1 /*
2 *
3 * Copyright 2015 gRPC authors.
4 *
5 * Licensed under the Apache License, Version 2.0 (the "License");
6 * you may not use this file except in compliance with the License.
7 * You may obtain a copy of the License at
8 *
9 * http://www.apache.org/licenses/LICENSE-2.0
10 *
11 * Unless required by applicable law or agreed to in writing, software
12 * distributed under the License is distributed on an "AS IS" BASIS,
13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 * See the License for the specific language governing permissions and
15 * limitations under the License.
16 *
17 */
18
19 #include <grpc/support/port_platform.h>
20
21 #include "src/core/lib/avl/avl.h"
22
23 #include <assert.h>
24 #include <stdlib.h>
25
26 #include <grpc/support/alloc.h>
27 #include <grpc/support/string_util.h>
28
29 #include "src/core/lib/gpr/useful.h"
30
grpc_avl_create(const grpc_avl_vtable * vtable)31 grpc_avl grpc_avl_create(const grpc_avl_vtable* vtable) {
32 grpc_avl out;
33 out.vtable = vtable;
34 out.root = nullptr;
35 return out;
36 }
37
ref_node(grpc_avl_node * node)38 static grpc_avl_node* ref_node(grpc_avl_node* node) {
39 if (node) {
40 gpr_ref(&node->refs);
41 }
42 return node;
43 }
44
unref_node(const grpc_avl_vtable * vtable,grpc_avl_node * node,void * user_data)45 static void unref_node(const grpc_avl_vtable* vtable, grpc_avl_node* node,
46 void* user_data) {
47 if (node == nullptr) {
48 return;
49 }
50 if (gpr_unref(&node->refs)) {
51 vtable->destroy_key(node->key, user_data);
52 vtable->destroy_value(node->value, user_data);
53 unref_node(vtable, node->left, user_data);
54 unref_node(vtable, node->right, user_data);
55 gpr_free(node);
56 }
57 }
58
node_height(grpc_avl_node * node)59 static long node_height(grpc_avl_node* node) {
60 return node == nullptr ? 0 : node->height;
61 }
62
63 #ifndef NDEBUG
calculate_height(grpc_avl_node * node)64 static long calculate_height(grpc_avl_node* node) {
65 return node == nullptr ? 0
66 : 1 + GPR_MAX(calculate_height(node->left),
67 calculate_height(node->right));
68 }
69
assert_invariants(grpc_avl_node * n)70 static grpc_avl_node* assert_invariants(grpc_avl_node* n) {
71 if (n == nullptr) return nullptr;
72 assert_invariants(n->left);
73 assert_invariants(n->right);
74 assert(calculate_height(n) == n->height);
75 assert(labs(node_height(n->left) - node_height(n->right)) <= 1);
76 return n;
77 }
78 #else
assert_invariants(grpc_avl_node * n)79 static grpc_avl_node* assert_invariants(grpc_avl_node* n) { return n; }
80 #endif
81
new_node(void * key,void * value,grpc_avl_node * left,grpc_avl_node * right)82 grpc_avl_node* new_node(void* key, void* value, grpc_avl_node* left,
83 grpc_avl_node* right) {
84 grpc_avl_node* node = static_cast<grpc_avl_node*>(gpr_malloc(sizeof(*node)));
85 gpr_ref_init(&node->refs, 1);
86 node->key = key;
87 node->value = value;
88 node->left = assert_invariants(left);
89 node->right = assert_invariants(right);
90 node->height = 1 + GPR_MAX(node_height(left), node_height(right));
91 return node;
92 }
93
get(const grpc_avl_vtable * vtable,grpc_avl_node * node,void * key,void * user_data)94 static grpc_avl_node* get(const grpc_avl_vtable* vtable, grpc_avl_node* node,
95 void* key, void* user_data) {
96 long cmp;
97
98 if (node == nullptr) {
99 return nullptr;
100 }
101
102 cmp = vtable->compare_keys(node->key, key, user_data);
103 if (cmp == 0) {
104 return node;
105 } else if (cmp > 0) {
106 return get(vtable, node->left, key, user_data);
107 } else {
108 return get(vtable, node->right, key, user_data);
109 }
110 }
111
grpc_avl_get(grpc_avl avl,void * key,void * user_data)112 void* grpc_avl_get(grpc_avl avl, void* key, void* user_data) {
113 grpc_avl_node* node = get(avl.vtable, avl.root, key, user_data);
114 return node ? node->value : nullptr;
115 }
116
grpc_avl_maybe_get(grpc_avl avl,void * key,void ** value,void * user_data)117 int grpc_avl_maybe_get(grpc_avl avl, void* key, void** value, void* user_data) {
