From 1bcf67a75f775b342653505465b5e8ee03974809 Mon Sep 17 00:00:00 2001
From: antirez <antirez@gmail.com>
Date: Thu, 5 Feb 2015 11:28:45 +0100
Subject: [PATCH] dict.c: dictGetRandomKeys() optimization for big->small table
case.
Related to issue #2306.
---
src/dict.c | 9 ++++++++-
1 file changed, 8 insertions(+), 1 deletion(-)
diff --git a/src/dict.c b/src/dict.c
index fbcdd35f..e197266e 100644
--- a/src/dict.c
+++ b/src/dict.c
@@ -704,7 +704,14 @@ unsigned int dictGetRandomKeys(dict *d, dictEntry **des, unsigned int count) {
/* Invariant of the dict.c rehashing: up to the indexes already
* visited in ht[0] during the rehashing, there are no populated
* buckets, so we can skip ht[0] for indexes between 0 and idx-1. */
- if (j == 0 && i < d->rehashidx) continue;
+ if (tables == 2 && j == 0 && i < d->rehashidx) {
+ /* Moreover, if we are currently out of range in the second
+ * table, there will be no elements in both tables up to
+ * the current rehashing index, so we jump if possible.
+ * (this happens when going from big to small table). */
+ if (i >= d->ht[1].size) i = d->rehashidx;
+ continue;
+ }
if (i >= d->ht[j].size) continue; /* Out of range for this table. */
dictEntry *he = d->ht[j].table[i];
while (he) {