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import java.net.InetAddress;
import java.net.UnknownHostException;
import java.net.ServerSocket;
import java.net.Socket;
import java.io.IOException;
import java.util.ArrayList;
import java.util.HashSet;
import java.util.concurrent.ThreadLocalRandom;
import java.util.concurrent.Semaphore;
import java.io.OutputStream;
import java.io.ObjectInputStream;
import java.io.InputStream;
class NodeAddr {
public int port;
public InetAddress addr;
public NodeAddr(String addr, int port) throws UnknownHostException {
this.port = port;
this.addr = InetAddress.getByName(addr);
}
public NodeAddr(String fulladdr) throws UnknownHostException {
String fields[] = fulladdr.split(":");
this.port = Integer.parseInt(fields[1]);
this.addr = InetAddress.getByName(fields[0]);
}
}
public class Node {
private NodeAddr bind;
private ArrayList<NodeAddr> neighbors;
private HashSet<String> seenMsgs;
private Semaphore lock;
public String name;
public Node(String bind, String name) throws UnknownHostException {
this.bind = new NodeAddr(bind);
this.neighbors = new ArrayList<>();
this.name = name;
this.seenMsgs = new HashSet<>();
this.lock = new Semaphore(1);
}
public void addNeighbor(String addr) throws UnknownHostException {
this.neighbors.add(new NodeAddr(addr));
}
public void start() throws IOException {
ServerSocket socket = null;
try {
socket = new ServerSocket(this.bind.port, 50, this.bind.addr);
while (true) {
Socket conn = socket.accept();
Handler h = new Handler(conn, this);
h.start();
}
} finally {
if (socket != null) {
socket.close();
}
}
}
public void sendMsgLocal(Message msg) throws Exception {
// Kind of hacky but thats how we do it
msg.id = ThreadLocalRandom.current().nextInt();
if (!this.checkMsg(msg)) {
this.sendMsg(msg);
}
}
private boolean checkMsg(Message msg) throws InterruptedException {
String msgid = String.format("%s%d", msg.from, msg.id);
this.lock.acquire();
if (this.seenMsgs.contains(msgid)) {
this.lock.release();
return true;
}
this.seenMsgs.add(msgid);
this.lock.release();
return false;
}
private void sendMsg(Message msg) throws Exception {
for (NodeAddr n : this.neighbors) {
Socket conn = null;
OutputStream out = null;
try {
conn = new Socket(n.addr, n.port);
out = conn.getOutputStream();
msg.send(out);
} finally {
if (conn != null) {
conn.close();
}
if (out != null) {
out.close();
}
}
}
}
public void handleMsg(Message msg) throws Exception {
if (this.checkMsg(msg)) {
return;
}
if (!msg.to.equals(this.name)) {
msg.trace(this.name);
// Forward
this.sendMsg(msg);
if (!msg.to.equals("")) {
return;
}
}
msg.handle(this);
}
}
class Handler extends Thread {
private Socket conn;
private Node node;
public Handler(Socket conn, Node node) {
this.conn = conn;
this.node = node;
}
public void run() {
InputStream in = null;
ObjectInputStream objin = null;
try {
in = this.conn.getInputStream();
objin = new ObjectInputStream(in);
Object obj = objin.readObject();
if (!(obj instanceof Message)) {
throw new Exception("Received object is not a message");
}
this.node.handleMsg((Message) obj);
} catch (Exception e) {
System.err.printf("Client err: %s%n", e);
}
}
}
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