vnfs/vLB/DNSManager/src/main/java/DNSMembershipManager.java

   1
   2 /*************************************************************************//**
   3  *
   4  * Copyright © 2017 AT&T Intellectual Property. All rights reserved.
   5  *
   6  * Licensed under the Apache License, Version 2.0 (the "License");
   7  * you may not use this file except in compliance with the License.
   8  * You may obtain a copy of the License at
   9  *        http://www.apache.org/licenses/LICENSE-2.0
  10  *
  11  * Unless required by applicable law or agreed to in writing, software
  12  * distributed under the License is distributed on an "AS IS" BASIS,
  13  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  14  * See the License for the specific language governing permissions and
  15  * limitations under the License.
  16  *
  17  ****************************************************************************/
  18
  19 package main.java;
  20
  21 import java.io.IOException;
  22 import java.util.HashSet;
  23 import java.util.Iterator;
  24 import java.util.Set;
  25
  26 public class DNSMembershipManager {
  27         /*
  28          * Uses Failure Detector (FD) to keep track of the DNS servers currently active.
  29          * @param port: the port that the FD service listens for incoming UDP packets
  30          * @param timeout: how often the FD checks the status of client processes
  31          * @param threshold: number of missing ping messages before declaring a client dead
  32          * @param debug: debug mode on/off
  33          */
  34
  35         static Set<String> active = new HashSet<String>();
  36
  37         @SuppressWarnings("static-access")
  38         public static void main(String[] args) throws IOException, InterruptedException {
  39                 if(args.length != 5) {
  40                         System.out.println("Missing input parameters");
  41                         System.out.println("Usage:");
  42                         System.out.print("\t- java FDServer [public IP address] [port] [timeout (sec)] [threshold] [debug]\n");
  43                         System.exit(0);
  44                 }
  45
  46                 // Input parameters: PORT, TIMEOUT, THRESHOLD
  47                 String IPADDR = args[0];
  48                 int PORT = Integer.parseInt(args[1]);
  49                 long TIMEOUT = Long.parseLong(args[2]) * 1000; // convert the FD timeout to milliseconds
  50                 int THRESHOLD = Integer.parseInt(args[3]);
  51                 int debug = Integer.parseInt(args[4]);
  52                 boolean DEBUG;
  53                 if(debug <= 0)
  54                         DEBUG = false;
  55                 else
  56                         DEBUG = true;
  57
  58                 // Start Failure Detector
  59                 FDServer fd = new FDServer(IPADDR, PORT, TIMEOUT, THRESHOLD, DEBUG);
  60
  61                 // Check the status of client processes periodically. We use the same timeout value as FD
  62                 Set<String> active = new HashSet<String>();
  63                 while(true) {
  64                         Set<String> alive_this_round = fd.getAliveProcesses();
  65                         Iterator<String> iter = alive_this_round.iterator();
  66                         String pid;
  67
  68                         // Check if there is some new DNS active
  69                         while(iter.hasNext()) {
  70                                 pid = iter.next();
  71                                 if(!active.contains(pid)) {
  72                                         active.add(pid);
  73                                         // Add the new vDNS to the set of vDNS servers
  74                                         String script = new String("bash /opt/FDserver/add_dns.sh " + pid);
  75                             Runtime.getRuntime().exec(script);
  76                                         if(DEBUG) System.out.println("Adding process " + pid + " to the list of DNSs");
  77                                 }
  78                         }
  79
  80                         // Remove possible dead DNSs
  81                         iter = active.iterator();
  82                         while(iter.hasNext()) {
  83                                 pid = iter.next();
  84                                 if(!alive_this_round.contains(pid)) {
  85                                         iter.remove(); // remove element from the iterator to avoid ConcurrentModificationException
  86                                         // Remove the new vDNS from the set of vDNS servers
  87                                         String script = new String("bash /opt/FDserver/remove_dns.sh " + pid);
  88                             Runtime.getRuntime().exec(script);
  89                                         if(DEBUG) System.out.println("Removing process " + pid + " from the list of DNSs");
  90                                 }
  91                         }
  92                         Thread.currentThread().sleep(TIMEOUT);
  93                 }
  94         }
  95 }