Add zend_hash_reindex

The implementation differs from the original in array.c in that it rehashes the hashtable in the same loop. This is approximately two times faster (not counting the rare case of a purely associative array).

Author: nikic

Zend/zend_hash.c

@@ -466,16 +466,37 @@ ZEND_API int zend_hash_rehash(HashTable *ht)
 }
 
 memset(ht->arBuckets, 0, ht->nTableSize * sizeof(Bucket *));
-p = ht->pListHead;
-while (p != NULL) {
+for (p = ht->pListHead; p != NULL; p = p->pListNext) {
 nIndex = p->h & ht->nTableMask;
 CONNECT_TO_BUCKET_DLLIST(p, ht->arBuckets[nIndex]);
 ht->arBuckets[nIndex] = p;
-p = p->pListNext;
 }
 return SUCCESS;
 }
 
+ZEND_API void zend_hash_reindex(HashTable *ht) {
+Bucket *p;
+uint nIndex;
+ulong offset = 0;
+
+IS_CONSISTENT(ht);
+if (UNEXPECTED(ht->nNumOfElements == 0)) {
+return;
+}
+
+memset(ht->arBuckets, 0, ht->nTableSize * sizeof(Bucket *));
+for (p = ht->pListHead; p != NULL; p = p->pListNext) {
+if (p->nKeyLength == 0) {
+p->h = offset++;
+}
+
+nIndex = p->h & ht->nTableMask;
+CONNECT_TO_BUCKET_DLLIST(p, ht->arBuckets[nIndex]);
+ht->arBuckets[nIndex] = p;
+}
+ht->nNextFreeElement = offset;
+}
+
 ZEND_API int zend_hash_del_key_or_index(HashTable *ht, const char *arKey, uint nKeyLength, ulong h, int flag)
 {
 uint nIndex;

Zend/zend_hash.h

@@ -227,6 +227,7 @@ ZEND_API int zend_hash_minmax(const HashTable *ht, compare_func_t compar, int fl
 ZEND_API int zend_hash_num_elements(const HashTable *ht);
 
 ZEND_API int zend_hash_rehash(HashTable *ht);
+ZEND_API void zend_hash_reindex(HashTable *ht);
 
 /*
  * DJBX33A (Daniel J. Bernstein, Times 33 with Addition)

ext/standard/array.c

@@ -1975,24 +1975,7 @@ static void _phpi_pop(INTERNAL_FUNCTION_PARAMETERS, int off_the_end)
 
 /* If we did a shift... re-index like it did before */
 if (!off_the_end) {
-unsigned int k = 0;
-int should_rehash = 0;
-Bucket *p = Z_ARRVAL_P(stack)->pListHead;
-while (p != NULL) {
-if (p->nKeyLength == 0) {
-if (p->h != k) {
-p->h = k++;
-should_rehash = 1;
-} else {
-k++;
-}
-}
-p = p->pListNext;
-}
-Z_ARRVAL_P(stack)->nNextFreeElement = k;
-if (should_rehash) {
-zend_hash_rehash(Z_ARRVAL_P(stack));
-}
+zend_hash_reindex(Z_ARRVAL_P(stack));
 } else if (!key_len && index >= Z_ARRVAL_P(stack)->nNextFreeElement - 1) {
 Z_ARRVAL_P(stack)->nNextFreeElement = Z_ARRVAL_P(stack)->nNextFreeElement - 1;
 }