private boolean isAlive(String IPadr) {
String responseFromNode = null;
boolean result = true;
// Initialise socket and read/write
try {
socket = new Socket(IPadr, 4017);
sender = new PrintWriter(socket.getOutputStream(), true);
receiver = new BufferedReader(new InputStreamReader(socket.getInputStream()));
} catch (UnknownHostException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
// Ask the node if it is alive
sender.println(protocol.checkAliveQuery());
// Listen for a reply for timeoutDuration seconds
long startTime = System.currentTimeMillis();
long timeout = startTime + timeoutDuration;
while (System.currentTimeMillis() < timeout) {
try // will it wait here?
{
responseFromNode = receiver.readLine();
} catch (IOException e) {
e.printStackTrace();
}
// Break if the node answered
if (responseFromNode != null) break;
}
// Evaluate node reply
if (responseFromNode == null) result = false;
else if (responseFromNode == protocol.checkAliveResponse()) result = true;
// Close socket and read/write
try {
receiver.close();
sender.close();
socket.close();
} catch (IOException e) {
e.printStackTrace();
}
return result;
}
private void updateSuccessor() {
// Initialise socket and read/write
try {
socket = new Socket(neighbours.getSucSucIp(), 4017); // speaking to suc-successor
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 successor
sender.println(protocol.getSuccessorQuery());
// Listen for his successor
String response = null;
try {
response = receiver.readLine();
} catch (IOException e) {
e.printStackTrace();
}
// If correct reply, update
if (response.contains(protocol.getSuccessorResponse())) {
// Assign suc-successor to successor
neighbours.setSucId(neighbours.getSucSucId());
neighbours.setSucIp(neighbours.getSucSucIp());
// Assign sucsuccessor's sucessor to the sucsuccessor
int firstWhiteSpace = response.indexOf(" ");
String usefulResponse = response.substring(firstWhiteSpace + 1, response.length());
int secondWhiteSpace = usefulResponse.indexOf(" ");
neighbours.setSucSucId(usefulResponse.substring(0, secondWhiteSpace));
neighbours.setSucSucIp(
usefulResponse.substring(secondWhiteSpace + 1, usefulResponse.length()));
}
// Close socket and read/write
try {
receiver.close();
sender.close();
socket.close();
} catch (IOException e) {
e.printStackTrace();
}
}
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();
}
}