add msg tag; recv all msgs before remove mq.

lichao

2021-04-23 628c1c21ffb19d8c96ed9ce89531595f9870ab1a

 src/socket.cpp

@@ -59,7 +59,7 @@
            return false;
         }
         auto onMsg = [&](MsgI &imsg) {
            DEFER1(imsg.Release(shm()));
            DEFER1(imsg.Release());
            BHMsgHead head;
            if (imsg.ParseHead(head)) {
               onRecvWithPerMsgCB(*this, imsg, head);
@@ -118,7 +118,7 @@
      if (msg.ParseHead(head)) {
         return true;
      } else {
         msg.Release(shm());
         msg.Release();
      }
   }
   return false;