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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.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, InterruptedException {
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     }
695   }
696 
697   /**
698    * Get the data at the specified znode and set a watch.
699    *
700    * Returns the data and sets a watch if the node exists.  Returns null and no
701    * watch is set if the node does not exist or there is an exception.
702    *
703    * @param zkw zk reference
704    * @param znode path of node
705    * @return data of the specified znode, or null
706    * @throws KeeperException if unexpected zookeeper exception
707    */
708   public static byte [] getDataAndWatch(ZooKeeperWatcher zkw, String znode)
709   throws KeeperException {
710     return getDataInternal(zkw, znode, null, true);
711   }
712 
713   /**
714    * Get the data at the specified znode and set a watch.
715    *
716    * Returns the data and sets a watch if the node exists.  Returns null and no
717    * watch is set if the node does not exist or there is an exception.
718    *
719    * @param zkw zk reference
720    * @param znode path of node
721    * @param stat object to populate the version of the znode
722    * @return data of the specified znode, or null
723    * @throws KeeperException if unexpected zookeeper exception
724    */
725   public static byte[] getDataAndWatch(ZooKeeperWatcher zkw, String znode,
726       Stat stat) throws KeeperException {
727     return getDataInternal(zkw, znode, stat, true);
728   }
729 
730   private static byte[] getDataInternal(ZooKeeperWatcher zkw, String znode, Stat stat,
731       boolean watcherSet)
732       throws KeeperException {
733     try {
734       byte [] data = zkw.getRecoverableZooKeeper().getData(znode, zkw, stat);
735       logRetrievedMsg(zkw, znode, data, watcherSet);
736       return data;
737     } catch (KeeperException.NoNodeException e) {
738       // This log can get pretty annoying when we cycle on 100ms waits.
739       // Enable trace if you really want to see it.
740       LOG.trace(zkw.prefix("Unable to get data of znode " + znode + " " +
741         "because node does not exist (not an error)"));
742       return null;
743     } catch (KeeperException e) {
744       LOG.warn(zkw.prefix("Unable to get data of znode " + znode), e);
745       zkw.keeperException(e);
746       return null;
747     } catch (InterruptedException e) {
748       LOG.warn(zkw.prefix("Unable to get data of znode " + znode), e);
749       zkw.interruptedException(e);
750       return null;
751     }
752   }
753 
754   /**
755    * Get the data at the specified znode without setting a watch.
756    *
757    * Returns the data if the node exists.  Returns null if the node does not
758    * exist.
759    *
760    * Sets the stats of the node in the passed Stat object.  Pass a null stat if
761    * not interested.
762    *
763    * @param zkw zk reference
764    * @param znode path of node
765    * @param stat node status to get if node exists
766    * @return data of the specified znode, or null if node does not exist
767    * @throws KeeperException if unexpected zookeeper exception
768    */
769   public static byte [] getDataNoWatch(ZooKeeperWatcher zkw, String znode,
770       Stat stat)
771   throws KeeperException {
772     try {
773       byte [] data = zkw.getRecoverableZooKeeper().getData(znode, null, stat);
774       logRetrievedMsg(zkw, znode, data, false);
775       return data;
776     } catch (KeeperException.NoNodeException e) {
777       LOG.debug(zkw.prefix("Unable to get data of znode " + znode + " " +
778           "because node does not exist (not necessarily an error)"));
779       return null;
780     } catch (KeeperException e) {
781       LOG.warn(zkw.prefix("Unable to get data of znode " + znode), e);
782       zkw.keeperException(e);
783       return null;
784     } catch (InterruptedException e) {
785       LOG.warn(zkw.prefix("Unable to get data of znode " + znode), e);
786       zkw.interruptedException(e);
787       return null;
788     }
789   }
790 
791   /**
792    * Returns the date of child znodes of the specified znode.  Also sets a watch on
793    * the specified znode which will capture a NodeDeleted event on the specified
794    * znode as well as NodeChildrenChanged if any children of the specified znode
795    * are created or deleted.
796    *
797    * Returns null if the specified node does not exist.  Otherwise returns a
798    * list of children of the specified node.  If the node exists but it has no
799    * children, an empty list will be returned.
800    *
801    * @param zkw zk reference
802    * @param baseNode path of node to list and watch children of
803    * @return list of data of children of the specified node, an empty list if the node
804    *          exists but has no children, and null if the node does not exist
805    * @throws KeeperException if unexpected zookeeper exception
806    * @deprecated Unused
807    */
808   public static List<NodeAndData> getChildDataAndWatchForNewChildren(
809       ZooKeeperWatcher zkw, String baseNode) throws KeeperException {
810     List<String> nodes =
811       ZKUtil.listChildrenAndWatchForNewChildren(zkw, baseNode);
812     if (nodes != null) {
813       List<NodeAndData> newNodes = new ArrayList<NodeAndData>();
814       for (String node : nodes) {
815         String nodePath = ZKUtil.joinZNode(baseNode, node);
816         byte[] data = ZKUtil.getDataAndWatch(zkw, nodePath);
817         newNodes.add(new NodeAndData(nodePath, data));
818       }
819       return newNodes;
820     }
821     return null;
822   }
823 
824   /**
825    * Update the data of an existing node with the expected version to have the
826    * specified data.
827    *
828    * Throws an exception if there is a version mismatch or some other problem.
829    *
830    * Sets no watches under any conditions.
831    *
832    * @param zkw zk reference
833    * @param znode
834    * @param data
835    * @param expectedVersion
836    * @throws KeeperException if unexpected zookeeper exception
837    * @throws KeeperException.BadVersionException if version mismatch
838    * @deprecated Unused
839    */
840   public static void updateExistingNodeData(ZooKeeperWatcher zkw, String znode,
841       byte [] data, int expectedVersion)
842   throws KeeperException {
843     try {
844       zkw.getRecoverableZooKeeper().setData(znode, data, expectedVersion);
845     } catch(InterruptedException ie) {
846       zkw.interruptedException(ie);
847     }
848   }
849 
850   //
851   // Data setting
852   //
853 
854   /**
855    * Sets the data of the existing znode to be the specified data.  Ensures that
856    * the current data has the specified expected version.
857    *
858    * <p>If the node does not exist, a {@link NoNodeException} will be thrown.
859    *
860    * <p>If their is a version mismatch, method returns null.
861    *
862    * <p>No watches are set but setting data will trigger other watchers of this
863    * node.
864    *
865    * <p>If there is another problem, a KeeperException will be thrown.
