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