There are 2 backend machines which will provide the same content. I'm trying to create a round-robin setup and fail-safe so that if one goes down, the request should be sent to other.
As for the round-robin thing, my code is working fine.
For the fail-safe thing, I'm trying to change one IP to some invalid ip (on which no service is running) and then it should connect to other. But it is getting hung up on the line:
client = new Socket(ip, port);
What can be done for this? If I'm not getting connection in 2 seconds, I don't want to retry (if that is what java does, can I reduce the retry timeout?).
Also, after long time, it throws IllegalStateException (I was not expecting it at all)
Here is my constructor for Connect.java:
//Variable declartion
private static int balancer = 0;
private static boolean[] down = {false, false};
private static int[] countDown = {0, 0};
private static final int maxRequests = 10000;
private static int countRequests = 0;
//Constructor
public Connect() throws NullPointerException{
int use = balancer;
int flag = 0;
countRequests = (countRequests + 1) % maxRequests;
if(countRequests == 0){
down[0] = down[1] = false;
}
if((balancer == 0 && down[0] == false) || down[1] == true){
ip = Config.IP1;
port = Config.PORT1;
use = 0;
System.out.println("balancer = 0");
}
else{
ip = Config.IP2;
port = Config.PORT2;
use = 1;
System.out.println("balancer = 1");
}
LOGGER.setLevel(Level.INFO);
// Single simple socket
try {
client = new Socket(ip, port);
System.out.println("client");
dos = new DataOutputStream(client.getOutputStream());
dis = new DataInputStream(client.getInputStream());
if(client == null || dos == null || dis == null){
throw new IOException("Connection could not be opened properly\n");
}
LOGGER.log(Level.INFO, "Connection to : " + ip + " Successfully opened");
balancer = (balancer == 0) ? 1 : 0;
countDown[use] = 0;
flag = 1;
} catch (IOException e) {
// TODO Auto-generated catch block
//e.printStackTrace();
countDown[use] ++;
if(countDown[use] >= 3){
down[use] = true;
}
LOGGER.log(Level.SEVERE, ": " + ip + " " + e.getMessage());
}
finally{ //if connection was not opened on first
if(flag == 0){
if(use == 0){
ip = Config.IP2;
port = Config.PORT2;
use = 1;
}
else{
ip = Config.IP1;
port = Config.PORT1;
use = 0;
}
try {
client = new Socket(ip, port);
dos = new DataOutputStream(client.getOutputStream());
dis = new DataInputStream(client.getInputStream());
if(client == null || dos == null || dis == null){
throw new IOException("Connection could not be opened properly\n");
}
LOGGER.log(Level.INFO, "Connection to " + ip + " Successfully opened");
balancer = (balancer == 0) ? 1 : 0;
countDown[use] = 0;
flag = 1;
} catch (IOException e) {
// TODO Auto-generated catch block
//e.printStackTrace();
countDown[use] ++;
if(countDown[use] >= 3){
down[use] = true;
}
LOGGER.log(Level.SEVERE, ": " + ip + " " + e.getMessage());
throw new NullPointerException("Connection could not be opened properly on both machines\n");
}
}
}
}
What I expected was an IO/NullPointer-Exception and then catch block will be executed
