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e3b92422 AN |
1 | // SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause) |
2 | ||
3 | /* | |
4 | * Generic non-thread safe hash map implementation. | |
5 | * | |
6 | * Copyright (c) 2019 Facebook | |
7 | */ | |
8 | #include <stdint.h> | |
9 | #include <stdlib.h> | |
10 | #include <stdio.h> | |
11 | #include <errno.h> | |
12 | #include <linux/err.h> | |
13 | #include "hashmap.h" | |
14 | ||
15 | /* start with 4 buckets */ | |
16 | #define HASHMAP_MIN_CAP_BITS 2 | |
17 | ||
18 | static void hashmap_add_entry(struct hashmap_entry **pprev, | |
19 | struct hashmap_entry *entry) | |
20 | { | |
21 | entry->next = *pprev; | |
22 | *pprev = entry; | |
23 | } | |
24 | ||
25 | static void hashmap_del_entry(struct hashmap_entry **pprev, | |
26 | struct hashmap_entry *entry) | |
27 | { | |
28 | *pprev = entry->next; | |
29 | entry->next = NULL; | |
30 | } | |
31 | ||
32 | void hashmap__init(struct hashmap *map, hashmap_hash_fn hash_fn, | |
33 | hashmap_equal_fn equal_fn, void *ctx) | |
34 | { | |
35 | map->hash_fn = hash_fn; | |
36 | map->equal_fn = equal_fn; | |
37 | map->ctx = ctx; | |
38 | ||
39 | map->buckets = NULL; | |
40 | map->cap = 0; | |
41 | map->cap_bits = 0; | |
42 | map->sz = 0; | |
43 | } | |
44 | ||
45 | struct hashmap *hashmap__new(hashmap_hash_fn hash_fn, | |
46 | hashmap_equal_fn equal_fn, | |
47 | void *ctx) | |
48 | { | |
49 | struct hashmap *map = malloc(sizeof(struct hashmap)); | |
50 | ||
51 | if (!map) | |
52 | return ERR_PTR(-ENOMEM); | |
53 | hashmap__init(map, hash_fn, equal_fn, ctx); | |
54 | return map; | |
55 | } | |
56 | ||
57 | void hashmap__clear(struct hashmap *map) | |
58 | { | |
59 | free(map->buckets); | |
60 | map->cap = map->cap_bits = map->sz = 0; | |
61 | } | |
62 | ||
63 | void hashmap__free(struct hashmap *map) | |
64 | { | |
65 | if (!map) | |
66 | return; | |
67 | ||
68 | hashmap__clear(map); | |
69 | free(map); | |
70 | } | |
71 | ||
72 | size_t hashmap__size(const struct hashmap *map) | |
73 | { | |
74 | return map->sz; | |
75 | } | |
76 | ||
77 | size_t hashmap__capacity(const struct hashmap *map) | |
78 | { | |
79 | return map->cap; | |
80 | } | |
81 | ||
82 | static bool hashmap_needs_to_grow(struct hashmap *map) | |
83 | { | |
84 | /* grow if empty or more than 75% filled */ | |
85 | return (map->cap == 0) || ((map->sz + 1) * 4 / 3 > map->cap); | |
86 | } | |
87 | ||
88 | static int hashmap_grow(struct hashmap *map) | |
89 | { | |
90 | struct hashmap_entry **new_buckets; | |
91 | struct hashmap_entry *cur, *tmp; | |
92 | size_t new_cap_bits, new_cap; | |
93 | size_t h; | |
94 | int bkt; | |
95 | ||
96 | new_cap_bits = map->cap_bits + 1; | |
97 | if (new_cap_bits < HASHMAP_MIN_CAP_BITS) | |
98 | new_cap_bits = HASHMAP_MIN_CAP_BITS; | |
99 | ||
100 | new_cap = 1UL << new_cap_bits; | |
101 | new_buckets = calloc(new_cap, sizeof(new_buckets[0])); | |
102 | if (!new_buckets) | |
103 | return -ENOMEM; | |
104 | ||
105 | hashmap__for_each_entry_safe(map, cur, tmp, bkt) { | |
106 | h = hash_bits(map->hash_fn(cur->key, map->ctx), new_cap_bits); | |
107 | hashmap_add_entry(&new_buckets[h], cur); | |
108 | } | |
109 | ||
110 | map->cap = new_cap; | |
111 | map->cap_bits = new_cap_bits; | |
112 | free(map->buckets); | |
113 | map->buckets = new_buckets; | |
114 | ||
