/* hash.c - hash tables for opkg
Steven M. Ayer, Jamey Hicks
-
+
Copyright (C) 2002 Compaq Computer Corporation
This program is free software; you can redistribute it and/or
General Public License for more details.
*/
-#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "hash_table.h"
#include "opkg_message.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;
- }
-
- 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;
+ if (hash->entries != NULL) {
+ opkg_msg(ERROR, "Internal error: non empty hash table.\n");
+ return;
+ }
+
+ 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_table_deinit(hash_table_t *hash)
+void hash_print_stats(hash_table_t * hash)
{
- free(hash->entries);
- hash->entries = NULL;
- hash->n_entries = 0;
+ 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_get(hash_table_t *hash, const char *key)
+void hash_table_deinit(hash_table_t * hash)
{
- int ndx= hash_index(hash, key);
- hash_entry_t *hash_entry = hash->entries + ndx;
- while (hash_entry)
- {
- if (hash_entry->key)
- {
- if (strcmp(key, hash_entry->key) == 0) {
- // opkg_message(NULL, OPKG_DEBUG, "Function: %s. Key found for '%s' \n", __FUNCTION__, key);
- return hash_entry->data;
- }
- }
- hash_entry = hash_entry->next;
- }
- return NULL;
+ int i;
+ if (!hash)
+ return;
+
+ /* free the reminaing entries */
+ 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 */
+ hash_entry = hash_entry->next;
+ while (hash_entry) {
+ hash_entry_t *old = hash_entry;
+ hash_entry = hash_entry->next;
+ free(old->key);
+ free(old);
+ }
+ }
+
+ free(hash->entries);
+
+ hash->entries = NULL;
+ hash->n_buckets = 0;
}
-int hash_table_insert(hash_table_t *hash, const char *key, void *value)
+void *hash_table_get(hash_table_t * hash, const char *key)
{
- 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 {
- /*
- * if this is a collision, we have to go to the end of the ll,
- * 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;
- hash_entry->next = (hash_entry_t *)malloc(sizeof(hash_entry_t));
- if (!hash_entry->next) {
- return -ENOMEM;
- }
- hash_entry = hash_entry->next;
- hash_entry->next = NULL;
- }
- }
- hash->n_elements++;
- hash_entry->key = strdup(key);
- hash_entry->data = value;
-
- return 0;
+ int ndx = hash_index(hash, key);
+ hash_entry_t *hash_entry = hash->entries + ndx;
+ while (hash_entry) {
+ if (hash_entry->key) {
+ if (strcmp(key, hash_entry->key) == 0) {
+ 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 (hash_entry->key) {
+ if (strcmp(hash_entry->key, key) == 0) {
+ /* alread in table, update the value */
+ hash_entry->data = value;
+ return 0;
+ } else {
+ /*
+ * if this is a collision, we have to go to the end of the ll,
+ * then add a new entry
+ * before we can hook up the value
+ */
+ 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 = 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;
+
+ return 0;
+}
-void hash_table_foreach(hash_table_t *hash, void (*f)(const char *key, void *entry, void *data), void *data)
-{
- int i;
- if (!hash || !f)
- return;
-
- for (i = 0; i < hash->n_entries; i++) {
- hash_entry_t *hash_entry = (hash->entries + i);
- do {
- if(hash_entry->key) {
- f(hash_entry->key, hash_entry->data, data);
- }
- } while((hash_entry = hash_entry->next));
- }
+int hash_table_remove(hash_table_t * hash, const char *key)
+{
+ int ndx = hash_index(hash, key);
+ hash_entry_t *hash_entry = hash->entries + ndx;
+ hash_entry_t *next_entry = NULL, *last_entry = NULL;
+ while (hash_entry) {
+ if (hash_entry->key) {
+ if (strcmp(key, hash_entry->key) == 0) {
+ free(hash_entry->key);
+ if (last_entry) {
+ last_entry->next = hash_entry->next;
+ free(hash_entry);
+ } else {
+ next_entry = hash_entry->next;
+ if (next_entry) {
+ memmove(hash_entry, next_entry,
+ sizeof(hash_entry_t));
+ free(next_entry);
+ } else {
+ memset(hash_entry, 0,
+ sizeof(hash_entry_t));
+ }
+ }
+ return 1;
+ }
+ }
+ last_entry = hash_entry;
+ hash_entry = hash_entry->next;
+ }
+ return 0;
}
+void hash_table_foreach(hash_table_t * hash,
+ void (*f) (const char *key, void *entry, void *data),
+ void *data)
+{
+ int i;
+ if (!hash || !f)
+ return;
+
+ for (i = 0; i < hash->n_buckets; i++) {
+ hash_entry_t *hash_entry = (hash->entries + i);
+ do {
+ if (hash_entry->key) {
+ f(hash_entry->key, hash_entry->data, data);
+ }
+ } while ((hash_entry = hash_entry->next));
+ }
+}
projects / oweals / opkg-lede.git / blobdiff