866    *
867    * @param zkw zk reference
868    * @param znode path of node
869    * @param data data to set for node
870    * @param expectedVersion version expected when setting data
871    * @return true if data set, false if version mismatch
872    * @throws KeeperException if unexpected zookeeper exception
873    */
874   public static boolean setData(ZooKeeperWatcher zkw, String znode,
875       byte [] data, int expectedVersion)
876   throws KeeperException, KeeperException.NoNodeException {
877     try {
878       return zkw.getRecoverableZooKeeper().setData(znode, data, expectedVersion) != null;
879     } catch (InterruptedException e) {
880       zkw.interruptedException(e);
881       return false;
882     }
883   }
884 
885   /**
886    * Set data into node creating node if it doesn't yet exist.
887    * Does not set watch.
888    *
889    * @param zkw zk reference
890    * @param znode path of node
891    * @param data data to set for node
892    * @throws KeeperException
893    */
894   public static void createSetData(final ZooKeeperWatcher zkw, final String znode,
895       final byte [] data)
896   throws KeeperException {
897     if (checkExists(zkw, znode) == -1) {
898       ZKUtil.createWithParents(zkw, znode, data);
899     } else {
900       ZKUtil.setData(zkw, znode, data);
901     }
902   }
903 
904   /**
905    * Sets the data of the existing znode to be the specified data.  The node
906    * must exist but no checks are done on the existing data or version.
907    *
908    * <p>If the node does not exist, a {@link NoNodeException} will be thrown.
909    *
910    * <p>No watches are set but setting data will trigger other watchers of this
911    * node.
912    *
913    * <p>If there is another problem, a KeeperException will be thrown.
914    *
915    * @param zkw zk reference
916    * @param znode path of node
917    * @param data data to set for node
918    * @throws KeeperException if unexpected zookeeper exception
919    */
920   public static void setData(ZooKeeperWatcher zkw, String znode, byte [] data)
921   throws KeeperException, KeeperException.NoNodeException {
922     setData(zkw, (SetData)ZKUtilOp.setData(znode, data));
923   }
924 
925   private static void setData(ZooKeeperWatcher zkw, SetData setData)
926   throws KeeperException, KeeperException.NoNodeException {
927     SetDataRequest sd = (SetDataRequest)toZooKeeperOp(zkw, setData).toRequestRecord();
928     setData(zkw, sd.getPath(), sd.getData(), sd.getVersion());
929   }
930 
931   /**
932    * Returns whether or not secure authentication is enabled
933    * (whether <code>hbase.security.authentication</code> is set to
934    * <code>kerberos</code>.
935    */
936   public static boolean isSecureZooKeeper(Configuration conf) {
937     // Detection for embedded HBase client with jaas configuration
938     // defined for third party programs.
939     try {
940       javax.security.auth.login.Configuration testConfig = javax.security.auth.login.Configuration.getConfiguration();
941       if(testConfig.getAppConfigurationEntry("Client") == null) {
942         return false;
943       }
944     } catch(Exception e) {
945       // No Jaas configuration defined.
946       return false;
947     }
948 
949     // Master & RSs uses hbase.zookeeper.client.*
950     return("kerberos".equalsIgnoreCase(conf.get("hbase.security.authentication")) &&
951          conf.get("hbase.zookeeper.client.keytab.file") != null);
952   }
953 
954   private static ArrayList<ACL> createACL(ZooKeeperWatcher zkw, String node) {
955     if (isSecureZooKeeper(zkw.getConfiguration())) {
956       // Certain znodes are accessed directly by the client,
957       // so they must be readable by non-authenticated clients
958       if ((node.equals(zkw.baseZNode) == true) ||
959           (node.equals(zkw.metaServerZNode) == true) ||
960           (node.equals(zkw.getMasterAddressZNode()) == true) ||
961           (node.equals(zkw.clusterIdZNode) == true) ||
962           (node.equals(zkw.rsZNode) == true) ||
963           (node.equals(zkw.backupMasterAddressesZNode) == true) ||
964           (node.startsWith(zkw.assignmentZNode) == true) ||
965           (node.startsWith(zkw.tableZNode) == true)) {
966         return ZooKeeperWatcher.CREATOR_ALL_AND_WORLD_READABLE;
967       }
968       return Ids.CREATOR_ALL_ACL;
969     } else {
970       return Ids.OPEN_ACL_UNSAFE;
971     }
972   }
973 
974   //
975   // Node creation
976   //
977 
978   /**
979    *
980    * Set the specified znode to be an ephemeral node carrying the specified
981    * data.
982    *
983    * If the node is created successfully, a watcher is also set on the node.
984    *
985    * If the node is not created successfully because it already exists, this
986    * method will also set a watcher on the node.
987    *
988    * If there is another problem, a KeeperException will be thrown.
989    *
990    * @param zkw zk reference
991    * @param znode path of node
992    * @param data data of node
993    * @return true if node created, false if not, watch set in both cases
994    * @throws KeeperException if unexpected zookeeper exception
995    */
996   public static boolean createEphemeralNodeAndWatch(ZooKeeperWatcher zkw,
997       String znode, byte [] data)
998   throws KeeperException {
999     boolean ret = true;
1000     try {
1001       zkw.getRecoverableZooKeeper().create(znode, data, createACL(zkw, znode),
1002           CreateMode.EPHEMERAL);
1003     } catch (KeeperException.NodeExistsException nee) {
1004       ret = false;
1005     } catch (InterruptedException e) {
1006       LOG.info("Interrupted", e);
1007       Thread.currentThread().interrupt();
1008     }
1009     if(!watchAndCheckExists(zkw, znode)) {
1010       // It did exist but now it doesn't, try again
1011       return createEphemeralNodeAndWatch(zkw, znode, data);
1012     }
1013     return ret;
1014   }
1015 
1016   /**
1017    * Creates the specified znode to be a persistent node carrying the specified
1018    * data.
1019    *
1020    * Returns true if the node was successfully created, false if the node
1021    * already existed.
1022    *
1023    * If the node is created successfully, a watcher is also set on the node.
1024    *
1025    * If the node is not created successfully because it already exists, this
1026    * method will also set a watcher on the node but return false.
1027    *
1028    * If there is another problem, a KeeperException will be thrown.
