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1   /**
2    *
3    * Licensed to the Apache Software Foundation (ASF) under one
4    * or more contributor license agreements.  See the NOTICE file
5    * distributed with this work for additional information
6    * regarding copyright ownership.  The ASF licenses this file
7    * to you under the Apache License, Version 2.0 (the
8    * "License"); you may not use this file except in compliance
9    * with the License.  You may obtain a copy of the License at
10   *
11   *     http://www.apache.org/licenses/LICENSE-2.0
12   *
13   * Unless required by applicable law or agreed to in writing, software
14   * distributed under the License is distributed on an "AS IS" BASIS,
15   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
16   * See the License for the specific language governing permissions and
17   * limitations under the License.
18   */
19  package org.apache.hadoop.hbase.zookeeper;
20  
21  import java.io.BufferedReader;
22  import java.io.IOException;
23  import java.io.InputStreamReader;
24  import java.io.PrintWriter;
25  import java.net.InetSocketAddress;
26  import java.net.Socket;
27  import java.util.ArrayList;
28  import java.util.Arrays;
29  import java.util.HashMap;
30  import java.util.LinkedList;
31  import java.util.List;
32  import java.util.Map;
33  import java.util.Properties;
34  
35  import javax.security.auth.login.AppConfigurationEntry;
36  import javax.security.auth.login.AppConfigurationEntry.LoginModuleControlFlag;
37  
38  import org.apache.hadoop.hbase.util.ByteStringer;
39  import org.apache.commons.lang.StringUtils;
40  import org.apache.commons.logging.Log;
41  import org.apache.commons.logging.LogFactory;
42  import org.apache.hadoop.hbase.classification.InterfaceAudience;
43  import org.apache.hadoop.conf.Configuration;
44  import org.apache.hadoop.hbase.HConstants;
45  import org.apache.hadoop.hbase.ServerName;
46  import org.apache.hadoop.hbase.exceptions.DeserializationException;
47  import org.apache.hadoop.hbase.protobuf.ProtobufUtil;
48  import org.apache.hadoop.hbase.protobuf.generated.ZooKeeperProtos;
49  import org.apache.hadoop.hbase.protobuf.generated.ZooKeeperProtos.RegionStoreSequenceIds;
50  import org.apache.hadoop.hbase.util.Bytes;
51  import org.apache.hadoop.hbase.util.Threads;
52  import org.apache.hadoop.hbase.zookeeper.ZKUtil.ZKUtilOp.CreateAndFailSilent;
53  import org.apache.hadoop.hbase.zookeeper.ZKUtil.ZKUtilOp.DeleteNodeFailSilent;
54  import org.apache.hadoop.hbase.zookeeper.ZKUtil.ZKUtilOp.SetData;
55  import org.apache.hadoop.security.SecurityUtil;
56  import org.apache.hadoop.security.authentication.util.KerberosUtil;
57  import org.apache.zookeeper.AsyncCallback;
58  import org.apache.zookeeper.CreateMode;
59  import org.apache.zookeeper.KeeperException;
60  import org.apache.zookeeper.KeeperException.NoNodeException;
61  import org.apache.zookeeper.Op;
62  import org.apache.zookeeper.Watcher;
63  import org.apache.zookeeper.ZooDefs.Ids;
64  import org.apache.zookeeper.ZooDefs.Perms;
65  import org.apache.zookeeper.ZooKeeper;
66  import org.apache.zookeeper.client.ZooKeeperSaslClient;
67  import org.apache.zookeeper.data.ACL;
68  import org.apache.zookeeper.data.Id;
69  import org.apache.zookeeper.data.Stat;
70  import org.apache.zookeeper.proto.CreateRequest;
71  import org.apache.zookeeper.proto.DeleteRequest;
72  import org.apache.zookeeper.proto.SetDataRequest;
73  import org.apache.zookeeper.server.ZooKeeperSaslServer;
74  
75  import com.google.protobuf.InvalidProtocolBufferException;
76  
77  /**
78   * Internal HBase utility class for ZooKeeper.
79   *
80   * <p>Contains only static methods and constants.
81   *
82   * <p>Methods all throw {@link KeeperException} if there is an unexpected
83   * zookeeper exception, so callers of these methods must handle appropriately.
84   * If ZK is required for the operation, the server will need to be aborted.
85   */
86  @InterfaceAudience.Private
87  public class ZKUtil {
88    private static final Log LOG = LogFactory.getLog(ZKUtil.class);
89  
90    // TODO: Replace this with ZooKeeper constant when ZOOKEEPER-277 is resolved.
91    public static final char ZNODE_PATH_SEPARATOR = '/';
92    private static int zkDumpConnectionTimeOut;
93  
94    /**
95     * Creates a new connection to ZooKeeper, pulling settings and ensemble config
96     * from the specified configuration object using methods from {@link ZKConfig}.
97     *
98     * Sets the connection status monitoring watcher to the specified watcher.
99     *
100    * @param conf configuration to pull ensemble and other settings from
101    * @param watcher watcher to monitor connection changes
102    * @return connection to zookeeper
103    * @throws IOException if unable to connect to zk or config problem
104    */
105   public static RecoverableZooKeeper connect(Configuration conf, Watcher watcher)
106   throws IOException {
107     Properties properties = ZKConfig.makeZKProps(conf);
108     String ensemble = ZKConfig.getZKQuorumServersString(properties);
109     return connect(conf, ensemble, watcher);
110   }
111 
112   public static RecoverableZooKeeper connect(Configuration conf, String ensemble,
113       Watcher watcher)
114   throws IOException {
115     return connect(conf, ensemble, watcher, null);
116   }
117 
118   public static RecoverableZooKeeper connect(Configuration conf, String ensemble,
119       Watcher watcher, final String identifier)
120   throws IOException {
121     if(ensemble == null) {
122       throw new IOException("Unable to determine ZooKeeper ensemble");
123     }
124     int timeout = conf.getInt(HConstants.ZK_SESSION_TIMEOUT,
125         HConstants.DEFAULT_ZK_SESSION_TIMEOUT);
126     if (LOG.isTraceEnabled()) {
127       LOG.trace(identifier + " opening connection to ZooKeeper ensemble=" + ensemble);
128     }
129     int retry = conf.getInt("zookeeper.recovery.retry", 3);
130     int retryIntervalMillis =
131       conf.getInt("zookeeper.recovery.retry.intervalmill", 1000);
132     zkDumpConnectionTimeOut = conf.getInt("zookeeper.dump.connection.timeout",
133         1000);
134     return new RecoverableZooKeeper(ensemble, timeout, watcher,
135         retry, retryIntervalMillis, identifier);
136   }
137 
138   /**
139    * Log in the current zookeeper server process using the given configuration
140    * keys for the credential file and login principal.
141    *
142    * <p><strong>This is only applicable when running on secure hbase</strong>
143    * On regular HBase (without security features), this will safely be ignored.
144    * </p>
145    *
146    * @param conf The configuration data to use
147    * @param keytabFileKey Property key used to configure the path to the credential file
148    * @param userNameKey Property key used to configure the login principal
149    * @param hostname Current hostname to use in any credentials
150    * @throws IOException underlying exception from SecurityUtil.login() call
151    */
152   public static void loginServer(Configuration conf, String keytabFileKey,
153       String userNameKey, String hostname) throws IOException {
154     login(conf, keytabFileKey, userNameKey, hostname,
155           ZooKeeperSaslServer.LOGIN_CONTEXT_NAME_KEY,
156           JaasConfiguration.SERVER_KEYTAB_KERBEROS_CONFIG_NAME);
157   }
158 
159   /**
160    * Log in the current zookeeper client using the given configuration
161    * keys for the credential file and login principal.
162    *
163    * <p><strong>This is only applicable when running on secure hbase</strong>
164    * On regular HBase (without security features), this will safely be ignored.
165    * </p>
166    *
167    * @param conf The configuration data to use
168    * @param keytabFileKey Property key used to configure the path to the credential file
169    * @param userNameKey Property key used to configure the login principal
170    * @param hostname Current hostname to use in any credentials
171    * @throws IOException underlying exception from SecurityUtil.login() call
172    */
173   public static void loginClient(Configuration conf, String keytabFileKey,
174       String userNameKey, String hostname) throws IOException {
175     login(conf, keytabFileKey, userNameKey, hostname,
176           ZooKeeperSaslClient.LOGIN_CONTEXT_NAME_KEY,
177           JaasConfiguration.CLIENT_KEYTAB_KERBEROS_CONFIG_NAME);
178   }
179 
180   /**
181    * Log in the current process using the given configuration keys for the
182    * credential file and login principal.
183    *
184    * <p><strong>This is only applicable when running on secure hbase</strong>
185    * On regular HBase (without security features), this will safely be ignored.
186    * </p>
187    *
188    * @param conf The configuration data to use
189    * @param keytabFileKey Property key used to configure the path to the credential file
190    * @param userNameKey Property key used to configure the login principal
191    * @param hostname Current hostname to use in any credentials
192    * @param loginContextProperty property name to expose the entry name
193    * @param loginContextName jaas entry name
194    * @throws IOException underlying exception from SecurityUtil.login() call
195    */
196   private static void login(Configuration conf, String keytabFileKey,
197       String userNameKey, String hostname,
198       String loginContextProperty, String loginContextName)
199       throws IOException {
200     if (!isSecureZooKeeper(conf))
201       return;
202 
203     // User has specified a jaas.conf, keep this one as the good one.
204     // HBASE_OPTS="-Djava.security.auth.login.config=jaas.conf"
205     if (System.getProperty("java.security.auth.login.config") != null)
206       return;
207 
208     // No keytab specified, no auth
209     String keytabFilename = conf.get(keytabFileKey);
210     if (keytabFilename == null) {
211       LOG.warn("no keytab specified for: " + keytabFileKey);
212       return;
213     }
214 
215     String principalConfig = conf.get(userNameKey, System.getProperty("user.name"));
216     String principalName = SecurityUtil.getServerPrincipal(principalConfig, hostname);
217 
218     // Initialize the "jaas.conf" for keyTab/principal,
219     // If keyTab is not specified use the Ticket Cache.
