*/
/*
+ 2013-05-02 (0.2.8):
+
+ * Use quadratic probing. When the capacity is power of 2, stepping function
+ i*(i+1)/2 guarantees to traverse each bucket. It is better than double
+ hashing on cache performance and is more robust than linear probing.
+
+ In theory, double hashing should be more robust than quadratic probing.
+ However, my implementation is probably not for large hash tables, because
+ the second hash function is closely tied to the first hash function,
+ which reduce the effectiveness of double hashing.
+
+ Reference: http://research.cs.vt.edu/AVresearch/hashing/quadratic.php
+
2011-12-29 (0.2.7):
* Minor code clean up; no actual effect.
Generic hash table library.
*/
-#define AC_VERSION_KHASH_H "0.2.6"
+#define AC_VERSION_KHASH_H "0.2.8"
#include <stdlib.h>
#include <string.h>
#include <limits.h>
-/* compipler specific configuration */
+/* compiler specific configuration */
#if UINT_MAX == 0xffffffffu
typedef unsigned int khint32_t;
typedef unsigned long long khint64_t;
#endif
+#ifndef kh_inline
#ifdef _MSC_VER
#define kh_inline __inline
#else
#define kh_inline inline
#endif
+#endif /* kh_inline */
typedef khint32_t khint_t;
typedef khint_t khiter_t;
#define __ac_set_isboth_false(flag, i) (flag[i>>4]&=~(3ul<<((i&0xfU)<<1)))
#define __ac_set_isdel_true(flag, i) (flag[i>>4]|=1ul<<((i&0xfU)<<1))
-#ifdef KHASH_LINEAR
-#define __ac_inc(k, m) 1
-#else
-#define __ac_inc(k, m) (((k)>>3 ^ (k)<<3) | 1) & (m)
-#endif
-
#define __ac_fsize(m) ((m) < 16? 1 : (m)>>4)
#ifndef kroundup32
static const double __ac_HASH_UPPER = 0.77;
#define __KHASH_TYPE(name, khkey_t, khval_t) \
- typedef struct { \
+ typedef struct kh_##name##_s { \
khint_t n_buckets, size, n_occupied, upper_bound; \
khint32_t *flags; \
khkey_t *keys; \
SCOPE khint_t kh_get_##name(const kh_##name##_t *h, khkey_t key) \
{ \
if (h->n_buckets) { \
- khint_t inc, k, i, last, mask; \
+ khint_t k, i, last, mask, step = 0; \
mask = h->n_buckets - 1; \
k = __hash_func(key); i = k & mask; \
- inc = __ac_inc(k, mask); last = i; /* inc==1 for linear probing */ \
+ last = i; \
while (!__ac_isempty(h->flags, i) && (__ac_isdel(h->flags, i) || !__hash_equal(h->keys[i], key))) { \
- i = (i + inc) & mask; \
+ i = (i + (++step)) & mask; \
if (i == last) return h->n_buckets; \
} \
return __ac_iseither(h->flags, i)? h->n_buckets : i; \
} else return 0; \
} \
SCOPE int kh_resize_##name(kh_##name##_t *h, khint_t new_n_buckets) \
- { /* This function uses 0.25*n_bucktes bytes of working space instead of [sizeof(key_t+val_t)+.25]*n_buckets. */ \
+ { /* This function uses 0.25*n_buckets bytes of working space instead of [sizeof(key_t+val_t)+.25]*n_buckets. */ \
khint32_t *new_flags = 0; \
khint_t j = 1; \
{ \
memset(new_flags, 0xaa, __ac_fsize(new_n_buckets) * sizeof(khint32_t)); \
if (h->n_buckets < new_n_buckets) { /* expand */ \
khkey_t *new_keys = (khkey_t*)krealloc((void *)h->keys, new_n_buckets * sizeof(khkey_t)); \
- if (!new_keys) return -1; \
+ if (!new_keys) { kfree(new_flags); return -1; } \
h->keys = new_keys; \
if (kh_is_map) { \
khval_t *new_vals = (khval_t*)krealloc((void *)h->vals, new_n_buckets * sizeof(khval_t)); \
- if (!new_vals) return -1; \
+ if (!new_vals) { kfree(new_flags); return -1; } \
h->vals = new_vals; \
} \
} /* otherwise shrink */ \
if (kh_is_map) val = h->vals[j]; \
__ac_set_isdel_true(h->flags, j); \
while (1) { /* kick-out process; sort of like in Cuckoo hashing */ \
- khint_t inc, k, i; \
+ khint_t k, i, step = 0; \
k = __hash_func(key); \
i = k & new_mask; \
- inc = __ac_inc(k, new_mask); \
- while (!__ac_isempty(new_flags, i)) i = (i + inc) & new_mask; \
+ while (!__ac_isempty(new_flags, i)) i = (i + (++step)) & new_mask; \
__ac_set_isempty_false(new_flags, i); \
if (i < h->n_buckets && __ac_iseither(h->flags, i) == 0) { /* kick out the existing element */ \
{ khkey_t tmp = h->keys[i]; h->keys[i] = key; key = tmp; } \
} \
} /* TODO: to implement automatically shrinking; resize() already support shrinking */ \
{ \
- khint_t inc, k, i, site, last, mask = h->n_buckets - 1; \
+ khint_t k, i, site, last, mask = h->n_buckets - 1, step = 0; \
x = site = h->n_buckets; k = __hash_func(key); i = k & mask; \
if (__ac_isempty(h->flags, i)) x = i; /* for speed up */ \
else { \
- inc = __ac_inc(k, mask); last = i; \
+ last = i; \
while (!__ac_isempty(h->flags, i) && (__ac_isdel(h->flags, i) || !__hash_equal(h->keys[i], key))) { \
if (__ac_isdel(h->flags, i)) site = i; \
- i = (i + inc) & mask; \
+ i = (i + (++step)) & mask; \
if (i == last) { x = site; break; } \
} \
if (x == h->n_buckets) { \
@param name Name of the hash table [symbol]
@param h Pointer to the hash table [khash_t(name)*]
@param k Key [type of keys]
- @param r Extra return code: 0 if the key is present in the hash table;
+ @param r Extra return code: -1 if the operation failed;
+ 0 if the key is present in the hash table;
1 if the bucket is empty (never used); 2 if the element in
the bucket has been deleted [int*]
@return Iterator to the inserted element [khint_t]
@param name Name of the hash table [symbol]
@param h Pointer to the hash table [khash_t(name)*]
@param k Key [type of keys]
- @return Iterator to the found element, or kh_end(h) is the element is absent [khint_t]
+ @return Iterator to the found element, or kh_end(h) if the element is absent [khint_t]
*/
#define kh_get(name, h, k) kh_get_##name(h, k)
#define KHASH_MAP_INIT_STR(name, khval_t) \
KHASH_INIT(name, kh_cstr_t, khval_t, 1, kh_str_hash_func, kh_str_hash_equal)
-#endif /* __AC_KHASH_H */
+#endif /* __AC_KHASH_H */
\ No newline at end of file
projects / libgit2.git / commitdiff