blob: a597f3e58b2440d58176e65569401c52afac7ecc (
plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
|
/*************************************************************************//**
*
* Copyright © 2017 AT&T Intellectual Property. All rights reserved.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*
****************************************************************************/
package main.java;
import java.io.IOException;
import java.util.HashSet;
import java.util.Iterator;
import java.util.Set;
public class DNSMembershipManager {
/*
* Uses Failure Detector (FD) to keep track of the DNS servers currently active.
* @param port: the port that the FD service listens for incoming UDP packets
* @param timeout: how often the FD checks the status of client processes
* @param threshold: number of missing ping messages before declaring a client dead
* @param debug: debug mode on/off
*/
static Set<String> active = new HashSet<String>();
@SuppressWarnings("static-access")
public static void main(String[] args) throws IOException, InterruptedException {
if(args.length != 5) {
System.out.println("Missing input parameters");
System.out.println("Usage:");
System.out.print("\t- java FDServer [public IP address] [port] [timeout (sec)] [threshold] [debug]\n");
System.exit(0);
}
// Input parameters: PORT, TIMEOUT, THRESHOLD
String IPADDR = args[0];
int PORT = Integer.parseInt(args[1]);
long TIMEOUT = Long.parseLong(args[2]) * 1000; // convert the FD timeout to milliseconds
int THRESHOLD = Integer.parseInt(args[3]);
int debug = Integer.parseInt(args[4]);
boolean DEBUG;
if(debug <= 0)
DEBUG = false;
else
DEBUG = true;
// Start Failure Detector
FDServer fd = new FDServer(IPADDR, PORT, TIMEOUT, THRESHOLD, DEBUG);
// Check the status of client processes periodically. We use the same timeout value as FD
Set<String> active = new HashSet<String>();
while(true) {
Set<String> alive_this_round = fd.getAliveProcesses();
Iterator<String> iter = alive_this_round.iterator();
String pid;
// Check if there is some new DNS active
while(iter.hasNext()) {
pid = iter.next();
if(!active.contains(pid)) {
active.add(pid);
// Add the new vDNS to the set of vDNS servers
String script = new String("bash /opt/FDserver/add_dns.sh " + pid);
Runtime.getRuntime().exec(script);
if(DEBUG) System.out.println("Adding process " + pid + " to the list of DNSs");
}
}
// Remove possible dead DNSs
iter = active.iterator();
while(iter.hasNext()) {
pid = iter.next();
if(!alive_this_round.contains(pid)) {
iter.remove(); // remove element from the iterator to avoid ConcurrentModificationException
// Remove the new vDNS from the set of vDNS servers
String script = new String("bash /opt/FDserver/remove_dns.sh " + pid);
Runtime.getRuntime().exec(script);
if(DEBUG) System.out.println("Removing process " + pid + " from the list of DNSs");
}
}
Thread.currentThread().sleep(TIMEOUT);
}
}
}
|