1029    *
1030    * @param zkw zk reference
1031    * @param znode path of node
1032    * @param data data of node
1033    * @return true if node created, false if not, watch set in both cases
1034    * @throws KeeperException if unexpected zookeeper exception
1035    */
1036   public static boolean createNodeIfNotExistsAndWatch(
1037       ZooKeeperWatcher zkw, String znode, byte [] data)
1038   throws KeeperException {
1039     boolean ret = true;
1040     try {
1041       zkw.getRecoverableZooKeeper().create(znode, data, createACL(zkw, znode),
1042           CreateMode.PERSISTENT);
1043     } catch (KeeperException.NodeExistsException nee) {
1044       ret = false;
1045     } catch (InterruptedException e) {
1046       zkw.interruptedException(e);
1047       return false;
1048     }
1049     try {
1050       zkw.getRecoverableZooKeeper().exists(znode, zkw);
1051     } catch (InterruptedException e) {
1052       zkw.interruptedException(e);
1053       return false;
1054     }
1055     return ret;
1056   }
1057 
1058   /**
1059    * Creates the specified znode with the specified data but does not watch it.
1060    *
1061    * Returns the znode of the newly created node
1062    *
1063    * If there is another problem, a KeeperException will be thrown.
1064    *
1065    * @param zkw zk reference
1066    * @param znode path of node
1067    * @param data data of node
1068    * @param createMode specifying whether the node to be created is ephemeral and/or sequential
1069    * @return true name of the newly created znode or null
1070    * @throws KeeperException if unexpected zookeeper exception
1071    */
1072   public static String createNodeIfNotExistsNoWatch(ZooKeeperWatcher zkw, String znode,
1073       byte[] data, CreateMode createMode) throws KeeperException {
1074 
1075     String createdZNode = null;
1076     try {
1077       createdZNode = zkw.getRecoverableZooKeeper().create(znode, data,
1078           createACL(zkw, znode), createMode);
1079     } catch (KeeperException.NodeExistsException nee) {
1080       return znode;
1081     } catch (InterruptedException e) {
1082       zkw.interruptedException(e);
1083       return null;
1084     }
1085     return createdZNode;
1086   }
1087 
1088   /**
1089    * Creates the specified node with the specified data and watches it.
1090    *
1091    * <p>Throws an exception if the node already exists.
1092    *
1093    * <p>The node created is persistent and open access.
1094    *
1095    * <p>Returns the version number of the created node if successful.
1096    *
1097    * @param zkw zk reference
1098    * @param znode path of node to create
1099    * @param data data of node to create
1100    * @return version of node created
1101    * @throws KeeperException if unexpected zookeeper exception
1102    * @throws KeeperException.NodeExistsException if node already exists
1103    */
1104   public static int createAndWatch(ZooKeeperWatcher zkw,
1105       String znode, byte [] data)
1106   throws KeeperException, KeeperException.NodeExistsException {
1107     try {
1108       zkw.getRecoverableZooKeeper().create(znode, data, createACL(zkw, znode),
1109           CreateMode.PERSISTENT);
1110       Stat stat = zkw.getRecoverableZooKeeper().exists(znode, zkw);
1111       if (stat == null){
1112         // Likely a race condition. Someone deleted the znode.
1113         throw KeeperException.create(KeeperException.Code.SYSTEMERROR,
1114             "ZK.exists returned null (i.e.: znode does not exist) for znode=" + znode);
1115       }
1116      return stat.getVersion();
1117     } catch (InterruptedException e) {
1118       zkw.interruptedException(e);
1119       return -1;
1120     }
1121   }
1122 
1123   /**
1124    * Async creates the specified node with the specified data.
1125    *
1126    * <p>Throws an exception if the node already exists.
1127    *
1128    * <p>The node created is persistent and open access.
1129    *
1130    * @param zkw zk reference
1131    * @param znode path of node to create
1132    * @param data data of node to create
1133    * @param cb
1134    * @param ctx
1135    * @throws KeeperException if unexpected zookeeper exception
1136    * @throws KeeperException.NodeExistsException if node already exists
1137    */
1138   public static void asyncCreate(ZooKeeperWatcher zkw,
1139       String znode, byte [] data, final AsyncCallback.StringCallback cb,
1140       final Object ctx) {
1141     zkw.getRecoverableZooKeeper().getZooKeeper().create(znode, data,
1142         createACL(zkw, znode), CreateMode.PERSISTENT, cb, ctx);
1143   }
1144 
1145   /**
1146    * Creates the specified node, iff the node does not exist.  Does not set a
1147    * watch and fails silently if the node already exists.
1148    *
1149    * The node created is persistent and open access.
1150    *
1151    * @param zkw zk reference
1152    * @param znode path of node
1153    * @throws KeeperException if unexpected zookeeper exception
1154    */
1155   public static void createAndFailSilent(ZooKeeperWatcher zkw,
1156       String znode) throws KeeperException {
1157     createAndFailSilent(zkw, znode, new byte[0]);
1158   }
1159 
1160   /**
1161    * Creates the specified node containing specified data, iff the node does not exist.  Does
1162    * not set a watch and fails silently if the node already exists.
1163    *
1164    * The node created is persistent and open access.
1165    *
1166    * @param zkw zk reference
1167    * @param znode path of node
1168    * @param data a byte array data to store in the znode
1169    * @throws KeeperException if unexpected zookeeper exception
1170    */
1171   public static void createAndFailSilent(ZooKeeperWatcher zkw,
1172       String znode, byte[] data)
1173   throws KeeperException {
1174     createAndFailSilent(zkw,
1175         (CreateAndFailSilent)ZKUtilOp.createAndFailSilent(znode, data));
1176   }
1177 
1178   private static void createAndFailSilent(ZooKeeperWatcher zkw, CreateAndFailSilent cafs)
1179   throws KeeperException {
1180     CreateRequest create = (CreateRequest)toZooKeeperOp(zkw, cafs).toRequestRecord();
1181     String znode = create.getPath();
1182     try {
1183       RecoverableZooKeeper zk = zkw.getRecoverableZooKeeper();
1184       if (zk.exists(znode, false) == null) {
1185         zk.create(znode, create.getData(), create.getAcl(), CreateMode.fromFlag(create.getFlags()));
1186       }
1187     } catch(KeeperException.NodeExistsException nee) {
1188     } catch(KeeperException.NoAuthException nee){
1189       try {
1190         if (null == zkw.getRecoverableZooKeeper().exists(znode, false)) {
1191           // If we failed to create the file and it does not already exist.
1192           throw(nee);
1193         }
1194       } catch (InterruptedException ie) {
1195         zkw.interruptedException(ie);
1196       }
1197 
1198     } catch(InterruptedException ie) {
1199       zkw.interruptedException(ie);
1200     }
1201   }
1202 
1203   /**
1204    * Creates the specified node and all parent nodes required for it to exist.
1205    *
1206    * No watches are set and no errors are thrown if the node already exists.
