refactor(tmq): add error code

include/util/taoserror.h

@@ -285,6 +285,7 @@ int32_t* taosGetErrno();
 #define TSDB_CODE_MND_TOPIC_SUBSCRIBED          TAOS_DEF_ERROR_CODE(0, 0x03EB)
 #define TSDB_CODE_MND_CGROUP_USED               TAOS_DEF_ERROR_CODE(0, 0x03EC)
 #define TSDB_CODE_MND_TOPIC_MUST_BE_DELETED     TAOS_DEF_ERROR_CODE(0, 0x03ED)
+#define TSDB_CODE_MND_IN_REBALANCE              TAOS_DEF_ERROR_CODE(0, 0x03EF)
 
 // mnode-stream
 #define TSDB_CODE_MND_STREAM_ALREADY_EXIST      TAOS_DEF_ERROR_CODE(0, 0x03F0)

source/dnode/mnode/impl/src/mndSubscribe.c

@@ -900,6 +900,7 @@ int32_t mndDropSubByTopic(SMnode *pMnode, STrans *pTrans, const char *topicName)
     // iter all vnode to delete handle
     if (taosHashGetSize(pSub->consumerHash) != 0) {
       sdbRelease(pSdb, pSub);
+      terrno = TSDB_CODE_MND_IN_REBALANCE;
       return -1;
     }
     int32_t sz = taosArrayGetSize(pSub->unassignedVgs);

source/dnode/mnode/impl/src/mndTopic.c

@@ -713,7 +713,6 @@ static int32_t mndProcessDropTopicReq(SRpcMsg *pReq) {
   mndReleaseTopic(pMnode, pTopic);
 
   if (code != 0) {
-    terrno = code;
     mError("topic:%s, failed to drop since %s", dropReq.name, terrstr());
     return -1;
   }

source/util/src/terror.c

@@ -288,6 +288,7 @@ TAOS_DEFINE_ERROR(TSDB_CODE_MND_CONSUMER_NOT_READY,       "Consumer not ready")
 TAOS_DEFINE_ERROR(TSDB_CODE_MND_TOPIC_SUBSCRIBED,         "Topic subscribed cannot be dropped")
 TAOS_DEFINE_ERROR(TSDB_CODE_MND_TOPIC_MUST_BE_DELETED,    "Topic must be dropped first")
 TAOS_DEFINE_ERROR(TSDB_CODE_MND_CGROUP_USED,              "Consumer group being used by some consumer")
+TAOS_DEFINE_ERROR(TSDB_CODE_MND_IN_REBALANCE,             "Topic being rebalanced")
 
 // mnode-stream
 TAOS_DEFINE_ERROR(TSDB_CODE_MND_STREAM_ALREADY_EXIST,     "Stream already exists")