220     // and set the zookeeper login context name.
221     JaasConfiguration jaasConf = new JaasConfiguration(loginContextName,
222         principalName, keytabFilename);
223     javax.security.auth.login.Configuration.setConfiguration(jaasConf);
224     System.setProperty(loginContextProperty, loginContextName);
225   }
226 
227   /**
228    * A JAAS configuration that defines the login modules that we want to use for login.
229    */
230   private static class JaasConfiguration extends javax.security.auth.login.Configuration {
231     private static final String SERVER_KEYTAB_KERBEROS_CONFIG_NAME =
232       "zookeeper-server-keytab-kerberos";
233     private static final String CLIENT_KEYTAB_KERBEROS_CONFIG_NAME =
234       "zookeeper-client-keytab-kerberos";
235 
236     private static final Map<String, String> BASIC_JAAS_OPTIONS =
237       new HashMap<String,String>();
238     static {
239       String jaasEnvVar = System.getenv("HBASE_JAAS_DEBUG");
240       if (jaasEnvVar != null && "true".equalsIgnoreCase(jaasEnvVar)) {
241         BASIC_JAAS_OPTIONS.put("debug", "true");
242       }
243     }
244 
245     private static final Map<String,String> KEYTAB_KERBEROS_OPTIONS =
246       new HashMap<String,String>();
247     static {
248       KEYTAB_KERBEROS_OPTIONS.put("doNotPrompt", "true");
249       KEYTAB_KERBEROS_OPTIONS.put("storeKey", "true");
250       KEYTAB_KERBEROS_OPTIONS.put("refreshKrb5Config", "true");
251       KEYTAB_KERBEROS_OPTIONS.putAll(BASIC_JAAS_OPTIONS);
252     }
253 
254     private static final AppConfigurationEntry KEYTAB_KERBEROS_LOGIN =
255       new AppConfigurationEntry(KerberosUtil.getKrb5LoginModuleName(),
256                                 LoginModuleControlFlag.REQUIRED,
257                                 KEYTAB_KERBEROS_OPTIONS);
258 
259     private static final AppConfigurationEntry[] KEYTAB_KERBEROS_CONF =
260       new AppConfigurationEntry[]{KEYTAB_KERBEROS_LOGIN};
261 
262     private javax.security.auth.login.Configuration baseConfig;
263     private final String loginContextName;
264     private final boolean useTicketCache;
265     private final String keytabFile;
266     private final String principal;
267 
268     public JaasConfiguration(String loginContextName, String principal) {
269       this(loginContextName, principal, null, true);
270     }
271 
272     public JaasConfiguration(String loginContextName, String principal, String keytabFile) {
273       this(loginContextName, principal, keytabFile, keytabFile == null || keytabFile.length() == 0);
274     }
275 
276     private JaasConfiguration(String loginContextName, String principal,
277                              String keytabFile, boolean useTicketCache) {
278       try {
279         this.baseConfig = javax.security.auth.login.Configuration.getConfiguration();
280       } catch (SecurityException e) {
281         this.baseConfig = null;
282       }
283       this.loginContextName = loginContextName;
284       this.useTicketCache = useTicketCache;
285       this.keytabFile = keytabFile;
286       this.principal = principal;
287       LOG.info("JaasConfiguration loginContextName=" + loginContextName +
288                " principal=" + principal + " useTicketCache=" + useTicketCache +
289                " keytabFile=" + keytabFile);
290     }
291 
292     @Override
293     public AppConfigurationEntry[] getAppConfigurationEntry(String appName) {
294       if (loginContextName.equals(appName)) {
295         if (!useTicketCache) {
296           KEYTAB_KERBEROS_OPTIONS.put("keyTab", keytabFile);
297           KEYTAB_KERBEROS_OPTIONS.put("useKeyTab", "true");
298         }
299         KEYTAB_KERBEROS_OPTIONS.put("principal", principal);
300         KEYTAB_KERBEROS_OPTIONS.put("useTicketCache", useTicketCache ? "true" : "false");
301         return KEYTAB_KERBEROS_CONF;
302       }
303       if (baseConfig != null) return baseConfig.getAppConfigurationEntry(appName);
304       return(null);
305     }
306   }
307 
308   //
309   // Helper methods
310   //
311 
312   /**
313    * Join the prefix znode name with the suffix znode name to generate a proper
314    * full znode name.
315    *
316    * Assumes prefix does not end with slash and suffix does not begin with it.
317    *
318    * @param prefix beginning of znode name
319    * @param suffix ending of znode name
320    * @return result of properly joining prefix with suffix
321    */
322   public static String joinZNode(String prefix, String suffix) {
323     return prefix + ZNODE_PATH_SEPARATOR + suffix;
324   }
325 
326   /**
327    * Returns the full path of the immediate parent of the specified node.
328    * @param node path to get parent of
329    * @return parent of path, null if passed the root node or an invalid node
330    */
331   public static String getParent(String node) {
332     int idx = node.lastIndexOf(ZNODE_PATH_SEPARATOR);
333     return idx <= 0 ? null : node.substring(0, idx);
334   }
335 
336   /**
337    * Get the name of the current node from the specified fully-qualified path.
338    * @param path fully-qualified path
339    * @return name of the current node
340    */
341   public static String getNodeName(String path) {
342     return path.substring(path.lastIndexOf("/")+1);
343   }
344 
345   /**
346    * Get the key to the ZK ensemble for this configuration without
347    * adding a name at the end
348    * @param conf Configuration to use to build the key
349    * @return ensemble key without a name
350    */
351   public static String getZooKeeperClusterKey(Configuration conf) {
352     return getZooKeeperClusterKey(conf, null);
353   }
354 
355   /**
356    * Get the key to the ZK ensemble for this configuration and append
357    * a name at the end
358    * @param conf Configuration to use to build the key
359    * @param name Name that should be appended at the end if not empty or null
360    * @return ensemble key with a name (if any)
361    */
362   public static String getZooKeeperClusterKey(Configuration conf, String name) {
363     String ensemble = conf.get(HConstants.ZOOKEEPER_QUORUM.replaceAll(
364         "[\\t\\n\\x0B\\f\\r]", ""));
365     StringBuilder builder = new StringBuilder(ensemble);
366     builder.append(":");
367     builder.append(conf.get(HConstants.ZOOKEEPER_CLIENT_PORT));
368     builder.append(":");
369     builder.append(conf.get(HConstants.ZOOKEEPER_ZNODE_PARENT));
370     if (name != null && !name.isEmpty()) {
371       builder.append(",");
372       builder.append(name);
373     }
374     return builder.toString();
375   }
376 
377   /**
378    * Apply the settings in the given key to the given configuration, this is
379    * used to communicate with distant clusters
380    * @param conf configuration object to configure
381    * @param key string that contains the 3 required configuratins
382    * @throws IOException
383    */
384   public static void applyClusterKeyToConf(Configuration conf, String key)
385       throws IOException{
386     String[] parts = transformClusterKey(key);
387     conf.set(HConstants.ZOOKEEPER_QUORUM, parts[0]);
388     conf.set(HConstants.ZOOKEEPER_CLIENT_PORT, parts[1]);
389     conf.set(HConstants.ZOOKEEPER_ZNODE_PARENT, parts[2]);
390   }
391 
392   /**
393    * Separate the given key into the three configurations it should contain:
394    * hbase.zookeeper.quorum, hbase.zookeeper.client.port
395    * and zookeeper.znode.parent
396    * @param key
397    * @return the three configuration in the described order
398    * @throws IOException
399    */
400   public static String[] transformClusterKey(String key) throws IOException {
401     String[] parts = key.split(":");
402     if (parts.length != 3) {
403       throw new IOException("Cluster key passed " + key + " is invalid, the format should be:" +
404           HConstants.ZOOKEEPER_QUORUM + ":hbase.zookeeper.client.port:"
405           + HConstants.ZOOKEEPER_ZNODE_PARENT);
406     }
407     return parts;
408   }
409 
410   //
411   // Existence checks and watches
412   //
413 
414   /**
415    * Watch the specified znode for delete/create/change events.  The watcher is
416    * set whether or not the node exists.  If the node already exists, the method
417    * returns true.  If the node does not exist, the method returns false.
418    *
419    * @param zkw zk reference
420    * @param znode path of node to watch
421    * @return true if znode exists, false if does not exist or error
422    * @throws KeeperException if unexpected zookeeper exception
423    */
424   public static boolean watchAndCheckExists(ZooKeeperWatcher zkw, String znode)
425   throws KeeperException {
426     try {
427       Stat s = zkw.getRecoverableZooKeeper().exists(znode, zkw);
428       boolean exists = s != null ? true : false;
429       if (exists) {
430         LOG.debug(zkw.prefix("Set watcher on existing znode=" + znode));
431       } else {
432         LOG.debug(zkw.prefix("Set watcher on znode that does not yet exist, " + znode));
433       }
434       return exists;
435     } catch (KeeperException e) {
436       LOG.warn(zkw.prefix("Unable to set watcher on znode " + znode), e);
437       zkw.keeperException(e);
438       return false;
439     } catch (InterruptedException e) {
440       LOG.warn(zkw.prefix("Unable to set watcher on znode " + znode), e);
441       zkw.interruptedException(e);
442       return false;
443     }
444   }
445 
446   /**
447    * Watch the specified znode, but only if exists. Useful when watching
448    * for deletions. Uses .getData() (and handles NoNodeException) instead
449    * of .exists() to accomplish this, as .getData() will only set a watch if
450    * the znode exists.
451    * @param zkw zk reference
452    * @param znode path of node to watch
453    * @return true if the watch is set, false if node does not exists
454    * @throws KeeperException if unexpected zookeeper exception
455    */
456   public static boolean setWatchIfNodeExists(ZooKeeperWatcher zkw, String znode)
457       throws KeeperException {
458     try {
459       zkw.getRecoverableZooKeeper().getData(znode, true, null);
460       return true;
461     } catch (NoNodeException e) {
462       return false;
463     } catch (InterruptedException e) {
464       LOG.warn(zkw.prefix("Unable to set watcher on znode " + znode), e);
465       zkw.interruptedException(e);
466       return false;
467     }
468   }
469 
470   /**
471    * Check if the specified node exists.  Sets no watches.
