#include <assert.h>
#include <limits.h>
#include <sys/time.h>
+#include <ctype.h>
#include "dict.h"
#include "zmalloc.h"
/* Using dictEnableResize() / dictDisableResize() we make possible to
* enable/disable resizing of the hash table as needed. This is very important
* for Redis, as we use copy-on-write and don't want to move too much memory
- * around when there is a child performing saving operations. */
+ * around when there is a child performing saving operations.
+ *
+ * Note that even when dict_can_resize is set to 0, not all resizes are
+ * prevented: an hash table is still allowed to grow if the ratio between
+ * the number of elements and the buckets > dict_force_resize_ratio. */
static int dict_can_resize = 1;
-
-/* ---------------------------- 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(size_t size)
-{
- void *p = zmalloc(size);
- if (p == NULL)
- _dictPanic("Out of memory");
- return p;
-}
-
-static void _dictFree(void *ptr) {
- zfree(ptr);
-}
+static unsigned int dict_force_resize_ratio = 5;
/* -------------------------- private prototypes ---------------------------- */
return hash;
}
+/* And a case insensitive version */
+unsigned int dictGenCaseHashFunction(const unsigned char *buf, int len) {
+ unsigned int hash = 5381;
+
+ while (len--)
+ hash = ((hash << 5) + hash) + (tolower(*buf++)); /* hash * 33 + c */
+ return hash;
+}
+
/* ----------------------------- API implementation ------------------------- */
/* Reset an hashtable already initialized with ht_init().
dict *dictCreate(dictType *type,
void *privDataPtr)
{
- dict *d = _dictAlloc(sizeof(*d));
+ dict *d = zmalloc(sizeof(*d));
_dictInit(d,type,privDataPtr);
return d;
}
/* Resize the table to the minimal size that contains all the elements,
- * but with the invariant of a USER/BUCKETS ration near to <= 1 */
+ * but with the invariant of a USER/BUCKETS ratio near to <= 1 */
int dictResize(dict *d)
{
int minimal;
if (dictIsRehashing(d) || d->ht[0].used > size)
return DICT_ERR;
+ /* Allocate the new hashtable and initialize all pointers to NULL */
n.size = realsize;
n.sizemask = realsize-1;
- n.table = _dictAlloc(realsize*sizeof(dictEntry*));
+ n.table = zcalloc(realsize*sizeof(dictEntry*));
n.used = 0;
- /* Initialize all the pointers to NULL */
- memset(n.table, 0, realsize*sizeof(dictEntry*));
-
/* Is this the first initialization? If so it's not really a rehashing
* we just set the first hash table so that it can accept keys. */
if (d->ht[0].table == NULL) {
/* Check if we already rehashed the whole table... */
if (d->ht[0].used == 0) {
- _dictFree(d->ht[0].table);
+ zfree(d->ht[0].table);
d->ht[0] = d->ht[1];
_dictReset(&d->ht[1]);
d->rehashidx = -1;
/* Note that rehashidx can't overflow as we are sure there are more
* elements because ht[0].used != 0 */
+ assert(d->ht[0].size > (unsigned)d->rehashidx);
while(d->ht[0].table[d->rehashidx] == NULL) d->rehashidx++;
de = d->ht[0].table[d->rehashidx];
/* Move all the keys in this bucket from the old to the new hash HT */
/* Allocates the memory and stores key */
ht = dictIsRehashing(d) ? &d->ht[1] : &d->ht[0];
- entry = _dictAlloc(sizeof(*entry));
+ entry = zmalloc(sizeof(*entry));
entry->next = ht->table[index];
ht->table[index] = entry;
ht->used++;
dictFreeEntryKey(d, he);
dictFreeEntryVal(d, he);
}
- _dictFree(he);
+ zfree(he);
d->ht[table].used--;
return DICT_OK;
}
nextHe = he->next;
dictFreeEntryKey(d, he);
dictFreeEntryVal(d, he);
- _dictFree(he);
+ zfree(he);
ht->used--;
he = nextHe;
}
}
/* Free the table and the allocated cache structure */
- _dictFree(ht->table);
+ zfree(ht->table);
/* Re-initialize the table */
_dictReset(ht);
return DICT_OK; /* never fails */
{
_dictClear(d,&d->ht[0]);
_dictClear(d,&d->ht[1]);
- _dictFree(d);
+ zfree(d);
}
dictEntry *dictFind(dict *d, const void *key)
dictIterator *dictGetIterator(dict *d)
{
- dictIterator *iter = _dictAlloc(sizeof(*iter));
+ dictIterator *iter = zmalloc(sizeof(*iter));
iter->d = d;
iter->table = 0;
void dictReleaseIterator(dictIterator *iter)
{
if (!(iter->index == -1 && iter->table == 0)) iter->d->iterators--;
- _dictFree(iter);
+ zfree(iter);
}
/* Return a random entry from the hash table. Useful to
/* Expand the hash table if needed */
static int _dictExpandIfNeeded(dict *d)
{
- /* If the hash table is empty expand it to the intial size,
- * if the table is "full" dobule its size. */
+ /* Incremental rehashing already in progress. Return. */
if (dictIsRehashing(d)) return DICT_OK;
- if (d->ht[0].size == 0)
- return dictExpand(d, DICT_HT_INITIAL_SIZE);
- if (d->ht[0].used >= d->ht[0].size && dict_can_resize)
+
+ /* If the hash table is empty expand it to the intial size. */
+ if (d->ht[0].size == 0) return dictExpand(d, DICT_HT_INITIAL_SIZE);
+
+ /* If we reached the 1:1 ratio, and we are allowed to resize the hash
+ * table (global setting) or we should avoid it but the ratio between
+ * elements/buckets is over the "safe" threshold, we resize doubling
+ * the number of buckets. */
+ if (d->ht[0].used >= d->ht[0].size &&
+ (dict_can_resize ||
+ d->ht[0].used/d->ht[0].size > dict_force_resize_ratio))
+ {
return dictExpand(d, ((d->ht[0].size > d->ht[0].used) ?
d->ht[0].size : d->ht[0].used)*2);
+ }
return DICT_OK;
}
dict_can_resize = 0;
}
+#if 0
+
+/* The following are just example hash table types implementations.
+ * Not useful for Redis so they are commented out.
+ */
+
/* ----------------------- StringCopy Hash Table Type ------------------------*/
static unsigned int _dictStringCopyHTHashFunction(const void *key)
static void *_dictStringDup(void *privdata, const void *key)
{
int len = strlen(key);
- char *copy = _dictAlloc(len+1);
+ char *copy = zmalloc(len+1);
DICT_NOTUSED(privdata);
memcpy(copy, key, len);
{
DICT_NOTUSED(privdata);
- _dictFree(key);
+ zfree(key);
}
dictType dictTypeHeapStringCopyKey = {
_dictStringDestructor, /* key destructor */
_dictStringDestructor, /* val destructor */
};
+#endif
projects / redis.git / blobdiff