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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.
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package org.apache.hadoop.hbase.zookeeper;

import java.io.Closeable;
import java.io.IOException;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.concurrent.CopyOnWriteArrayList;
import java.util.concurrent.CountDownLatch;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.hadoop.hbase.classification.InterfaceAudience;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.hbase.Abortable;
import org.apache.hadoop.hbase.AuthUtil;
import org.apache.hadoop.hbase.HConstants;
import org.apache.hadoop.hbase.HRegionInfo;
import org.apache.hadoop.hbase.ZooKeeperConnectionException;
import org.apache.hadoop.hbase.classification.InterfaceAudience;
import org.apache.hadoop.hbase.security.Superusers;
import org.apache.hadoop.security.UserGroupInformation;
import org.apache.zookeeper.KeeperException;
import org.apache.zookeeper.WatchedEvent;
import org.apache.zookeeper.Watcher;
import org.apache.zookeeper.ZooDefs;
import org.apache.zookeeper.ZooDefs.Ids;
import org.apache.zookeeper.ZooDefs.Perms;
import org.apache.zookeeper.data.ACL;
import org.apache.zookeeper.data.Id;
import org.apache.zookeeper.data.Stat;

/**
 * Acts as the single ZooKeeper Watcher.  One instance of this is instantiated
 * for each Master, RegionServer, and client process.
 *
 * 

This is the only class that implements {@link Watcher}. Other internal * classes which need to be notified of ZooKeeper events must register with * the local instance of this watcher via {@link #registerListener}. * *

