From 32f45215c33e8b8d801c4c339e18504918082936 Mon Sep 17 00:00:00 2001
From: Binbin <binloveplay1314@qq.com>
Date: Mon, 29 May 2023 14:55:17 +0800
Subject: [PATCH] Try lazyfree temp zset in ZUNION / ZINTER / ZDIFF and
 optimize ZINTERCARD to avoid create temp zset (#12229)

We check lazyfree_lazy_server_del in sunionDiffGenericCommand
to see if we need to lazyfree the temp set. Now do the same in
zunionInterDiffGenericCommand to lazyfree the temp zset.

This is a minor change, follow #5903. Also improved the comments.

Additionally, avoid creating unused zset object in ZINTERCARD,
results in some 10% performance improvement.
---
 src/t_set.c  |  4 ++--
 src/t_zset.c | 18 +++++++++++++-----
 2 files changed, 15 insertions(+), 7 deletions(-)

diff --git a/src/t_set.c b/src/t_set.c
index fb85d220f..7e3a9ce81 100644
--- a/src/t_set.c
+++ b/src/t_set.c
@@ -1540,8 +1540,8 @@ void sunionDiffGenericCommand(client *c, robj **setkeys, int setnum,
         }
     }
 
-    /* We need a temp set object to store our union. If the dstkey
-     * is not NULL (that is, we are inside an SUNIONSTORE operation) then
+    /* We need a temp set object to store our union/diff. If the dstkey
+     * is not NULL (that is, we are inside an SUNIONSTORE/SDIFFSTORE operation) then
      * this set object will be the resulting object to set into the target key*/
     dstset = createIntsetObject();
 
diff --git a/src/t_zset.c b/src/t_zset.c
index 6f0306c65..7717a4a14 100644
--- a/src/t_zset.c
+++ b/src/t_zset.c
@@ -2575,8 +2575,8 @@ void zunionInterDiffGenericCommand(client *c, robj *dstkey, int numkeysIndex, in
     zsetopval zval;
     sds tmp;
     size_t maxelelen = 0, totelelen = 0;
-    robj *dstobj;
-    zset *dstzset;
+    robj *dstobj = NULL;
+    zset *dstzset = NULL;
     zskiplistNode *znode;
     int withscores = 0;
     unsigned long cardinality = 0;
@@ -2686,8 +2686,14 @@ void zunionInterDiffGenericCommand(client *c, robj *dstkey, int numkeysIndex, in
         qsort(src,setnum,sizeof(zsetopsrc),zuiCompareByCardinality);
     }
 
-    dstobj = createZsetObject();
-    dstzset = dstobj->ptr;
+    /* We need a temp zset object to store our union/inter/diff. If the dstkey
+     * is not NULL (that is, we are inside an ZUNIONSTORE/ZINTERSTORE/ZDIFFSTORE operation) then
+     * this zset object will be the resulting object to zset into the target key.
+     * In SINTERCARD case, we don't need the temp obj, so we can avoid creating it. */
+    if (!cardinality_only) {
+        dstobj = createZsetObject();
+        dstzset = dstobj->ptr;
+    }
     memset(&zval, 0, sizeof(zval));
 
     if (op == SET_OP_INTER) {
@@ -2826,6 +2832,7 @@ void zunionInterDiffGenericCommand(client *c, robj *dstkey, int numkeysIndex, in
                 server.dirty++;
             }
         }
+        decrRefCount(dstobj);
     } else if (cardinality_only) {
         addReplyLongLong(c, cardinality);
     } else {
@@ -2846,8 +2853,9 @@ void zunionInterDiffGenericCommand(client *c, robj *dstkey, int numkeysIndex, in
             if (withscores) addReplyDouble(c,zn->score);
             zn = zn->level[0].forward;
         }
+        server.lazyfree_lazy_server_del ? freeObjAsync(NULL, dstobj, -1) :
+                                          decrRefCount(dstobj);
     }
-    decrRefCount(dstobj);
     zfree(src);
 }