private void updatePredecessor() {
// Initialise socket and read/write
try {
socket = new Socket(neighbours.getPrePreIp(), 4017); // speaking to pre-predecessor
sender = new PrintWriter(socket.getOutputStream(), true);
receiver = new BufferedReader(new InputStreamReader(socket.getInputStream()));
} catch (UnknownHostException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
// Ask for his predecessor
sender.println(protocol.getPredecessorQuery());
// Listen for his predecessor - assuming that he is alive
String response = null;
try {
response = receiver.readLine();
} catch (IOException e) {
e.printStackTrace();
}
// If correct reply, update predecessor
if (response.contains(protocol.getPredecessorResponse())) {
// Assign pre-predecessor to predecessor
neighbours.setPreId(neighbours.getPrePreId());
neighbours.setPreIp(neighbours.getPrePreIp());
// Assign pre-pre-predecessor to pre-predecessor
int whiteSpace1 = response.indexOf(" ");
String usefulResponse = response.substring(whiteSpace1 + 1, response.length());
int whiteSpace2 = usefulResponse.indexOf(" ");
neighbours.setPrePreId(usefulResponse.substring(0, whiteSpace2));
neighbours.setPrePreIp(usefulResponse.substring(whiteSpace2 + 1, usefulResponse.length()));
}
// Close socket and read/write
try {
receiver.close();
sender.close();
socket.close();
} catch (IOException e) {
e.printStackTrace();
}
}
public void run() {
boolean flag = true;
while (flag) {
if (!isAlive(neighbours.getPreIp())) // Predecessor
updatePredecessor();
if (!isAlive(neighbours.getPrePreIp())) // PrePredecessor
updatePrePredecessor();
if (!isAlive(neighbours.getSucIp())) // Successor
updateSuccessor();
}
}