Java tutorial
/* * 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.hms.controller; import java.io.File; import java.io.IOException; import java.util.Collection; import java.util.prefs.Preferences; import org.apache.commons.configuration.HierarchicalINIConfiguration; import org.apache.commons.logging.Log; import org.apache.commons.logging.LogFactory; import org.apache.hms.common.conf.CommonConfigurationKeys; import org.apache.hms.common.util.DaemonWatcher; import org.apache.hms.common.util.ExceptionUtil; import org.apache.hms.common.util.MulticastDNS; import org.apache.hms.common.util.ServiceDiscoveryUtil; import org.apache.hms.controller.ClientHandler; import org.apache.hms.controller.CommandHandler; import org.apache.zookeeper.CreateMode; import org.apache.zookeeper.KeeperException; import org.apache.zookeeper.WatchedEvent; import org.apache.zookeeper.Watcher; import org.apache.zookeeper.ZooKeeper; import org.apache.zookeeper.ZooDefs.Ids; import org.mortbay.jetty.Server; import org.mortbay.jetty.servlet.Context; import org.mortbay.jetty.servlet.DefaultServlet; import org.mortbay.jetty.servlet.ServletHolder; import org.mortbay.resource.Resource; import org.mortbay.resource.ResourceCollection; import com.sun.jersey.spi.container.servlet.ServletContainer; public class Controller implements Watcher { private static Log LOG = LogFactory.getLog(Controller.class); public static String CONTROLLER_PREFIX = "v1"; public static int CONTROLLER_PORT = 4080; private static Controller instance = new Controller(); private Server server = null; private String credential = null; private ZooKeeper zk; private ClientHandler clientHandler; private CommandHandler commandHandler; public volatile boolean running = true; // true while controller runs private String zookeeperAddress = CommonConfigurationKeys.ZOOKEEPER_ADDRESS_DEFAULT; public static Controller getInstance() { return instance; } public ZooKeeper getZKInstance() { return this.zk; } public ClientHandler getClientHandler() { return clientHandler; } public CommandHandler getCommandHandler() { return commandHandler; } public void process(WatchedEvent event) { if (event.getType() == Event.EventType.None) { // We are are being told that the state of the // connection has changed switch (event.getState()) { case SyncConnected: // In this particular example we don't need to do anything // here - watches are automatically re-registered with // server and any watches triggered while the client was // disconnected will be delivered (in order of course) break; case Expired: // It's all over running = false; commandHandler.stop(); break; } } } public void parseConfig() { StringBuilder confPath = new StringBuilder(); String confDir = System.getProperty("HMS_CONF_DIR"); if (confDir == null) { confDir = "/etc/hms"; } confPath.append(confDir); confPath.append("/hms.ini"); try { HierarchicalINIConfiguration ini = new HierarchicalINIConfiguration(confPath.toString()); zookeeperAddress = ini.getSection("zookeeper").getString("quorum", null); String user = ini.getSection("zookeeper").getString("user", null); String password = ini.getSection("zookeeper").getString("password", null); if (user != null && password != null) { credential = new StringBuilder().append(user).append(":").append(password).toString(); } } catch (Exception e) { LOG.warn("Invalid HMS configuration file: " + confPath); zookeeperAddress = null; } LOG.info("ZooKeeper Quorum in " + confPath.toString() + ": " + zookeeperAddress); } // Resolve the list of zookeeper hosts from HMS beacons public void initmDNS() { try { ServiceDiscoveryUtil sdu = new ServiceDiscoveryUtil(CommonConfigurationKeys.ZEROCONF_ZOOKEEPER_TYPE); sdu.start(); Thread.sleep(5000); Collection<String> list = sdu.resolve(); if (list.size() > 0) { StringBuffer buf = new StringBuffer(); String delimiter = ""; for (String addr : list) { buf.append(delimiter); buf.append(addr); delimiter = ","; } zookeeperAddress = buf.toString(); } sdu.close(); if (zookeeperAddress.equals("")) { throw new RuntimeException("Unknown ZooKeeper location."); } LOG.info("Discovered zookeeper location: " + zookeeperAddress); } catch (Exception e) { zookeeperAddress = CommonConfigurationKeys.ZOOKEEPER_ADDRESS_DEFAULT; LOG.info("Use default zookeeper location: " + zookeeperAddress); } } public void start() { try { //System.out.close(); //System.err.close(); parseConfig(); if (zookeeperAddress == null) { initmDNS(); } run(); } catch (Exception e) { LOG.error(ExceptionUtil.getStackTrace(e)); System.exit(-1); } } private void createDirectory(String path) throws KeeperException, InterruptedException { try { zk.create(path, new byte[0], Ids.OPEN_ACL_UNSAFE, CreateMode.PERSISTENT); if (credential != null) { zk.setACL(path, Ids.CREATOR_ALL_ACL, -1); } LOG.info("Created HMS cluster root at " + CommonConfigurationKeys.ZOOKEEPER_CLUSTER_ROOT_DEFAULT); } catch (KeeperException.NodeExistsException e) { } catch (KeeperException.AuthFailedException e) { LOG.warn("Failed to authenticate for " + path); } } private void initializeZooKeeper() throws KeeperException, InterruptedException, IOException { zk = new ZooKeeper(zookeeperAddress, 600000, this); if (credential != null) { zk.addAuthInfo("digest", credential.getBytes()); } String[] list = { CommonConfigurationKeys.ZOOKEEPER_CLUSTER_ROOT_DEFAULT, CommonConfigurationKeys.ZOOKEEPER_COMMAND_QUEUE_PATH_DEFAULT, CommonConfigurationKeys.ZOOKEEPER_LOCK_QUEUE_PATH_DEFAULT, CommonConfigurationKeys.ZOOKEEPER_LIVE_CONTROLLER_PATH_DEFAULT, CommonConfigurationKeys.ZOOKEEPER_NODES_MANIFEST_PATH_DEFAULT, CommonConfigurationKeys.ZOOKEEPER_STATUS_QUEUE_PATH_DEFAULT, CommonConfigurationKeys.ZOOKEEPER_SOFTWARE_MANIFEST_PATH_DEFAULT, CommonConfigurationKeys.ZOOKEEPER_CONFIG_BLUEPRINT_PATH_DEFAULT }; for (String path : list) { createDirectory(path); } } public void run() { try { initializeZooKeeper(); LOG.info("Connected to ZooKeeper"); clientHandler = new ClientHandler(zk); commandHandler = new CommandHandler(zk, 200); commandHandler.start(); } catch (Exception e) { LOG.error(ExceptionUtil.getStackTrace(e)); } server = new Server(CONTROLLER_PORT); try { Context root = new Context(server, "/", Context.SESSIONS); String HMS_HOME = System.getenv("HMS_HOME"); root.setBaseResource( new ResourceCollection(new Resource[] { Resource.newResource(HMS_HOME + "/webapps/") })); ServletHolder rootServlet = root.addServlet(DefaultServlet.class, "/"); rootServlet.setInitOrder(1); ServletHolder sh = new ServletHolder(ServletContainer.class); sh.setInitParameter("com.sun.jersey.config.property.resourceConfigClass", "com.sun.jersey.api.core.PackagesResourceConfig"); sh.setInitParameter("com.sun.jersey.config.property.packages", "org.apache.hms.controller.rest"); root.addServlet(sh, "/" + CONTROLLER_PREFIX + "/*"); sh.setInitOrder(2); server.setStopAtShutdown(true); server.start(); } catch (Exception e) { LOG.error(ExceptionUtil.getStackTrace(e)); } } public void stop() throws Exception { try { commandHandler.stop(); server.stop(); } catch (Exception e) { LOG.error(ExceptionUtil.getStackTrace(e)); } } /** * Wait for service to finish. * (Normally, it runs forever.) */ public void join() { try { this.commandHandler.join(); } catch (InterruptedException ie) { } } public static void main(String[] args) { DaemonWatcher.createInstance(System.getProperty("PID"), 9100); try { Controller controller = Controller.getInstance(); if (controller != null) { controller.start(); controller.join(); } } catch (Throwable t) { DaemonWatcher.bailout(1); } } }