diff options
| -rw-r--r-- | hashmap.c | 12 | ||||
| -rw-r--r-- | hashmap.h | 24 |
2 files changed, 35 insertions, 1 deletions
@@ -104,11 +104,19 @@ static inline unsigned int bucket(const struct hashmap *map, return key->hash & (map->tablesize - 1); } +int hashmap_bucket(const struct hashmap *map, unsigned int hash) +{ + return hash & (map->tablesize - 1); +} + static void rehash(struct hashmap *map, unsigned int newsize) { unsigned int i, oldsize = map->tablesize; struct hashmap_entry **oldtable = map->table; + if (map->disallow_rehash) + return; + alloc_table(map, newsize); for (i = 0; i < oldsize; i++) { struct hashmap_entry *e = oldtable[i]; @@ -141,7 +149,9 @@ void hashmap_init(struct hashmap *map, hashmap_cmp_fn equals_function, size_t initial_size) { unsigned int size = HASHMAP_INITIAL_SIZE; - map->size = 0; + + memset(map, 0, sizeof(*map)); + map->cmpfn = equals_function ? equals_function : always_equal; /* calculate initial table size and allocate the table */ @@ -39,6 +39,7 @@ struct hashmap { struct hashmap_entry **table; hashmap_cmp_fn cmpfn; unsigned int size, tablesize, grow_at, shrink_at; + unsigned disallow_rehash : 1; }; struct hashmap_iter { @@ -77,6 +78,29 @@ static inline void *hashmap_get_from_hash(const struct hashmap *map, return hashmap_get(map, &key, keydata); } +int hashmap_bucket(const struct hashmap *map, unsigned int hash); + +/* + * Disallow/allow rehashing of the hashmap. + * This is useful if the caller knows that the hashmap + * needs multi-threaded access. The caller is still + * required to guard/lock searches and inserts in a + * manner appropriate to their usage. This simply + * prevents the table from being unexpectedly re-mapped. + * + * If is up to the caller to ensure that the hashmap is + * initialized to a reasonable size to prevent poor + * performance. + * + * When value=1, prevent future rehashes on adds and deleted. + * When value=0, allow future rehahses. This DOES NOT force + * a rehash now. + */ +static inline void hashmap_disallow_rehash(struct hashmap *map, unsigned value) +{ + map->disallow_rehash = value; +} + /* hashmap_iter functions */ extern void hashmap_iter_init(struct hashmap *map, struct hashmap_iter *iter); |