115 | return 0; | |
116 | } | |
117 | ||
118 | static bool hashmap_find_entry(const struct hashmap *map, | |
119 | const void *key, size_t hash, | |
120 | struct hashmap_entry ***pprev, | |
121 | struct hashmap_entry **entry) | |
122 | { | |
123 | struct hashmap_entry *cur, **prev_ptr; | |
124 | ||
125 | if (!map->buckets) | |
126 | return false; | |
127 | ||
128 | for (prev_ptr = &map->buckets[hash], cur = *prev_ptr; | |
129 | cur; | |
130 | prev_ptr = &cur->next, cur = cur->next) { | |
131 | if (map->equal_fn(cur->key, key, map->ctx)) { | |
132 | if (pprev) | |
133 | *pprev = prev_ptr; | |
134 | *entry = cur; | |
135 | return true; | |
136 | } | |
137 | } | |
138 | ||
139 | return false; | |
140 | } | |
141 | ||
142 | int hashmap__insert(struct hashmap *map, const void *key, void *value, | |
143 | enum hashmap_insert_strategy strategy, | |
144 | const void **old_key, void **old_value) | |
145 | { | |
146 | struct hashmap_entry *entry; | |
147 | size_t h; | |
148 | int err; | |
149 | ||
150 | if (old_key) | |
151 | *old_key = NULL; | |
152 | if (old_value) | |
153 | *old_value = NULL; | |
154 | ||
155 | h = hash_bits(map->hash_fn(key, map->ctx), map->cap_bits); | |
156 | if (strategy != HASHMAP_APPEND && | |
157 | hashmap_find_entry(map, key, h, NULL, &entry)) { | |
158 | if (old_key) | |
159 | *old_key = entry->key; | |
160 | if (old_value) | |
161 | *old_value = entry->value; | |
162 | ||
163 | if (strategy == HASHMAP_SET || strategy == HASHMAP_UPDATE) { | |
164 | entry->key = key; | |
165 | entry->value = value; | |
166 | return 0; | |
167 | } else if (strategy == HASHMAP_ADD) { | |
168 | return -EEXIST; | |
169 | } | |
170 | } | |
171 | ||
172 | if (strategy == HASHMAP_UPDATE) | |
173 | return -ENOENT; | |
174 | ||
175 | if (hashmap_needs_to_grow(map)) { | |
176 | err = hashmap_grow(map); | |
177 | if (err) | |
178 | return err; | |
179 | h = hash_bits(map->hash_fn(key, map->ctx), map->cap_bits); | |
180 | } | |
181 | ||
182 | entry = malloc(sizeof(struct hashmap_entry)); | |
183 | if (!entry) | |
184 | return -ENOMEM; | |
185 | ||
186 | entry->key = key; | |
187 | entry->value = value; | |
188 | hashmap_add_entry(&map->buckets[h], entry); | |
189 | map->sz++; | |
190 | ||
191 | return 0; | |
192 | } | |
193 | ||
194 | bool hashmap__find(const struct hashmap *map, const void *key, void **value) | |
195 | { | |
196 | struct hashmap_entry *entry; | |
197 | size_t h; | |
198 | ||
199 | h = hash_bits(map->hash_fn(key, map->ctx), map->cap_bits); | |
200 | if (!hashmap_find_entry(map, key, h, NULL, &entry)) | |
201 | return false; | |
202 | ||
203 | if (value) | |
204 | *value = entry->value; | |
205 | return true; | |
206 | } | |
207 | ||
208 | bool hashmap__delete(struct hashmap *map, const void *key, | |
209 | const void **old_key, void **old_value) | |
210 | { | |
211 | struct hashmap_entry **pprev, *entry; | |
212 | size_t h; | |
213 | ||
214 | h = hash_bits(map->hash_fn(key, map->ctx), map->cap_bits); | |
215 | if (!hashmap_find_entry(map, key, h, &pprev, &entry)) | |
216 | return false; | |
217 | ||
218 | if (old_key) | |
219 | *old_key = entry->key; | |
220 | if (old_value) | |
221 | *old_value = entry->value; | |
222 | ||
223 | hashmap_del_entry(pprev, entry); | |
224 | free(entry); | |
225 | map->sz--; | |
226 | ||
227 | return true; | |
228 | } | |
229 |