refactor(sync): optimize leader transfer

source/libs/sync/src/syncMain.c

@@ -436,8 +436,15 @@ int32_t syncNodeLeaderTransfer(SSyncNode* pSyncNode) {
   }
 
   int32_t ret = 0;
-  if (pSyncNode->state == TAOS_SYNC_STATE_LEADER) {
+  if (pSyncNode->state == TAOS_SYNC_STATE_LEADER && pSyncNode->replicaNum > 1) {
     SNodeInfo newLeader = (pSyncNode->peersNodeInfo)[0];
+    if (pSyncNode->peersNum == 2) {
+      SyncIndex matchIndex0 = syncIndexMgrGetIndex(pSyncNode->pMatchIndex, &(pSyncNode->peersId[0]));
+      SyncIndex matchIndex1 = syncIndexMgrGetIndex(pSyncNode->pMatchIndex, &(pSyncNode->peersId[1]));
+      if (matchIndex1 > matchIndex0) {
+        newLeader = (pSyncNode->peersNodeInfo)[1];
+      }
+    }
     ret = syncNodeLeaderTransferTo(pSyncNode, newLeader);
   }