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* Added hash_count_elements() and hash_count_used_slots() (mainly for

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diagnostic purposes).
* hash_init() adjusts the table size to a prime number, which should
  result in a better element distribution, particularly since usually a
  power of two is passed.


git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@22210 a95241bf-73f2-0310-859d-f6bbb57e9c96
This commit is contained in:
Ingo Weinhold 2007-09-09 17:19:52 +00:00
parent 8687956af2
commit 40c3aedf8d
2 changed files with 45 additions and 0 deletions
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2
headers/private/kernel/util/khash.h
View File

@ -38,6 +38,8 @@ struct hash_iterator *hash_open(struct hash_table *table, struct hash_iterator *
void hash_close(struct hash_table *table, struct hash_iterator *i, bool free_iterator);
void *hash_next(struct hash_table *table, struct hash_iterator *i);
void hash_rewind(struct hash_table *table, struct hash_iterator *i);
uint32 hash_count_elements(struct hash_table *table);
uint32 hash_count_used_slots(struct hash_table *table);
/* function pointers must look like this:
*

43
src/system/kernel/util/khash.c
View File

@ -43,6 +43,27 @@ struct hash_table {
#define PUT_IN_NEXT(t, e, val) (*(unsigned long *)NEXT_ADDR(t, e) = (long)(val))
const uint32 kPrimes [] = {
13, 31, 61, 127, 251,
509, 1021, 2039, 4093, 8191, 16381, 32749, 65521, 131071, 262139,
524287, 1048573, 2097143, 4194301, 8388593, 16777213, 33554393, 67108859,
134217689, 268435399, 536870909, 1073741789, 2147483647, 0
};
static uint32
get_prime_table_size(uint32 size)
{
int i;
for (i = 0; kPrimes[i] != 0; i++) {
if (kPrimes[i] > size)
return kPrimes[i];
}
return kPrimes[i - 1];
}
static inline void *
next_element(hash_table *table, void *element)
{
@ -59,6 +80,8 @@ hash_init(uint32 table_size, int next_ptr_offset,
struct hash_table *t;
unsigned int i;
table_size = get_prime_table_size(table_size);
if (compare_func == NULL || hash_func == NULL) {
dprintf("hash_init() called with NULL function pointer\n");
return NULL;
@ -303,3 +326,23 @@ hash_hash_string(const char *string)
return hash;
}
uint32
hash_count_elements(struct hash_table *table)
{
return table->num_elements;
}
uint32
hash_count_used_slots(struct hash_table *table)
{
uint32 usedSlots = 0;
uint32 i;
for (i = 0; i < table->table_size; i++) {
if (table->table[i] != NULL)
usedSlots++;
}
return usedSlots;
}