From c0f45bf12e34121bdf5c117e215586d2b92c4aec Mon Sep 17 00:00:00 2001
From: sundb <sundbcn@gmail.com>
Date: Wed, 25 Nov 2020 03:40:58 +0800
Subject: [PATCH] Avoid excessive malloc and free in copyCommand robj creation
 (#8067)

Avoid multiple conditional judgments
Avoid allocating robj->ptr when we're gonna replace it right after.
---
 src/t_hash.c | 27 +++++++++------------------
 src/t_list.c |  5 ++---
 src/t_set.c  | 24 +++++++-----------------
 src/t_zset.c | 24 ++++++------------------
 4 files changed, 24 insertions(+), 56 deletions(-)

diff --git a/src/t_hash.c b/src/t_hash.c
index 5c844ce30..f3fde87aa 100644
--- a/src/t_hash.c
+++ b/src/t_hash.c
@@ -515,29 +515,17 @@ robj *hashTypeDup(robj *o) {
 
     serverAssert(o->type == OBJ_HASH);
 
-    switch (o->encoding) {
-        case OBJ_ENCODING_ZIPLIST:
-            hobj = createHashObject();
-            break;
-        case OBJ_ENCODING_HT:
-            hobj = createHashObject();
-            hashTypeConvert(hobj, OBJ_ENCODING_HT);
-            dict *d = o->ptr;
-            dictExpand(hobj->ptr, dictSize(d));
-            break;
-        default:
-            serverPanic("Wrong encoding.");
-            break;
-    }
-
     if(o->encoding == OBJ_ENCODING_ZIPLIST){
         unsigned char *zl = o->ptr;
         size_t sz = ziplistBlobLen(zl);
         unsigned char *new_zl = zmalloc(sz);
         memcpy(new_zl, zl, sz);
-        zfree(hobj->ptr);
-        hobj->ptr = new_zl;
+        hobj = createObject(OBJ_HASH, new_zl);
+        hobj->encoding = OBJ_ENCODING_ZIPLIST;
     } else if(o->encoding == OBJ_ENCODING_HT){
+        dict *d = dictCreate(&hashDictType, NULL);
+        dictExpand(d, dictSize((const dict*)o->ptr));
+
         hi = hashTypeInitIterator(o);
         while (hashTypeNext(hi) != C_ERR) {
             sds field, value;
@@ -549,9 +537,12 @@ robj *hashTypeDup(robj *o) {
             newvalue = sdsdup(value);
 
             /* Add a field-value pair to a new hash object. */
-            dictAdd(hobj->ptr,newfield,newvalue);
+            dictAdd(d,newfield,newvalue);
         }
         hashTypeReleaseIterator(hi);
+
+        hobj = createObject(OBJ_HASH, d);
+        hobj->encoding = OBJ_ENCODING_HT;
     } else {
         serverPanic("Unknown hash encoding");
     }
diff --git a/src/t_list.c b/src/t_list.c
index ce1472d93..acabe7be2 100644
--- a/src/t_list.c
+++ b/src/t_list.c
@@ -202,14 +202,13 @@ robj *listTypeDup(robj *o) {
 
     switch (o->encoding) {
         case OBJ_ENCODING_QUICKLIST:
-            lobj = createQuicklistObject();
+            lobj = createObject(OBJ_LIST, quicklistDup(o->ptr));
+            lobj->encoding = OBJ_ENCODING_QUICKLIST;
             break;
         default:
             serverPanic("Wrong encoding.");
             break;
     }
-    zfree(lobj->ptr);
-    lobj->ptr = quicklistDup(o->ptr);
     return lobj;
 }
 
diff --git a/src/t_set.c b/src/t_set.c
index cb4c5002f..b2da14cd5 100644
--- a/src/t_set.c
+++ b/src/t_set.c
@@ -275,27 +275,17 @@ robj *setTypeDup(robj *o) {
     serverAssert(o->type == OBJ_SET);
 
     /* Create a new set object that have the same encoding as the original object's encoding */
-    switch (o->encoding) {
-        case OBJ_ENCODING_INTSET:
-            set = createIntsetObject();
-            break;
-        case OBJ_ENCODING_HT:
-            set = createSetObject();
-            dict *d = o->ptr;
-            dictExpand(set->ptr, dictSize(d));
-            break;
-        default:
-            serverPanic("Wrong encoding.");
-            break;
-    }
-    if (set->encoding == OBJ_ENCODING_INTSET) {
+    if (o->encoding == OBJ_ENCODING_INTSET) {
         intset *is = o->ptr;
         size_t size = intsetBlobLen(is);
         intset *newis = zmalloc(size);
         memcpy(newis,is,size);
-        zfree(set->ptr);
-        set->ptr = newis;
-    } else if (set->encoding == OBJ_ENCODING_HT) {
+        set = createObject(OBJ_SET, newis);
+        set->encoding = OBJ_ENCODING_INTSET;
+    } else if (o->encoding == OBJ_ENCODING_HT) {
+        set = createSetObject();
+        dict *d = o->ptr;
+        dictExpand(set->ptr, dictSize(d));
         si = setTypeInitIterator(o);
         while (setTypeNext(si, &elesds, &intobj) != -1) {
             setTypeAdd(set, elesds);
diff --git a/src/t_zset.c b/src/t_zset.c
index 1f5f00a62..a6ce20132 100644
--- a/src/t_zset.c
+++ b/src/t_zset.c
@@ -1567,30 +1567,18 @@ robj *zsetDup(robj *o) {
     serverAssert(o->type == OBJ_ZSET);
 
     /* Create a new sorted set object that have the same encoding as the original object's encoding */
-    switch (o->encoding) {
-        case OBJ_ENCODING_ZIPLIST:
-            zobj = createZsetZiplistObject();
-            break;
-        case OBJ_ENCODING_SKIPLIST:
-            zobj = createZsetObject();
-            zs = o->ptr;
-            new_zs = zobj->ptr;
-            dictExpand(new_zs->dict,dictSize(zs->dict));
-            break;
-        default:
-            serverPanic("Wrong encoding.");
-            break;
-    }
-    if (zobj->encoding == OBJ_ENCODING_ZIPLIST) {
+    if (o->encoding == OBJ_ENCODING_ZIPLIST) {
         unsigned char *zl = o->ptr;
         size_t sz = ziplistBlobLen(zl);
         unsigned char *new_zl = zmalloc(sz);
         memcpy(new_zl, zl, sz);
-        zfree(zobj->ptr);
-        zobj->ptr = new_zl;
-    } else if (zobj->encoding == OBJ_ENCODING_SKIPLIST) {
+        zobj = createObject(OBJ_ZSET, new_zl);
+        zobj->encoding = OBJ_ENCODING_ZIPLIST;
+    } else if (o->encoding == OBJ_ENCODING_SKIPLIST) {
+        zobj = createZsetObject();
         zs = o->ptr;
         new_zs = zobj->ptr;
+        dictExpand(new_zs->dict,dictSize(zs->dict));
         zskiplist *zsl = zs->zsl;
         zskiplistNode *ln;
         sds ele;