source: src/main/java/geniusweb/partiesserver/websocket/ActiveThreads.java@ 30

package geniusweb.partiesserver.websocket;

import java.util.LinkedList;
import java.util.List;
import java.util.logging.Level;

import tudelft.utilities.logging.Reporter;

/**
 * Keeps track of threads active for a PartySocket. Needed so that we can kill
 * all relevant threads when it comes to forced termination.
 */
public class ActiveThreads {
        private final List<Thread> threads = new LinkedList<>();
        private final Reporter log;

        public ActiveThreads(Reporter log) {
                this.log = log;
        }

        /**
         * Add the current thread as active thread
         */
        public synchronized void add() {
                threads.add(Thread.currentThread());
        }

        /**
         * Remove the current thread as active thread. To be called when thread
         * finished nicely.
         */
        public synchronized void remove() {
                threads.remove(Thread.currentThread());

        }

        /**
         * 
         * @return true if no threads currently running.
         */
        public synchronized boolean isEmpty() {
                return threads.isEmpty();
        }

        @SuppressWarnings("deprecation")
        public synchronized void killall() {

                /*
                 * The method stop(Throwable) does not work anymore. we need to call
                 * stop() which will result in nonsense stacktrace pointing to US
                 * instead of the real problem. Only solution is to print stacktrace
                 * ourselves.
                 */
                for (Thread thread : threads) {
                        String stacktrace = "";
                        for (StackTraceElement element : thread.getStackTrace()) {
                                stacktrace += "\t" + element.toString() + "\n";
                        }

                        /* the most powerful kill, deprecated but required here. */
                        try {
                                thread.stop();
                                log.log(Level.INFO,
                                                "Killed thread with stack trace\n" + stacktrace);
                        } catch (ThreadDeath e) {
                                System.out.println("Noticed thread already was stopped.");
                        }
                }
                threads.clear();
        }
}