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
Linux® is a registered trademark of Linus Torvalds in the United States and other countries.
TOMOYO® is a registered trademark of NTT DATA CORPORATION.