472    *
473    * @param zkw zk reference
474    * @param znode path of node to watch
475    * @return version of the node if it exists, -1 if does not exist
476    * @throws KeeperException if unexpected zookeeper exception
477    */
478   public static int checkExists(ZooKeeperWatcher zkw, String znode)
479   throws KeeperException {
480     try {
481       Stat s = zkw.getRecoverableZooKeeper().exists(znode, null);
482       return s != null ? s.getVersion() : -1;
483     } catch (KeeperException e) {
484       LOG.warn(zkw.prefix("Unable to set watcher on znode (" + znode + ")"), e);
485       zkw.keeperException(e);
486       return -1;
487     } catch (InterruptedException e) {
488       LOG.warn(zkw.prefix("Unable to set watcher on znode (" + znode + ")"), e);
489       zkw.interruptedException(e);
490       return -1;
491     }
492   }
493 
494   //
495   // Znode listings
496   //
497 
498   /**
499    * Lists the children znodes of the specified znode.  Also sets a watch on
500    * the specified znode which will capture a NodeDeleted event on the specified
501    * znode as well as NodeChildrenChanged if any children of the specified znode
502    * are created or deleted.
503    *
504    * Returns null if the specified node does not exist.  Otherwise returns a
505    * list of children of the specified node.  If the node exists but it has no
506    * children, an empty list will be returned.
507    *
508    * @param zkw zk reference
509    * @param znode path of node to list and watch children of
510    * @return list of children of the specified node, an empty list if the node
511    *          exists but has no children, and null if the node does not exist
512    * @throws KeeperException if unexpected zookeeper exception
513    */
514   public static List<String> listChildrenAndWatchForNewChildren(
515       ZooKeeperWatcher zkw, String znode)
516   throws KeeperException {
517     try {
518       List<String> children = zkw.getRecoverableZooKeeper().getChildren(znode, zkw);
519       return children;
520     } catch(KeeperException.NoNodeException ke) {
521       LOG.debug(zkw.prefix("Unable to list children of znode " + znode + " " +
522           "because node does not exist (not an error)"));
523       return null;
524     } catch (KeeperException e) {
525       LOG.warn(zkw.prefix("Unable to list children of znode " + znode + " "), e);
526       zkw.keeperException(e);
527       return null;
528     } catch (InterruptedException e) {
529       LOG.warn(zkw.prefix("Unable to list children of znode " + znode + " "), e);
530       zkw.interruptedException(e);
531       return null;
532     }
533   }
534 
535   /**
536    * List all the children of the specified znode, setting a watch for children
537    * changes and also setting a watch on every individual child in order to get
538    * the NodeCreated and NodeDeleted events.
539    * @param zkw zookeeper reference
540    * @param znode node to get children of and watch
541    * @return list of znode names, null if the node doesn't exist
542    * @throws KeeperException
543    */
544   public static List<String> listChildrenAndWatchThem(ZooKeeperWatcher zkw,
545       String znode) throws KeeperException {
546     List<String> children = listChildrenAndWatchForNewChildren(zkw, znode);
547     if (children == null) {
548       return null;
549     }
550     for (String child : children) {
551       watchAndCheckExists(zkw, joinZNode(znode, child));
552     }
553     return children;
554   }
555 
556   /**
557    * Lists the children of the specified znode without setting any watches.
558    *
559    * Sets no watches at all, this method is best effort.
560    *
561    * Returns an empty list if the node has no children.  Returns null if the
562    * parent node itself does not exist.
563    *
564    * @param zkw zookeeper reference
565    * @param znode node to get children
566    * @return list of data of children of specified znode, empty if no children,
567    *         null if parent does not exist
568    * @throws KeeperException if unexpected zookeeper exception
569    */
570   public static List<String> listChildrenNoWatch(ZooKeeperWatcher zkw, String znode)
571   throws KeeperException {
572     List<String> children = null;
573     try {
574       // List the children without watching
575       children = zkw.getRecoverableZooKeeper().getChildren(znode, null);
576     } catch(KeeperException.NoNodeException nne) {
577       return null;
578     } catch(InterruptedException ie) {
579       zkw.interruptedException(ie);
580     }
581     return children;
582   }
583 
584   /**
585    * Simple class to hold a node path and node data.
586    * @deprecated Unused
587    */
588   @Deprecated
589   public static class NodeAndData {
590     private String node;
591     private byte [] data;
592     public NodeAndData(String node, byte [] data) {
593       this.node = node;
594       this.data = data;
595     }
596     public String getNode() {
597       return node;
598     }
599     public byte [] getData() {
600       return data;
601     }
602     @Override
603     public String toString() {
604       return node;
605     }
606     public boolean isEmpty() {
607       return (data.length == 0);
608     }
609   }
610 
611   /**
612    * Checks if the specified znode has any children.  Sets no watches.
613    *
614    * Returns true if the node exists and has children.  Returns false if the
615    * node does not exist or if the node does not have any children.
616    *
617    * Used during master initialization to determine if the master is a
618    * failed-over-to master or the first master during initial cluster startup.
619    * If the directory for regionserver ephemeral nodes is empty then this is
620    * a cluster startup, if not then it is not cluster startup.
621    *
622    * @param zkw zk reference
623    * @param znode path of node to check for children of
624    * @return true if node has children, false if not or node does not exist
625    * @throws KeeperException if unexpected zookeeper exception
626    */
627   public static boolean nodeHasChildren(ZooKeeperWatcher zkw, String znode)
628   throws KeeperException {
629     try {
630       return !zkw.getRecoverableZooKeeper().getChildren(znode, null).isEmpty();
631     } catch(KeeperException.NoNodeException ke) {
632       LOG.debug(zkw.prefix("Unable to list children of znode " + znode + " " +
633       "because node does not exist (not an error)"));
634       return false;
635     } catch (KeeperException e) {
636       LOG.warn(zkw.prefix("Unable to list children of znode " + znode), e);
637       zkw.keeperException(e);
638       return false;
639     } catch (InterruptedException e) {
640       LOG.warn(zkw.prefix("Unable to list children of znode " + znode), e);
641       zkw.interruptedException(e);
642       return false;
643     }
644   }
645 
646   /**
647    * Get the number of children of the specified node.
648    *
649    * If the node does not exist or has no children, returns 0.
650    *
651    * Sets no watches at all.
652    *
653    * @param zkw zk reference
654    * @param znode path of node to count children of
655    * @return number of children of specified node, 0 if none or parent does not
656    *         exist
657    * @throws KeeperException if unexpected zookeeper exception
658    */
659   public static int getNumberOfChildren(ZooKeeperWatcher zkw, String znode)
660   throws KeeperException {
661     try {
662       Stat stat = zkw.getRecoverableZooKeeper().exists(znode, null);
663       return stat == null ? 0 : stat.getNumChildren();
664     } catch(KeeperException e) {
665       LOG.warn(zkw.prefix("Unable to get children of node " + znode));
666       zkw.keeperException(e);
667     } catch(InterruptedException e) {
668       zkw.interruptedException(e);
669     }
670     return 0;
671   }
672 
673   //
674   // Data retrieval
675   //
676 
677   /**
678    * Get znode data. Does not set a watcher.
679    * @return ZNode data, null if the node does not exist or if there is an
680    *  error.
681    */
682   public static byte [] getData(ZooKeeperWatcher zkw, String znode)
683   throws KeeperException {
684     try {
685       byte [] data = zkw.getRecoverableZooKeeper().getData(znode, null, null);
686       logRetrievedMsg(zkw, znode, data, false);
687       return data;
688     } catch (KeeperException.NoNodeException e) {
689       LOG.debug(zkw.prefix("Unable to get data of znode " + znode + " " +
690         "because node does not exist (not an error)"));
691       return null;
692     } catch (KeeperException e) {
693       LOG.warn(zkw.prefix("Unable to get data of znode " + znode), e);
694       zkw.keeperException(e);
695       return null;
696     } catch (InterruptedException e) {
697       LOG.warn(zkw.prefix("Unable to get data of znode " + znode), e);
698       zkw.interruptedException(e);
699       return null;
700     }
701   }
702 
703   /**
704    * Get the data at the specified znode and set a watch.
705    *
706    * Returns the data and sets a watch if the node exists.  Returns null and no
707    * watch is set if the node does not exist or there is an exception.
708    *
709    * @param zkw zk reference
710    * @param znode path of node
711    * @return data of the specified znode, or null
712    * @throws KeeperException if unexpected zookeeper exception
713    */
714   public static byte [] getDataAndWatch(ZooKeeperWatcher zkw, String znode)
715   throws KeeperException {
716     return getDataInternal(zkw, znode, null, true);
717   }
718 
719   /**
720    * Get the data at the specified znode and set a watch.
721    *
722    * Returns the data and sets a watch if the node exists.  Returns null and no
723    * watch is set if the node does not exist or there is an exception.
724    *
725    * @param zkw zk reference
726    * @param znode path of node
727    * @param stat object to populate the version of the znode
728    * @return data of the specified znode, or null
729    * @throws KeeperException if unexpected zookeeper exception
730    */
731   public static byte[] getDataAndWatch(ZooKeeperWatcher zkw, String znode,
732       Stat stat) throws KeeperException {
733     return getDataInternal(zkw, znode, stat, true);
734   }
735 
736   private static byte[] getDataInternal(ZooKeeperWatcher zkw, String znode, Stat stat,
737       boolean watcherSet)
738       throws KeeperException {
739     try {
740       byte [] data = zkw.getRecoverableZooKeeper().getData(znode, zkw, stat);
741       logRetrievedMsg(zkw, znode, data, watcherSet);
742       return data;
743     } catch (KeeperException.NoNodeException e) {
744       // This log can get pretty annoying when we cycle on 100ms waits.
745       // Enable trace if you really want to see it.
