periodically attempt to contact dead members

src/main/java/org/apache/gossip/manager/ActiveGossipThread.java

@@ -45,7 +45,13 @@ abstract public class ActiveGossipThread implements Runnable {
     while (keepRunning.get()) {
       try {
         TimeUnit.MILLISECONDS.sleep(gossipManager.getSettings().getGossipInterval());
+        
+        // contact a live member.
         sendMembershipList(gossipManager.getMyself(), gossipManager.getLiveMembers());
+        
+        // contact a dead member.
+        sendMembershipList(gossipManager.getMyself(), gossipManager.getDeadMembers());
+        
       } catch (InterruptedException e) {
         GossipService.LOGGER.error(e);
         keepRunning.set(false);

src/main/java/org/apache/gossip/manager/GossipCore.java

@@ -131,7 +131,7 @@ public class GossipCore {
     if (t == null){
       return null;
     }
-    Future<Response> response = service.submit( new Callable<Response>(){
+    final Future<Response> response = service.submit( new Callable<Response>(){
       @Override
       public Response call() throws Exception {
         while(true){
@@ -156,7 +156,8 @@ public class GossipCore {
       LOGGER.error(e.getMessage(), e);
       return null;
     } catch (TimeoutException e) {
-      LOGGER.error(e.getMessage(), e);
+      boolean cancelled = response.cancel(true);
+      LOGGER.error(String.format("Threadpool timeout attempting to contact %s, cancelled ? %b", uri.toString(), cancelled));
       return null; 
     } finally {
       if (t != null){

src/main/java/org/apache/gossip/manager/GossipManager.java

@@ -132,6 +132,21 @@ public abstract class GossipManager extends Thread implements NotificationListen
     return settings;
   }
 
+  // TODO: Use some java 8 goodness for these functions.
+  
+  /**
+   * @return a read only list of members found in the DOWN state.
+   */
+  public List<LocalGossipMember> getDeadMembers() {
+    List<LocalGossipMember> down = new ArrayList<>();
+    for (Entry<LocalGossipMember, GossipState> entry : members.entrySet()) {
+      if (GossipState.DOWN.equals(entry.getValue())) {
+        down.add(entry.getKey());
+      }
+    }
+    return Collections.unmodifiableList(down);
+  }
+
   /**
    * 
    * @return a read only list of members found in the UP state

src/main/java/org/apache/gossip/manager/random/RandomActiveGossipThread.java

@@ -71,12 +71,16 @@ public class RandomActiveGossipThread extends ActiveGossipThread {
   }
 
   protected void sendMembershipList(LocalGossipMember me, List<LocalGossipMember> memberList) {
-    GossipService.LOGGER.debug("Send sendMembershipList() is called.");
+    
     me.setHeartbeat(System.currentTimeMillis());
     LocalGossipMember member = selectPartner(memberList);
     if (member == null) {
+      GossipService.LOGGER.debug("Send sendMembershipList() is called without action");
       return;
+    } else {
+      GossipService.LOGGER.debug("Send sendMembershipList() is called to " + member.toString());
     }
+    
     try (DatagramSocket socket = new DatagramSocket()) {
       socket.setSoTimeout(gossipManager.getSettings().getGossipInterval());
       UdpActiveGossipMessage message = new UdpActiveGossipMessage();