[GitHub] [incubator-livy] yiheng commented on a change in pull request #276: [LIVY-723] Server Registration

[GitBox <gi...@apache.org>]

yiheng commented on a change in pull request #276: [LIVY-723] Server Registration
URL: https://github.com/apache/incubator-livy/pull/276#discussion_r391523456
 
 

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 File path: server/src/main/scala/org/apache/livy/cluster/ZKClusterManager.scala
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+/*
+ * 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.livy.cluster
+
+import java.util.UUID
+
+import scala.collection.mutable
+import scala.collection.mutable.{ArrayBuffer, Set}
+
+import org.apache.livy.rsc.RSCConf.Entry.LAUNCHER_ADDRESS
+import org.apache.livy.LivyConf.{SERVER_PORT, ZK_SERVICE_DIR}
+import org.apache.livy.LivyConf
+import org.apache.livy.Logging
+import org.apache.livy.server.recovery.ZooKeeperManager
+
+class ZKClusterManager(livyConf: LivyConf, zkManager: ZooKeeperManager)
+  extends ClusterManager with Logging {
+  private val serverIP = livyConf.get(LAUNCHER_ADDRESS)
+  require(serverIP != null, "Please config the livy.rsc.launcher.address")
+
+  private val port = livyConf.getInt(SERVER_PORT)
+  private val serviceDir = livyConf.get(ZK_SERVICE_DIR)
+
+  private val nodes = new mutable.HashSet[ServiceNode]()
+  private val nodeJoinListeners = new ArrayBuffer[ServiceNode => Unit]()
+  private val nodeLeaveListeners = new ArrayBuffer[ServiceNode => Unit]()
+
+  zkManager.getChildren(serviceDir).foreach(node => {
+    val serviceNode = zkManager.get[ServiceNode](serviceDir + "/" + node).get
+    nodes.add(serviceNode)
+  })
+
+  // Start listening
+  zkManager.watchAddNode(serviceDir, nodeAddHandler)
+  zkManager.watchRemoveNode(serviceDir, nodeRemoveHandler)
+
+  override def register(): Unit = {
+    val node = ServiceNode(serverIP, port, UUID.randomUUID().toString)
+    zkManager.createEphemeralNode(serviceDir + "/" + serverIP + ":" + port, node)
+  }
+
+  override def getNodes(): Set[ServiceNode] = {
+    nodes
+  }
+
+  override def registerNodeJoinListener(listener: ServiceNode => Unit): Unit = {
+    nodeJoinListeners.append(listener)
+  }
+
+  override def registerNodeLeaveListener(listener : ServiceNode => Unit): Unit = {
+    nodeLeaveListeners.append(listener)
+  }
+
+  private def nodeAddHandler(path: String, node: ServiceNode): Unit = {
+    logger.info("Detect new node join: " + node)
+    nodes.add(node)
+    nodeJoinListeners.foreach(_(node))
+  }
+
+  private def nodeRemoveHandler(path: String, node: ServiceNode): Unit = {
+    logger.info("Detect node leave: " + node)
+    nodes.remove(node)
+    nodeLeaveListeners.foreach(_(node))
 
 Review comment:
   Here we notify all registered listeners on the server. The listenser may take action based on the node join/leave event.

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