746       LOG.trace(zkw.prefix("Unable to get data of znode " + znode + " " +
747         "because node does not exist (not an error)"));
748       return null;
749     } catch (KeeperException e) {
750       LOG.warn(zkw.prefix("Unable to get data of znode " + znode), e);
751       zkw.keeperException(e);
752       return null;
753     } catch (InterruptedException e) {
754       LOG.warn(zkw.prefix("Unable to get data of znode " + znode), e);
755       zkw.interruptedException(e);
756       return null;
757     }
758   }
759 
760   /**
761    * Get the data at the specified znode without setting a watch.
762    *
763    * Returns the data if the node exists.  Returns null if the node does not
764    * exist.
765    *
766    * Sets the stats of the node in the passed Stat object.  Pass a null stat if
767    * not interested.
768    *
769    * @param zkw zk reference
770    * @param znode path of node
771    * @param stat node status to get if node exists
772    * @return data of the specified znode, or null if node does not exist
773    * @throws KeeperException if unexpected zookeeper exception
774    */
775   public static byte [] getDataNoWatch(ZooKeeperWatcher zkw, String znode,
776       Stat stat)
777   throws KeeperException {
778     try {
779       byte [] data = zkw.getRecoverableZooKeeper().getData(znode, null, stat);
780       logRetrievedMsg(zkw, znode, data, false);
781       return data;
782     } catch (KeeperException.NoNodeException e) {
783       LOG.debug(zkw.prefix("Unable to get data of znode " + znode + " " +
784           "because node does not exist (not necessarily an error)"));
785       return null;
786     } catch (KeeperException e) {
787       LOG.warn(zkw.prefix("Unable to get data of znode " + znode), e);
788       zkw.keeperException(e);
789       return null;
790     } catch (InterruptedException e) {
791       LOG.warn(zkw.prefix("Unable to get data of znode " + znode), e);
792       zkw.interruptedException(e);
793       return null;
794     }
795   }
796 
797   /**
798    * Returns the date of child znodes of the specified znode.  Also sets a watch on
799    * the specified znode which will capture a NodeDeleted event on the specified
800    * znode as well as NodeChildrenChanged if any children of the specified znode
801    * are created or deleted.
802    *
803    * Returns null if the specified node does not exist.  Otherwise returns a
804    * list of children of the specified node.  If the node exists but it has no
805    * children, an empty list will be returned.
806    *
807    * @param zkw zk reference
808    * @param baseNode path of node to list and watch children of
809    * @return list of data of children of the specified node, an empty list if the node
810    *          exists but has no children, and null if the node does not exist
811    * @throws KeeperException if unexpected zookeeper exception
812    * @deprecated Unused
813    */
814   public static List<NodeAndData> getChildDataAndWatchForNewChildren(
815       ZooKeeperWatcher zkw, String baseNode) throws KeeperException {
816     List<String> nodes =
817       ZKUtil.listChildrenAndWatchForNewChildren(zkw, baseNode);
818     List<NodeAndData> newNodes = new ArrayList<NodeAndData>();
819     if (nodes != null) {
820       for (String node : nodes) {
821         String nodePath = ZKUtil.joinZNode(baseNode, node);
822         byte[] data = ZKUtil.getDataAndWatch(zkw, nodePath);
823         newNodes.add(new NodeAndData(nodePath, data));
824       }
825     }
826     return newNodes;
827   }
828 
829   /**
830    * Update the data of an existing node with the expected version to have the
831    * specified data.
832    *
833    * Throws an exception if there is a version mismatch or some other problem.
834    *
835    * Sets no watches under any conditions.
836    *
837    * @param zkw zk reference
838    * @param znode
839    * @param data
840    * @param expectedVersion
841    * @throws KeeperException if unexpected zookeeper exception
842    * @throws KeeperException.BadVersionException if version mismatch
843    * @deprecated Unused
844    */
845   public static void updateExistingNodeData(ZooKeeperWatcher zkw, String znode,
846       byte [] data, int expectedVersion)
847   throws KeeperException {
848     try {
849       zkw.getRecoverableZooKeeper().setData(znode, data, expectedVersion);
850     } catch(InterruptedException ie) {
851       zkw.interruptedException(ie);
852     }
853   }
854 
855   //
856   // Data setting
857   //
858 
859   /**
860    * Sets the data of the existing znode to be the specified data.  Ensures that
861    * the current data has the specified expected version.
862    *
863    * <p>If the node does not exist, a {@link NoNodeException} will be thrown.
864    *
865    * <p>If their is a version mismatch, method returns null.
866    *
867    * <p>No watches are set but setting data will trigger other watchers of this
868    * node.
869    *
870    * <p>If there is another problem, a KeeperException will be thrown.
871    *
872    * @param zkw zk reference
873    * @param znode path of node
874    * @param data data to set for node
875    * @param expectedVersion version expected when setting data
876    * @return true if data set, false if version mismatch
877    * @throws KeeperException if unexpected zookeeper exception
878    */
879   public static boolean setData(ZooKeeperWatcher zkw, String znode,
880       byte [] data, int expectedVersion)
881   throws KeeperException, KeeperException.NoNodeException {
882     try {
883       return zkw.getRecoverableZooKeeper().setData(znode, data, expectedVersion) != null;
884     } catch (InterruptedException e) {
885       zkw.interruptedException(e);
886       return false;
887     }
888   }
889 
890   /**
891    * Set data into node creating node if it doesn't yet exist.
892    * Does not set watch.
893    *
894    * @param zkw zk reference
895    * @param znode path of node
896    * @param data data to set for node
897    * @throws KeeperException
898    */
899   public static void createSetData(final ZooKeeperWatcher zkw, final String znode,
900       final byte [] data)
901   throws KeeperException {
902     if (checkExists(zkw, znode) == -1) {
903       ZKUtil.createWithParents(zkw, znode, data);
904     } else {
905       ZKUtil.setData(zkw, znode, data);
906     }
907   }
908 
909   /**
910    * Sets the data of the existing znode to be the specified data.  The node
911    * must exist but no checks are done on the existing data or version.
912    *
913    * <p>If the node does not exist, a {@link NoNodeException} will be thrown.
914    *
915    * <p>No watches are set but setting data will trigger other watchers of this
916    * node.
917    *
918    * <p>If there is another problem, a KeeperException will be thrown.
919    *
920    * @param zkw zk reference
921    * @param znode path of node
922    * @param data data to set for node
923    * @throws KeeperException if unexpected zookeeper exception
924    */
925   public static void setData(ZooKeeperWatcher zkw, String znode, byte [] data)
926   throws KeeperException, KeeperException.NoNodeException {
927     setData(zkw, (SetData)ZKUtilOp.setData(znode, data));
928   }
929 
930   private static void setData(ZooKeeperWatcher zkw, SetData setData)
931   throws KeeperException, KeeperException.NoNodeException {
932     SetDataRequest sd = (SetDataRequest)toZooKeeperOp(zkw, setData).toRequestRecord();
933     setData(zkw, sd.getPath(), sd.getData(), sd.getVersion());
934   }
935 
936   /**
937    * Returns whether or not secure authentication is enabled
938    * (whether <code>hbase.security.authentication</code> is set to
939    * <code>kerberos</code>.
940    */
941   public static boolean isSecureZooKeeper(Configuration conf) {
942     // Detection for embedded HBase client with jaas configuration
943     // defined for third party programs.
944     try {
945       javax.security.auth.login.Configuration testConfig = javax.security.auth.login.Configuration.getConfiguration();
946       if(testConfig.getAppConfigurationEntry("Client") == null) {
947         return false;
948       }
949     } catch(Exception e) {
950       // No Jaas configuration defined.
951       return false;
952     }
953 
954     // Master & RSs uses hbase.zookeeper.client.*
955     return("kerberos".equalsIgnoreCase(conf.get("hbase.security.authentication")) &&
956          conf.get("hbase.zookeeper.client.keytab.file") != null);
957   }
958 
959   private static ArrayList<ACL> createACL(ZooKeeperWatcher zkw, String node) {
960     if (!node.startsWith(zkw.baseZNode)) {
961       return Ids.OPEN_ACL_UNSAFE;
962     }
963     if (isSecureZooKeeper(zkw.getConfiguration())) {
964       String superUser = zkw.getConfiguration().get("hbase.superuser");
965       ArrayList<ACL> acls = new ArrayList<ACL>();
966       // add permission to hbase supper user
967       if (superUser != null) {
968         acls.add(new ACL(Perms.ALL, new Id("auth", superUser)));
969       }
970       // Certain znodes are accessed directly by the client,
971       // so they must be readable by non-authenticated clients
972       if ((node.equals(zkw.baseZNode) == true) ||
973           (node.equals(zkw.metaServerZNode) == true) ||
974           (node.equals(zkw.getMasterAddressZNode()) == true) ||
975           (node.equals(zkw.clusterIdZNode) == true) ||
976           (node.equals(zkw.rsZNode) == true) ||
977           (node.equals(zkw.backupMasterAddressesZNode) == true) ||
978           (node.startsWith(zkw.assignmentZNode) == true) ||
979           (node.startsWith(zkw.tableZNode) == true)) {
980         acls.addAll(Ids.CREATOR_ALL_ACL);
981         acls.addAll(Ids.READ_ACL_UNSAFE);
982       } else {
983         acls.addAll(Ids.CREATOR_ALL_ACL);
984       }
985       return acls;
986     } else {
987       return Ids.OPEN_ACL_UNSAFE;
988     }
989   }
990 
991   //
992   // Node creation
993   //
994 
995   /**
996    *
997    * Set the specified znode to be an ephemeral node carrying the specified
998    * data.
999    *
1000    * If the node is created successfully, a watcher is also set on the node.
1001    *
1002    * If the node is not created successfully because it already exists, this
1003    * method will also set a watcher on the node.
1004    *
1005    * If there is another problem, a KeeperException will be thrown.
