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 | #ifndef __LIBBPF_HASHMAP_H |
9 | #define __LIBBPF_HASHMAP_H |
10 | |
11 | #include <stdbool.h> |
12 | #include <stddef.h> |
13 | #include <limits.h> |
14 | |
15 | static inline size_t hash_bits(size_t h, int bits) |
16 | { |
17 | /* shuffle bits and return requested number of upper bits */ |
18 | if (bits == 0) |
19 | return 0; |
20 | |
21 | #if (__SIZEOF_SIZE_T__ == __SIZEOF_LONG_LONG__) |
22 | /* LP64 case */ |
23 | return (h * 11400714819323198485llu) >> (__SIZEOF_LONG_LONG__ * 8 - bits); |
24 | #elif (__SIZEOF_SIZE_T__ <= __SIZEOF_LONG__) |
25 | return (h * 2654435769lu) >> (__SIZEOF_LONG__ * 8 - bits); |
26 | #else |
27 | # error "Unsupported size_t size" |
28 | #endif |
29 | } |
30 | |
31 | /* generic C-string hashing function */ |
32 | static inline size_t str_hash(const char *s) |
33 | { |
34 | size_t h = 0; |
35 | |
36 | while (*s) { |
37 | h = h * 31 + *s; |
38 | s++; |
39 | } |
40 | return h; |
41 | } |
42 | |
43 | typedef size_t (*hashmap_hash_fn)(long key, void *ctx); |
44 | typedef bool (*hashmap_equal_fn)(long key1, long key2, void *ctx); |
45 | |
46 | /* |
47 | * Hashmap interface is polymorphic, keys and values could be either |
48 | * long-sized integers or pointers, this is achieved as follows: |
49 | * - interface functions that operate on keys and values are hidden |
50 | * behind auxiliary macros, e.g. hashmap_insert <-> hashmap__insert; |
51 | * - these auxiliary macros cast the key and value parameters as |
52 | * long or long *, so the user does not have to specify the casts explicitly; |
53 | * - for pointer parameters (e.g. old_key) the size of the pointed |
54 | * type is verified by hashmap_cast_ptr using _Static_assert; |
55 | * - when iterating using hashmap__for_each_* forms |
56 | * hasmap_entry->key should be used for integer keys and |
57 | * hasmap_entry->pkey should be used for pointer keys, |
58 | * same goes for values. |
59 | */ |
60 | struct hashmap_entry { |
61 | union { |
62 | long key; |
63 | const void *pkey; |
64 | }; |
65 | union { |
66 | long value; |
67 | void *pvalue; |
68 | }; |
69 | struct hashmap_entry *next; |
70 | }; |
71 | |
72 | struct hashmap { |
73 | hashmap_hash_fn hash_fn; |
74 | hashmap_equal_fn equal_fn; |
75 | void *ctx; |
76 | |
77 | struct hashmap_entry **buckets; |
78 | size_t cap; |
79 | size_t cap_bits; |
80 | size_t sz; |
81 | }; |
82 | |
83 | void hashmap__init(struct hashmap *map, hashmap_hash_fn hash_fn, |
84 | hashmap_equal_fn equal_fn, void *ctx); |
85 | struct hashmap *hashmap__new(hashmap_hash_fn hash_fn, |
86 | hashmap_equal_fn equal_fn, |
87 | void *ctx); |
88 | void hashmap__clear(struct hashmap *map); |
89 | void hashmap__free(struct hashmap *map); |
90 | |
91 | size_t hashmap__size(const struct hashmap *map); |
92 | size_t hashmap__capacity(const struct hashmap *map); |
93 | |
94 | /* |
95 | * Hashmap insertion strategy: |
96 | * - HASHMAP_ADD - only add key/value if key doesn't exist yet; |
97 | * - HASHMAP_SET - add key/value pair if key doesn't exist yet; otherwise, |
98 | * update value; |
99 | * - HASHMAP_UPDATE - update value, if key already exists; otherwise, do |
100 | * nothing and return -ENOENT; |
101 | * - HASHMAP_APPEND - always add key/value pair, even if key already exists. |
102 | * This turns hashmap into a multimap by allowing multiple values to be |
103 | * associated with the same key. Most useful read API for such hashmap is |
104 | * hashmap__for_each_key_entry() iteration. If hashmap__find() is still |
105 | * used, it will return last inserted key/value entry (first in a bucket |
106 | * chain). |
107 | */ |
108 | enum hashmap_insert_strategy { |
109 | HASHMAP_ADD, |
110 | HASHMAP_SET, |
111 | HASHMAP_UPDATE, |
112 | HASHMAP_APPEND, |
113 | }; |
114 | |
115 | #define hashmap_cast_ptr(p) ({ \ |
116 | _Static_assert((__builtin_constant_p((p)) ? (p) == NULL : 0) || \ |
117 | sizeof(*(p)) == sizeof(long), \ |
