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/* Hash Tables Implementation.
*
* This file implements in memory hash tables with insert/del/replace/find/
* get-random-element operations. Hash tables will auto resize if needed
* tables of power of two in size are used, collisions are handled by
* chaining. See the source code for more information... :)
*
* Copyright (c) 2006-2009, Salvatore Sanfilippo <antirez at gmail dot com>
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* * Redistributions of source code must retain the above copyright notice,
* this list of conditions and the following disclaimer.
* * Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* * Neither the name of Redis nor the names of its contributors may be used
* to endorse or promote products derived from this software without
* specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <stdarg.h>
#include <assert.h>
#include "dict.h"
#include "zmalloc.h"
/* ---------------------------- Utility funcitons --------------------------- */
static void _dictPanic(const char *fmt, ...)
{
va_list ap;
va_start(ap, fmt);
fprintf(stderr, "\nDICT LIBRARY PANIC: ");
vfprintf(stderr, fmt, ap);
fprintf(stderr, "\n\n");
va_end(ap);
}
/* ------------------------- Heap Management Wrappers------------------------ */
static void *_dictAlloc(int size)
{
void *p = zmalloc(size);
if (p == NULL)
_dictPanic("Out of memory");
return p;
}
static void _dictFree(void *ptr) {
zfree(ptr);
}
/* -------------------------- private prototypes ---------------------------- */
static int _dictExpandIfNeeded(dict *ht);
static unsigned int _dictNextPower(unsigned int size);
static int _dictKeyIndex(dict *ht, const void *key);
static int _dictInit(dict *ht, dictType *type, void *privDataPtr);
/* -------------------------- hash functions -------------------------------- */
/* Thomas Wang's 32 bit Mix Function */
unsigned int dictIntHashFunction(unsigned int key)
{
key += ~(key << 15);
key ^= (key >> 10);
key += (key << 3);
key ^= (key >> 6);
key += ~(key << 11);
key ^= (key >> 16);
return key;
}
/* Identity hash function for integer keys */
unsigned int dictIdentityHashFunction(unsigned int key)
{
return key;
}
/* Generic hash function (a popular one from Bernstein).
* I tested a few and this was the best. */
unsigned int dictGenHashFunction(const unsigned char *buf, int len) {
unsigned int hash = 5381;
while (len--)
hash = ((hash << 5) + hash) + (*buf++); /* hash * 33 + c */
return hash;
}
/* ----------------------------- API implementation ------------------------- */
/* Reset an hashtable already initialized with ht_init().
* NOTE: This function should only called by ht_destroy(). */
static void _dictReset(dict *ht)
{
ht->table = NULL;
ht->size = 0;
ht->sizemask = 0;
ht->used = 0;
}
/* Create a new hash table */
dict *dictCreate(dictType *type,
void *privDataPtr)
{
dict *ht = _dictAlloc(sizeof(*ht));
_dictInit(ht,type,privDataPtr);
return ht;
}
/* Initialize the hash table */
int _dictInit(dict *ht, dictType *type,
void *privDataPtr)
{
_dictReset(ht);
ht->type = type;
ht->privdata = privDataPtr;
