Andrew's git - gitweb.git/blob

aaf09e047e3f7a6907718392ca4f303c04d9c74a
   1#ifndef HASHMAP_H
   2#define HASHMAP_H
   3
   4/*
   5 * Generic implementation of hash-based key-value mappings.
   6 * See Documentation/technical/api-hashmap.txt.
   7 */
   8
   9/* FNV-1 functions */
  10
  11extern unsigned int strhash(const char *buf);
  12extern unsigned int strihash(const char *buf);
  13extern unsigned int memhash(const void *buf, size_t len);
  14extern unsigned int memihash(const void *buf, size_t len);
  15extern unsigned int memihash_cont(unsigned int hash_seed, const void *buf, size_t len);
  16
  17static inline unsigned int sha1hash(const unsigned char *sha1)
  18{
  19        /*
  20         * Equivalent to 'return *(unsigned int *)sha1;', but safe on
  21         * platforms that don't support unaligned reads.
  22         */
  23        unsigned int hash;
  24        memcpy(&hash, sha1, sizeof(hash));
  25        return hash;
  26}
  27
  28/* data structures */
  29
  30struct hashmap_entry {
  31        struct hashmap_entry *next;
  32        unsigned int hash;
  33};
  34
  35typedef int (*hashmap_cmp_fn)(const void *hashmap_cmp_fn_data,
  36                              const void *entry, const void *entry_or_key,
  37                              const void *keydata);
  38
  39struct hashmap {
  40        struct hashmap_entry **table;
  41        hashmap_cmp_fn cmpfn;
  42        const void *cmpfn_data;
  43        unsigned int size, tablesize, grow_at, shrink_at;
  44        unsigned disallow_rehash : 1;
  45};
  46
  47struct hashmap_iter {
  48        struct hashmap *map;
  49        struct hashmap_entry *next;
  50        unsigned int tablepos;
  51};
  52
  53/* hashmap functions */
  54
  55extern void hashmap_init(struct hashmap *map,
  56                         hashmap_cmp_fn equals_function,
  57                         const void *equals_function_data,
  58                         size_t initial_size);
  59extern void hashmap_free(struct hashmap *map, int free_entries);
  60
  61/* hashmap_entry functions */
  62
  63static inline void hashmap_entry_init(void *entry, unsigned int hash)
  64{
  65        struct hashmap_entry *e = entry;
  66        e->hash = hash;
  67        e->next = NULL;
  68}
  69extern void *hashmap_get(const struct hashmap *map, const void *key,
  70                const void *keydata);
  71extern void *hashmap_get_next(const struct hashmap *map, const void *entry);
  72extern void hashmap_add(struct hashmap *map, void *entry);
  73extern void *hashmap_put(struct hashmap *map, void *entry);
  74extern void *hashmap_remove(struct hashmap *map, const void *key,
  75                const void *keydata);
  76
  77static inline void *hashmap_get_from_hash(const struct hashmap *map,
  78                unsigned int hash, const void *keydata)
  79{
  80        struct hashmap_entry key;
  81        hashmap_entry_init(&key, hash);
  82        return hashmap_get(map, &key, keydata);
  83}
  84
  85int hashmap_bucket(const struct hashmap *map, unsigned int hash);
  86
  87/*
  88 * Disallow/allow rehashing of the hashmap.
  89 * This is useful if the caller knows that the hashmap
  90 * needs multi-threaded access.  The caller is still
  91 * required to guard/lock searches and inserts in a
  92 * manner appropriate to their usage.  This simply
  93 * prevents the table from being unexpectedly re-mapped.
  94 *
  95 * If is up to the caller to ensure that the hashmap is
  96 * initialized to a reasonable size to prevent poor
  97 * performance.
  98 *
  99 * When value=1, prevent future rehashes on adds and deleted.
 100 * When value=0, allow future rehahses.  This DOES NOT force
 101 * a rehash now.
 102 */
 103static inline void hashmap_disallow_rehash(struct hashmap *map, unsigned value)
 104{
 105        map->disallow_rehash = value;
 106}
 107
 108/* hashmap_iter functions */
 109
 110extern void hashmap_iter_init(struct hashmap *map, struct hashmap_iter *iter);
 111extern void *hashmap_iter_next(struct hashmap_iter *iter);
 112static inline void *hashmap_iter_first(struct hashmap *map,
 113                struct hashmap_iter *iter)
 114{
 115        hashmap_iter_init(map, iter);
 116        return hashmap_iter_next(iter);
 117}
 118
 119/* string interning */
 120
 121extern const void *memintern(const void *data, size_t len);
 122static inline const char *strintern(const char *string)
 123{
 124        return memintern(string, strlen(string));
 125}
 126
 127#endif