From 1f12be30723abf6487e65557be501e54a0ed8463 Mon Sep 17 00:00:00 2001
From: sundb <sundbcn@gmail.com>
Date: Mon, 8 Feb 2021 18:41:16 +0800
Subject: [PATCH] Fix random probability check in ziplistRandomPairsUnique
 (#8467)

When (remaining == (total_size - index)), element will definitely be random to.
But when rand() == RAND_MAX, the element will miss, this will trigger assert
in serverAssert(ziplistRandomPairsUnique(zsetobj->ptr, count, keys, vals) == count).
---
 src/ziplist.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/ziplist.c b/src/ziplist.c
index 2c0074d5d..35a0f283a 100644
--- a/src/ziplist.c
+++ b/src/ziplist.c
@@ -1608,7 +1608,7 @@ unsigned int ziplistRandomPairsUnique(unsigned char *zl, unsigned int count, zip
     while (picked < count && p) {
         double randomDouble = ((double)rand()) / RAND_MAX;
         double threshold = ((double)remaining) / (total_size - index);
-        if(randomDouble < threshold){
+        if (randomDouble <= threshold) {
             assert(ziplistGet(p, &key, &klen, &klval));
             ziplistSaveValue(key, klen, klval, &keys[picked]);
             p = ziplistNext(zl, p);