return DICT_OK;
}
/* Resize the table to the minimal size that contains all the elements,
* but with the invariant of a USER/BUCKETS ration near to <= 1 */
int dictResize(dict *ht)
{
int minimal = ht->used;
if (minimal < DICT_HT_INITIAL_SIZE)
minimal = DICT_HT_INITIAL_SIZE;
return dictExpand(ht, minimal);
}
/* Expand or create the hashtable */
int dictExpand(dict *ht, unsigned int size)
{
dict n; /* the new hashtable */
unsigned int realsize = _dictNextPower(size), i;
/* the size is invalid if it is smaller than the number of
* elements already inside the hashtable */
if (ht->used > size)
return DICT_ERR;
_dictInit(&n, ht->type, ht->privdata);
n.size = realsize;
n.sizemask = realsize-1;
n.table = _dictAlloc(realsize*sizeof(dictEntry*));
/* Initialize all the pointers to NULL */
memset(n.table, 0, realsize*sizeof(dictEntry*));
/* Copy all the elements from the old to the new table:
* note that if the old hash table is empty ht->size is zero,
* so dictExpand just creates an hash table. */
n.used = ht->used;
for (i = 0; i < ht->size && ht->used > 0; i++) {
dictEntry *he, *nextHe;
if (ht->table[i] == NULL) continue;
/* For each hash entry on this slot... */
he = ht->table[i];
while(he) {
unsigned int h;
nextHe = he->next;
/* Get the new element index */
h = dictHashKey(ht, he->key) & n.sizemask;
he->next = n.table[h];
n.table[h] = he;
ht->used--;
/* Pass to the next element */
he = nextHe;
}
}
assert(ht->used == 0);
_dictFree(ht->table);
/* Remap the new hashtable in the old */
*ht = n;
return DICT_OK;
}
/* Add an element to the target hash table */
int dictAdd(dict *ht, void *key, void *val)
{
int index;
dictEntry *entry;
/* Get the index of the new element, or -1 if
* the element already exists. */
if ((index = _dictKeyIndex(ht, key)) == -1)
return DICT_ERR;
/* Allocates the memory and stores key */
entry = _dictAlloc(sizeof(*entry));
entry->next = ht->table[index];
ht->table[index] = entry;
/* Set the hash entry fields. */
dictSetHashKey(ht, entry, key);
dictSetHashVal(ht, entry, val);
ht->used++;
return DICT_OK;
}
/* Add an element, discarding the old if the key already exists */
int dictReplace(dict *ht, void *key, void *val)
{
dictEntry *entry;
/* Try to add the element. If the key
* does not exists dictAdd will suceed. */
if (dictAdd(ht, key, val) == DICT_OK)
return DICT_OK;
/* It already exists, get the entry */
entry = dictFind(ht, key);
/* Free the old value and set the new one */
dictFreeEntryVal(ht, entry);
dictSetHashVal(ht, entry, val);
return DICT_OK;
}
/* Search and remove an element */
static int dictGenericDelete(dict *ht, const void *key, int nofree)
{
unsigned int h;
dictEntry *he, *prevHe;
if (ht->size == 0)
return DICT_ERR;
h = dictHashKey(ht, key) & ht->sizemask;
he = ht->table[h];
prevHe = NULL;
while(he) {
if (dictCompareHashKeys(ht, key, he->key)) {
/* Unlink the element from the list */
if (prevHe)
prevHe->next = he->next;
else
ht->table[h] = he->next;
if (!nofree) {
dictFreeEntryKey(ht, he);
dictFreeEntryVal(ht, he);
}
_dictFree(he);
ht->used--;
return DICT_OK;
}
prevHe = he;
he = he->next;
}
return DICT_ERR; /* not found */
}
