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)(const void *key, void *ctx);
44 typedef bool (*hashmap_equal_fn)(const void *key1, const void *key2, void *ctx);
45
46 struct hashmap_entry {
47 const void *key;
48 void *value;
49 struct hashmap_entry *next;
50 };
51
52 struct hashmap {
53 hashmap_hash_fn hash_fn;
54 hashmap_equal_fn equal_fn;
55 void *ctx;
56
57 struct hashmap_entry **buckets;
58 size_t cap;
59 size_t cap_bits;
60 size_t sz;
61 };
62
63 #define HASHMAP_INIT(hash_fn, equal_fn, ctx) { \
64 .hash_fn = (hash_fn), \
65 .equal_fn = (equal_fn), \
66 .ctx = (ctx), \
67 .buckets = NULL, \
68 .cap = 0, \
69 .cap_bits = 0, \
70 .sz = 0, \
71 }
72
73 void hashmap__init(struct hashmap *map, hashmap_hash_fn hash_fn,
74 hashmap_equal_fn equal_fn, void *ctx);
75 struct hashmap *hashmap__new(hashmap_hash_fn hash_fn,
76 hashmap_equal_fn equal_fn,
77 void *ctx);
78 void hashmap__clear(struct hashmap *map);
79 void hashmap__free(struct hashmap *map);
80
81 size_t hashmap__size(const struct hashmap *map);
82 size_t hashmap__capacity(const struct hashmap *map);
83
84 /*
85 * Hashmap insertion strategy:
86 * - HASHMAP_ADD - only add key/value if key doesn't exist yet;
87 * - HASHMAP_SET - add key/value pair if key doesn't exist yet; otherwise,
88 * update value;
89 * - HASHMAP_UPDATE - update value, if key already exists; otherwise, do
90 * nothing and return -ENOENT;
91 * - HASHMAP_APPEND - always add key/value pair, even if key already exists.
92 * This turns hashmap into a multimap by allowing multiple values to be
93 * associated with the same key. Most useful read API for such hashmap is
94 * hashmap__for_each_key_entry() iteration. If hashmap__find() is still
95 * used, it will return last inserted key/value entry (first in a bucket
96 * chain).
97 */
98 enum hashmap_insert_strategy {
99 HASHMAP_ADD,
100 HASHMAP_SET,
101 HASHMAP_UPDATE,
102 HASHMAP_APPEND,
103 };
104
105 /*
106 * hashmap__insert() adds key/value entry w/ various semantics, depending on
107 * provided strategy value. If a given key/value pair replaced already
108 * existing key/value pair, both old key and old value will be returned
109 * through old_key and old_value to allow calling code do proper memory
110 * management.
111 */
112 int hashmap__insert(struct hashmap *map, const void *key, void *value,
113 enum hashmap_insert_strategy strategy,
114 const void **old_key, void **old_value);
115
hashmap__add(struct hashmap * map,const void * key,void * value)116 static inline int hashmap__add(struct hashmap *map,
117 const void *key, void *value)
118 {
119 return hashmap__insert(map, key, value, HASHMAP_ADD, NULL, NULL);
120 }
121
hashmap__set(struct hashmap * map,const void * key,void * value,const void ** old_key,void ** old_value)122 static inline int hashmap__set(struct hashmap *map,
123 const void *key, void *value,
124 const void **old_key, void **old_value)
125 {
126 return hashmap__insert(map, key, value, HASHMAP_SET,
127 old_key, old_value);
128 }
129
hashmap__update(struct hashmap * map,const void * key,void * value,const void ** old_key,void ** old_value)130 static inline int hashmap__update(struct hashmap *map,
131 const void *key, void *value,
132 const void **old_key, void **old_value)
133 {
134 return hashmap__insert(map, key, value, HASHMAP_UPDATE,
135 old_key, old_value);
136 }
137
hashmap__append(struct hashmap * map,const void * key,void * value)138 static inline int hashmap__append(struct hashmap *map,
139 const void *key, void *value)
140 {
141 return hashmap__insert(map, key, value, HASHMAP_APPEND, NULL, NULL);
142 }
143
144 bool hashmap__delete(struct hashmap *map, const void *key,
145 const void **old_key, void **old_value);
146
147 bool hashmap__find(const struct hashmap *map, const void *key, void **value);
148
149 /*
150 * hashmap__for_each_entry - iterate over all entries in hashmap
151 * @map: hashmap to iterate
152 * @cur: struct hashmap_entry * used as a loop cursor
153 * @bkt: integer used as a bucket loop cursor
154 */
155 #define hashmap__for_each_entry(map, cur, bkt) \
156 for (bkt = 0; bkt < map->cap; bkt++) \
157 for (cur = map->buckets[bkt]; cur; cur = cur->next)
158
159 /*
160 * hashmap__for_each_entry_safe - iterate over all entries in hashmap, safe
161 * against removals
162 * @map: hashmap to iterate
163 * @cur: struct hashmap_entry * used as a loop cursor
164 * @tmp: struct hashmap_entry * used as a temporary next cursor storage
165 * @bkt: integer used as a bucket loop cursor
166 */
167 #define hashmap__for_each_entry_safe(map, cur, tmp, bkt) \
168 for (bkt = 0; bkt < map->cap; bkt++) \
169 for (cur = map->buckets[bkt]; \
170 cur && ({tmp = cur->next; true; }); \
171 cur = tmp)
172
173 /*
174 * hashmap__for_each_key_entry - iterate over entries associated with given key
175 * @map: hashmap to iterate
176 * @cur: struct hashmap_entry * used as a loop cursor
177 * @key: key to iterate entries for
178 */
179 #define hashmap__for_each_key_entry(map, cur, _key) \
180 for (cur = map->buckets \
181 ? map->buckets[hash_bits(map->hash_fn((_key), map->ctx), map->cap_bits)] \
182 : NULL; \
183 cur; \
184 cur = cur->next) \
185 if (map->equal_fn(cur->key, (_key), map->ctx))
186
187 #define hashmap__for_each_key_entry_safe(map, cur, tmp, _key) \
188 for (cur = map->buckets \
189 ? map->buckets[hash_bits(map->hash_fn((_key), map->ctx), map->cap_bits)] \
190 : NULL; \
191 cur && ({ tmp = cur->next; true; }); \
192 cur = tmp) \
193 if (map->equal_fn(cur->key, (_key), map->ctx))
194
195 #endif /* __LIBBPF_HASHMAP_H */
196