This class also holds and manages the connection to ZooKeeper. Code to * deal with connection related events and exceptions are handled here. */ @InterfaceAudience.Private public class ZooKeeperWatcher implements Watcher, Abortable, Closeable { private static final Log LOG = LogFactory.getLog(ZooKeeperWatcher.class); // Identifier for this watcher (for logging only). It is made of the prefix // passed on construction and the zookeeper sessionid. private String prefix; private String identifier; // zookeeper quorum private String quorum; // zookeeper connection private final RecoverableZooKeeper recoverableZooKeeper; // abortable in case of zk failure protected Abortable abortable; // Used if abortable is null private boolean aborted = false; // listeners to be notified private final List listeners = new CopyOnWriteArrayList(); // Used by ZKUtil:waitForZKConnectionIfAuthenticating to wait for SASL // negotiation to complete public CountDownLatch saslLatch = new CountDownLatch(1); // node names // base znode for this cluster public String baseZNode; //znodes containing the locations of the servers hosting the meta replicas private Map metaReplicaZnodes = new HashMap(); // znode containing ephemeral nodes of the regionservers public String rsZNode; // znode containing ephemeral nodes of the draining regionservers public String drainingZNode; // znode of currently active master private String masterAddressZNode; // znode of this master in backup master directory, if not the active master public String backupMasterAddressesZNode; // znode containing the current cluster state public String clusterStateZNode; // znode used for region transitioning and assignment public String assignmentZNode; // znode used for table disabling/enabling public String tableZNode; // znode containing the unique cluster ID public String clusterIdZNode; // znode used for log splitting work assignment public String splitLogZNode; // znode containing the state of the load balancer public String balancerZNode; // znode containing the state of region normalizer private String regionNormalizerZNode; // znode containing the state of all switches, currently there are split and merge child node. private String switchZNode; // znode containing the lock for the tables public String tableLockZNode; // znode containing the state of the snapshot auto-cleanup String snapshotCleanupZNode; // znode containing the state of recovering regions public String recoveringRegionsZNode; // znode containing namespace descriptors public static String namespaceZNode = "namespace"; // znode of indicating master maintenance mode public static String masterMaintZNode = "masterMaintenance"; // Certain ZooKeeper nodes need to be world-readable public static final ArrayList CREATOR_ALL_AND_WORLD_READABLE = new ArrayList() { { add(new ACL(ZooDefs.Perms.READ,ZooDefs.Ids.ANYONE_ID_UNSAFE)); add(new ACL(ZooDefs.Perms.ALL,ZooDefs.Ids.AUTH_IDS)); }}; public final static String META_ZNODE_PREFIX = "meta-region-server"; private static final String DEFAULT_SNAPSHOT_CLEANUP_ZNODE = "snapshot-cleanup"; private final Configuration conf; /* A pattern that matches a Kerberos name, borrowed from Hadoop's KerberosName */ private static final Pattern NAME_PATTERN = Pattern.compile("([^/@]*)(/([^/@]*))?@([^/@]*)"); /** * Instantiate a ZooKeeper connection and watcher. * @param identifier string that is passed to RecoverableZookeeper to be used as * identifier for this instance. Use null for default. * @throws IOException * @throws ZooKeeperConnectionException */ public ZooKeeperWatcher(Configuration conf, String identifier, Abortable abortable) throws ZooKeeperConnectionException, IOException { this(conf, identifier, abortable, false); } /** * Instantiate a ZooKeeper connection and watcher. * @param conf * @param identifier string that is passed to RecoverableZookeeper to be used as identifier for * this instance. Use null for default. * @param abortable Can be null if there is on error there is no host to abort: e.g. client * context. * @param canCreateBaseZNode * @throws IOException * @throws ZooKeeperConnectionException */ public ZooKeeperWatcher(Configuration conf, String identifier, Abortable abortable, boolean canCreateBaseZNode) throws IOException, ZooKeeperConnectionException { this.conf = conf; this.quorum = ZKConfig.getZKQuorumServersString(conf); this.prefix = identifier; // Identifier will get the sessionid appended later below down when we // handle the syncconnect event. this.identifier = identifier + "0x0"; this.abortable = abortable; setNodeNames(conf); PendingWatcher pendingWatcher = new PendingWatcher(); this.recoverableZooKeeper = ZKUtil.connect(conf, quorum, pendingWatcher, identifier); pendingWatcher.prepare(this); if (canCreateBaseZNode) { try { createBaseZNodes(); } catch (ZooKeeperConnectionException zce) { try { this.recoverableZooKeeper.close(); } catch (InterruptedException ie) { LOG.debug("Encountered InterruptedException when closing " + this.recoverableZooKeeper); Thread.currentThread().interrupt(); } throw zce; } } } private void createBaseZNodes() throws ZooKeeperConnectionException { try { // Create all the necessary "directories" of znodes ZKUtil.createWithParents(this, baseZNode); if (conf.getBoolean("hbase.assignment.usezk", true)) { ZKUtil.createAndFailSilent(this, assignmentZNode); } ZKUtil.createAndFailSilent(this, rsZNode); ZKUtil.createAndFailSilent(this, drainingZNode); ZKUtil.createAndFailSilent(this, tableZNode); ZKUtil.createAndFailSilent(this, splitLogZNode); ZKUtil.createAndFailSilent(this, backupMasterAddressesZNode); ZKUtil.createAndFailSilent(this, tableLockZNode); ZKUtil.createAndFailSilent(this, recoveringRegionsZNode); ZKUtil.createAndFailSilent(this, masterMaintZNode); } catch (KeeperException e) { throw new ZooKeeperConnectionException( prefix("Unexpected KeeperException creating base node"), e); } } /** Returns whether the znode is supposed to be readable by the client * and DOES NOT contain sensitive information (world readable).