package org.apidesign.deadlock.startuplock;

 import java.io.DataOutputStream;

 import java.io.File;

 import java.io.FileOutputStream;

 import java.io.IOException;

 import java.net.ServerSocket;

 public final class CLIHandler {

     // BEGIN: cli.vision

     public static int start(File lockFile) throws IOException {

         if (lockFile.exists ()) {

             // read the port number and connect to it

             int alive = readPortNumber(lockFile);

             if (alive != -1) {

                 // exit

                 return alive;

             }

         }

         // otherwise try to create the file yourself

         lockFile.createNewFile();

         DataOutputStream os = new DataOutputStream(

             new FileOutputStream(lockFile)

         );

         ServerSocket server = new ServerSocket();

         int p = server.getLocalPort();

         os.writeInt(p);

         return p;

     }

     // END: cli.vision

     private static int readPortNumber(File lockFile) throws IOException {

         return -1;

     }

 }