int dictDelete(dict *ht, const void *key) {
return dictGenericDelete(ht,key,0);
}
int dictDeleteNoFree(dict *ht, const void *key) {
return dictGenericDelete(ht,key,1);
}
/* Destroy an entire hash table */
int _dictClear(dict *ht)
{
unsigned int i;
/* Free all the elements */
for (i = 0; i < ht->size && ht->used > 0; i++) {
dictEntry *he, *nextHe;
if ((he = ht->table[i]) == NULL) continue;
while(he) {
nextHe = he->next;
dictFreeEntryKey(ht, he);
dictFreeEntryVal(ht, he);
_dictFree(he);
ht->used--;
he = nextHe;
}
}
/* Free the table and the allocated cache structure */
_dictFree(ht->table);
/* Re-initialize the table */
_dictReset(ht);
return DICT_OK; /* never fails */
}
/* Clear & Release the hash table */
void dictRelease(dict *ht)
{
_dictClear(ht);
_dictFree(ht);
}
dictEntry *dictFind(dict *ht, const void *key)
{
dictEntry *he;
unsigned int h;
if (ht->size == 0) return NULL;
h = dictHashKey(ht, key) & ht->sizemask;
he = ht->table[h];
while(he) {
if (dictCompareHashKeys(ht, key, he->key))
return he;
he = he->next;
}
return NULL;
}
dictIterator *dictGetIterator(dict *ht)
{
dictIterator *iter = _dictAlloc(sizeof(*iter));
iter->ht = ht;
iter->index = -1;
iter->entry = NULL;
iter->nextEntry = NULL;
return iter;
}
dictEntry *dictNext(dictIterator *iter)
{
while (1) {
if (iter->entry == NULL) {
iter->index++;
if (iter->index >=
(signed)iter->ht->size) break;
iter->entry = iter->ht->table[iter->index];
} else {
iter->entry = iter->nextEntry;
}
if (iter->entry) {
/* We need to save the 'next' here, the iterator user
* may delete the entry we are returning. */
iter->nextEntry = iter->entry->next;
return iter->entry;
}
}
return NULL;
}
void dictReleaseIterator(dictIterator *iter)
{
_dictFree(iter);
}
/* Return a random entry from the hash table. Useful to
* implement randomized algorithms */
dictEntry *dictGetRandomKey(dict *ht)
{
dictEntry *he;
unsigned int h;
int listlen, listele;
if (ht->size == 0) return NULL;
do {
h = random() & ht->sizemask;
he = ht->table[h];
} while(he == NULL);
/* Now we found a non empty bucket, but it is a linked
* list and we need to get a random element from the list.
* The only sane way to do so is to count the element and
* select a random index. */
listlen = 0;
while(he) {
he = he->next;
listlen++;
}
listele = random() % listlen;
he = ht->table[h];
while(listele--) he = he->next;
return he;
}
/* ------------------------- private functions ------------------------------ */
/* Expand the hash table if needed */
static int _dictExpandIfNeeded(dict *ht)
{
/* If the hash table is empty expand it to the intial size,
* if the table is "full" dobule its size. */
if (ht->size == 0)
return dictExpand(ht, DICT_HT_INITIAL_SIZE);
if (ht->used == ht->size)
return dictExpand(ht, ht->size*2);
return DICT_OK;
}
/* Our hash table capability is a power of two */
static unsigned int _dictNextPower(unsigned int size)
{
unsigned int i = DICT_HT_INITIAL_SIZE;
if (size >= 2147483648U)
return 2147483648U;
while(1) {
if (i >= size)
return i;
i *= 2;
}
}
/* Returns the index of a free slot that can be populated with
* an hash entry for the given 'key'.
