#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;
+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().
}
/* 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;
/* 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;
}