*/ public boolean isClientReadable(String node) { // Developer notice: These znodes are world readable. DO NOT add more znodes here UNLESS // all clients need to access this data to work. Using zk for sharing data to clients (other // than service lookup case is not a recommended design pattern. return node.equals(baseZNode) || isAnyMetaReplicaZnode(node) || node.equals(getMasterAddressZNode()) || node.equals(clusterIdZNode)|| node.equals(rsZNode) || // /hbase/table and /hbase/table/foo is allowed, /hbase/table-lock is not node.equals(tableZNode) || node.startsWith(tableZNode + "/"); } /** * On master start, we check the znode ACLs under the root directory and set the ACLs properly * if needed. If the cluster goes from an unsecure setup to a secure setup, this step is needed * so that the existing znodes created with open permissions are now changed with restrictive * perms. */ public void checkAndSetZNodeAcls() { if (!ZKUtil.isSecureZooKeeper(getConfiguration())) { LOG.info("not a secure deployment, proceeding"); return; } // Check the base znodes permission first. Only do the recursion if base znode's perms are not // correct. try { List actualAcls = recoverableZooKeeper.getAcl(baseZNode, new Stat()); if (!isBaseZnodeAclSetup(actualAcls)) { LOG.info("setting znode ACLs"); setZnodeAclsRecursive(baseZNode); } } catch(KeeperException.NoNodeException nne) { return; } catch(InterruptedException ie) { interruptedExceptionNoThrow(ie, false); } catch (IOException|KeeperException e) { LOG.warn("Received exception while checking and setting zookeeper ACLs", e); } } /** * Set the znode perms recursively. This will do post-order recursion, so that baseZnode ACLs * will be set last in case the master fails in between. * @param znode */ private void setZnodeAclsRecursive(String znode) throws KeeperException, InterruptedException { List children = recoverableZooKeeper.getChildren(znode, false); for (String child : children) { setZnodeAclsRecursive(ZKUtil.joinZNode(znode, child)); } List acls = ZKUtil.createACL(this, znode, true); LOG.info("Setting ACLs for znode:" + znode + " , acl:" + acls); recoverableZooKeeper.setAcl(znode, acls, -1); } /** * Checks whether the ACLs returned from the base znode (/hbase) is set for secure setup. * @param acls acls from zookeeper * @return whether ACLs are set for the base znode * @throws IOException */ private boolean isBaseZnodeAclSetup(List acls) throws IOException { if (LOG.isDebugEnabled()) { LOG.debug("Checking znode ACLs"); } String[] superUsers = conf.getStrings(Superusers.SUPERUSER_CONF_KEY); // Check whether ACL set for all superusers if (superUsers != null && !checkACLForSuperUsers(superUsers, acls)) { return false; } // this assumes that current authenticated user is the same as zookeeper client user // configured via JAAS String hbaseUser = UserGroupInformation.getCurrentUser().getShortUserName(); if (acls.isEmpty()) { if (LOG.isDebugEnabled()) { LOG.debug("ACL is empty"); } return false; } for (ACL acl : acls) { int perms = acl.getPerms(); Id id = acl.getId(); // We should only set at most 3 possible ACLs for 3 Ids. One for everyone, one for superuser // and one for the hbase user if (Ids.ANYONE_ID_UNSAFE.equals(id)) { if (perms != Perms.READ) { if (LOG.isDebugEnabled()) { LOG.debug(String.format("permissions for '%s' are not correct: have 0x%x, want 0x%x", id, perms, Perms.READ)); } return false; } } else if (superUsers != null && isSuperUserId(superUsers, id)) { if (perms != Perms.ALL) { if (LOG.isDebugEnabled()) { LOG.debug(String.format("permissions for '%s' are not correct: have 0x%x, want 0x%x", id, perms, Perms.ALL)); } return false; } } else if ("sasl".equals(id.getScheme())) { String name = id.getId(); // If ZooKeeper recorded the Kerberos full name in the ACL, use only the shortname Matcher match = NAME_PATTERN.matcher(name); if (match.matches()) { name = match.group(1); } if (name.equals(hbaseUser)) { if (perms != Perms.ALL) { if (LOG.isDebugEnabled()) { LOG.debug(String.format("permissions for '%s' are not correct: have 0x%x, want 0x%x", id, perms, Perms.ALL)); } return false; } } else { if (LOG.isDebugEnabled()) { LOG.debug("Unexpected shortname in SASL ACL: " + id); } return false; } } else { if (LOG.isDebugEnabled()) { LOG.debug("unexpected ACL id '" + id + "'"); } return false; } } return true; } /* * Validate whether ACL set for all superusers. */ private boolean checkACLForSuperUsers(String[] superUsers, List acls) { for (String user : superUsers) { boolean hasAccess = false; // TODO: Validate super group members also when ZK supports setting node ACL for groups. if (!AuthUtil.isGroupPrincipal(user)) { for (ACL acl : acls) { if (user.equals(acl.getId().getId())) { if (acl.getPerms() == Perms.ALL) { hasAccess = true; } else { if (LOG.isDebugEnabled()) { LOG.debug(String.format( "superuser '%s' does not have correct permissions: have 0x%x, want 0x%x", acl.getId().getId(), acl.getPerms(), Perms.ALL)); } } break; } } if (!hasAccess) { return false; } } } return true; } /* * Validate whether ACL ID is superuser. */ public static boolean isSuperUserId(String[] superUsers, Id id) { for (String user : superUsers) { // TODO: Validate super group members also when ZK supports setting node ACL for groups. if (!AuthUtil.isGroupPrincipal(user) && new Id("sasl", user).equals(id)) { return true; } } return false; } @Override public String toString() { return this.identifier + ", quorum=" + quorum + ", baseZNode=" + baseZNode; } /** * Adds this instance's identifier as a prefix to the passed str * @param str String to amend. * @return A new string with this instance's identifier as prefix: e.g. * if passed 'hello world', the returned string could be */ public String prefix(final String str) { return this.toString() + " " + str; } /** * Set