GOSSIP-25 Create reaper process to expire per-node data

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

@@ -0,0 +1,8 @@
+package org.apache.gossip.manager;
+
+public interface Clock {
+
+  long currentTimeMillis();
+  long nanoTime();
+  
+}

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

@@ -0,0 +1,58 @@
+package org.apache.gossip.manager;
+
+import java.util.Map.Entry;
+import java.util.concurrent.ConcurrentHashMap;
+import java.util.concurrent.Executors;
+import java.util.concurrent.ScheduledExecutorService;
+import java.util.concurrent.TimeUnit;
+
+import org.apache.gossip.model.GossipDataMessage;
+
+/**
+ * We wish to periodically sweep user data and remove entries past their timestamp. This
+ * implementation periodically sweeps through the data and removes old entries. While it might make
+ * sense to use a more specific high performance data-structure to handle eviction, keep in mind
+ * that we are not looking to store a large quantity of data as we currently have to transmit this
+ * data cluster wide.
+ */
+public class DataReaper {
+
+  private final GossipCore gossipCore;
+  private final ScheduledExecutorService scheduledExecutor = Executors.newScheduledThreadPool(1);
+  private final Clock clock;
+  
+  public DataReaper(GossipCore gossipCore, Clock clock){
+    this.gossipCore = gossipCore;
+    this.clock = clock;
+  }
+  
+  public void init(){
+    Runnable reapPerNodeData = () -> {
+      runOnce();
+    };
+    scheduledExecutor.scheduleAtFixedRate(reapPerNodeData, 0, 5, TimeUnit.SECONDS);
+  }
+  
+  void runOnce(){
+    for (Entry<String, ConcurrentHashMap<String, GossipDataMessage>> node : gossipCore.getPerNodeData().entrySet()){
+      reapData(node.getValue());
+    }
+  }
+  
+  void reapData(ConcurrentHashMap<String, GossipDataMessage> concurrentHashMap){
+    for (Entry<String, GossipDataMessage> entry : concurrentHashMap.entrySet()){
+      if (entry.getValue().getExpireAt() < clock.currentTimeMillis()){
+        concurrentHashMap.remove(entry.getKey(), entry.getValue());
+      }
+    }
+  }
+  
+  public void close(){
+    scheduledExecutor.shutdown();
+    try {
+      scheduledExecutor.awaitTermination(5, TimeUnit.SECONDS);
+    } catch (InterruptedException e) {
+      
+    }
+  }
+}

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

@@ -47,16 +47,21 @@ public class GossipCore {
     perNodeData = new ConcurrentHashMap<>();
   }
   
-  /**
-   *  
-   * @param message
-   */
+
   public void addPerNodeData(GossipDataMessage message){
-    ConcurrentHashMap<String,GossipDataMessage> m = new ConcurrentHashMap<>();
-    m.put(message.getKey(), message);
-    m = perNodeData.putIfAbsent(message.getNodeId(), m);
-    if (m != null){
-      m.put(message.getKey(), message);    //TODO only put if > ts
+    ConcurrentHashMap<String,GossipDataMessage> nodeMap = new ConcurrentHashMap<>();
+    nodeMap.put(message.getKey(), message);
+    nodeMap = perNodeData.putIfAbsent(message.getNodeId(), nodeMap);
+    if (nodeMap != null){
+      //m.put(message.getKey(), message);    //TODO only put if > ts
+      GossipDataMessage current = nodeMap.get(message.getKey());
+      if (current == null){
+        nodeMap.replace(message.getKey(), null, message);
+      } else {
+        if (current.getTimestamp() < message.getTimestamp()){
+          nodeMap.replace(message.getKey(), current, message);
+        }
+      }
     }
   }
   

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

@@ -22,6 +22,7 @@ import java.util.ArrayList;
 import java.util.Collections;
 import java.util.List;
 import java.util.Map.Entry;
+import java.util.Objects;
 import java.util.concurrent.ConcurrentHashMap;
 import java.util.concurrent.ConcurrentSkipListMap;
 import java.util.concurrent.ExecutorService;
@@ -67,14 +68,20 @@ public abstract class GossipManager implements NotificationListener {
 
   private ExecutorService gossipThreadExecutor;
   