1006    *
1007    * @param zkw zk reference
1008    * @param znode path of node
1009    * @param data data of node
1010    * @return true if node created, false if not, watch set in both cases
1011    * @throws KeeperException if unexpected zookeeper exception
1012    */
1013   public static boolean createEphemeralNodeAndWatch(ZooKeeperWatcher zkw,
1014       String znode, byte [] data)
1015   throws KeeperException {
1016     boolean ret = true;
1017     try {
1018       zkw.getRecoverableZooKeeper().create(znode, data, createACL(zkw, znode),
1019           CreateMode.EPHEMERAL);
1020     } catch (KeeperException.NodeExistsException nee) {
1021       ret = false;
1022     } catch (InterruptedException e) {
1023       LOG.info("Interrupted", e);
1024       Thread.currentThread().interrupt();
1025     }
1026     if(!watchAndCheckExists(zkw, znode)) {
1027       // It did exist but now it doesn't, try again
1028       return createEphemeralNodeAndWatch(zkw, znode, data);
1029     }
1030     return ret;
1031   }
1032 
1033   /**
1034    * Creates the specified znode to be a persistent node carrying the specified
1035    * data.
1036    *
1037    * Returns true if the node was successfully created, false if the node
1038    * already existed.
1039    *
1040    * If the node is created successfully, a watcher is also set on the node.
1041    *
1042    * If the node is not created successfully because it already exists, this
1043    * method will also set a watcher on the node but return false.
1044    *
1045    * If there is another problem, a KeeperException will be thrown.
1046    *
1047    * @param zkw zk reference
1048    * @param znode path of node
1049    * @param data data of node
1050    * @return true if node created, false if not, watch set in both cases
1051    * @throws KeeperException if unexpected zookeeper exception
1052    */
1053   public static boolean createNodeIfNotExistsAndWatch(
1054       ZooKeeperWatcher zkw, String znode, byte [] data)
1055   throws KeeperException {
1056     boolean ret = true;
1057     try {
1058       zkw.getRecoverableZooKeeper().create(znode, data, createACL(zkw, znode),
1059           CreateMode.PERSISTENT);
1060     } catch (KeeperException.NodeExistsException nee) {
1061       ret = false;
1062     } catch (InterruptedException e) {
1063       zkw.interruptedException(e);
1064       return false;
1065     }
1066     try {
1067       zkw.getRecoverableZooKeeper().exists(znode, zkw);
1068     } catch (InterruptedException e) {
1069       zkw.interruptedException(e);
1070       return false;
1071     }
1072     return ret;
1073   }
1074 
1075   /**
1076    * Creates the specified znode with the specified data but does not watch it.
1077    *
1078    * Returns the znode of the newly created node
1079    *
1080    * If there is another problem, a KeeperException will be thrown.
1081    *
1082    * @param zkw zk reference
1083    * @param znode path of node
1084    * @param data data of node
1085    * @param createMode specifying whether the node to be created is ephemeral and/or sequential
1086    * @return true name of the newly created znode or null
1087    * @throws KeeperException if unexpected zookeeper exception
1088    */
1089   public static String createNodeIfNotExistsNoWatch(ZooKeeperWatcher zkw, String znode,
1090       byte[] data, CreateMode createMode) throws KeeperException {
1091 
1092     String createdZNode = null;
1093     try {
1094       createdZNode = zkw.getRecoverableZooKeeper().create(znode, data,
1095           createACL(zkw, znode), createMode);
1096     } catch (KeeperException.NodeExistsException nee) {
1097       return znode;
1098     } catch (InterruptedException e) {
1099       zkw.interruptedException(e);
1100       return null;
1101     }
1102     return createdZNode;
1103   }
1104 
1105   /**
1106    * Creates the specified node with the specified data and watches it.
1107    *
1108    * <p>Throws an exception if the node already exists.
1109    *
1110    * <p>The node created is persistent and open access.
1111    *
1112    * <p>Returns the version number of the created node if successful.
1113    *
1114    * @param zkw zk reference
1115    * @param znode path of node to create
1116    * @param data data of node to create
1117    * @return version of node created
1118    * @throws KeeperException if unexpected zookeeper exception
1119    * @throws KeeperException.NodeExistsException if node already exists
1120    */
1121   public static int createAndWatch(ZooKeeperWatcher zkw,
1122       String znode, byte [] data)
1123   throws KeeperException, KeeperException.NodeExistsException {
1124     try {
1125       zkw.getRecoverableZooKeeper().create(znode, data, createACL(zkw, znode),
1126           CreateMode.PERSISTENT);
1127       Stat stat = zkw.getRecoverableZooKeeper().exists(znode, zkw);
1128       if (stat == null){
1129         // Likely a race condition. Someone deleted the znode.
1130         throw KeeperException.create(KeeperException.Code.SYSTEMERROR,
1131             "ZK.exists returned null (i.e.: znode does not exist) for znode=" + znode);
1132       }
1133      return stat.getVersion();
1134     } catch (InterruptedException e) {
1135       zkw.interruptedException(e);
1136       return -1;
1137     }
1138   }
1139 
1140   /**
1141    * Async creates the specified node with the specified data.
1142    *
1143    * <p>Throws an exception if the node already exists.
1144    *
1145    * <p>The node created is persistent and open access.
1146    *
1147    * @param zkw zk reference
1148    * @param znode path of node to create
1149    * @param data data of node to create
1150    * @param cb
1151    * @param ctx
1152    * @throws KeeperException if unexpected zookeeper exception
1153    * @throws KeeperException.NodeExistsException if node already exists
1154    */
1155   public static void asyncCreate(ZooKeeperWatcher zkw,
1156       String znode, byte [] data, final AsyncCallback.StringCallback cb,
1157       final Object ctx) {
1158     zkw.getRecoverableZooKeeper().getZooKeeper().create(znode, data,
1159         createACL(zkw, znode), CreateMode.PERSISTENT, cb, ctx);
1160   }
1161 
1162   /**
1163    * Creates the specified node, iff the node does not exist.  Does not set a
1164    * watch and fails silently if the node already exists.
1165    *
1166    * The node created is persistent and open access.
1167    *
1168    * @param zkw zk reference
1169    * @param znode path of node
1170    * @throws KeeperException if unexpected zookeeper exception
1171    */
1172   public static void createAndFailSilent(ZooKeeperWatcher zkw,
1173       String znode) throws KeeperException {
1174     createAndFailSilent(zkw, znode, new byte[0]);
1175   }
1176 
1177   /**
1178    * Creates the specified node containing specified data, iff the node does not exist.  Does
1179    * not set a watch and fails silently if the node already exists.
1180    *
1181    * The node created is persistent and open access.
1182    *
1183    * @param zkw zk reference
1184    * @param znode path of node
1185    * @param data a byte array data to store in the znode
1186    * @throws KeeperException if unexpected zookeeper exception
1187    */
1188   public static void createAndFailSilent(ZooKeeperWatcher zkw,
1189       String znode, byte[] data)
1190   throws KeeperException {
1191     createAndFailSilent(zkw,
1192         (CreateAndFailSilent)ZKUtilOp.createAndFailSilent(znode, data));
1193   }
1194   
1195   private static void createAndFailSilent(ZooKeeperWatcher zkw, CreateAndFailSilent cafs)
1196   throws KeeperException {
1197     CreateRequest create = (CreateRequest)toZooKeeperOp(zkw, cafs).toRequestRecord();
1198     String znode = create.getPath();
1199     try {
1200       RecoverableZooKeeper zk = zkw.getRecoverableZooKeeper();
1201       if (zk.exists(znode, false) == null) {
1202         zk.create(znode, create.getData(), create.getAcl(), CreateMode.fromFlag(create.getFlags()));
1203       }
1204     } catch(KeeperException.NodeExistsException nee) {
1205     } catch(KeeperException.NoAuthException nee){
1206       try {
1207         if (null == zkw.getRecoverableZooKeeper().exists(znode, false)) {
1208           // If we failed to create the file and it does not already exist.
1209           throw(nee);
1210         }
1211       } catch (InterruptedException ie) {
1212         zkw.interruptedException(ie);
1213       }
1214 
1215     } catch(InterruptedException ie) {
1216       zkw.interruptedException(ie);
1217     }
1218   }
1219 
1220   /**
1221    * Creates the specified node and all parent nodes required for it to exist.
1222    *
1223    * No watches are set and no errors are thrown if the node already exists.
1224    *
1225    * The nodes created are persistent and open access.
1226    *
1227    * @param zkw zk reference
1228    * @param znode path of node
1229    * @throws KeeperException if unexpected zookeeper exception
1230    */
1231   public static void createWithParents(ZooKeeperWatcher zkw, String znode)
1232   throws KeeperException {
1233     createWithParents(zkw, znode, new byte[0]);
1234   }
1235 
1236   /**
1237    * Creates the specified node and all parent nodes required for it to exist.  The creation of
1238    * parent znodes is not atomic with the leafe znode creation but the data is written atomically
1239    * when the leaf node is created.
1240    *
1241    * No watches are set and no errors are thrown if the node already exists.
1242    *
1243    * The nodes created are persistent and open access.
1244    *
1245    * @param zkw zk reference
1246    * @param znode path of node
1247    * @throws KeeperException if unexpected zookeeper exception
1248    */
1249   public static void createWithParents(ZooKeeperWatcher zkw, String znode, byte[] data)
1250   throws KeeperException {
1251     try {
1252       if(znode == null) {
1253         return;
1254       }
1255       zkw.getRecoverableZooKeeper().create(znode, data, createACL(zkw, znode),
1256           CreateMode.PERSISTENT);
1257     } catch(KeeperException.NodeExistsException nee) {
1258       return;
1259     } catch(KeeperException.NoNodeException nne) {
1260       createWithParents(zkw, getParent(znode));
1261       createWithParents(zkw, znode, data);
1262     } catch(InterruptedException ie) {
1263       zkw.interruptedException(ie);
1264     }
1265   }
1266 
1267   //
1268   // Deletes
1269   //
1270 
1271   /**
1272    * Delete the specified node.  Sets no watches.  Throws all exceptions.
1273    */
1274   public static void deleteNode(ZooKeeperWatcher zkw, String node)
1275   throws KeeperException {
1276     deleteNode(zkw, node, -1);
1277   }
1278 
1279   /**
1280    * Delete the specified node with the specified version.  Sets no watches.
1281    * Throws all exceptions.
