1 | /* |
2 | * librd - Rapid Development C library |
3 | * |
4 | * Copyright (c) 2012-2016, Magnus Edenhill |
5 | * All rights reserved. |
6 | * |
7 | * Redistribution and use in source and binary forms, with or without |
8 | * modification, are permitted provided that the following conditions are met: |
9 | * |
10 | * 1. Redistributions of source code must retain the above copyright notice, |
11 | * this list of conditions and the following disclaimer. |
12 | * 2. Redistributions in binary form must reproduce the above copyright notice, |
13 | * this list of conditions and the following disclaimer in the documentation |
14 | * and/or other materials provided with the distribution. |
15 | * |
16 | * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" |
17 | * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE |
18 | * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE |
19 | * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE |
20 | * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR |
21 | * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF |
22 | * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS |
23 | * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN |
24 | * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) |
25 | * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE |
26 | * POSSIBILITY OF SUCH DAMAGE. |
27 | */ |
28 | |
29 | #include "rdkafka_int.h" |
30 | #include "rdavl.h" |
31 | |
32 | /* |
33 | * AVL tree. |
34 | * Inspired by Ian Piumarta's tree.h implementation. |
35 | */ |
36 | |
37 | #define RD_AVL_NODE_HEIGHT(ran) ((ran) ? (ran)->ran_height : 0) |
38 | |
39 | #define RD_AVL_NODE_DELTA(ran) \ |
40 | (RD_AVL_NODE_HEIGHT((ran)->ran_p[RD_AVL_LEFT]) - \ |
41 | RD_AVL_NODE_HEIGHT((ran)->ran_p[RD_AVL_RIGHT])) |
42 | |
43 | #define RD_DELTA_MAX 1 |
44 | |
45 | |
46 | static rd_avl_node_t *rd_avl_balance_node (rd_avl_node_t *ran); |
47 | |
48 | static rd_avl_node_t *rd_avl_rotate (rd_avl_node_t *ran, rd_avl_dir_t dir) { |
49 | rd_avl_node_t *n; |
50 | static const rd_avl_dir_t odirmap[] = { /* opposite direction map */ |
51 | [RD_AVL_RIGHT] = RD_AVL_LEFT, |
52 | [RD_AVL_LEFT] = RD_AVL_RIGHT |
53 | }; |
54 | const int odir = odirmap[dir]; |
55 | |
56 | n = ran->ran_p[odir]; |
57 | ran->ran_p[odir] = n->ran_p[dir]; |
58 | n->ran_p[dir] = rd_avl_balance_node(ran); |
59 | |
60 | return rd_avl_balance_node(n); |
61 | } |
62 | |
63 | static rd_avl_node_t *rd_avl_balance_node (rd_avl_node_t *ran) { |
64 | const int d = RD_AVL_NODE_DELTA(ran); |
65 | int h; |
66 | |
67 | if (d < -RD_DELTA_MAX) { |
68 | if (RD_AVL_NODE_DELTA(ran->ran_p[RD_AVL_RIGHT]) > 0) |
69 | ran->ran_p[RD_AVL_RIGHT] = |
70 | rd_avl_rotate(ran->ran_p[RD_AVL_RIGHT], |
71 | RD_AVL_RIGHT); |
72 | return rd_avl_rotate(ran, RD_AVL_LEFT); |
73 | |
74 | } else if (d > RD_DELTA_MAX) { |
75 | if (RD_AVL_NODE_DELTA(ran->ran_p[RD_AVL_LEFT]) < 0) |
76 | ran->ran_p[RD_AVL_LEFT] = |
77 | rd_avl_rotate(ran->ran_p[RD_AVL_LEFT], |
78 | RD_AVL_LEFT); |
79 | |
80 | return rd_avl_rotate(ran, RD_AVL_RIGHT); |
81 | } |
82 | |
83 | ran->ran_height = 0; |
84 | |
85 | if ((h = RD_AVL_NODE_HEIGHT(ran->ran_p[RD_AVL_LEFT])) > ran->ran_height) |
86 | ran->ran_height = h; |
87 | |
88 | if ((h = RD_AVL_NODE_HEIGHT(ran->ran_p[RD_AVL_RIGHT])) >ran->ran_height) |
89 | ran->ran_height = h; |
90 | |
91 | ran->ran_height++; |