the local variable node names using the specified configuration. */ private void setNodeNames(Configuration conf) { baseZNode = conf.get(HConstants.ZOOKEEPER_ZNODE_PARENT, HConstants.DEFAULT_ZOOKEEPER_ZNODE_PARENT); metaReplicaZnodes.put(0, ZKUtil.joinZNode(baseZNode, conf.get("zookeeper.znode.metaserver", "meta-region-server"))); int numMetaReplicas = conf.getInt(HConstants.META_REPLICAS_NUM, HConstants.DEFAULT_META_REPLICA_NUM); for (int i = 1; i < numMetaReplicas; i++) { String str = ZKUtil.joinZNode(baseZNode, conf.get("zookeeper.znode.metaserver", "meta-region-server") + "-" + i); metaReplicaZnodes.put(i, str); } rsZNode = ZKUtil.joinZNode(baseZNode, conf.get("zookeeper.znode.rs", "rs")); drainingZNode = ZKUtil.joinZNode(baseZNode, conf.get("zookeeper.znode.draining.rs", "draining")); masterAddressZNode = ZKUtil.joinZNode(baseZNode, conf.get("zookeeper.znode.master", "master")); backupMasterAddressesZNode = ZKUtil.joinZNode(baseZNode, conf.get("zookeeper.znode.backup.masters", "backup-masters")); clusterStateZNode = ZKUtil.joinZNode(baseZNode, conf.get("zookeeper.znode.state", "running")); assignmentZNode = ZKUtil.joinZNode(baseZNode, conf.get("zookeeper.znode.unassigned", "region-in-transition")); tableZNode = ZKUtil.joinZNode(baseZNode, conf.get("zookeeper.znode.tableEnableDisable", "table")); clusterIdZNode = ZKUtil.joinZNode(baseZNode, conf.get("zookeeper.znode.clusterId", "hbaseid")); splitLogZNode = ZKUtil.joinZNode(baseZNode, conf.get("zookeeper.znode.splitlog", HConstants.SPLIT_LOGDIR_NAME)); balancerZNode = ZKUtil.joinZNode(baseZNode, conf.get("zookeeper.znode.balancer", "balancer")); regionNormalizerZNode = ZKUtil.joinZNode(baseZNode, conf.get("zookeeper.znode.regionNormalizer", "normalizer")); switchZNode = ZKUtil.joinZNode(baseZNode, conf.get("zookeeper.znode.switch", "switch")); tableLockZNode = ZKUtil.joinZNode(baseZNode, conf.get("zookeeper.znode.tableLock", "table-lock")); snapshotCleanupZNode = ZKUtil.joinZNode(baseZNode, conf.get("zookeeper.znode.snapshot.cleanup", DEFAULT_SNAPSHOT_CLEANUP_ZNODE)); recoveringRegionsZNode = ZKUtil.joinZNode(baseZNode, conf.get("zookeeper.znode.recovering.regions", "recovering-regions")); namespaceZNode = ZKUtil.joinZNode(baseZNode, conf.get("zookeeper.znode.namespace", "namespace")); masterMaintZNode = ZKUtil.joinZNode(baseZNode, conf.get("zookeeper.znode.masterMaintenance", "master-maintenance")); } /** * Is the znode of any meta replica * @param node * @return true or false */ public boolean isAnyMetaReplicaZnode(String node) { if (metaReplicaZnodes.values().contains(node)) { return true; } return false; } /** * Is it the default meta replica's znode * @param node * @return true or false */ public boolean isDefaultMetaReplicaZnode(String node) { if (getZNodeForReplica(HRegionInfo.DEFAULT_REPLICA_ID).equals(node)) { return true; } return false; } /** * Get the znodes corresponding to the meta replicas from ZK * @return list of znodes * @throws KeeperException */ public List getMetaReplicaNodes() throws KeeperException { List childrenOfBaseNode = ZKUtil.listChildrenNoWatch(this, baseZNode); List metaReplicaNodes = new ArrayList(2); if (childrenOfBaseNode != null) { String pattern = conf.get("zookeeper.znode.metaserver","meta-region-server"); for (String child : childrenOfBaseNode) { if (child.startsWith(pattern)) metaReplicaNodes.add(child); } } return metaReplicaNodes; } /** * Get the znode string corresponding to a replicaId * @param replicaId * @return znode */ public String getZNodeForReplica(int replicaId) { String str = metaReplicaZnodes.get(replicaId); // return a newly created path but don't update the cache of paths // This is mostly needed for tests that attempt to create meta replicas // from outside the master if (str == null) { str = ZKUtil.joinZNode(baseZNode, conf.get("zookeeper.znode.metaserver", "meta-region-server") + "-" + replicaId); } return str; } /** * Parse the meta replicaId from the passed znode * @param znode * @return replicaId */ public int getMetaReplicaIdFromZnode(String znode) { String pattern = conf.get("zookeeper.znode.metaserver","meta-region-server"); if (znode.equals(pattern)) return HRegionInfo.DEFAULT_REPLICA_ID; // the non-default replicas are of the pattern meta-region-server- String nonDefaultPattern = pattern + "-"; return Integer.parseInt(znode.substring(nonDefaultPattern.length())); } /** * Register the specified listener to receive ZooKeeper events. * @param listener */ public void registerListener(ZooKeeperListener listener) { listeners.add(listener); } /** * Register the specified listener to receive ZooKeeper events and add it as * the first in the list of current listeners. * @param listener */ public void registerListenerFirst(ZooKeeperListener listener) { listeners.add(0, listener); } public void unregisterListener(ZooKeeperListener listener) { listeners.remove(listener); } /** * Clean all existing listeners */ public void unregisterAllListeners() { listeners.clear(); } /** * Get a copy of current registered listeners */ public List getListeners() { return new ArrayList(listeners); } /** * @return The number of currently registered listeners */ public int getNumberOfListeners() { return listeners.size(); } /** * Get the connection to ZooKeeper. * @return connection reference to zookeeper */ public RecoverableZooKeeper getRecoverableZooKeeper() { return recoverableZooKeeper; } public void reconnectAfterExpiration() throws IOException, KeeperException, InterruptedException { recoverableZooKeeper.reconnectAfterExpiration(); } /** * Get the quorum address of this instance. * @return quorum string of this zookeeper connection instance */ public String getQuorum() { return quorum; } /** * @return the base znode of this zookeeper connection instance. */ public String getBaseZNode() { return baseZNode; } /** * Method called from ZooKeeper for events and connection status. *

