| /* | |
| * Generic implementation of hash-based key value mappings. | |
| */ | |
| #include "cache.h" | |
| #include "hashmap.h" | |
| #define FNV32_BASE ((unsigned int) 0x811c9dc5) | |
| #define FNV32_PRIME ((unsigned int) 0x01000193) | |
| unsigned int strhash(const char *str) | |
| { | |
| unsigned int c, hash = FNV32_BASE; | |
| while ((c = (unsigned char) *str++)) | |
| hash = (hash * FNV32_PRIME) ^ c; | |
| return hash; | |
| } | |
| unsigned int strihash(const char *str) | |
| { | |
| unsigned int c, hash = FNV32_BASE; | |
| while ((c = (unsigned char) *str++)) { | |
| if (c >= 'a' && c <= 'z') | |
| c -= 'a' - 'A'; | |
| hash = (hash * FNV32_PRIME) ^ c; | |
| } | |
| return hash; | |
| } | |
| unsigned int memhash(const void *buf, size_t len) | |
| { | |
| unsigned int hash = FNV32_BASE; | |
| unsigned char *ucbuf = (unsigned char *) buf; | |
| while (len--) { | |
| unsigned int c = *ucbuf++; | |
| hash = (hash * FNV32_PRIME) ^ c; | |
| } | |
| return hash; | |
| } | |
| unsigned int memihash(const void *buf, size_t len) | |
| { | |
| unsigned int hash = FNV32_BASE; | |
| unsigned char *ucbuf = (unsigned char *) buf; | |
| while (len--) { | |
| unsigned int c = *ucbuf++; | |
| if (c >= 'a' && c <= 'z') | |
| c -= 'a' - 'A'; | |
| hash = (hash * FNV32_PRIME) ^ c; | |
| } | |
| return hash; | |
| } | |
| /* | |
| * Incoporate another chunk of data into a memihash | |
| * computation. | |
| */ | |
| unsigned int memihash_cont(unsigned int hash_seed, const void *buf, size_t len) | |
| { | |
| unsigned int hash = hash_seed; | |
| unsigned char *ucbuf = (unsigned char *) buf; | |
| while (len--) { | |
| unsigned int c = *ucbuf++; | |
| if (c >= 'a' && c <= 'z') | |
| c -= 'a' - 'A'; | |
| hash = (hash * FNV32_PRIME) ^ c; | |
| } | |
| return hash; | |
| } | |
| #define HASHMAP_INITIAL_SIZE 64 | |
| /* grow / shrink by 2^2 */ | |
| #define HASHMAP_RESIZE_BITS 2 | |
| /* load factor in percent */ | |
| #define HASHMAP_LOAD_FACTOR 80 | |
| static void alloc_table(struct hashmap *map, unsigned int size) | |
| { | |
| map->tablesize = size; | |
| map->table = xcalloc(size, sizeof(struct hashmap_entry *)); | |
| /* calculate resize thresholds for new size */ | |
| map->grow_at = (unsigned int) ((uint64_t) size * HASHMAP_LOAD_FACTOR / 100); | |
| if (size <= HASHMAP_INITIAL_SIZE) | |
| map->shrink_at = 0; | |
| else | |
| /* | |
| * The shrink-threshold must be slightly smaller than | |
| * (grow-threshold / resize-factor) to prevent erratic resizing, | |
| * thus we divide by (resize-factor + 1). | |
| */ | |
| map->shrink_at = map->grow_at / ((1 << HASHMAP_RESIZE_BITS) + 1); | |
| } | |
| static inline int entry_equals(const struct hashmap *map, | |
| const struct hashmap_entry *e1, const struct hashmap_entry *e2, | |
| const void *keydata) | |
| { | |
| return (e1 == e2) || | |
| (e1->hash == e2->hash && | |
| !map->cmpfn(map->cmpfn_data, e1, e2, keydata)); | |
| } | |
| static inline unsigned int bucket(const struct hashmap *map, | |
| const struct hashmap_entry *key) | |
| { | |
| 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]; | |
| while (e) { | |
| struct hashmap_entry *next = e->next; | |
| unsigned int b = bucket(map, e); | |
| e->next = map->table[b]; | |
| map->table[b] = e; | |
| e = next; | |
| } | |
| } | |
| free(oldtable); | |
| } | |
| static inline struct hashmap_entry **find_entry_ptr(const struct hashmap *map, | |
| const struct hashmap_entry *key, const void *keydata) | |
| { | |
| struct hashmap_entry **e = &map->table[bucket(map, key)]; | |
| while (*e && !entry_equals(map, *e, key, keydata)) | |
| e = &(*e)->next; | |
| return e; | |
| } | |
| static int always_equal(const void *unused_cmp_data, | |
| const void *unused1, | |
| const void *unused2, | |
| const void *unused_keydata) | |
| { | |
| return 0; | |
| } | |
| void hashmap_init(struct hashmap *map, hashmap_cmp_fn equals_function, | |
| const void *cmpfn_data, size_t initial_size) | |