1207    *
1208    * The nodes created are persistent and open access.
1209    *
1210    * @param zkw zk reference
1211    * @param znode path of node
1212    * @throws KeeperException if unexpected zookeeper exception
1213    */
1214   public static void createWithParents(ZooKeeperWatcher zkw, String znode)
1215   throws KeeperException {
1216     createWithParents(zkw, znode, new byte[0]);
1217   }
1218 
1219   /**
1220    * Creates the specified node and all parent nodes required for it to exist.  The creation of
1221    * parent znodes is not atomic with the leafe znode creation but the data is written atomically
1222    * when the leaf node is created.
1223    *
1224    * No watches are set and no errors are thrown if the node already exists.
1225    *
1226    * The nodes created are persistent and open access.
1227    *
1228    * @param zkw zk reference
1229    * @param znode path of node
1230    * @throws KeeperException if unexpected zookeeper exception
1231    */
1232   public static void createWithParents(ZooKeeperWatcher zkw, String znode, byte[] data)
1233   throws KeeperException {
1234     try {
1235       if(znode == null) {
1236         return;
1237       }
1238       zkw.getRecoverableZooKeeper().create(znode, data, createACL(zkw, znode),
1239           CreateMode.PERSISTENT);
1240     } catch(KeeperException.NodeExistsException nee) {
1241       return;
1242     } catch(KeeperException.NoNodeException nne) {
1243       createWithParents(zkw, getParent(znode));
1244       createWithParents(zkw, znode, data);
1245     } catch(InterruptedException ie) {
1246       zkw.interruptedException(ie);
1247     }
1248   }
1249 
1250   //
1251   // Deletes
1252   //
1253 
1254   /**
1255    * Delete the specified node.  Sets no watches.  Throws all exceptions.
1256    */
1257   public static void deleteNode(ZooKeeperWatcher zkw, String node)
1258   throws KeeperException {
1259     deleteNode(zkw, node, -1);
1260   }
1261 
1262   /**
1263    * Delete the specified node with the specified version.  Sets no watches.
1264    * Throws all exceptions.
1265    */
1266   public static boolean deleteNode(ZooKeeperWatcher zkw, String node,
1267       int version)
1268   throws KeeperException {
1269     try {
1270       zkw.getRecoverableZooKeeper().delete(node, version);
1271       return true;
1272     } catch(KeeperException.BadVersionException bve) {
1273       return false;
1274     } catch(InterruptedException ie) {
1275       zkw.interruptedException(ie);
1276       return false;
1277     }
1278   }
1279 
1280   /**
1281    * Deletes the specified node.  Fails silent if the node does not exist.
1282    * @param zkw
1283    * @param node
1284    * @throws KeeperException
1285    */
1286   public static void deleteNodeFailSilent(ZooKeeperWatcher zkw, String node)
1287   throws KeeperException {
1288     deleteNodeFailSilent(zkw,
1289       (DeleteNodeFailSilent)ZKUtilOp.deleteNodeFailSilent(node));
1290   }
1291 
1292   private static void deleteNodeFailSilent(ZooKeeperWatcher zkw,
1293       DeleteNodeFailSilent dnfs) throws KeeperException {
1294     DeleteRequest delete = (DeleteRequest)toZooKeeperOp(zkw, dnfs).toRequestRecord();
1295     try {
1296       zkw.getRecoverableZooKeeper().delete(delete.getPath(), delete.getVersion());
1297     } catch(KeeperException.NoNodeException nne) {
1298     } catch(InterruptedException ie) {
1299       zkw.interruptedException(ie);
1300     }
1301   }
1302 
1303 
1304   /**
1305    * Delete the specified node and all of it's children.
1306    * <p>
1307    * If the node does not exist, just returns.
1308    * <p>
1309    * Sets no watches. Throws all exceptions besides dealing with deletion of
1310    * children.
1311    */
1312   public static void deleteNodeRecursively(ZooKeeperWatcher zkw, String node)
1313   throws KeeperException {
1314     try {
1315       List<String> children = ZKUtil.listChildrenNoWatch(zkw, node);
1316       // the node is already deleted, so we just finish
1317       if (children == null) return;
1318 
1319       if(!children.isEmpty()) {
1320         for(String child : children) {
1321           deleteNodeRecursively(zkw, joinZNode(node, child));
1322         }
1323       }
1324       zkw.getRecoverableZooKeeper().delete(node, -1);
1325     } catch(InterruptedException ie) {
1326       zkw.interruptedException(ie);
1327     }
1328   }
1329 
1330   /**
1331    * Delete all the children of the specified node but not the node itself.
1332    *
1333    * Sets no watches.  Throws all exceptions besides dealing with deletion of
1334    * children.
1335    */
1336   public static void deleteChildrenRecursively(ZooKeeperWatcher zkw, String node)
1337   throws KeeperException {
1338     List<String> children = ZKUtil.listChildrenNoWatch(zkw, node);
1339     if (children == null || children.isEmpty()) return;
1340     for(String child : children) {
1341       deleteNodeRecursively(zkw, joinZNode(node, child));
1342     }
1343   }
1344 
1345   /**
1346    * Represents an action taken by ZKUtil, e.g. createAndFailSilent.
1347    * These actions are higher-level than ZKOp actions, which represent
1348    * individual actions in the ZooKeeper API, like create.
