paper3—Algorithm1-Engine-Trigger-on-FCD—temp

//source code: /run/media/root/E6B2798BB279614B/.../PAPER/paper-3/twin-engine-trigger-code/server-client-pthread-c
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Description: when FCD start, this algorithm will run as a deamon

normterm: normal termination;
  normterm=0, SMD is not normal termination;
  normterm=1, SMD is normal termination;
smdtime: time of receiving heartbeat from SMD last;
selftime: the most current time of FCD being active;
initconn: Initial connection from SMD to FCD;
  initconn=1, initial value is 1;
downtime: suppose server restart time is 30s;

select selftime from fcd_state_table where id=1;
downtime=currenttime - selftime;
update fcd_state_table set selftime=currenttime where id=1;

PROCEDURE: MAIN
  socket();
  bind();
  listen();
  while true do
    accept();  //waiting for connect from SMD
    pthread_create(THREAD);
  done
END PROCEDURE

PROCEDURE: THREAD
  receive guestname from SMD;
  select normterm from user_table where username=guestname;
  select processid from process_table where username=guestname and state=active and exectime≈current;

  while true do //communication between FCD & SMD
    select smdtime from user_table where username=guestname;
    period=-1; //used to determine whether SMD access FCD continuously
    if receive heartbeat from SMD then
      period=currenttime - smdtime;
    end if
    update user_table set smdtime=currenttime where username=guestname;
    if 0< period< 8 or initconn then //normal visits
      send heartbeat to SMD;
      send information for current process to SMD;
      initconn=0;
    end if
    if receive finish from SMD then //normal termination
      update user_table set normterm=1 where username=guestname;
      exit; //guest finished his tasks
    end if
    //server restart, process is not normal end
    //after disconnect, SMD reconnect FCD
    if downtime > 30 and !normterm or receive reconnect from SMD then
      FCD receive current process information from SMD;
      update correlative tables where processid=processid;
    end if
    sleep 1s;
  done
END PROCEDURE