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
hash_bits(size_t h,int bits)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 */
str_hash(const char * s)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 #define HASHMAP_INIT(hash_fn, equal_fn, ctx) { \
84 .hash_fn = (hash_fn), \
85 .equal_fn = (equal_fn), \
86 .ctx = (ctx), \
87 .buckets = NULL, \
88 .cap = 0, \
89 .cap_bits = 0, \
90 .sz = 0, \
91 }
92
93 void hashmap__init(struct hashmap *map, hashmap_hash_fn hash_fn,
94 hashmap_equal_fn equal_fn, void *ctx);
95 struct hashmap *hashmap__new(hashmap_hash_fn hash_fn,
96 hashmap_equal_fn equal_fn,
97 void *ctx);
98 void hashmap__clear(struct hashmap *map);
99 void hashmap__free(struct hashmap *map);
100
101 size_t hashmap__size(const struct hashmap *map);
102 size_t hashmap__capacity(const struct hashmap *map);
103
104 /*
105 * Hashmap insertion strategy:
106 * - HASHMAP_ADD - only add key/value if key doesn't exist yet;
107 * - HASHMAP_SET - add key/value pair if key doesn't exist yet; otherwise,
108 * update value;
109 * - HASHMAP_UPDATE - update value, if key already exists; otherwise, do
110 * nothing and return -ENOENT;
111 * - HASHMAP_APPEND - always add key/value pair, even if key already exists.
112 * This turns hashmap into a multimap by allowing multiple values to be
113 * associated with the same key. Most useful read API for such hashmap is
114 * hashmap__for_each_key_entry() iteration. If hashmap__find() is still
115 * used, it will return last inserted key/value entry (first in a bucket
116 * chain).
117 */
118 enum hashmap_insert_strategy {
119 HASHMAP_ADD,
120 HASHMAP_SET,
121 HASHMAP_UPDATE,
122 HASHMAP_APPEND,
123 };
124
125 #define hashmap_cast_ptr(p) ({ \
126 _Static_assert((__builtin_constant_p((p)) ? (p) == NULL : 0) || \
127 sizeof(*(p)) == sizeof(long), \
128 #p " pointee should be a long-sized integer or a pointer"); \
129 (long *)(p); \
130 })
131
132 /*
133 * hashmap__insert() adds key/value entry w/ various semantics, depending on
134 * provided strategy value. If a given key/value pair replaced already
135 * existing key/value pair, both old key and old value will be returned
136 * through old_key and old_value to allow calling code do proper memory
137 * management.
138 */
139 int hashmap_insert(struct hashmap *map, long key, long value,
140 enum hashmap_insert_strategy strategy,
141 long *old_key, long *old_value);
142
143 #define hashmap__insert(map, key, value, strategy, old_key, old_value) \
144 hashmap_insert((map), (long)(key), (long)(value), (strategy), \
145 hashmap_cast_ptr(old_key), \
146 hashmap_cast_ptr(old_value))
147
148 #define hashmap__add(map, key, value) \
149 hashmap__insert((map), (key), (value), HASHMAP_ADD, NULL, NULL)
150
151 #define hashmap__set(map, key, value, old_key, old_value) \
152 hashmap__insert((map), (key), (value), HASHMAP_SET, (old_key), (old_value))
153
154 #define hashmap__update(map, key, value, old_key, old_value) \
155 hashmap__insert((map), (key), (value), HASHMAP_UPDATE, (old_key), (old_value))
156
157 #define hashmap__append(map, key, value) \
158 hashmap__insert((map), (key), (value), HASHMAP_APPEND, NULL, NULL)
159
160 bool hashmap_delete(struct hashmap *map, long key, long *old_key, long *old_value);
161
162 #define hashmap__delete(map, key, old_key, old_value) \
163 hashmap_delete((map), (long)(key), \
164 hashmap_cast_ptr(old_key), \
165 hashmap_cast_ptr(old_value))
166
167 bool hashmap_find(const struct hashmap *map, long key, long *value);
168
169 #define hashmap__find(map, key, value) \
170 hashmap_find((map), (long)(key), hashmap_cast_ptr(value))
171
172 /*
173 * hashmap__for_each_entry - iterate over all entries in hashmap
174 * @map: hashmap to iterate
175 * @cur: struct hashmap_entry * used as a loop cursor
176 * @bkt: integer used as a bucket loop cursor
177 */
178 #define hashmap__for_each_entry(map, cur, bkt) \
179 for (bkt = 0; bkt < map->cap; bkt++) \
180 for (cur = map->buckets[bkt]; cur; cur = cur->next)
181
182 /*
183 * hashmap__for_each_entry_safe - iterate over all entries in hashmap, safe
184 * against removals
185 * @map: hashmap to iterate
186 * @cur: struct hashmap_entry * used as a loop cursor
187 * @tmp: struct hashmap_entry * used as a temporary next cursor storage
188 * @bkt: integer used as a bucket loop cursor
189 */
190 #define hashmap__for_each_entry_safe(map, cur, tmp, bkt) \
191 for (bkt = 0; bkt < map->cap; bkt++) \
192 for (cur = map->buckets[bkt]; \
193 cur && ({tmp = cur->next; true; }); \
194 cur = tmp)
195
196 /*
197 * hashmap__for_each_key_entry - iterate over entries associated with given key
198 * @map: hashmap to iterate
199 * @cur: struct hashmap_entry * used as a loop cursor
200 * @key: key to iterate entries for
201 */
202 #define hashmap__for_each_key_entry(map, cur, _key) \
203 for (cur = map->buckets \
204 ? map->buckets[hash_bits(map->hash_fn((_key), map->ctx), map->cap_bits)] \
205 : NULL; \
206 cur; \
207 cur = cur->next) \
208 if (map->equal_fn(cur->key, (_key), map->ctx))
209
210 #define hashmap__for_each_key_entry_safe(map, cur, tmp, _key) \
211 for (cur = map->buckets \
212 ? map->buckets[hash_bits(map->hash_fn((_key), map->ctx), map->cap_bits)] \
213 : NULL; \
214 cur && ({ tmp = cur->next; true; }); \
215 cur = tmp) \
216 if (map->equal_fn(cur->key, (_key), map->ctx))
217
218 #endif /* __LIBBPF_HASHMAP_H */
219