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 #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