1349    */
1350   public abstract static class ZKUtilOp {
1351     private String path;
1352 
1353     private ZKUtilOp(String path) {
1354       this.path = path;
1355     }
1356 
1357     /**
1358      * @return a createAndFailSilent ZKUtilOp
1359      */
1360     public static ZKUtilOp createAndFailSilent(String path, byte[] data) {
1361       return new CreateAndFailSilent(path, data);
1362     }
1363 
1364     /**
1365      * @return a deleteNodeFailSilent ZKUtilOP
1366      */
1367     public static ZKUtilOp deleteNodeFailSilent(String path) {
1368       return new DeleteNodeFailSilent(path);
1369     }
1370 
1371     /**
1372      * @return a setData ZKUtilOp
1373      */
1374     public static ZKUtilOp setData(String path, byte [] data) {
1375       return new SetData(path, data);
1376     }
1377 
1378     /**
1379      * @return path to znode where the ZKOp will occur
1380      */
1381     public String getPath() {
1382       return path;
1383     }
1384 
1385     /**
1386      * ZKUtilOp representing createAndFailSilent in ZooKeeper
1387      * (attempt to create node, ignore error if already exists)
1388      */
1389     public static class CreateAndFailSilent extends ZKUtilOp {
1390       private byte [] data;
1391 
1392       private CreateAndFailSilent(String path, byte [] data) {
1393         super(path);
1394         this.data = data;
1395       }
1396 
1397       public byte[] getData() {
1398         return data;
1399       }
1400 
1401       @Override
1402       public boolean equals(Object o) {
1403         if (this == o) return true;
1404         if (!(o instanceof CreateAndFailSilent)) return false;
1405 
1406         CreateAndFailSilent op = (CreateAndFailSilent) o;
1407         return getPath().equals(op.getPath()) && Arrays.equals(data, op.data);
1408       }
1409 
1410       @Override
1411       public int hashCode() {
1412         int ret = 17 + getPath().hashCode() * 31;
1413         return ret * 31 + Bytes.hashCode(data);
1414       }
1415     }
1416 
1417     /**
1418      * ZKUtilOp representing deleteNodeFailSilent in ZooKeeper
1419      * (attempt to delete node, ignore error if node doesn't exist)
1420      */
1421     public static class DeleteNodeFailSilent extends ZKUtilOp {
1422       private DeleteNodeFailSilent(String path) {
1423         super(path);
1424       }
1425 
1426       @Override
1427       public boolean equals(Object o) {
1428         if (this == o) return true;
1429         if (!(o instanceof DeleteNodeFailSilent)) return false;
1430 
1431         return super.equals(o);
1432       }
1433 
1434       @Override
1435       public int hashCode() {
1436         return getPath().hashCode();
1437       }
1438     }
1439 
1440     /**
1441      * ZKUtilOp representing setData in ZooKeeper
1442      */
1443     public static class SetData extends ZKUtilOp {
1444       private byte [] data;
1445 
1446       private SetData(String path, byte [] data) {
1447         super(path);
1448         this.data = data;
1449       }
1450 
1451       public byte[] getData() {
1452         return data;
1453       }
1454 
1455       @Override
1456       public boolean equals(Object o) {
1457         if (this == o) return true;
1458         if (!(o instanceof SetData)) return false;
1459 
1460         SetData op = (SetData) o;
1461         return getPath().equals(op.getPath()) && Arrays.equals(data, op.data);
1462       }
1463 
1464       @Override
1465       public int hashCode() {
1466         int ret = getPath().hashCode();
1467         return ret * 31 + Bytes.hashCode(data);
1468       }
1469     }
1470   }
1471 
1472   /**
1473    * Convert from ZKUtilOp to ZKOp
1474    */
1475   private static Op toZooKeeperOp(ZooKeeperWatcher zkw, ZKUtilOp op)
1476   throws UnsupportedOperationException {
1477     if(op == null) return null;
1478 
1479     if (op instanceof CreateAndFailSilent) {
1480       CreateAndFailSilent cafs = (CreateAndFailSilent)op;
1481       return Op.create(cafs.getPath(), cafs.getData(), createACL(zkw, cafs.getPath()),
1482         CreateMode.PERSISTENT);
1483     } else if (op instanceof DeleteNodeFailSilent) {
1484       DeleteNodeFailSilent dnfs = (DeleteNodeFailSilent)op;
1485       return Op.delete(dnfs.getPath(), -1);
1486     } else if (op instanceof SetData) {
1487       SetData sd = (SetData)op;
1488       return Op.setData(sd.getPath(), sd.getData(), -1);
1489     } else {
1490       throw new UnsupportedOperationException("Unexpected ZKUtilOp type: "
1491         + op.getClass().getName());
1492     }
1493   }
1494 
1495   /**
1496    * If hbase.zookeeper.useMulti is true, use ZooKeeper's multi-update functionality.
1497    * Otherwise, run the list of operations sequentially.
1498    *
1499    * If all of the following are true:
1500    * - runSequentialOnMultiFailure is true
1501    * - hbase.zookeeper.useMulti is true
1502    * - on calling multi, we get a ZooKeeper exception that can be handled by a sequential call(*)
1503    * Then:
1504    * - we retry the operations one-by-one (sequentially)
1505    *
1506    * Note *: an example is receiving a NodeExistsException from a "create" call.  Without multi,
1507    * a user could call "createAndFailSilent" to ensure that a node exists if they don't care who
1508    * actually created the node (i.e. the NodeExistsException from ZooKeeper is caught).
1509    * This will cause all operations in the multi to fail, however, because
1510    * the NodeExistsException that zk.create throws will fail the multi transaction.
1511    * In this case, if the previous conditions hold, the commands are run sequentially, which should
1512    * result in the correct final state, but means that the operations will not run atomically.
1513    *
1514    * @throws KeeperException
1515    */
1516   public static void multiOrSequential(ZooKeeperWatcher zkw, List<ZKUtilOp> ops,
1517       boolean runSequentialOnMultiFailure) throws KeeperException {
1518     if (ops == null) return;
1519     boolean useMulti = zkw.getConfiguration().getBoolean(HConstants.ZOOKEEPER_USEMULTI, false);
1520 
1521     if (useMulti) {
1522       List<Op> zkOps = new LinkedList<Op>();
1523       for (ZKUtilOp op : ops) {
1524         zkOps.add(toZooKeeperOp(zkw, op));
1525       }
1526       try {
1527         zkw.getRecoverableZooKeeper().multi(zkOps);
1528       } catch (KeeperException ke) {
1529        switch (ke.code()) {
1530          case NODEEXISTS:
1531          case NONODE:
1532          case BADVERSION:
1533          case NOAUTH:
1534            // if we get an exception that could be solved by running sequentially
1535            // (and the client asked us to), then break out and run sequentially