* If the key already exists, -1 is returned. */
static int _dictKeyIndex(dict *ht, const void *key)
{
unsigned int h;
dictEntry *he;
/* Expand the hashtable if needed */
if (_dictExpandIfNeeded(ht) == DICT_ERR)
return -1;
/* Compute the key hash value */
h = dictHashKey(ht, key) & ht->sizemask;
/* Search if this slot does not already contain the given key */
he = ht->table[h];
while(he) {
if (dictCompareHashKeys(ht, key, he->key))
return -1;
he = he->next;
}
return h;
}
void dictEmpty(dict *ht) {
_dictClear(ht);
}
#define DICT_STATS_VECTLEN 50
void dictPrintStats(dict *ht) {
unsigned int i, slots = 0, chainlen, maxchainlen = 0;
unsigned int totchainlen = 0;
unsigned int clvector[DICT_STATS_VECTLEN];
if (ht->used == 0) {
printf("No stats available for empty dictionaries\n");
return;
}
for (i = 0; i < DICT_STATS_VECTLEN; i++) clvector[i] = 0;
for (i = 0; i < ht->size; i++) {
dictEntry *he;
if (ht->table[i] == NULL) {
clvector[0]++;
continue;
}
slots++;
/* For each hash entry on this slot... */
chainlen = 0;
he = ht->table[i];
while(he) {
chainlen++;
he = he->next;
}
clvector[(chainlen < DICT_STATS_VECTLEN) ? chainlen : (DICT_STATS_VECTLEN-1)]++;
if (chainlen > maxchainlen) maxchainlen = chainlen;
totchainlen += chainlen;
}
printf("Hash table stats:\n");
printf(" table size: %d\n", ht->size);
printf(" number of elements: %d\n", ht->used);
printf(" different slots: %d\n", slots);
printf(" max chain length: %d\n", maxchainlen);
printf(" avg chain length (counted): %.02f\n", (float)totchainlen/slots);
printf(" avg chain length (computed): %.02f\n", (float)ht->used/slots);
printf(" Chain length distribution:\n");
for (i = 0; i < DICT_STATS_VECTLEN-1; i++) {
if (clvector[i] == 0) continue;
printf(" %s%d: %d (%.02f%%)\n",(i == DICT_STATS_VECTLEN-1)?">= ":"", i, clvector[i], ((float)clvector[i]/ht->size)*100);
}
}
/* ----------------------- StringCopy Hash Table Type ------------------------*/
static unsigned int _dictStringCopyHTHashFunction(const void *key)
{
return dictGenHashFunction(key, strlen(key));
}
static void *_dictStringCopyHTKeyDup(void *privdata, const void *key)
{
int len = strlen(key);
char *copy = _dictAlloc(len+1);
DICT_NOTUSED(privdata);
memcpy(copy, key, len);
copy[len] = '\0';
return copy;
}
static void *_dictStringKeyValCopyHTValDup(void *privdata, const void *val)
{
int len = strlen(val);
char *copy = _dictAlloc(len+1);
DICT_NOTUSED(privdata);
memcpy(copy, val, len);
copy[len] = '\0';
return copy;
}
static int _dictStringCopyHTKeyCompare(void *privdata, const void *key1,
const void *key2)
{
DICT_NOTUSED(privdata);
return strcmp(key1, key2) == 0;
}
static void _dictStringCopyHTKeyDestructor(void *privdata, void *key)
{
DICT_NOTUSED(privdata);
_dictFree((void*)key); /* ATTENTION: const cast */
}
static void _dictStringKeyValCopyHTValDestructor(void *privdata, void *val)
{
DICT_NOTUSED(privdata);
_dictFree((void*)val); /* ATTENTION: const cast */
}
dictType dictTypeHeapStringCopyKey = {
_dictStringCopyHTHashFunction, /* hash function */
_dictStringCopyHTKeyDup, /* key dup */
NULL, /* val dup */
_dictStringCopyHTKeyCompare, /* key compare */
_dictStringCopyHTKeyDestructor, /* key destructor */
NULL /* val destructor */
};
/* This is like StringCopy but does not auto-duplicate the key.
* It's used for intepreter's shared strings. */
dictType dictTypeHeapStrings = {
_dictStringCopyHTHashFunction, /* hash function */
NULL, /* key dup */
NULL, /* val dup */
_dictStringCopyHTKeyCompare, /* key compare */
_dictStringCopyHTKeyDestructor, /* key destructor */
NULL /* val destructor */
};
/* This is like StringCopy but also automatically handle dynamic
* allocated C strings as values. */
dictType dictTypeHeapStringCopyKeyValue = {
_dictStringCopyHTHashFunction, /* hash function */
_dictStringCopyHTKeyDup, /* key dup */
_dictStringKeyValCopyHTValDup, /* val dup */
_dictStringCopyHTKeyCompare, /* key compare */
_dictStringCopyHTKeyDestructor, /* key destructor */
_dictStringKeyValCopyHTValDestructor, /* val destructor */
};
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