fix active_trx_count leak when add memtable fail

src/storage/memtable/ob_memtable_context.cpp

@@ -260,17 +260,20 @@ int ObMemtableCtx::set_host_(ObMemtable* host, const bool for_replay)
     ret = OB_NOT_MASTER;
   } else if (host == get_active_mt()) {
     // do nothing
+  } else if (memtable_arr_wrap_.is_contain_this_memtable(host)) {
+    ret = OB_ERR_UNEXPECTED;
+    TRANS_LOG(ERROR, "memstore already exist", K(ret), K(*this), KP(host));
   } else if (memtable_arr_wrap_.is_reach_max_memtable_cnt()) {
     ret = OB_ERR_UNEXPECTED;
     TRANS_LOG(ERROR, "reach max memstore in storage", K(ret), K(*this), KP(host));
-  } else {
-    if (memtable_arr_wrap_.is_contain_this_memtable(host)) {
-      ret = OB_ERR_UNEXPECTED;
-      TRANS_LOG(ERROR, "memstore already exist", K(ret), K(*this), KP(host));
   } else if (OB_FAIL(host->inc_active_trx_count())) {
     TRANS_LOG(ERROR, "increase active_trx_count error", K(ret), K(*this), KP(host));
+  } else if (OB_FAIL(memtable_arr_wrap_.add_memtable(host))) {
+    int tmp_ret = OB_SUCCESS;
+    if (OB_SUCCESS != (tmp_ret = host->dec_active_trx_count())) {
+      TRANS_LOG(ERROR, "decrease active_trx_count error when add memtable fail", K(tmp_ret), K(ret), K(*this), KP(host));
     } else {
-      memtable_arr_wrap_.add_memtable(host);
+      TRANS_LOG(WARN, "decrease active_trx_count success when add memtable fail", K(ret), K(*this), KP(host));
     }
   }
   return ret;