1536            if (runSequentialOnMultiFailure) {
1537              LOG.info("On call to ZK.multi, received exception: " + ke.toString() + "."
1538                + "  Attempting to run operations sequentially because"
1539                + " runSequentialOnMultiFailure is: " + runSequentialOnMultiFailure + ".");
1540              processSequentially(zkw, ops);
1541              break;
1542            }
1543           default:
1544             throw ke;
1545         }
1546       } catch (InterruptedException ie) {
1547         zkw.interruptedException(ie);
1548       }
1549     } else {
1550       // run sequentially
1551       processSequentially(zkw, ops);
1552     }
1553 
1554   }
1555 
1556   private static void processSequentially(ZooKeeperWatcher zkw, List<ZKUtilOp> ops)
1557       throws KeeperException, NoNodeException {
1558     for (ZKUtilOp op : ops) {
1559       if (op instanceof CreateAndFailSilent) {
1560         createAndFailSilent(zkw, (CreateAndFailSilent) op);
1561       } else if (op instanceof DeleteNodeFailSilent) {
1562         deleteNodeFailSilent(zkw, (DeleteNodeFailSilent) op);
1563       } else if (op instanceof SetData) {
1564         setData(zkw, (SetData) op);
1565       } else {
1566         throw new UnsupportedOperationException("Unexpected ZKUtilOp type: "
1567             + op.getClass().getName());
1568       }
1569     }
1570   }
1571 
1572   //
1573   // ZooKeeper cluster information
1574   //
1575 
1576   /** @return String dump of everything in ZooKeeper. */
1577   public static String dump(ZooKeeperWatcher zkw) {
1578     StringBuilder sb = new StringBuilder();
1579     try {
1580       sb.append("HBase is rooted at ").append(zkw.baseZNode);
1581       sb.append("\nActive master address: ");
1582       try {
1583         sb.append(MasterAddressTracker.getMasterAddress(zkw));
1584       } catch (IOException e) {
1585         sb.append("<<FAILED LOOKUP: " + e.getMessage() + ">>");
1586       }
1587       sb.append("\nBackup master addresses:");
1588       for (String child : listChildrenNoWatch(zkw,
1589                                               zkw.backupMasterAddressesZNode)) {
1590         sb.append("\n ").append(child);
1591       }
1592       sb.append("\nRegion server holding hbase:meta: "
1593         + new MetaTableLocator().getMetaRegionLocation(zkw));
1594       sb.append("\nRegion servers:");
1595       for (String child : listChildrenNoWatch(zkw, zkw.rsZNode)) {
1596         sb.append("\n ").append(child);
1597       }
1598       try {
1599         getReplicationZnodesDump(zkw, sb);
1600       } catch (KeeperException ke) {
1601         LOG.warn("Couldn't get the replication znode dump", ke);
1602       }
1603       sb.append("\nQuorum Server Statistics:");
1604       String[] servers = zkw.getQuorum().split(",");
1605       for (String server : servers) {
1606         sb.append("\n ").append(server);
1607         try {
1608           String[] stat = getServerStats(server, ZKUtil.zkDumpConnectionTimeOut);
1609 
1610           if (stat == null) {
1611             sb.append("[Error] invalid quorum server: " + server);
1612             break;
1613           }
1614 
1615           for (String s : stat) {
1616             sb.append("\n  ").append(s);
1617           }
1618         } catch (Exception e) {
1619           sb.append("\n  ERROR: ").append(e.getMessage());
1620         }
1621       }
1622     } catch (KeeperException ke) {
1623       sb.append("\nFATAL ZooKeeper Exception!\n");
1624       sb.append("\n" + ke.getMessage());
1625     }
1626     return sb.toString();
1627   }
1628 
1629   /**
1630    * Appends replication znodes to the passed StringBuilder.
1631    * @param zkw
1632    * @param sb
1633    * @throws KeeperException
1634    */
1635   private static void getReplicationZnodesDump(ZooKeeperWatcher zkw, StringBuilder sb)
1636       throws KeeperException {
1637     String replicationZNodeName = zkw.getConfiguration().get("zookeeper.znode.replication",
1638       "replication");
1639     String replicationZnode = joinZNode(zkw.baseZNode, replicationZNodeName);
1640     if (ZKUtil.checkExists(zkw, replicationZnode) == -1) return;
1641     // do a ls -r on this znode
1642     sb.append("\n").append(replicationZnode).append(": ");
1643     List<String> children = ZKUtil.listChildrenNoWatch(zkw, replicationZnode);
1644     for (String child : children) {
1645       String znode = joinZNode(replicationZnode, child);
1646       if (child.equals(zkw.getConfiguration().get("zookeeper.znode.replication.peers", "peers"))) {
1647         appendPeersZnodes(zkw, znode, sb);
1648       } else if (child.equals(zkw.getConfiguration().
1649           get("zookeeper.znode.replication.rs", "rs"))) {
1650         appendRSZnodes(zkw, znode, sb);
1651       }
1652     }
1653   }
1654 
1655   private static void appendRSZnodes(ZooKeeperWatcher zkw, String znode, StringBuilder sb)
1656       throws KeeperException {
1657     List<String> stack = new LinkedList<String>();
1658     stack.add(znode);
1659     do {
1660       String znodeToProcess = stack.remove(stack.size() - 1);
1661       sb.append("\n").append(znodeToProcess).append(": ");
1662       byte[] data;
1663       try {
1664         data = ZKUtil.getData(zkw, znodeToProcess);
1665       } catch (InterruptedException e) {
1666         zkw.interruptedException(e);
1667         return;
1668       }
1669       if (data != null && data.length > 0) { // log position
1670         long position = 0;
1671         try {
1672           position = ZKUtil.parseHLogPositionFrom(ZKUtil.getData(zkw, znodeToProcess));
1673           sb.append(position);
1674         } catch (DeserializationException ignored) {
1675         } catch (InterruptedException e) {
1676           zkw.interruptedException(e);
1677           return;
1678         }
1679       }
1680       for (String zNodeChild : ZKUtil.listChildrenNoWatch(zkw, znodeToProcess)) {
1681         stack.add(ZKUtil.joinZNode(znodeToProcess, zNodeChild));
1682       }
1683     } while (stack.size() > 0);
1684   }
1685 
1686   private static void appendPeersZnodes(ZooKeeperWatcher zkw, String peersZnode,
1687     StringBuilder sb) throws KeeperException {
1688     int pblen = ProtobufUtil.lengthOfPBMagic();
1689     sb.append("\n").append(peersZnode).append(": ");
1690     for (String peerIdZnode : ZKUtil.listChildrenNoWatch(zkw, peersZnode)) {
1691       String znodeToProcess = ZKUtil.joinZNode(peersZnode, peerIdZnode);
1692       byte[] data;
1693       try {
1694         data = ZKUtil.getData(zkw, znodeToProcess);
1695       } catch (InterruptedException e) {
1696         zkw.interruptedException(e);
1697         return;
1698       }
1699       // parse the data of the above peer znode.
1700       try {
1701       String clusterKey = ZooKeeperProtos.ReplicationPeer.newBuilder().
1702         mergeFrom(data, pblen, data.length - pblen).getClusterkey();
1703       sb.append("\n").append(znodeToProcess).append(": ").append(clusterKey);
1704       // add the peer-state.