118 | #p " pointee should be a long-sized integer or a pointer"); \ |
119 | (long *)(p); \ |
120 | }) |
121 | |
122 | /* |
123 | * hashmap__insert() adds key/value entry w/ various semantics, depending on |
124 | * provided strategy value. If a given key/value pair replaced already |
125 | * existing key/value pair, both old key and old value will be returned |
126 | * through old_key and old_value to allow calling code do proper memory |
127 | * management. |
128 | */ |
129 | int hashmap_insert(struct hashmap *map, long key, long value, |
130 | enum hashmap_insert_strategy strategy, |
131 | long *old_key, long *old_value); |
132 | |
133 | #define hashmap__insert(map, key, value, strategy, old_key, old_value) \ |
134 | hashmap_insert((map), (long)(key), (long)(value), (strategy), \ |
135 | hashmap_cast_ptr(old_key), \ |
136 | hashmap_cast_ptr(old_value)) |
137 | |
138 | #define hashmap__add(map, key, value) \ |
139 | hashmap__insert((map), (key), (value), HASHMAP_ADD, NULL, NULL) |
140 | |
141 | #define hashmap__set(map, key, value, old_key, old_value) \ |
142 | hashmap__insert((map), (key), (value), HASHMAP_SET, (old_key), (old_value)) |
143 | |
144 | #define hashmap__update(map, key, value, old_key, old_value) \ |
145 | hashmap__insert((map), (key), (value), HASHMAP_UPDATE, (old_key), (old_value)) |
146 | |
147 | #define hashmap__append(map, key, value) \ |
148 | hashmap__insert((map), (key), (value), HASHMAP_APPEND, NULL, NULL) |
149 | |
150 | bool hashmap_delete(struct hashmap *map, long key, long *old_key, long *old_value); |
151 | |
152 | #define hashmap__delete(map, key, old_key, old_value) \ |
153 | hashmap_delete((map), (long)(key), \ |
154 | hashmap_cast_ptr(old_key), \ |
155 | hashmap_cast_ptr(old_value)) |
156 | |
157 | bool hashmap_find(const struct hashmap *map, long key, long *value); |
158 | |
159 | #define hashmap__find(map, key, value) \ |
160 | hashmap_find((map), (long)(key), hashmap_cast_ptr(value)) |
161 | |
162 | /* |
163 | * hashmap__for_each_entry - iterate over all entries in hashmap |
164 | * @map: hashmap to iterate |
165 | * @cur: struct hashmap_entry * used as a loop cursor |
166 | * @bkt: integer used as a bucket loop cursor |
167 | */ |
168 | #define hashmap__for_each_entry(map, cur, bkt) \ |
169 | for (bkt = 0; bkt < map->cap; bkt++) \ |
170 | for (cur = map->buckets[bkt]; cur; cur = cur->next) |
171 | |
172 | /* |
173 | * hashmap__for_each_entry_safe - iterate over all entries in hashmap, safe |
174 | * against removals |
175 | * @map: hashmap to iterate |
176 | * @cur: struct hashmap_entry * used as a loop cursor |
177 | * @tmp: struct hashmap_entry * used as a temporary next cursor storage |
178 | * @bkt: integer used as a bucket loop cursor |
179 | */ |
180 | #define hashmap__for_each_entry_safe(map, cur, tmp, bkt) \ |
181 | for (bkt = 0; bkt < map->cap; bkt++) \ |
182 | for (cur = map->buckets[bkt]; \ |
183 | cur && ({tmp = cur->next; true; }); \ |
184 | cur = tmp) |
185 | |
186 | /* |
187 | * hashmap__for_each_key_entry - iterate over entries associated with given key |
188 | * @map: hashmap to iterate |
189 | * @cur: struct hashmap_entry * used as a loop cursor |
190 | * @key: key to iterate entries for |
191 | */ |
192 | #define hashmap__for_each_key_entry(map, cur, _key) \ |
193 | for (cur = map->buckets \ |
194 | ? map->buckets[hash_bits(map->hash_fn((_key), map->ctx), map->cap_bits)] \ |
195 | : NULL; \ |
196 | cur; \ |
197 | cur = cur->next) \ |
198 | if (map->equal_fn(cur->key, (_key), map->ctx)) |
199 | |
200 | #define hashmap__for_each_key_entry_safe(map, cur, tmp, _key) \ |
201 | for (cur = map->buckets \ |
202 | ? map->buckets[hash_bits(map->hash_fn((_key), map->ctx), map->cap_bits)] \ |
203 | : NULL; \ |
204 | cur && ({ tmp = cur->next; true; }); \ |
205 | cur = tmp) \ |
206 | if (map->equal_fn(cur->key, (_key), map->ctx)) |
207 | |
208 | #endif /* __LIBBPF_HASHMAP_H */ |
209 | |