1282    */
1283   public static boolean deleteNode(ZooKeeperWatcher zkw, String node,
1284       int version)
1285   throws KeeperException {
1286     try {
1287       zkw.getRecoverableZooKeeper().delete(node, version);
1288       return true;
1289     } catch(KeeperException.BadVersionException bve) {
1290       return false;
1291     } catch(InterruptedException ie) {
1292       zkw.interruptedException(ie);
1293       return false;
1294     }
1295   }
1296 
1297   /**
1298    * Deletes the specified node.  Fails silent if the node does not exist.
1299    * @param zkw
1300    * @param node
1301    * @throws KeeperException
1302    */
1303   public static void deleteNodeFailSilent(ZooKeeperWatcher zkw, String node)
1304   throws KeeperException {
1305     deleteNodeFailSilent(zkw,
1306       (DeleteNodeFailSilent)ZKUtilOp.deleteNodeFailSilent(node));
1307   }
1308 
1309   private static void deleteNodeFailSilent(ZooKeeperWatcher zkw,
1310       DeleteNodeFailSilent dnfs) throws KeeperException {
1311     DeleteRequest delete = (DeleteRequest)toZooKeeperOp(zkw, dnfs).toRequestRecord();
1312     try {
1313       zkw.getRecoverableZooKeeper().delete(delete.getPath(), delete.getVersion());
1314     } catch(KeeperException.NoNodeException nne) {
1315     } catch(InterruptedException ie) {
1316       zkw.interruptedException(ie);
1317     }
1318   }
1319 
1320 
1321   /**
1322    * Delete the specified node and all of it's children.
1323    * <p>
1324    * If the node does not exist, just returns.
1325    * <p>
1326    * Sets no watches. Throws all exceptions besides dealing with deletion of
1327    * children.
1328    */
1329   public static void deleteNodeRecursively(ZooKeeperWatcher zkw, String node)
1330   throws KeeperException {
1331     try {
1332       List<String> children = ZKUtil.listChildrenNoWatch(zkw, node);
1333       // the node is already deleted, so we just finish
1334       if (children == null) return;
1335 
1336       if(!children.isEmpty()) {
1337         for(String child : children) {
1338           deleteNodeRecursively(zkw, joinZNode(node, child));
1339         }
1340       }
1341       //Zookeeper Watches are one time triggers; When children of parent nodes are deleted recursively.
1342       //Must set another watch, get notified of delete node
1343       if (zkw.getRecoverableZooKeeper().exists(node, zkw) != null){
1344         zkw.getRecoverableZooKeeper().delete(node, -1);
1345       }
1346     } catch(InterruptedException ie) {
1347       zkw.interruptedException(ie);
1348     }
1349   }
1350 
1351   /**
1352    * Delete all the children of the specified node but not the node itself.
1353    *
1354    * Sets no watches.  Throws all exceptions besides dealing with deletion of
1355    * children.
1356    */
1357   public static void deleteChildrenRecursively(ZooKeeperWatcher zkw, String node)
1358   throws KeeperException {
1359     List<String> children = ZKUtil.listChildrenNoWatch(zkw, node);
1360     if (children == null || children.isEmpty()) return;
1361     for(String child : children) {
1362       deleteNodeRecursively(zkw, joinZNode(node, child));
1363     }
1364   }
1365 
1366   /**
1367    * Represents an action taken by ZKUtil, e.g. createAndFailSilent.
1368    * These actions are higher-level than ZKOp actions, which represent
1369    * individual actions in the ZooKeeper API, like create.
1370    */
1371   public abstract static class ZKUtilOp {
1372     private String path;
1373 
1374     private ZKUtilOp(String path) {
1375       this.path = path;
1376     }
1377 
1378     /**
1379      * @return a createAndFailSilent ZKUtilOp
1380      */
1381     public static ZKUtilOp createAndFailSilent(String path, byte[] data) {
1382       return new CreateAndFailSilent(path, data);
1383     }
1384 
1385     /**
1386      * @return a deleteNodeFailSilent ZKUtilOP
1387      */
1388     public static ZKUtilOp deleteNodeFailSilent(String path) {
1389       return new DeleteNodeFailSilent(path);
1390     }
1391 
1392     /**
1393      * @return a setData ZKUtilOp
1394      */
1395     public static ZKUtilOp setData(String path, byte [] data) {
1396       return new SetData(path, data);
1397     }
1398 
1399     /**
1400      * @return path to znode where the ZKOp will occur
1401      */
1402     public String getPath() {
1403       return path;
1404     }
1405 
1406     /**
1407      * ZKUtilOp representing createAndFailSilent in ZooKeeper
1408      * (attempt to create node, ignore error if already exists)
1409      */
1410     public static class CreateAndFailSilent extends ZKUtilOp {
1411       private byte [] data;
1412 
1413       private CreateAndFailSilent(String path, byte [] data) {
1414         super(path);
1415         this.data = data;
1416       }
1417 
1418       public byte[] getData() {
1419         return data;
1420       }
1421 
1422       @Override
1423       public boolean equals(Object o) {
1424         if (this == o) return true;
1425         if (!(o instanceof CreateAndFailSilent)) return false;
1426 
1427         CreateAndFailSilent op = (CreateAndFailSilent) o;
1428         return getPath().equals(op.getPath()) && Arrays.equals(data, op.data);
1429       }
1430 
1431       @Override
1432       public int hashCode() {
1433         int ret = 17 + getPath().hashCode() * 31;
1434         return ret * 31 + Bytes.hashCode(data);
1435       }
1436     }
1437 
1438     /**
1439      * ZKUtilOp representing deleteNodeFailSilent in ZooKeeper
1440      * (attempt to delete node, ignore error if node doesn't exist)
1441      */
1442     public static class DeleteNodeFailSilent extends ZKUtilOp {
1443       private DeleteNodeFailSilent(String path) {
1444         super(path);
1445       }
1446 
1447       @Override
1448       public boolean equals(Object o) {
1449         if (this == o) return true;
1450         if (!(o instanceof DeleteNodeFailSilent)) return false;
1451 
1452         return super.equals(o);
1453       }
1454 
1455       @Override
1456       public int hashCode() {
1457         return getPath().hashCode();
1458       }
1459     }
1460 
1461     /**
1462      * ZKUtilOp representing setData in ZooKeeper
1463      */
1464     public static class SetData extends ZKUtilOp {
1465       private byte [] data;
1466 
1467       private SetData(String path, byte [] data) {
1468         super(path);
1469         this.data = data;
1470       }
1471 
1472       public byte[] getData() {
1473         return data;
1474       }
1475 
1476       @Override
1477       public boolean equals(Object o) {
1478         if (this == o) return true;
1479         if (!(o instanceof SetData)) return false;
1480 
1481         SetData op = (SetData) o;
1482         return getPath().equals(op.getPath()) && Arrays.equals(data, op.data);
1483       }
1484 
1485       @Override
1486       public int hashCode() {
1487         int ret = getPath().hashCode();
1488         return ret * 31 + Bytes.hashCode(data);
1489       }
1490     }
1491   }
1492 
1493   /**
1494    * Convert from ZKUtilOp to ZKOp
1495    */
1496   private static Op toZooKeeperOp(ZooKeeperWatcher zkw, ZKUtilOp op)
1497   throws UnsupportedOperationException {
1498     if(op == null) return null;
1499 
1500     if (op instanceof CreateAndFailSilent) {
1501       CreateAndFailSilent cafs = (CreateAndFailSilent)op;
1502       return Op.create(cafs.getPath(), cafs.getData(), createACL(zkw, cafs.getPath()),
1503         CreateMode.PERSISTENT);
1504     } else if (op instanceof DeleteNodeFailSilent) {
1505       DeleteNodeFailSilent dnfs = (DeleteNodeFailSilent)op;
1506       return Op.delete(dnfs.getPath(), -1);
1507     } else if (op instanceof SetData) {
1508       SetData sd = (SetData)op;
1509       return Op.setData(sd.getPath(), sd.getData(), -1);
1510     } else {
1511       throw new UnsupportedOperationException("Unexpected ZKUtilOp type: "
1512         + op.getClass().getName());
1513     }
1514   }
1515 
1516   /**
1517    * If hbase.zookeeper.useMulti is true, use ZooKeeper's multi-update functionality.
1518    * Otherwise, run the list of operations sequentially.
1519    *
1520    * If all of the following are true:
1521    * - runSequentialOnMultiFailure is true
1522    * - hbase.zookeeper.useMulti is true
1523    * - on calling multi, we get a ZooKeeper exception that can be handled by a sequential call(*)
1524    * Then:
1525    * - we retry the operations one-by-one (sequentially)
1526    *
1527    * Note *: an example is receiving a NodeExistsException from a "create" call.  Without multi,
1528    * a user could call "createAndFailSilent" to ensure that a node exists if they don't care who
1529    * actually created the node (i.e. the NodeExistsException from ZooKeeper is caught).
1530    * This will cause all operations in the multi to fail, however, because
1531    * the NodeExistsException that zk.create throws will fail the multi transaction.
1532    * In this case, if the previous conditions hold, the commands are run sequentially, which should
1533    * result in the correct final state, but means that the operations will not run atomically.