1705       appendPeerState(zkw, znodeToProcess, sb);
1706       } catch (InvalidProtocolBufferException ipbe) {
1707         LOG.warn("Got Exception while parsing peer: " + znodeToProcess, ipbe);
1708       }
1709     }
1710   }
1711 
1712   private static void appendPeerState(ZooKeeperWatcher zkw, String znodeToProcess,
1713       StringBuilder sb) throws KeeperException, InvalidProtocolBufferException {
1714     String peerState = zkw.getConfiguration().get("zookeeper.znode.replication.peers.state",
1715       "peer-state");
1716     int pblen = ProtobufUtil.lengthOfPBMagic();
1717     for (String child : ZKUtil.listChildrenNoWatch(zkw, znodeToProcess)) {
1718       if (!child.equals(peerState)) continue;
1719       String peerStateZnode = ZKUtil.joinZNode(znodeToProcess, child);
1720       sb.append("\n").append(peerStateZnode).append(": ");
1721       byte[] peerStateData;
1722       try {
1723         peerStateData = ZKUtil.getData(zkw, peerStateZnode);
1724         sb.append(ZooKeeperProtos.ReplicationState.newBuilder()
1725             .mergeFrom(peerStateData, pblen, peerStateData.length - pblen).getState().name());
1726       } catch (InterruptedException e) {
1727         zkw.interruptedException(e);
1728         return;
1729       }
1730     }
1731   }
1732 
1733   /**
1734    * Gets the statistics from the given server.
1735    *
1736    * @param server  The server to get the statistics from.
1737    * @param timeout  The socket timeout to use.
1738    * @return The array of response strings.
1739    * @throws IOException When the socket communication fails.
1740    */
1741   public static String[] getServerStats(String server, int timeout)
1742   throws IOException {
1743     String[] sp = server.split(":");
1744     if (sp == null || sp.length == 0) {
1745       return null;
1746     }
1747 
1748     String host = sp[0];
1749     int port = sp.length > 1 ? Integer.parseInt(sp[1])
1750         : HConstants.DEFAULT_ZOOKEPER_CLIENT_PORT;
1751 
1752     Socket socket = new Socket();
1753     InetSocketAddress sockAddr = new InetSocketAddress(host, port);
1754     socket.connect(sockAddr, timeout);
1755 
1756     socket.setSoTimeout(timeout);
1757     PrintWriter out = new PrintWriter(socket.getOutputStream(), true);
1758     BufferedReader in = new BufferedReader(new InputStreamReader(
1759       socket.getInputStream()));
1760     out.println("stat");
1761     out.flush();
1762     ArrayList<String> res = new ArrayList<String>();
1763     while (true) {
1764       String line = in.readLine();
1765       if (line != null) {
1766         res.add(line);
1767       } else {
1768         break;
1769       }
1770     }
1771     socket.close();
1772     return res.toArray(new String[res.size()]);
1773   }
1774 
1775   private static void logRetrievedMsg(final ZooKeeperWatcher zkw,
1776       final String znode, final byte [] data, final boolean watcherSet) {
1777     if (!LOG.isTraceEnabled()) return;
1778     LOG.trace(zkw.prefix("Retrieved " + ((data == null)? 0: data.length) +
1779       " byte(s) of data from znode " + znode +
1780       (watcherSet? " and set watcher; ": "; data=") +
1781       (data == null? "null": data.length == 0? "empty": (
1782           znode.startsWith(zkw.assignmentZNode)?
1783             ZKAssign.toString(data): // We should not be doing this reaching into another class
1784           znode.startsWith(zkw.metaServerZNode)?
1785             getServerNameOrEmptyString(data):
1786           znode.startsWith(zkw.backupMasterAddressesZNode)?
1787             getServerNameOrEmptyString(data):
1788           StringUtils.abbreviate(Bytes.toStringBinary(data), 32)))));
1789   }
1790 
1791   private static String getServerNameOrEmptyString(final byte [] data) {
1792     try {
1793       return ServerName.parseFrom(data).toString();
1794     } catch (DeserializationException e) {
1795       return "";
1796     }
1797   }
1798 
1799   /**
1800    * Waits for HBase installation's base (parent) znode to become available.
1801    * @throws IOException on ZK errors
1802    */
1803   public static void waitForBaseZNode(Configuration conf) throws IOException {
1804     LOG.info("Waiting until the base znode is available");
1805     String parentZNode = conf.get(HConstants.ZOOKEEPER_ZNODE_PARENT,
1806         HConstants.DEFAULT_ZOOKEEPER_ZNODE_PARENT);
1807     ZooKeeper zk = new ZooKeeper(ZKConfig.getZKQuorumServersString(conf),
1808         conf.getInt(HConstants.ZK_SESSION_TIMEOUT,
1809         HConstants.DEFAULT_ZK_SESSION_TIMEOUT), EmptyWatcher.instance);
1810 
1811     final int maxTimeMs = 10000;
1812     final int maxNumAttempts = maxTimeMs / HConstants.SOCKET_RETRY_WAIT_MS;
1813 
1814     KeeperException keeperEx = null;
1815     try {
1816       try {
1817         for (int attempt = 0; attempt < maxNumAttempts; ++attempt) {
1818           try {
1819             if (zk.exists(parentZNode, false) != null) {
1820               LOG.info("Parent znode exists: " + parentZNode);
1821               keeperEx = null;
1822               break;
1823             }
1824           } catch (KeeperException e) {
1825             keeperEx = e;
1826           }
1827           Threads.sleepWithoutInterrupt(HConstants.SOCKET_RETRY_WAIT_MS);
1828         }
1829       } finally {
1830         zk.close();
1831       }
1832     } catch (InterruptedException ex) {
1833       Thread.currentThread().interrupt();
1834     }
1835 
1836     if (keeperEx != null) {
1837       throw new IOException(keeperEx);
1838     }
1839   }
1840 
1841 
1842   public static byte[] blockUntilAvailable(
1843     final ZooKeeperWatcher zkw, final String znode, final long timeout)
1844     throws InterruptedException {
1845     if (timeout < 0) throw new IllegalArgumentException();
1846     if (zkw == null) throw new IllegalArgumentException();
1847     if (znode == null) throw new IllegalArgumentException();
1848 
1849     byte[] data = null;
1850     boolean finished = false;
1851     final long endTime = System.currentTimeMillis() + timeout;
1852     while (!finished) {
1853       try {
1854         data = ZKUtil.getData(zkw, znode);
1855       } catch(KeeperException e) {
1856         LOG.warn("Unexpected exception handling blockUntilAvailable", e);
1857       }
1858 
1859       if (data == null && (System.currentTimeMillis() +
1860         HConstants.SOCKET_RETRY_WAIT_MS < endTime)) {
1861         Thread.sleep(HConstants.SOCKET_RETRY_WAIT_MS);
1862       } else {
1863         finished = true;
1864       }
1865     }
1866 
1867     return data;
1868   }
1869 
1870 
1871   /**
1872    * Convert a {@link DeserializationException} to a more palatable {@link KeeperException}.