118 grpc_avl_node* node = get(avl.vtable, avl.root, key, user_data);
119 if (node != nullptr) {
120 *value = node->value;
121 return 1;
122 }
123 return 0;
124 }
125
rotate_left(const grpc_avl_vtable * vtable,void * key,void * value,grpc_avl_node * left,grpc_avl_node * right,void * user_data)126 static grpc_avl_node* rotate_left(const grpc_avl_vtable* vtable, void* key,
127 void* value, grpc_avl_node* left,
128 grpc_avl_node* right, void* user_data) {
129 grpc_avl_node* n = new_node(vtable->copy_key(right->key, user_data),
130 vtable->copy_value(right->value, user_data),
131 new_node(key, value, left, ref_node(right->left)),
132 ref_node(right->right));
133 unref_node(vtable, right, user_data);
134 return n;
135 }
136
rotate_right(const grpc_avl_vtable * vtable,void * key,void * value,grpc_avl_node * left,grpc_avl_node * right,void * user_data)137 static grpc_avl_node* rotate_right(const grpc_avl_vtable* vtable, void* key,
138 void* value, grpc_avl_node* left,
139 grpc_avl_node* right, void* user_data) {
140 grpc_avl_node* n =
141 new_node(vtable->copy_key(left->key, user_data),
142 vtable->copy_value(left->value, user_data), ref_node(left->left),
143 new_node(key, value, ref_node(left->right), right));
144 unref_node(vtable, left, user_data);
145 return n;
146 }
147
rotate_left_right(const grpc_avl_vtable * vtable,void * key,void * value,grpc_avl_node * left,grpc_avl_node * right,void * user_data)148 static grpc_avl_node* rotate_left_right(const grpc_avl_vtable* vtable,
149 void* key, void* value,
150 grpc_avl_node* left,
151 grpc_avl_node* right, void* user_data) {
152 /* rotate_right(..., rotate_left(left), right) */
153 grpc_avl_node* n =
154 new_node(vtable->copy_key(left->right->key, user_data),
155 vtable->copy_value(left->right->value, user_data),
156 new_node(vtable->copy_key(left->key, user_data),
157 vtable->copy_value(left->value, user_data),
158 ref_node(left->left), ref_node(left->right->left)),
159 new_node(key, value, ref_node(left->right->right), right));
160 unref_node(vtable, left, user_data);
161 return n;
162 }
163
rotate_right_left(const grpc_avl_vtable * vtable,void * key,void * value,grpc_avl_node * left,grpc_avl_node * right,void * user_data)164 static grpc_avl_node* rotate_right_left(const grpc_avl_vtable* vtable,
165 void* key, void* value,
166 grpc_avl_node* left,
167 grpc_avl_node* right, void* user_data) {
168 /* rotate_left(..., left, rotate_right(right)) */
169 grpc_avl_node* n =
170 new_node(vtable->copy_key(right->left->key, user_data),
171 vtable->copy_value(right->left->value, user_data),
172 new_node(key, value, left, ref_node(right->left->left)),
173 new_node(vtable->copy_key(right->key, user_data),
174 vtable->copy_value(right->value, user_data),
175 ref_node(right->left->right), ref_node(right->right)));
176 unref_node(vtable, right, user_data);
177 return n;
178 }
179
rebalance(const grpc_avl_vtable * vtable,void * key,void * value,grpc_avl_node * left,grpc_avl_node * right,void * user_data)180 static grpc_avl_node* rebalance(const grpc_avl_vtable* vtable, void* key,
181 void* value, grpc_avl_node* left,
182 grpc_avl_node* right, void* user_data) {
183 switch (node_height(left) - node_height(right)) {
184 case 2:
185 if (node_height(left->left) - node_height(left->right) == -1) {
186 return assert_invariants(
187 rotate_left_right(vtable, key, value, left, right, user_data));
188 } else {
189 return assert_invariants(
190 rotate_right(vtable, key, value, left, right, user_data));
191 }
192 case -2:
193 if (node_height(right->left) - node_height(right->right) == 1) {
194 return assert_invariants(
195 rotate_right_left(vtable, key, value, left, right, user_data));
196 } else {
197 return assert_invariants(
198 rotate_left(vtable, key, value, left, right, user_data));
199 }
200 default:
201 return assert_invariants(new_node(key, value, left, right));
202 }
203 }
204
add_key(const grpc_avl_vtable * vtable,grpc_avl_node * node,void * key,void * value,void * user_data)205 static grpc_avl_node* add_key(const grpc_avl_vtable* vtable,