92 | |
93 | return ran; |
94 | } |
95 | |
96 | rd_avl_node_t *rd_avl_insert_node (rd_avl_t *ravl, |
97 | rd_avl_node_t *parent, |
98 | rd_avl_node_t *ran, |
99 | rd_avl_node_t **existing) { |
100 | rd_avl_dir_t dir; |
101 | int r; |
102 | |
103 | if (!parent) |
104 | return ran; |
105 | |
106 | if ((r = ravl->ravl_cmp(ran->ran_elm, parent->ran_elm)) == 0) { |
107 | /* Replace existing node with new one. */ |
108 | ran->ran_p[RD_AVL_LEFT] = parent->ran_p[RD_AVL_LEFT]; |
109 | ran->ran_p[RD_AVL_RIGHT] = parent->ran_p[RD_AVL_RIGHT]; |
110 | ran->ran_height = parent->ran_height; |
111 | *existing = parent; |
112 | return ran; |
113 | } |
114 | |
115 | if (r < 0) |
116 | dir = RD_AVL_LEFT; |
117 | else |
118 | dir = RD_AVL_RIGHT; |
119 | |
120 | parent->ran_p[dir] = rd_avl_insert_node(ravl, parent->ran_p[dir], |
121 | ran, existing); |
122 | return rd_avl_balance_node(parent); |
123 | } |
124 | |
125 | |
126 | static rd_avl_node_t *rd_avl_move (rd_avl_node_t *dst, rd_avl_node_t *src, |
127 | rd_avl_dir_t dir) { |
128 | |
129 | if (!dst) |
130 | return src; |
131 | |
132 | dst->ran_p[dir] = rd_avl_move(dst->ran_p[dir], src, dir); |
133 | |
134 | return rd_avl_balance_node(dst); |
135 | } |
136 | |
137 | static rd_avl_node_t *rd_avl_remove_node0 (rd_avl_node_t *ran) { |
138 | rd_avl_node_t *tmp; |
139 | |
140 | tmp = rd_avl_move(ran->ran_p[RD_AVL_LEFT], |
141 | ran->ran_p[RD_AVL_RIGHT], |
142 | RD_AVL_RIGHT); |
143 | |
144 | ran->ran_p[RD_AVL_LEFT] = ran->ran_p[RD_AVL_RIGHT] = NULL; |
145 | return tmp; |
146 | } |
147 | |
148 | |
149 | rd_avl_node_t *rd_avl_remove_elm0 (rd_avl_t *ravl, rd_avl_node_t *parent, |
150 | const void *elm) { |
151 | rd_avl_dir_t dir; |
152 | int r; |
153 | |
154 | if (!parent) |
155 | return NULL; |
156 | |
157 | |
158 | if ((r = ravl->ravl_cmp(elm, parent->ran_elm)) == 0) |
159 | return rd_avl_remove_node0(parent); |
160 | else if (r < 0) |
161 | dir = RD_AVL_LEFT; |
162 | else /* > 0 */ |
163 | dir = RD_AVL_RIGHT; |
164 | |
165 | parent->ran_p[dir] = |
166 | rd_avl_remove_elm0(ravl, parent->ran_p[dir], elm); |
167 | |
168 | return rd_avl_balance_node(parent); |
169 | } |
170 | |
171 | |
172 | |
173 | rd_avl_node_t *rd_avl_find_node (const rd_avl_t *ravl, |
174 | const rd_avl_node_t *begin, |
175 | const void *elm) { |
176 | int r; |
177 | |
178 | if (!begin) |
179 | return NULL; |
180 | else if (!(r = ravl->ravl_cmp(elm, begin->ran_elm))) |
181 | return (rd_avl_node_t *)begin; |
182 | else if (r < 0) |
183 | return rd_avl_find_node(ravl, begin->ran_p[RD_AVL_LEFT], elm); |
184 | else /* r > 0 */ |
185 | return rd_avl_find_node(ravl, begin->ran_p[RD_AVL_RIGHT], elm); |
186 | } |
187 | |
188 | |
189 | |
190 | void rd_avl_destroy (rd_avl_t *ravl) { |
191 | if (ravl->ravl_flags & RD_AVL_F_LOCKS) |
192 | rwlock_destroy(&ravl->ravl_rwlock); |
193 | |
194 | if (ravl->ravl_flags & RD_AVL_F_OWNER) |
195 | free(ravl); |
196 | } |
197 | |
198 | rd_avl_t *rd_avl_init (rd_avl_t *ravl, rd_avl_cmp_t cmp, int flags) { |
199 | |
200 | if (!ravl) { |
201 | ravl = calloc(1, sizeof(*ravl)); |
202 | flags |= RD_AVL_F_OWNER; |
203 | } else { |
204 | memset(ravl, 0, sizeof(*ravl)); |
205 | } |
206 | |
207 | ravl->ravl_flags = flags; |
208 | ravl->ravl_cmp = cmp; |
209 | |
210 | if (flags & RD_AVL_F_LOCKS) |
211 | rwlock_init(&ravl->ravl_rwlock); |
212 | |
213 | return ravl; |
214 | } |
215 | |