tools/perf/util/hashmap.h

   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)(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
 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
 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
 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
 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 */