* Valid events are passed along to listeners. Connection status changes * are dealt with locally. */ @Override public void process(WatchedEvent event) { LOG.debug(prefix("Received ZooKeeper Event, " + "type=" + event.getType() + ", " + "state=" + event.getState() + ", " + "path=" + event.getPath())); switch(event.getType()) { // If event type is NONE, this is a connection status change case None: { connectionEvent(event); break; } // Otherwise pass along to the listeners case NodeCreated: { for(ZooKeeperListener listener : listeners) { listener.nodeCreated(event.getPath()); } break; } case NodeDeleted: { for(ZooKeeperListener listener : listeners) { listener.nodeDeleted(event.getPath()); } break; } case NodeDataChanged: { for(ZooKeeperListener listener : listeners) { listener.nodeDataChanged(event.getPath()); } break; } case NodeChildrenChanged: { for(ZooKeeperListener listener : listeners) { listener.nodeChildrenChanged(event.getPath()); } break; } } } // Connection management /** * Called when there is a connection-related event via the Watcher callback. *

* If Disconnected or Expired, this should shutdown the cluster. But, since * we send a KeeperException.SessionExpiredException along with the abort * call, it's possible for the Abortable to catch it and try to create a new * session with ZooKeeper. This is what the client does in HCM. *

* @param event */ private void connectionEvent(WatchedEvent event) { switch(event.getState()) { case SyncConnected: this.identifier = this.prefix + "-0x" + Long.toHexString(this.recoverableZooKeeper.getSessionId()); // Update our identifier. Otherwise ignore. LOG.debug(this.identifier + " connected"); break; // Abort the server if Disconnected or Expired case Disconnected: LOG.debug(prefix("Received Disconnected from ZooKeeper, ignoring")); break; case Expired: String msg = prefix(this.identifier + " received expired from " + "ZooKeeper, aborting"); // TODO: One thought is to add call to ZooKeeperListener so say, // ZooKeeperNodeTracker can zero out its data values. if (this.abortable != null) { this.abortable.abort(msg, new KeeperException.SessionExpiredException()); } break; case ConnectedReadOnly: case SaslAuthenticated: case AuthFailed: break; default: throw new IllegalStateException("Received event is not valid: " + event.getState()); } } /** * Forces a synchronization of this ZooKeeper client connection. *

