paper4—Multi-MPE_Trigger_Algorithm—temp

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Description: when SMD start, this algorithm will run as a deamon, two roles: Master,
 Slave. When the SMD is elected as a Master role, then, the MPE will be the master MPE accessed by other SMD, and related process data will backup to other
 SMD (Slave MPE).

ctrl: Master or Slave, this value is set by batman-adv;
  ctrl=0, SMD is Slave role;
  ctrl=1, SMD is elected as a Master role;

changed: Master or Slave, this value is set by batman-adv;
  changed=0, Master SMD is not changed, so, do not need to create thread in MAIN again for data synchronization;
  changed=1, Master SMD is changed, so, need to create thread in MAIN again for data synchronization;

changed=0;
is_me=-1;
prev_state=-1; //0:Slave; 1:Master;

//READ_CTRL, set URL of application system. Access master_ip in browser.
PROCEDURE: READ_CTRL
prev_ip=0.0.0.0;
while true do
  read the value of ctrl set by batman-adv;
  read master_ip of Master SMD;
  if master_ip==me_ip and is_me!=-1 then
    prev_state=is_me;
    is_me=1;
  else if master_ip!=me_ip and is_me!=-1 then
    prev_state=is_me;
    is_me=0;
  end if
  if master_ip!=prev_ip then
    changed=1;
    prev_ip=master_ip;
    add (or update) "master_ip mpe.localhost" in /etc/hosts;
  end if
  sleep 1s;
done
END PROCEDURE READ_CTRL

//******************************
 MAIN Thread
PROCEDURE: MAIN
pthread_create(READ_CTRL);
sleep 1s; //waiting for READ_CTRL to read the value of ctrl and master_ip of Master SMD
start=1; //set initial state
while true do
  if start==1 and ctrl==1 then
    start=0;
    is_me=1;
    pthread_create(Master);
    pthread_join(Master);
  else if start==1 and ctrl==0 then
    start=0;
    is_me=0;
    pthread_create(Slave);
    pthread_join(Slave);
  else if start==0 and changed==1 and ctrl==1 then
    pthread_create(Master);
    pthread_join(Master);
  else if start==0 and changed==1 and ctrl==0 then
    sleep(2);    //waiting master initialize
    pthread_create(Master);
    pthread_join(Master);
  else //start==0 and changed==0
    continue;
  end if
done
END PROCEDURE MAIN

//******************************
 Master Thread
PROCEDURE: Master
socket();
bind();
listen();
while true do
  accept(); //waiting for connect from Slave
  pthread_create(M_THREAD);
done
END PROCEDURE Master

//******************************
 M_THREAD Thread
PROCEDURE: M_THREAD
while true do //communication between Master & Slave
  if database updating then
    send synchronous data to Slave;
  end if
done
END PROCEDURE M_THREAD

//******************************
 Slave Thread
PROCEDURE: Slave
socket();
connect();
while true do
  if receive synchronous data from Master then
    update database;
  end if
done
END PROCEDURE Slave