206 grpc_avl_node* node, void* key, void* value,
207 void* user_data) {
208 long cmp;
209 if (node == nullptr) {
210 return new_node(key, value, nullptr, nullptr);
211 }
212 cmp = vtable->compare_keys(node->key, key, user_data);
213 if (cmp == 0) {
214 return new_node(key, value, ref_node(node->left), ref_node(node->right));
215 } else if (cmp > 0) {
216 return rebalance(vtable, vtable->copy_key(node->key, user_data),
217 vtable->copy_value(node->value, user_data),
218 add_key(vtable, node->left, key, value, user_data),
219 ref_node(node->right), user_data);
220 } else {
221 return rebalance(
222 vtable, vtable->copy_key(node->key, user_data),
223 vtable->copy_value(node->value, user_data), ref_node(node->left),
224 add_key(vtable, node->right, key, value, user_data), user_data);
225 }
226 }
227
grpc_avl_add(grpc_avl avl,void * key,void * value,void * user_data)228 grpc_avl grpc_avl_add(grpc_avl avl, void* key, void* value, void* user_data) {
229 grpc_avl_node* old_root = avl.root;
230 avl.root = add_key(avl.vtable, avl.root, key, value, user_data);
231 assert_invariants(avl.root);
232 unref_node(avl.vtable, old_root, user_data);
233 return avl;
234 }
235
in_order_head(grpc_avl_node * node)236 static grpc_avl_node* in_order_head(grpc_avl_node* node) {
237 while (node->left != nullptr) {
238 node = node->left;
239 }
240 return node;
241 }
242
in_order_tail(grpc_avl_node * node)243 static grpc_avl_node* in_order_tail(grpc_avl_node* node) {
244 while (node->right != nullptr) {
245 node = node->right;
246 }
247 return node;
248 }
249
remove_key(const grpc_avl_vtable * vtable,grpc_avl_node * node,void * key,void * user_data)250 static grpc_avl_node* remove_key(const grpc_avl_vtable* vtable,
251 grpc_avl_node* node, void* key,
252 void* user_data) {
253 long cmp;
254 if (node == nullptr) {
255 return nullptr;
256 }
257 cmp = vtable->compare_keys(node->key, key, user_data);
258 if (cmp == 0) {
259 if (node->left == nullptr) {
260 return ref_node(node->right);
261 } else if (node->right == nullptr) {
262 return ref_node(node->left);
263 } else if (node->left->height < node->right->height) {
264 grpc_avl_node* h = in_order_head(node->right);
265 return rebalance(
266 vtable, vtable->copy_key(h->key, user_data),
267 vtable->copy_value(h->value, user_data), ref_node(node->left),
268 remove_key(vtable, node->right, h->key, user_data), user_data);
269 } else {
270 grpc_avl_node* h = in_order_tail(node->left);
271 return rebalance(vtable, vtable->copy_key(h->key, user_data),
272 vtable->copy_value(h->value, user_data),
273 remove_key(vtable, node->left, h->key, user_data),
274 ref_node(node->right), user_data);
275 }
276 } else if (cmp > 0) {
277 return rebalance(vtable, vtable->copy_key(node->key, user_data),
278 vtable->copy_value(node->value, user_data),
279 remove_key(vtable, node->left, key, user_data),
280 ref_node(node->right), user_data);
281 } else {
282 return rebalance(
283 vtable, vtable->copy_key(node->key, user_data),
284 vtable->copy_value(node->value, user_data), ref_node(node->left),
285 remove_key(vtable, node->right, key, user_data), user_data);
286 }
287 }
288
grpc_avl_remove(grpc_avl avl,void * key,void * user_data)289 grpc_avl grpc_avl_remove(grpc_avl avl, void* key, void* user_data) {
290 grpc_avl_node* old_root = avl.root;
291 avl.root = remove_key(avl.vtable, avl.root, key, user_data);
292 assert_invariants(avl.root);
293 unref_node(avl.vtable, old_root, user_data);
294 return avl;
295 }
296
grpc_avl_ref(grpc_avl avl,void * user_data)297 grpc_avl grpc_avl_ref(grpc_avl avl, void* user_data) {
298 ref_node(avl.root);
299 return avl;
300 }
301
grpc_avl_unref(grpc_avl avl,void * user_data)302 void grpc_avl_unref(grpc_avl avl, void* user_data) {
303 unref_node(avl.vtable, avl.root, user_data);
304 }
305
grpc_avl_is_empty(grpc_avl avl)306 int grpc_avl_is_empty(grpc_avl avl) { return avl.root == nullptr; }
307