Detect broken connections when they occur with a thread that wakes up every 2 seconds

src/gameloop/LocalGameLoop.java

@@ -105,6 +105,29 @@ public class LocalGameLoop extends Thread{
         LOGGER.info("Released relayer");
     }
 
+
+    /**
+     * a separate thread which will verify periodically whether the network connection is still alive
+     * wakes up every 2 seconds, thus it is not a performance issue
+     */
+    private Runnable BrokenConnectionVerifier=new Runnable() {
+        @Override
+        public void run() {
+            while (true) {
+                if (LocalGameLoop.getInstance().isPlaying) {
+                    //System.out.println("Broken Connection verifier!");
+                    if (getNetworkConnection().isBroken())
+                        GameStarter.initiateBrokenConnectionMeasures();
+                }
+                try {
+                    sleep(2000);
+                } catch (InterruptedException e) {
+                    e.printStackTrace();
+                }
+            }
+        }
+    };
+
     public synchronized boolean getIsPlaying()
     {
         return isPlaying;
@@ -132,6 +155,8 @@ public class LocalGameLoop extends Thread{
 
     @Override
     public void run() {
+        //start the thread which verifies if the connection is still alive
+        (new Thread(BrokenConnectionVerifier)).start();
         LOGGER.info("LocalGameLoop Thread started+"+currentThread().getId());
         while (true) {
             //System.out.println("DummyLocalGameLoopThread, game is "+isPlaying);
@@ -183,14 +208,11 @@ public class LocalGameLoop extends Thread{
     /**
      * Entities, relayers and objects related to the GameContent should not have a direct reference to the network connection
      * this is why I insert here a sendEvent method
+     * it is inefficient to test whether the connection is alive here
      */
     public void sendEvent(NetworkObject event)
     {
-        if (getNetworkConnection().isBroken())
-            GameStarter.initiateBrokenConnectionMeasures();
-        else {
-            getNetworkConnection().sendEvent(event);
-        }
+        getNetworkConnection().sendEvent(event);
     }
 
     /**

src/network/inner_shell/ClientConnection.java

@@ -44,7 +44,8 @@ public class ClientConnection extends NetworkConnection{
     /**
      * Send an event to the server.
      * The event is written on the socket.
-     * Still to be implemented - throwing exceptions when the connection is not open
+     * Exceptions are not implemented per se, they are included into isBroken(), which can be tested before trying to read
+     * or write(but that is not efficient)
      * @param e the event to send; e has to be serializable and not empty
      */
     @Override

src/network/inner_shell/NetworkConnection.java

@@ -94,7 +94,11 @@ public abstract class NetworkConnection {
         }
     }
 
-    //public visibility
+    /**
+     * tests whether a thread encountered a problem and updated the flag of the connection as broken
+     * actively tests if the connection is not broken now
+     * @return a boolean representing whether the connection is broken or not
+     */
     public boolean isBroken() {
         //attempt to send a test event first
         //must not be sunchronized because broken might need to be updated when we attempt to send a test event
@@ -104,6 +108,16 @@ public abstract class NetworkConnection {
         return broken;
     }
 
+    /**
+     * like isBroken(), but does not do an active test and just looks at whether a thread encountered a problem
+     * this could be an alternative to using isBroken and the timer
+     * by calling this every time before sending or receiving an event
+     * @return a boolean with the value of broken
+     */
+    public boolean isSoftBroken(){
+        return broken;
+    }
+
     //package visibility
     synchronized void setBroken(boolean broken) {
         this.broken = broken;