| /* |
| * 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; |
| } |
| |
| #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(e1, e2, keydata)); |
| } |
| |
| static inline unsigned int bucket(const struct hashmap *map, |
| const struct hashmap_entry *key) |
| { |
| return key->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; |
| |
| 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 *unused1, const void *unused2, const void *unused3) |
| { |
| return 0; |
| } |
| |
| void hashmap_init(struct hashmap *map, hashmap_cmp_fn equals_function, |
| size_t initial_size) |
| { |
| unsigned int size = HASHMAP_INITIAL_SIZE; |
| map->size = 0; |
| map->cmpfn = equals_function ? equals_function : always_equal; |
| |
| /* 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 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, 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; |
| } |