1534    *
1535    * @throws KeeperException
1536    */
1537   public static void multiOrSequential(ZooKeeperWatcher zkw, List<ZKUtilOp> ops,
1538       boolean runSequentialOnMultiFailure) throws KeeperException {
1539     if (ops == null) return;
1540     boolean useMulti = zkw.getConfiguration().getBoolean(HConstants.ZOOKEEPER_USEMULTI, false);
1541 
1542     if (useMulti) {
1543       List<Op> zkOps = new LinkedList<Op>();
1544       for (ZKUtilOp op : ops) {
1545         zkOps.add(toZooKeeperOp(zkw, op));
1546       }
1547       try {
1548         zkw.getRecoverableZooKeeper().multi(zkOps);
1549       } catch (KeeperException ke) {
1550        switch (ke.code()) {
1551          case NODEEXISTS:
1552          case NONODE:
1553          case BADVERSION:
1554          case NOAUTH:
1555            // if we get an exception that could be solved by running sequentially
1556            // (and the client asked us to), then break out and run sequentially
1557            if (runSequentialOnMultiFailure) {
1558              LOG.info("On call to ZK.multi, received exception: " + ke.toString() + "."
1559                + "  Attempting to run operations sequentially because"
1560                + " runSequentialOnMultiFailure is: " + runSequentialOnMultiFailure + ".");
1561              processSequentially(zkw, ops);
1562              break;
1563            }
1564           default:
1565             throw ke;
1566         }
1567       } catch (InterruptedException ie) {
1568         zkw.interruptedException(ie);
1569       }
1570     } else {
1571       // run sequentially
1572       processSequentially(zkw, ops);
1573     }
1574 
1575   }
1576 
1577   private static void processSequentially(ZooKeeperWatcher zkw, List<ZKUtilOp> ops)
1578       throws KeeperException, NoNodeException {
1579     for (ZKUtilOp op : ops) {
1580       if (op instanceof CreateAndFailSilent) {
1581         createAndFailSilent(zkw, (CreateAndFailSilent) op);
1582       } else if (op instanceof DeleteNodeFailSilent) {
1583         deleteNodeFailSilent(zkw, (DeleteNodeFailSilent) op);
1584       } else if (op instanceof SetData) {
1585         setData(zkw, (SetData) op);
1586       } else {
1587         throw new UnsupportedOperationException("Unexpected ZKUtilOp type: "
1588             + op.getClass().getName());
1589       }
1590     }
1591   }
1592 
1593   //
1594   // ZooKeeper cluster information
1595   //
1596 
1597   /** @return String dump of everything in ZooKeeper. */
1598   public static String dump(ZooKeeperWatcher zkw) {
1599     StringBuilder sb = new StringBuilder();
1600     try {
1601       sb.append("HBase is rooted at ").append(zkw.baseZNode);
1602       sb.append("\nActive master address: ");
1603       try {
1604         sb.append(MasterAddressTracker.getMasterAddress(zkw));
1605       } catch (IOException e) {
1606         sb.append("<<FAILED LOOKUP: " + e.getMessage() + ">>");
1607       }
1608       sb.append("\nBackup master addresses:");
1609       for (String child : listChildrenNoWatch(zkw,
1610                                               zkw.backupMasterAddressesZNode)) {
1611         sb.append("\n ").append(child);
1612       }
1613       sb.append("\nRegion server holding hbase:meta: " + MetaRegionTracker.getMetaRegionLocation(zkw));
1614       sb.append("\nRegion servers:");
1615       for (String child : listChildrenNoWatch(zkw, zkw.rsZNode)) {
1616         sb.append("\n ").append(child);
1617       }
1618       try {
1619         getReplicationZnodesDump(zkw, sb);
1620       } catch (KeeperException ke) {
1621         LOG.warn("Couldn't get the replication znode dump", ke);
1622       }
1623       sb.append("\nQuorum Server Statistics:");
1624       String[] servers = zkw.getQuorum().split(",");
1625       for (String server : servers) {
1626         sb.append("\n ").append(server);
1627         try {
1628           String[] stat = getServerStats(server, ZKUtil.zkDumpConnectionTimeOut);
1629 
1630           if (stat == null) {
1631             sb.append("[Error] invalid quorum server: " + server);
1632             break;
1633           }
1634 
1635           for (String s : stat) {
1636             sb.append("\n  ").append(s);
1637           }
1638         } catch (Exception e) {
1639           sb.append("\n  ERROR: ").append(e.getMessage());
1640         }
1641       }
1642     } catch (KeeperException ke) {
1643       sb.append("\nFATAL ZooKeeper Exception!\n");
1644       sb.append("\n" + ke.getMessage());
1645     }
1646     return sb.toString();
1647   }
1648 
1649   /**
1650    * Appends replication znodes to the passed StringBuilder.
1651    * @param zkw
1652    * @param sb
1653    * @throws KeeperException
1654    */
1655   private static void getReplicationZnodesDump(ZooKeeperWatcher zkw, StringBuilder sb)
1656       throws KeeperException {
1657     String replicationZNodeName = zkw.getConfiguration().get("zookeeper.znode.replication",
1658       "replication");
1659     String replicationZnode = joinZNode(zkw.baseZNode, replicationZNodeName);
1660     if (ZKUtil.checkExists(zkw, replicationZnode) == -1) return;
1661     // do a ls -r on this znode
1662     sb.append("\n").append(replicationZnode).append(": ");
1663     List<String> children = ZKUtil.listChildrenNoWatch(zkw, replicationZnode);
1664     for (String child : children) {
1665       String znode = joinZNode(replicationZnode, child);
1666       if (child.equals(zkw.getConfiguration().get("zookeeper.znode.replication.peers", "peers"))) {
1667         appendPeersZnodes(zkw, znode, sb);
1668       } else if (child.equals(zkw.getConfiguration().
1669           get("zookeeper.znode.replication.rs", "rs"))) {
1670         appendRSZnodes(zkw, znode, sb);
1671       }
1672     }
1673   }
1674 
1675   private static void appendRSZnodes(ZooKeeperWatcher zkw, String znode, StringBuilder sb)
1676       throws KeeperException {
1677     List<String> stack = new LinkedList<String>();
1678     stack.add(znode);
1679     do {
1680       String znodeToProcess = stack.remove(stack.size() - 1);
1681       sb.append("\n").append(znodeToProcess).append(": ");
1682       byte[] data = ZKUtil.getData(zkw, znodeToProcess);
1683       if (data != null && data.length > 0) { // log position
1684         long position = 0;
1685         try {
1686           position = ZKUtil.parseHLogPositionFrom(ZKUtil.getData(zkw, znodeToProcess));
1687           sb.append(position);
1688         } catch (Exception e) {
1689         }
1690       }
1691       for (String zNodeChild : ZKUtil.listChildrenNoWatch(zkw, znodeToProcess)) {
1692         stack.add(ZKUtil.joinZNode(znodeToProcess, zNodeChild));
1693       }
1694     } while (stack.size() > 0);
1695   }
1696 
1697   private static void appendPeersZnodes(ZooKeeperWatcher zkw, String peersZnode,
1698     StringBuilder sb) throws KeeperException {
1699     int pblen = ProtobufUtil.lengthOfPBMagic();
1700     sb.append("\n").append(peersZnode).append(": ");
1701     for (String peerIdZnode : ZKUtil.listChildrenNoWatch(zkw, peersZnode)) {
1702       String znodeToProcess = ZKUtil.joinZNode(peersZnode, peerIdZnode);
1703       byte[] data = ZKUtil.getData(zkw, znodeToProcess);
1704       // parse the data of the above peer znode.
1705       try {
1706       String clusterKey = ZooKeeperProtos.ReplicationPeer.newBuilder().
1707         mergeFrom(data, pblen, data.length - pblen).getClusterkey();
1708       sb.append("\n").append(znodeToProcess).append(": ").append(clusterKey);
1709       // add the peer-state.
1710       appendPeerState(zkw, znodeToProcess, sb);
1711       } catch (InvalidProtocolBufferException ipbe) {
1712         LOG.warn("Got Exception while parsing peer: " + znodeToProcess, ipbe);
1713       }
1714     }
1715   }
1716 
1717   private static void appendPeerState(ZooKeeperWatcher zkw, String znodeToProcess,
1718       StringBuilder sb) throws KeeperException, InvalidProtocolBufferException {
1719     String peerState = zkw.getConfiguration().get("zookeeper.znode.replication.peers.state",
1720       "peer-state");
1721     int pblen = ProtobufUtil.lengthOfPBMagic();
1722     for (String child : ZKUtil.listChildrenNoWatch(zkw, znodeToProcess)) {
1723       if (!child.equals(peerState)) continue;
1724       String peerStateZnode = ZKUtil.joinZNode(znodeToProcess, child);
1725       sb.append("\n").append(peerStateZnode).append(": ");
1726       byte[] peerStateData = ZKUtil.getData(zkw, peerStateZnode);
1727       sb.append(ZooKeeperProtos.ReplicationState.newBuilder()
1728           .mergeFrom(peerStateData, pblen, peerStateData.length - pblen).getState().name());
1729     }
1730   }
1731 
1732   /**
1733    * Gets the statistics from the given server.
1734    *
1735    * @param server  The server to get the statistics from.
1736    * @param timeout  The socket timeout to use.
1737    * @return The array of response strings.
1738    * @throws IOException When the socket communication fails.
1739    */
1740   public static String[] getServerStats(String server, int timeout)
1741   throws IOException {
1742     String[] sp = server.split(":");
1743     if (sp == null || sp.length == 0) {
1744       return null;
1745     }
1746 
1747     String host = sp[0];
1748     int port = sp.length > 1 ? Integer.parseInt(sp[1])
1749         : HConstants.DEFAULT_ZOOKEPER_CLIENT_PORT;
1750 
1751     Socket socket = new Socket();
1752     InetSocketAddress sockAddr = new InetSocketAddress(host, port);
1753     socket.connect(sockAddr, timeout);
1754 
1755     socket.setSoTimeout(timeout);
1756     PrintWriter out = new PrintWriter(socket.getOutputStream(), true);
1757     BufferedReader in = new BufferedReader(new InputStreamReader(
1758       socket.getInputStream()));
1759     out.println("stat");
1760     out.flush();
1761     ArrayList<String> res = new ArrayList<String>();
1762     while (true) {
1763       String line = in.readLine();
1764       if (line != null) {
1765         res.add(line);
1766       } else {
1767         break;
1768       }
1769     }
1770     socket.close();
1771     return res.toArray(new String[res.size()]);
1772   }
1773 
1774   private static void logRetrievedMsg(final ZooKeeperWatcher zkw,
1775       final String znode, final byte [] data, final boolean watcherSet) {
1776     if (!LOG.isTraceEnabled()) return;
1777     LOG.trace(zkw.prefix("Retrieved " + ((data == null)? 0: data.length) +
1778       " byte(s) of data from znode " + znode +
1779       (watcherSet? " and set watcher; ": "; data=") +
1780       (data == null? "null": data.length == 0? "empty": (
1781           znode.startsWith(zkw.assignmentZNode)?