* Executing this method before running other methods will ensure that the * subsequent operations are up-to-date and consistent as of the time that * the sync is complete. *

* This is used for compareAndSwap type operations where we need to read the * data of an existing node and delete or transition that node, utilizing the * previously read version and data. We want to ensure that the version read * is up-to-date from when we begin the operation. */ public void sync(String path) throws KeeperException { this.recoverableZooKeeper.sync(path, null, null); } /** * Handles KeeperExceptions in client calls. *

* This may be temporary but for now this gives one place to deal with these. *

* TODO: Currently this method rethrows the exception to let the caller handle *

* @param ke * @throws KeeperException */ public void keeperException(KeeperException ke) throws KeeperException { LOG.error(prefix("Received unexpected KeeperException, re-throwing exception"), ke); throw ke; } /** * Handles InterruptedExceptions in client calls. * @param ie the InterruptedException instance thrown * @throws KeeperException the exception to throw, transformed from the InterruptedException */ public void interruptedException(InterruptedException ie) throws KeeperException { interruptedExceptionNoThrow(ie, true); // Throw a system error exception to let upper level handle it throw new KeeperException.SystemErrorException(); } /** * Log the InterruptedException and interrupt current thread * @param ie The IterruptedException to log * @param throwLater Whether we will throw the exception latter */ public void interruptedExceptionNoThrow(InterruptedException ie, boolean throwLater) { LOG.debug(prefix("Received InterruptedException, will interrupt current thread" + (throwLater ? " and rethrow a SystemErrorException" : "")), ie); // At least preserve interrupt. Thread.currentThread().interrupt(); } /** * Close the connection to ZooKeeper. * */ @Override public void close() { try { recoverableZooKeeper.close(); } catch (InterruptedException e) { Thread.currentThread().interrupt(); } } public Configuration getConfiguration() { return conf; } @Override public void abort(String why, Throwable e) { if (this.abortable != null) this.abortable.abort(why, e); else this.aborted = true; } @Override public boolean isAborted() { return this.abortable == null? this.aborted: this.abortable.isAborted(); } /** * @return Path to the currently active master. */ public String getMasterAddressZNode() { return this.masterAddressZNode; } /** * @return ZooKeeper znode for region normalizer state */ public String getRegionNormalizerZNode() { return regionNormalizerZNode; } /** * @return ZK node for switch * */ public String getSwitchZNode() { return switchZNode; } }





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