General Public License for more details.
*/
-#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "libbb/libbb.h"
-static int hash_index(hash_table_t *hash, const char *pkg_name);
-static int rotating(const char *key, int len, int prime);
-
-static int hash_index(hash_table_t *hash, const char *pkg_name)
+static unsigned long
+djb2_hash(const unsigned char *str)
{
- return rotating(pkg_name, strlen(pkg_name), hash->n_entries);
+ unsigned long hash = 5381;
+ int c;
+ while ((c = *str++))
+ hash = ((hash << 5) + hash) + c; /* hash * 33 + c */
+ return hash;
}
-
-static int rotating(const char *key, int len, int prime)
+
+static int
+hash_index(hash_table_t *hash, const char *key)
{
- unsigned int hash, i;
- for (hash=len, i=0; i<len; ++i)
- hash = (hash<<4)^(hash>>28)^key[i];
- return (hash % prime);
+ return djb2_hash((const unsigned char *)key) % hash->n_buckets;
}
-
/*
* this is an open table keyed by strings
*/
-int hash_table_init(const char *name, hash_table_t *hash, int len)
+void
+hash_table_init(const char *name, hash_table_t *hash, int len)
{
- static int primes_table[] = {
- 379, 761, 983, 1423, 2711, 3361, 3931, 4679, 5519, 6701, 9587,
- 19471, 23143, 33961, 46499, 49727, 99529, 0
- };
- int *picker;
-
- if (hash->entries != NULL) {
- /* we have been here already */
- return 0;
- }
+ if (hash->entries != NULL) {
+ fprintf(stderr, "ERROR: %s called on a non empty hash table\n",
+ __FUNCTION__);
+ return;
+ }
- hash->name = name;
- hash->entries = NULL;
- hash->n_entries = 0;
- hash->hash_entry_key = NULL;
-
- picker = primes_table;
- while(*picker && (*picker++ < len));
- if(!*picker)
- fprintf(stderr, "%s: primes table might not be big enough (! << %d)\n", __FUNCTION__, len);
- --picker;
-
- hash->n_entries = *picker;
- hash->entries = (hash_entry_t *)calloc(hash->n_entries, sizeof(hash_entry_t));
- if (hash->entries == NULL) {
- fprintf(stderr, "%s: Out of memory.\n", __FUNCTION__);
- return ENOMEM;
- }
- return 0;
+ memset(hash, 0, sizeof(hash_table_t));
+
+ hash->name = name;
+ hash->n_buckets = len;
+ hash->entries = xcalloc(hash->n_buckets, sizeof(hash_entry_t));
+}
+
+void
+hash_print_stats(hash_table_t *hash)
+{
+ printf("hash_table: %s, %d bytes\n"
+ "\tn_buckets=%d, n_elements=%d, n_collisions=%d\n"
+ "\tmax_bucket_len=%d, n_used_buckets=%d, ave_bucket_len=%.2f\n"
+ "\tn_hits=%d, n_misses=%d\n",
+ hash->name,
+ hash->n_buckets*(int)sizeof(hash_entry_t),
+ hash->n_buckets,
+ hash->n_elements,
+ hash->n_collisions,
+ hash->max_bucket_len,
+ hash->n_used_buckets,
+ (hash->n_used_buckets ?
+ ((float)hash->n_elements)/hash->n_used_buckets : 0.0f),
+ hash->n_hits,
+ hash->n_misses);
}
void hash_table_deinit(hash_table_t *hash)
return;
/* free the reminaing entries */
- for (i = 0; i < hash->n_entries; i++) {
+ for (i = 0; i < hash->n_buckets; i++) {
hash_entry_t *hash_entry = (hash->entries + i);
free (hash_entry->key);
/* skip the first entry as this is part of the array */
free (hash->entries);
hash->entries = NULL;
- hash->n_entries = 0;
+ hash->n_buckets = 0;
}
void *hash_table_get(hash_table_t *hash, const char *key)
{
if (strcmp(key, hash_entry->key) == 0) {
// opkg_message(NULL, OPKG_DEBUG, "Function: %s. Key found for '%s' \n", __FUNCTION__, key);
+ hash->n_hits++;
return hash_entry->data;
}
}
hash_entry = hash_entry->next;
}
+ hash->n_misses++;
return NULL;
}
int hash_table_insert(hash_table_t *hash, const char *key, void *value)
{
+ int bucket_len = 0;
int ndx= hash_index(hash, key);
hash_entry_t *hash_entry = hash->entries + ndx;
- if (0) opkg_message(NULL, OPKG_DEBUG2, "Function: %s. Inserting in hash for '%s' \n", __FUNCTION__, key);
if (hash_entry->key) {
if (strcmp(hash_entry->key, key) == 0) {
/* alread in table, update the value */
- if (0) opkg_message(NULL, OPKG_DEBUG2, "Function: %s. Value already in hash for '%s' \n", __FUNCTION__, key);
hash_entry->data = value;
return 0;
} else {
* then add a new entry
* before we can hook up the value
*/
- if (0) opkg_message(NULL, OPKG_DEBUG2, "Function: %s. Value already in hash by collision for '%s' \n", __FUNCTION__, key);
while (hash_entry->next) {
hash_entry = hash_entry->next;
if (strcmp(hash_entry->key, key) == 0) {
hash_entry->data = value;
return 0;
}
+ bucket_len++;
}
- hash_entry->next = (hash_entry_t *)calloc(1, sizeof(hash_entry_t));
- if (!hash_entry->next) {
- return -ENOMEM;
- }
+ hash_entry->next = xcalloc(1, sizeof(hash_entry_t));
hash_entry = hash_entry->next;
hash_entry->next = NULL;
+
+ hash->n_collisions++;
+ if (++bucket_len > hash->max_bucket_len)
+ hash->max_bucket_len = bucket_len;
}
- }
+ } else
+ hash->n_used_buckets++;
+
hash->n_elements++;
hash_entry->key = xstrdup(key);
hash_entry->data = value;
if (!hash || !f)
return;
- for (i = 0; i < hash->n_entries; i++) {
+ for (i = 0; i < hash->n_buckets; i++) {
hash_entry_t *hash_entry = (hash->entries + i);
do {
if(hash_entry->key) {
projects / oweals / opkg-lede.git / blobdiff