GOSSIP-36 Persist ring state

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

@@ -0,0 +1,111 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */ 
+package org.apache.gossip.manager;
+
+import java.io.File;
+import java.io.FileInputStream;
+import java.io.FileOutputStream;
+import java.io.IOException;
+import java.util.concurrent.ConcurrentHashMap;
+
+import org.apache.gossip.model.GossipDataMessage;
+import org.apache.gossip.model.SharedGossipDataMessage;
+import org.apache.log4j.Logger;
+
+import com.fasterxml.jackson.databind.ObjectMapper;
+
+public class UserDataPersister implements Runnable {
+  
+  private static final Logger LOGGER = Logger.getLogger(UserDataPersister.class);
+  private static final ObjectMapper MAPPER = new ObjectMapper();
+  private final GossipManager parent;
+  private final GossipCore gossipCore; 
+  
+  UserDataPersister(GossipManager parent, GossipCore gossipCore){
+    this.parent = parent;
+    this.gossipCore = gossipCore;
+    MAPPER.enableDefaultTyping();
+  }
+  
+  File computeSharedTarget(){
+    return new File(parent.getSettings().getPathToDataState(), "shareddata."
+            + parent.getMyself().getClusterName() + "." + parent.getMyself().getId() + ".json");
+  }
+  
+  File computePerNodeTarget() {
+    return new File(parent.getSettings().getPathToDataState(), "pernodedata."
+            + parent.getMyself().getClusterName() + "." + parent.getMyself().getId() + ".json");
+  }
+  
+  @SuppressWarnings("unchecked")
+  ConcurrentHashMap<String, ConcurrentHashMap<String, GossipDataMessage>> readPerNodeFromDisk(){
+    if (!parent.getSettings().isPersistDataState()){
+      return new ConcurrentHashMap<String, ConcurrentHashMap<String, GossipDataMessage>>();
+    }
+    try (FileInputStream fos = new FileInputStream(computePerNodeTarget())){
+      return MAPPER.readValue(fos, ConcurrentHashMap.class);
+    } catch (IOException e) {
+      LOGGER.debug(e);
+    }
+    return new ConcurrentHashMap<String, ConcurrentHashMap<String, GossipDataMessage>>();
+  }
+  
+  void writePerNodeToDisk(){
+    if (!parent.getSettings().isPersistDataState()){
+      return;
+    }
+    try (FileOutputStream fos = new FileOutputStream(computePerNodeTarget())){
+      MAPPER.writeValue(fos, gossipCore.getPerNodeData());
+    } catch (IOException e) {
+      LOGGER.warn(e);
+    }
+  }
+  
+  void writeSharedToDisk(){
+    if (!parent.getSettings().isPersistDataState()){
+      return;
+    }
+    try (FileOutputStream fos = new FileOutputStream(computeSharedTarget())){
+      MAPPER.writeValue(fos, gossipCore.getSharedData());
+    } catch (IOException e) {
+      LOGGER.warn(e);
+    }
+  }
+
+  @SuppressWarnings("unchecked")
+  ConcurrentHashMap<String, SharedGossipDataMessage> readSharedDataFromDisk(){
+    if (!parent.getSettings().isPersistRingState()){
+      return new ConcurrentHashMap<String, SharedGossipDataMessage>();
+    }
+    try (FileInputStream fos = new FileInputStream(computeSharedTarget())){
+      return MAPPER.readValue(fos, ConcurrentHashMap.class);
+    } catch (IOException e) {
+      LOGGER.debug(e);
+    }
+    return new ConcurrentHashMap<String, SharedGossipDataMessage>();
+  }
+  
+  /**
+   * Writes all pernode and shared data to disk 
+   */
+  @Override
+  public void run() {
+    writePerNodeToDisk();
+    writeSharedToDisk();
+  }
+}