static void
grow_hash_table (struct hash_table *ht)
{
struct mapping *old_mappings = ht->mappings;
struct mapping *old_end = ht->mappings + ht->size;
struct mapping *mp, *mappings;
int newsize;
newsize = prime_size (ht->size * 2);
#if 0
printf ("growing from %d to %d\n", ht->size, newsize);
#endif
ht->size = newsize;
ht->resize_threshold = newsize * 3 / 4;
mappings = xmalloc (ht->size * sizeof (struct mapping));
memset (mappings, '\0', ht->size * sizeof (struct mapping));
ht->mappings = mappings;
for (mp = old_mappings; mp < old_end; mp++)
if (!EMPTY_MAPPING_P (mp))
{
struct mapping *new_mp = mappings + HASH_POSITION (ht, mp->key);
/* We don't need to call test function and worry about
collisions because all the keys come from the hash table
and are therefore guaranteed to be unique. */
LOOP_NON_EMPTY (new_mp, mappings, newsize)
;
*new_mp = *mp;
}
xfree (old_mappings);
}
struct hash_table *
hash_table_new (int items,
unsigned long (*hash_function) (const void *),
int (*test_function) (const void *, const void *))
{
int size;
struct hash_table *ht = xnew (struct hash_table);
ht->hash_function = hash_function ? hash_function : hash_pointer;
ht->test_function = test_function ? test_function : cmp_pointer;
/* If the size of struct hash_table ever becomes a concern, this
field can go. (Wget doesn't create many hashes.) */
ht->prime_offset = 0;
/* Calculate the size that ensures that the table will store at
least ITEMS keys without the need to resize. */
size = 1 + items / HASH_MAX_FULLNESS;
size = prime_size (size, &ht->prime_offset);
ht->size = size;
ht->resize_threshold = size * HASH_MAX_FULLNESS;
/*assert (ht->resize_threshold >= items);*/
ht->cells = xnew_array (struct cell, ht->size);
/* Mark cells as empty. We use 0xff rather than 0 to mark empty
keys because it allows us to use NULL/0 as keys. */
memset (ht->cells, INVALID_PTR_CHAR, size * sizeof (struct cell));
ht->count = 0;
return ht;
}
int createhash(hash* h,int defaultsize,hashfun_t hf)
{
h->prime_offset=0;
h->size=prime_size(defaultsize,&h->prime_offset);
if((h->addr=(cell*)malloc(sizeof(cell)*h->size))==0)
return 1;
h->hashfunction=hf?hf:defaulthash;
h->currentsize=0;
h->tombsize=0;
int i;
for(i=0;i<h->size;++i) //初始化为空
(h->addr+i)->stat=EMPTY;
return 0;
}
/*
*增长过程，把原来表的size和prime_size变动了。并更新了存储空间。currentsize不变,tombsize清零
*/
static int grow(hash* h)
{
int oldsize=h->size;
h->size=prime_size(oldsize*hash_resize_factor,&h->prime_offset); //更新size...函数调用prime_size还会自动更新prime_offset
cell* oldaddr=h->addr;
if((h->addr=(cell*)malloc(h->size*sizeof(cell)))==0) //更新存储空间
return 1;
int i;
for(i=0;i<h->size;++i)
(h->addr+i)->stat=EMPTY; //初始化新表
h->currentsize=0; //currentsize计数清零
for(i=0;i<oldsize;++i) //把原来表的数据转到新存储空间
{
if((oldaddr+i)->stat==OCCUPY)
push(h,(oldaddr+i)->key,(oldaddr+i)->value); //这里会更新currentsize计数
}
free(oldaddr); //销毁原来的存储空间
h->tombsize=0; //tomb计数清0
return 0;
}
struct hash_table *
hash_table_new (int initial_size,
unsigned long (*hash_function) (const void *),
int (*test_function) (const void *, const void *))
{
struct hash_table *ht
= (struct hash_table *)xmalloc (sizeof (struct hash_table));
ht->hash_function = hash_function;
ht->test_function = test_function;
ht->size = prime_size (initial_size);
ht->resize_threshold = ht->size * 3 / 4;
ht->count = 0;
ht->mappings = xmalloc (ht->size * sizeof (struct mapping));
memset (ht->mappings, '\0', ht->size * sizeof (struct mapping));
return ht;
}
static void
grow_hash_table (struct hash_table *ht)
{
hashfun_t hasher = ht->hash_function;
struct cell *old_cells = ht->cells;
struct cell *old_end = ht->cells + ht->size;
struct cell *c, *cells;
int newsize;
newsize = prime_size (ht->size * HASH_RESIZE_FACTOR, &ht->prime_offset);
#if 0
printf ("growing from %d to %d; fullness %.2f%% to %.2f%%\n",
ht->size, newsize,
100.0 * ht->count / ht->size,
100.0 * ht->count / newsize);
#endif
ht->size = newsize;
ht->resize_threshold = newsize * HASH_MAX_FULLNESS;
cells = xnew_array (struct cell, newsize);
memset (cells, INVALID_PTR_CHAR, newsize * sizeof (struct cell));
ht->cells = cells;
for (c = old_cells; c < old_end; c++)
if (CELL_OCCUPIED (c))
{
struct cell *new_c;
/* We don't need to test for uniqueness of keys because they
come from the hash table and are therefore known to be
unique. */
new_c = cells + HASH_POSITION (c->key, hasher, newsize);
FOREACH_OCCUPIED_ADJACENT (new_c, cells, newsize)
;
*new_c = *c;
}
xfree (old_cells);
}