1782             ZKAssign.toString(data): // We should not be doing this reaching into another class
1783           znode.startsWith(zkw.metaServerZNode)?
1784             getServerNameOrEmptyString(data):
1785           znode.startsWith(zkw.backupMasterAddressesZNode)?
1786             getServerNameOrEmptyString(data):
1787           StringUtils.abbreviate(Bytes.toStringBinary(data), 32)))));
1788   }
1789 
1790   private static String getServerNameOrEmptyString(final byte [] data) {
1791     try {
1792       return ServerName.parseFrom(data).toString();
1793     } catch (DeserializationException e) {
1794       return "";
1795     }
1796   }
1797 
1798   /**
1799    * Waits for HBase installation's base (parent) znode to become available.
1800    * @throws IOException on ZK errors
1801    */
1802   public static void waitForBaseZNode(Configuration conf) throws IOException {
1803     LOG.info("Waiting until the base znode is available");
1804     String parentZNode = conf.get(HConstants.ZOOKEEPER_ZNODE_PARENT,
1805         HConstants.DEFAULT_ZOOKEEPER_ZNODE_PARENT);
1806     ZooKeeper zk = new ZooKeeper(ZKConfig.getZKQuorumServersString(conf),
1807         conf.getInt(HConstants.ZK_SESSION_TIMEOUT,
1808         HConstants.DEFAULT_ZK_SESSION_TIMEOUT), EmptyWatcher.instance);
1809 
1810     final int maxTimeMs = 10000;
1811     final int maxNumAttempts = maxTimeMs / HConstants.SOCKET_RETRY_WAIT_MS;
1812 
1813     KeeperException keeperEx = null;
1814     try {
1815       try {
1816         for (int attempt = 0; attempt < maxNumAttempts; ++attempt) {
1817           try {
1818             if (zk.exists(parentZNode, false) != null) {
1819               LOG.info("Parent znode exists: " + parentZNode);
1820               keeperEx = null;
1821               break;
1822             }
1823           } catch (KeeperException e) {
1824             keeperEx = e;
1825           }
1826           Threads.sleepWithoutInterrupt(HConstants.SOCKET_RETRY_WAIT_MS);
1827         }
1828       } finally {
1829         zk.close();
1830       }
1831     } catch (InterruptedException ex) {
1832       Thread.currentThread().interrupt();
1833     }
1834 
1835     if (keeperEx != null) {
1836       throw new IOException(keeperEx);
1837     }
1838   }
1839 
1840 
1841   public static byte[] blockUntilAvailable(
1842     final ZooKeeperWatcher zkw, final String znode, final long timeout)
1843     throws InterruptedException {
1844     if (timeout < 0) throw new IllegalArgumentException();
1845     if (zkw == null) throw new IllegalArgumentException();
1846     if (znode == null) throw new IllegalArgumentException();
1847 
1848     byte[] data = null;
1849     boolean finished = false;
1850     final long endTime = System.currentTimeMillis() + timeout;
1851     while (!finished) {
1852       try {
1853         data = ZKUtil.getData(zkw, znode);
1854       } catch(KeeperException e) {
1855         if (e instanceof KeeperException.SessionExpiredException
1856             || e instanceof KeeperException.AuthFailedException) {
1857           // non-recoverable errors so stop here
1858           throw new InterruptedException("interrupted due to " + e);
1859         }
1860         LOG.warn("Unexpected exception handling blockUntilAvailable", e);
1861       }
1862 
1863       if (data == null && (System.currentTimeMillis() +
1864         HConstants.SOCKET_RETRY_WAIT_MS < endTime)) {
1865         Thread.sleep(HConstants.SOCKET_RETRY_WAIT_MS);
1866       } else {
1867         finished = true;
1868       }
1869     }
1870 
1871     return data;
1872   }
1873 
1874 
1875   /**
1876    * Convert a {@link DeserializationException} to a more palatable {@link KeeperException}.
1877    * Used when can't let a {@link DeserializationException} out w/o changing public API.
1878    * @param e Exception to convert
1879    * @return Converted exception
1880    */
1881   public static KeeperException convert(final DeserializationException e) {
1882     KeeperException ke = new KeeperException.DataInconsistencyException();
1883     ke.initCause(e);
1884     return ke;
1885   }
1886 
1887   /**
1888    * Recursively print the current state of ZK (non-transactional)
1889    * @param root name of the root directory in zk to print
1890    * @throws KeeperException
1891    */
1892   public static void logZKTree(ZooKeeperWatcher zkw, String root) {
1893     if (!LOG.isDebugEnabled()) return;
1894     LOG.debug("Current zk system:");
1895     String prefix = "|-";
1896     LOG.debug(prefix + root);
1897     try {
1898       logZKTree(zkw, root, prefix);
1899     } catch (KeeperException e) {
1900       throw new RuntimeException(e);
1901     }
1902   }
1903 
1904   /**
1905    * Helper method to print the current state of the ZK tree.
1906    * @see #logZKTree(ZooKeeperWatcher, String)
1907    * @throws KeeperException if an unexpected exception occurs
1908    */
1909   protected static void logZKTree(ZooKeeperWatcher zkw, String root, String prefix) throws KeeperException {
1910     List<String> children = ZKUtil.listChildrenNoWatch(zkw, root);
1911     if (children == null) return;
1912     for (String child : children) {
1913       LOG.debug(prefix + child);
1914       String node = ZKUtil.joinZNode(root.equals("/") ? "" : root, child);
1915       logZKTree(zkw, node, prefix + "---");
1916     }
1917   }
1918 
1919   /**
1920    * @param position
1921    * @return Serialized protobuf of <code>position</code> with pb magic prefix prepended suitable
1922    *         for use as content of an hlog position in a replication queue.
1923    */
1924   public static byte[] positionToByteArray(final long position) {
1925     byte[] bytes = ZooKeeperProtos.ReplicationHLogPosition.newBuilder().setPosition(position)
1926         .build().toByteArray();
1927     return ProtobufUtil.prependPBMagic(bytes);
1928   }
1929 
1930   /**
1931    * @param bytes - Content of a HLog position znode.
1932    * @return long - The current HLog position.
1933    * @throws DeserializationException
1934    */
1935   public static long parseHLogPositionFrom(final byte[] bytes) throws DeserializationException {
1936     if (bytes == null) {
1937       throw new DeserializationException("Unable to parse null HLog position.");
1938     }
1939     if (ProtobufUtil.isPBMagicPrefix(bytes)) {
1940       int pblen = ProtobufUtil.lengthOfPBMagic();
1941       ZooKeeperProtos.ReplicationHLogPosition.Builder builder =
1942           ZooKeeperProtos.ReplicationHLogPosition.newBuilder();
1943       ZooKeeperProtos.ReplicationHLogPosition position;
1944       try {
1945         position = builder.mergeFrom(bytes, pblen, bytes.length - pblen).build();
1946       } catch (InvalidProtocolBufferException e) {
1947         throw new DeserializationException(e);
1948       }
1949       return position.getPosition();
1950     } else {
1951       if (bytes.length > 0) {
1952         return Bytes.toLong(bytes);
1953       }
1954       return 0;
1955     }
1956   }
1957 
1958   /**
1959    * @param regionLastFlushedSequenceId the flushed sequence id of a region which is the min of its
1960    *          store max seq ids
1961    * @param storeSequenceIds column family to sequence Id map
1962    * @return Serialized protobuf of <code>RegionSequenceIds</code> with pb magic prefix prepended
1963    *         suitable for use to filter wal edits in distributedLogReplay mode
1964    */
1965   public static byte[] regionSequenceIdsToByteArray(final Long regionLastFlushedSequenceId,
1966       final Map<byte[], Long> storeSequenceIds) {
1967     ZooKeeperProtos.RegionStoreSequenceIds.Builder regionSequenceIdsBuilder =
1968         ZooKeeperProtos.RegionStoreSequenceIds.newBuilder();
1969     ZooKeeperProtos.StoreSequenceId.Builder storeSequenceIdBuilder =
1970         ZooKeeperProtos.StoreSequenceId.newBuilder();
1971     if (storeSequenceIds != null) {
1972       for (Map.Entry<byte[], Long> e : storeSequenceIds.entrySet()){
1973         byte[] columnFamilyName = e.getKey();
1974         Long curSeqId = e.getValue();
1975         storeSequenceIdBuilder.setFamilyName(ByteStringer.wrap(columnFamilyName));
1976         storeSequenceIdBuilder.setSequenceId(curSeqId);
1977         regionSequenceIdsBuilder.addStoreSequenceId(storeSequenceIdBuilder.build());
1978         storeSequenceIdBuilder.clear();
1979       }
1980     }
1981     regionSequenceIdsBuilder.setLastFlushedSequenceId(regionLastFlushedSequenceId);
1982     byte[] result = regionSequenceIdsBuilder.build().toByteArray();
1983     return ProtobufUtil.prependPBMagic(result);
1984   }
1985 
1986   /**
1987    * @param bytes Content of serialized data of RegionStoreSequenceIds
1988    * @return a RegionStoreSequenceIds object
1989    * @throws DeserializationException
1990    */
1991   public static RegionStoreSequenceIds parseRegionStoreSequenceIds(final byte[] bytes)
1992       throws DeserializationException {
1993     if (bytes == null || !ProtobufUtil.isPBMagicPrefix(bytes)) {
1994       throw new DeserializationException("Unable to parse RegionStoreSequenceIds.");
1995     }
1996     RegionStoreSequenceIds.Builder regionSequenceIdsBuilder =
1997         ZooKeeperProtos.RegionStoreSequenceIds.newBuilder();
1998     int pblen = ProtobufUtil.lengthOfPBMagic();
1999     RegionStoreSequenceIds storeIds = null;
2000     try {
2001       storeIds = regionSequenceIdsBuilder.mergeFrom(bytes, pblen, bytes.length - pblen).build();
2002     } catch (InvalidProtocolBufferException e) {
2003       throw new DeserializationException(e);
2004     }
2005     return storeIds;
2006   }
2007 }