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 /* make sure libbpf doesn't use kernel-only integer typedefs */
16 #pragma GCC poison u8 u16 u32 u64 s8 s16 s32 s64
17
18 /* prevent accidental re-addition of reallocarray() */
19 #pragma GCC poison reallocarray
20
21 /* start with 4 buckets */
22 #define HASHMAP_MIN_CAP_BITS 2
23
24 static void hashmap_add_entry(struct hashmap_entry **pprev,
25 struct hashmap_entry *entry)
26 {
27 entry->next = *pprev;
28 *pprev = entry;
29 }
30
31 static void hashmap_del_entry(struct hashmap_entry **pprev,
32 struct hashmap_entry *entry)
33 {
34 *pprev = entry->next;
35 entry->next = NULL;
36 }
37
38 void hashmap__init(struct hashmap *map, hashmap_hash_fn hash_fn,
39 hashmap_equal_fn equal_fn, void *ctx)
40 {
41 map->hash_fn = hash_fn;
42 map->equal_fn = equal_fn;
43 map->ctx = ctx;
44
45 map->buckets = NULL;
46 map->cap = 0;
47 map->cap_bits = 0;
48 map->sz = 0;
49 }
50
51 struct hashmap *hashmap__new(hashmap_hash_fn hash_fn,
52 hashmap_equal_fn equal_fn,
53 void *ctx)
54 {
55 struct hashmap *map = malloc(sizeof(struct hashmap));
56
57 if (!map)
58 return ERR_PTR(-ENOMEM);
59 hashmap__init(map, hash_fn, equal_fn, ctx);
60 return map;
61 }
62
63 void hashmap__clear(struct hashmap *map)
64 {
65 struct hashmap_entry *cur, *tmp;
66 size_t bkt;
67
68 hashmap__for_each_entry_safe(map, cur, tmp, bkt) {
69 free(cur);
70 }
71 free(map->buckets);
72 map->buckets = NULL;
73 map->cap = map->cap_bits = map->sz = 0;
74 }
75
76 void hashmap__free(struct hashmap *map)
77 {
78 if (IS_ERR_OR_NULL(map))
79 return;
80
81 hashmap__clear(map);
82 free(map);
83 }
84
85 size_t hashmap__size(const struct hashmap *map)
86 {
87 return map->sz;
88 }
89
90 size_t hashmap__capacity(const struct hashmap *map)
91 {
92 return map->cap;
93 }
94
95 static bool hashmap_needs_to_grow(struct hashmap *map)
96 {
97 /* grow if empty or more than 75% filled */
98 return (map->cap == 0) || ((map->sz + 1) * 4 / 3 > map->cap);
99 }
100
101 static int hashmap_grow(struct hashmap *map)
102 {
103 struct hashmap_entry **new_buckets;
104 struct hashmap_entry *cur, *tmp;
105 size_t new_cap_bits, new_cap;
106 size_t h, bkt;
107
108 new_cap_bits = map->cap_bits + 1;
109 if (new_cap_bits < HASHMAP_MIN_CAP_BITS)
110 new_cap_bits = HASHMAP_MIN_CAP_BITS;
111
112 new_cap = 1UL << new_cap_bits;
113 new_buckets = calloc(new_cap, sizeof(new_buckets[0]));
114 if (!new_buckets)
115 return -ENOMEM;
116
117 hashmap__for_each_entry_safe(map, cur, tmp, bkt) {
118 h = hash_bits(map->hash_fn(cur->key, map->ctx), new_cap_bits);
119 hashmap_add_entry(&new_buckets[h], cur);
120 }
121
122 map->cap = new_cap;
123 map->cap_bits = new_cap_bits;
124 free(map->buckets);
125 map->buckets = new_buckets;
126
127 return 0;
128 }
129
130 static bool hashmap_find_entry(const struct hashmap *map,
131 const long key, size_t hash,
132 struct hashmap_entry ***pprev,
133 struct hashmap_entry **entry)
134 {
135 struct hashmap_entry *cur, **prev_ptr;
136
137 if (!map->buckets)
138 return false;
139
140 for (prev_ptr = &map->buckets[hash], cur = *prev_ptr;
141 cur;
142 prev_ptr = &cur->next, cur = cur->next) {
143 if (map->equal_fn(cur->key, key, map->ctx)) {
144 if (pprev)
145 *pprev = prev_ptr;
146 *entry = cur;
147 return true;
148 }
149 }
150
151 return false;
152 }
153
154 int hashmap_insert(struct hashmap *map, long key, long value,
155 enum hashmap_insert_strategy strategy,
156 long *old_key, long *old_value)
157 {
158 struct hashmap_entry *entry;
159 size_t h;
160 int err;
161
162 if (old_key)
163 *old_key = 0;
164 if (old_value)
165 *old_value = 0;
166
167 h = hash_bits(map->hash_fn(key, map->ctx), map->cap_bits);
168 if (strategy != HASHMAP_APPEND &&
169 hashmap_find_entry(map, key, h, NULL, &entry)) {
170 if (old_key)
171 *old_key = entry->key;
172 if (old_value)
173 *old_value = entry->value;
174
175 if (strategy == HASHMAP_SET || strategy == HASHMAP_UPDATE) {
176 entry->key = key;
177 entry->value = value;
178 return 0;
179 } else if (strategy == HASHMAP_ADD) {
180 return -EEXIST;
181 }
182 }
183
184 if (strategy == HASHMAP_UPDATE)
185 return -ENOENT;
186
187 if (hashmap_needs_to_grow(map)) {
188 err = hashmap_grow(map);
189 if (err)
190 return err;
191 h = hash_bits(map->hash_fn(key, map->ctx), map->cap_bits);
192 }
193
194 entry = malloc(sizeof(struct hashmap_entry));
195 if (!entry)
196 return -ENOMEM;
197
198 entry->key = key;
199 entry->value = value;
200 hashmap_add_entry(&map->buckets[h], entry);
201 map->sz++;
202
203 return 0;
204 }
205
206 bool hashmap_find(const struct hashmap *map, long key, long *value)
207 {
208 struct hashmap_entry *entry;
209 size_t h;
210
211 h = hash_bits(map->hash_fn(key, map->ctx), map->cap_bits);
212 if (!hashmap_find_entry(map, key, h, NULL, &entry))
213 return false;
214
215 if (value)
216 *value = entry->value;
217 return true;
218 }
219
220 bool hashmap_delete(struct hashmap *map, long key,
221 long *old_key, long *old_value)
222 {
223 struct hashmap_entry **pprev, *entry;
224 size_t h;
225
226 h = hash_bits(map->hash_fn(key, map->ctx), map->cap_bits);
227 if (!hashmap_find_entry(map, key, h, &pprev, &entry))
228 return false;
229
230 if (old_key)
231 *old_key = entry->key;
232 if (old_value)
233 *old_value = entry->value;
234
235 hashmap_del_entry(pprev, entry);
236 free(entry);
237 map->sz--;
238
239 return true;
240 }
241
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