1873    * Used when can't let a {@link DeserializationException} out w/o changing public API.
1874    * @param e Exception to convert
1875    * @return Converted exception
1876    */
1877   public static KeeperException convert(final DeserializationException e) {
1878     KeeperException ke = new KeeperException.DataInconsistencyException();
1879     ke.initCause(e);
1880     return ke;
1881   }
1882 
1883   /**
1884    * Recursively print the current state of ZK (non-transactional)
1885    * @param root name of the root directory in zk to print
1886    * @throws KeeperException
1887    */
1888   public static void logZKTree(ZooKeeperWatcher zkw, String root) {
1889     if (!LOG.isDebugEnabled()) return;
1890     LOG.debug("Current zk system:");
1891     String prefix = "|-";
1892     LOG.debug(prefix + root);
1893     try {
1894       logZKTree(zkw, root, prefix);
1895     } catch (KeeperException e) {
1896       throw new RuntimeException(e);
1897     }
1898   }
1899 
1900   /**
1901    * Helper method to print the current state of the ZK tree.
1902    * @see #logZKTree(ZooKeeperWatcher, String)
1903    * @throws KeeperException if an unexpected exception occurs
1904    */
1905   protected static void logZKTree(ZooKeeperWatcher zkw, String root, String prefix) throws KeeperException {
1906     List<String> children = ZKUtil.listChildrenNoWatch(zkw, root);
1907     if (children == null) return;
1908     for (String child : children) {
1909       LOG.debug(prefix + child);
1910       String node = ZKUtil.joinZNode(root.equals("/") ? "" : root, child);
1911       logZKTree(zkw, node, prefix + "---");
1912     }
1913   }
1914 
1915   /**
1916    * @param position
1917    * @return Serialized protobuf of <code>position</code> with pb magic prefix prepended suitable
1918    *         for use as content of an hlog position in a replication queue.
1919    */
1920   public static byte[] positionToByteArray(final long position) {
1921     byte[] bytes = ZooKeeperProtos.ReplicationHLogPosition.newBuilder().setPosition(position)
1922         .build().toByteArray();
1923     return ProtobufUtil.prependPBMagic(bytes);
1924   }
1925 
1926   /**
1927    * @param bytes - Content of a HLog position znode.
1928    * @return long - The current HLog position.
1929    * @throws DeserializationException
1930    */
1931   public static long parseHLogPositionFrom(final byte[] bytes) throws DeserializationException {
1932     if (bytes == null) {
1933       throw new DeserializationException("Unable to parse null HLog position.");
1934     }
1935     if (ProtobufUtil.isPBMagicPrefix(bytes)) {
1936       int pblen = ProtobufUtil.lengthOfPBMagic();
1937       ZooKeeperProtos.ReplicationHLogPosition.Builder builder =
1938           ZooKeeperProtos.ReplicationHLogPosition.newBuilder();
1939       ZooKeeperProtos.ReplicationHLogPosition position;
1940       try {
1941         position = builder.mergeFrom(bytes, pblen, bytes.length - pblen).build();
1942       } catch (InvalidProtocolBufferException e) {
1943         throw new DeserializationException(e);
1944       }
1945       return position.getPosition();
1946     } else {
1947       if (bytes.length > 0) {
1948         return Bytes.toLong(bytes);
1949       }
1950       return 0;
1951     }
1952   }
1953 
1954   /**
1955    * @param regionLastFlushedSequenceId the flushed sequence id of a region which is the min of its
1956    *          store max seq ids
1957    * @param storeSequenceIds column family to sequence Id map
1958    * @return Serialized protobuf of <code>RegionSequenceIds</code> with pb magic prefix prepended
1959    *         suitable for use to filter wal edits in distributedLogReplay mode
1960    */
1961   public static byte[] regionSequenceIdsToByteArray(final Long regionLastFlushedSequenceId,
1962       final Map<byte[], Long> storeSequenceIds) {
1963     ZooKeeperProtos.RegionStoreSequenceIds.Builder regionSequenceIdsBuilder =
1964         ZooKeeperProtos.RegionStoreSequenceIds.newBuilder();
1965     ZooKeeperProtos.StoreSequenceId.Builder storeSequenceIdBuilder =
1966         ZooKeeperProtos.StoreSequenceId.newBuilder();
1967     if (storeSequenceIds != null) {
1968       for (Map.Entry<byte[], Long> e : storeSequenceIds.entrySet()){
1969         byte[] columnFamilyName = e.getKey();
1970         Long curSeqId = e.getValue();
1971         storeSequenceIdBuilder.setFamilyName(ByteStringer.wrap(columnFamilyName));
1972         storeSequenceIdBuilder.setSequenceId(curSeqId);
1973         regionSequenceIdsBuilder.addStoreSequenceId(storeSequenceIdBuilder.build());
1974         storeSequenceIdBuilder.clear();
1975       }
1976     }
1977     regionSequenceIdsBuilder.setLastFlushedSequenceId(regionLastFlushedSequenceId);
1978     byte[] result = regionSequenceIdsBuilder.build().toByteArray();
1979     return ProtobufUtil.prependPBMagic(result);
1980   }
1981 
1982   /**
1983    * @param bytes Content of serialized data of RegionStoreSequenceIds
1984    * @return a RegionStoreSequenceIds object
1985    * @throws DeserializationException
1986    */
1987   public static RegionStoreSequenceIds parseRegionStoreSequenceIds(final byte[] bytes)
1988       throws DeserializationException {
1989     if (bytes == null || !ProtobufUtil.isPBMagicPrefix(bytes)) {
1990       throw new DeserializationException("Unable to parse RegionStoreSequenceIds.");
1991     }
1992     RegionStoreSequenceIds.Builder regionSequenceIdsBuilder =
1993         ZooKeeperProtos.RegionStoreSequenceIds.newBuilder();
1994     int pblen = ProtobufUtil.lengthOfPBMagic();
1995     RegionStoreSequenceIds storeIds = null;
1996     try {
1997       storeIds = regionSequenceIdsBuilder.mergeFrom(bytes, pblen, bytes.length - pblen).build();
1998     } catch (InvalidProtocolBufferException e) {
1999       throw new DeserializationException(e);
2000     }
2001     return storeIds;
2002   }
2003 }