebalance = NULL; 228 } else { 229 unsigned long pc2 = successor->__rb_parent_color; 230 successor->__rb_parent_color = pc; 231 rebalance = __rb_is_black(pc2) ? parent : NULL; 232 } 233 tmp = successor; 234 } 235 236 augment->propagate(tmp, NULL); 237 return rebalance; 238 } 239 240 static __always_inline void 241 rb_erase_augmented(struct rb_node *node, struct rb_root *root, 242 const struct rb_augment_callbacks *augment) 243 { 244 struct rb_node *rebalance = __rb_erase_augmented(node, root, augment); 245 if (rebalance) 246 __rb_erase_color(rebalance, root, augment->rotate); 247 } 248 249 #endif /* _LINUX_RBTREE_AUGMENTED_H */ 250