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authorNikita Popov <nikic@php.net>2016-07-18 23:40:07 +0200
committerNikita Popov <nikic@php.net>2016-07-18 23:42:07 +0200
commitd91e2e47d4cd68b2d9978181a36d5c304f61eb51 (patch)
tree05ef33ce6422f0f2ec76f86b0c462d6458dd2bdc
parent7f3375d5f28b1447ccc659e9867d67cf3bb86ba7 (diff)
downloadphp-git-d91e2e47d4cd68b2d9978181a36d5c304f61eb51.tar.gz
Increase array_rand() rehashing treshold
From 3/8 to 3/4. I was thinking in terms of nTableSize, where a requirement > 1/2 is not tenable. However, we're actually working with nNumUsed, in which case more than 1/4 tombstones should be quite unusual.
-rw-r--r--ext/standard/array.c10
1 files changed, 5 insertions, 5 deletions
diff --git a/ext/standard/array.c b/ext/standard/array.c
index 3ffced130c..359bd978d4 100644
--- a/ext/standard/array.c
+++ b/ext/standard/array.c
@@ -5056,8 +5056,8 @@ PHP_FUNCTION(array_rand)
if (num_req == 1) {
HashTable *ht = Z_ARRVAL_P(input);
- /* Compact the hashtable if less than 3/8 of elements are used */
- if (num_avail < ht->nNumUsed - (ht->nNumUsed>>1) - (ht->nNumUsed>>2)) {
+ /* Compact the hashtable if less than 3/4 of elements are used */
+ if (num_avail < ht->nNumUsed - (ht->nNumUsed>>2)) {
if (ht->u.flags & HASH_FLAG_PACKED) {
zend_hash_packed_to_hash(ht);
} else {
@@ -5066,9 +5066,9 @@ PHP_FUNCTION(array_rand)
}
/* Sample random buckets until we hit one that is not empty.
- * The worst case probability of hitting an empty element is 1-3/8. The worst case
- * probability of hitting N empty elements in a row is (1-3/8)**N.
- * For N=10 this becomes smaller than 1%. */
+ * The worst case probability of hitting an empty element is 1-3/4. The worst case
+ * probability of hitting N empty elements in a row is (1-3/4)**N.
+ * For N=5 this becomes smaller than 0.1%. */
do {
zend_long randval = php_mt_rand_range(0, ht->nNumUsed - 1);
Bucket *bucket = &ht->arData[randval];