public void update_MessageTrace(String msg){
    if(reorder_msg==0 || reorder_msg==1){
      synchronized(test_network.MessageTrace){
        String whoamI=""; 
        if(test_index<test_network.numProposers())
          whoamI="Proposer - "+test_index;
        if(test_index>=test_network.numProposers() && test_index<test_network.numAcceptors()+test_network.numProposers())
          whoamI="Acceptor - "+test_index;
        if(test_index>=test_network.numAcceptors()+test_network.numProposers() && test_index<test_network.test_totalProcesses)
          whoamI="Learner  - "+test_index;
        test_network.MessageTrace.add(getCurTime()+" "+whoamI+msg);
      }
    }
  }