-  private GossipCore gossipCore;
+  private final GossipCore gossipCore;
+  
+  private final DataReaper dataReaper;
+  
+  private final Clock clock;
 
   public GossipManager(String cluster,
           URI uri, String id, GossipSettings settings,
           List<GossipMember> gossipMembers, GossipListener listener) {
     
     this.settings = settings;
-    this.gossipCore = new GossipCore(this);
+    gossipCore = new GossipCore(this);
+    clock = new SystemClock();
+    dataReaper = new DataReaper(gossipCore, clock);
     me = new LocalGossipMember(cluster, uri, id, System.currentTimeMillis(), this,
             settings.getCleanupInterval());
     members = new ConcurrentSkipListMap<>();
@@ -192,6 +199,7 @@ public abstract class GossipManager implements NotificationListener {
     gossipThreadExecutor.execute(passiveGossipThread);
     activeGossipThread = new ActiveGossipThread(this, this.gossipCore);
     activeGossipThread.init();
+    dataReaper.init();
     GossipService.LOGGER.debug("The GossipService is started.");
   }
 
@@ -202,6 +210,7 @@ public abstract class GossipManager implements NotificationListener {
     gossipServiceRunning.set(false);
     gossipThreadExecutor.shutdown();
     gossipCore.shutdown();
+    dataReaper.close();
     if (passiveGossipThread != null) {
       passiveGossipThread.shutdown();
     }
@@ -218,7 +227,10 @@ public abstract class GossipManager implements NotificationListener {
     }
   }
   
-  public void gossipData(GossipDataMessage message){
+  public void gossipPerNodeData(GossipDataMessage message){
+    Objects.nonNull(message.getKey());
+    Objects.nonNull(message.getTimestamp());
+    Objects.nonNull(message.getPayload());
     message.setNodeId(me.getId());
     gossipCore.addPerNodeData(message);
   }
@@ -228,8 +240,19 @@ public abstract class GossipManager implements NotificationListener {
     if (j == null){
       return null;
     } else {
-      return j.get(key);
+      GossipDataMessage l = j.get(key);
+      if (l == null){
+        return null;
+      }
+      if (l.getExpireAt() != null && l.getExpireAt() < clock.currentTimeMillis()) {
+        return null;
+      }
+      return l;
     }
   }
+
+  public DataReaper getDataReaper() {
+    return dataReaper;
+  }
             
 }

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

@@ -23,15 +23,11 @@ import java.net.DatagramSocket;
 import java.net.InetSocketAddress;
 import java.net.SocketAddress;
 import java.net.SocketException;
-import java.util.List;
 import java.util.concurrent.atomic.AtomicBoolean;
 
-import org.apache.gossip.GossipMember;
-import org.apache.gossip.GossipService;
 import org.apache.gossip.model.Base;
 import org.apache.log4j.Logger;
 import org.codehaus.jackson.map.ObjectMapper;
-import org.apache.gossip.RemoteGossipMember;
 
 /**
  * [The passive thread: reply to incoming gossip request.] This class handles the passive cycle,
@@ -107,9 +103,9 @@ abstract public class PassiveGossipThread implements Runnable {
   }
 
   private void debug(int packetLength, byte[] jsonBytes) {
-    if (GossipService.LOGGER.isDebugEnabled()){
+    if (LOGGER.isDebugEnabled()){
       String receivedMessage = new String(jsonBytes);
-      GossipService.LOGGER.debug("Received message (" + packetLength + " bytes): "
+      LOGGER.debug("Received message (" + packetLength + " bytes): "
             + receivedMessage);
     }
   }

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

@@ -0,0 +1,15 @@
+package org.apache.gossip.manager;
+
+public class SystemClock implements Clock {
+
+  @Override
+  public long currentTimeMillis() {
+    return System.currentTimeMillis();
+  }
+
+  @Override
+  public long nanoTime() {
+    return System.nanoTime();
+  }
+
+}