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