| { | |
| unsigned int size = HASHMAP_INITIAL_SIZE; | |
| memset(map, 0, sizeof(*map)); | |
| map->cmpfn = equals_function ? equals_function : always_equal; | |
| map->cmpfn_data = cmpfn_data; | |
| /* calculate initial table size and allocate the table */ | |
| initial_size = (unsigned int) ((uint64_t) initial_size * 100 | |
| / HASHMAP_LOAD_FACTOR); | |
| while (initial_size > size) | |
| size <<= HASHMAP_RESIZE_BITS; | |
| alloc_table(map, size); | |
| } | |
| void hashmap_free(struct hashmap *map, int free_entries) | |
| { | |
| if (!map || !map->table) | |
| return; | |
| if (free_entries) { | |
| struct hashmap_iter iter; | |
| struct hashmap_entry *e; | |
| hashmap_iter_init(map, &iter); | |
| while ((e = hashmap_iter_next(&iter))) | |
| free(e); | |
| } | |
| free(map->table); | |
| memset(map, 0, sizeof(*map)); | |
| } | |
| void *hashmap_get(const struct hashmap *map, const void *key, const void *keydata) | |
| { | |
| return *find_entry_ptr(map, key, keydata); | |
| } | |
| void *hashmap_get_next(const struct hashmap *map, const void *entry) | |
| { | |
| struct hashmap_entry *e = ((struct hashmap_entry *) entry)->next; | |
| for (; e; e = e->next) | |
| if (entry_equals(map, entry, e, NULL)) | |
| return e; | |
| return NULL; | |
| } | |
| void hashmap_add(struct hashmap *map, void *entry) | |
| { | |
| unsigned int b = bucket(map, entry); | |
| /* add entry */ | |
| ((struct hashmap_entry *) entry)->next = map->table[b]; | |
| map->table[b] = entry; | |
| /* fix size and rehash if appropriate */ | |
| map->size++; | |
| if (map->size > map->grow_at) | |
| rehash(map, map->tablesize << HASHMAP_RESIZE_BITS); | |
| } | |
| void *hashmap_remove(struct hashmap *map, const void *key, const void *keydata) | |
| { | |
| struct hashmap_entry *old; | |
| struct hashmap_entry **e = find_entry_ptr(map, key, keydata); | |
| if (!*e) | |
| return NULL; | |
| /* remove existing entry */ | |
| old = *e; | |
| *e = old->next; | |
| old->next = NULL; | |
| /* fix size and rehash if appropriate */ | |
| map->size--; | |
| if (map->size < map->shrink_at) | |
| rehash(map, map->tablesize >> HASHMAP_RESIZE_BITS); | |
| return old; | |
| } | |
| void *hashmap_put(struct hashmap *map, void *entry) | |
| { | |
| struct hashmap_entry *old = hashmap_remove(map, entry, NULL); | |
| hashmap_add(map, entry); | |
| return old; | |
| } | |
| void hashmap_iter_init(struct hashmap *map, struct hashmap_iter *iter) | |
| { | |
| iter->map = map; | |
| iter->tablepos = 0; | |
| iter->next = NULL; | |
| } | |
| void *hashmap_iter_next(struct hashmap_iter *iter) | |
| { | |
| struct hashmap_entry *current = iter->next; | |
| for (;;) { | |
| if (current) { | |
| iter->next = current->next; | |
| return current; | |
| } | |
| if (iter->tablepos >= iter->map->tablesize) | |
| return NULL; | |
| current = iter->map->table[iter->tablepos++]; | |
| } | |
| } | |
| struct pool_entry { | |
| struct hashmap_entry ent; | |
| size_t len; | |
| unsigned char data[FLEX_ARRAY]; | |
| }; | |
| static int pool_entry_cmp(const void *unused_cmp_data, | |
| const struct pool_entry *e1, | |
| const struct pool_entry *e2, | |
| const unsigned char *keydata) | |
| { | |
| return e1->data != keydata && | |
| (e1->len != e2->len || memcmp(e1->data, keydata, e1->len)); | |
| } | |
| const void *memintern(const void *data, size_t len) | |
| { | |
| static struct hashmap map; | |
| struct pool_entry key, *e; | |
| /* initialize string pool hashmap */ | |
| if (!map.tablesize) | |
| hashmap_init(&map, (hashmap_cmp_fn) pool_entry_cmp, NULL, 0); | |
| /* lookup interned string in pool */ | |
| hashmap_entry_init(&key, memhash(data, len)); | |
| key.len = len; | |
| e = hashmap_get(&map, &key, data); | |
| if (!e) { | |
| /* not found: create it */ | |
| FLEX_ALLOC_MEM(e, data, data, len); | |
| hashmap_entry_init(e, key.ent.hash); | |
| e->len = len; | |
| hashmap_add(&map, e); | |
| } | |
| return e->data; | |
| } |
