code cleanup & walkthrough

also removing Retryable and renaming ZeppelinhubConnection

zeppelin-zengine/src/main/java/org/apache/zeppelin/notebook/repo/zeppelinhub/ZeppelinHubRepo.java

@@ -38,7 +38,6 @@ import com.google.gson.reflect.TypeToken;
 /**
  * ZeppelinHub repo class.
  */
-
 public class ZeppelinHubRepo implements NotebookRepo {
   private static final Logger LOG = LoggerFactory.getLogger(ZeppelinhubRestApiHandler.class);
   private static final String DEFAULT_SERVER = "https://www.zeppelinhub.com";

zeppelin-zengine/src/main/java/org/apache/zeppelin/notebook/repo/zeppelinhub/websocket/Client.java

@@ -50,9 +50,9 @@ public class Client {
   public void start() {
     if (zeppelinhubClient != null) {
       zeppelinhubClient.start();
-      if (zeppelinClient != null) {
-        zeppelinClient.start();
-      }
+    }
+    if (zeppelinClient != null) {
+      zeppelinClient.start();
     }
   }
 
@@ -65,7 +65,7 @@ public class Client {
     }
   }
 
-  public void relayToHub(String message) {
+  public void relayToZeppelinHub(String message) {
     zeppelinhubClient.send(message);
   }
 

zeppelin-zengine/src/main/java/org/apache/zeppelin/notebook/repo/zeppelinhub/websocket/ZeppelinClient.java

@@ -197,7 +197,7 @@ public class ZeppelinClient {
       LOG.warn("Client isn't initialized yet");
       return;
     }
-    client.relayToHub(hubMsg.serialize());
+    client.relayToZeppelinHub(hubMsg.serialize());
   }
 
   /**

zeppelin-zengine/src/main/java/org/apache/zeppelin/notebook/repo/zeppelinhub/websocket/ZeppelinhubClient.java

@@ -189,9 +189,6 @@ public class ZeppelinhubClient {
         case RUN_NOTEBOOK:
           runAllParagraph(hubMsg.meta.get("noteId"), msg);
           break;
-        case PONG:
-          // do nothing
-          break;
         default:
           LOG.warn("Received {} from ZeppelinHub, not handled", op);
           break;

zeppelin-zengine/src/main/java/org/apache/zeppelin/notebook/repo/zeppelinhub/websocket/listener/ZeppelinhubWebsocket.java

@@ -63,7 +63,6 @@ public class ZeppelinhubWebsocket implements WebSocketListener {
 
   @Override
   public void onWebSocketText(String message) {
-    LOG.info("Got msg {}", message);
     // handle message from ZeppelinHub.
     ZeppelinhubClient client = ZeppelinhubClient.getInstance();
     if (client != null) {

zeppelin-zengine/src/main/java/org/apache/zeppelin/notebook/repo/zeppelinhub/websocket/scheduler/Retryable.java

@@ -1,68 +0,0 @@
-/*
- * 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.zeppelin.notebook.repo.zeppelinhub.websocket.scheduler;
-
-import org.slf4j.Logger;
-import org.slf4j.LoggerFactory;
-
-/**
- * todo: add description.
- * 
- * @author anthonyc
- *
- */
-abstract class Retryable {
-  private static final Logger LOG = LoggerFactory.getLogger(Retryable.class);
-  protected abstract void attempt() throws Exception;
-
-  /*
-   * @delay: initial delay (ms)
-   * 
-   * @interval: interval between re-trials (ms)
-   * 
-   * @timeout: timeout after which re-trials are aborted (ms)
-   */
-  public void execute(long delay, long interval, long timeout) throws Exception {
-    long start = System.currentTimeMillis();
-    if (delay > 0L) {
-      sleep(delay);
-    }
-    while (true) {
-      try {
-        attempt();
-        return;
-      } catch (Exception e) {
-        if (System.currentTimeMillis() - start < timeout) {
-          LOG.info("Retrying in " + interval + " ms");
-          sleep(interval);
-          // continue
-        } else {
-          throw e;
-        }
-      }
-    }
-  }
-
-  private void sleep(long millis) {
-    try {
-      Thread.sleep(millis);
-    } catch (InterruptedException interruptedException) {
-      // continue
-    }
-  }
-
-}