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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.Deque;
30  import java.util.HashMap;
31  import java.util.LinkedList;
32  import java.util.List;
33  import java.util.Map;
34  import java.util.Properties;
35  
36  import javax.security.auth.login.AppConfigurationEntry;
37  import javax.security.auth.login.AppConfigurationEntry.LoginModuleControlFlag;
38  
39  import org.apache.hadoop.hbase.util.ByteStringer;
40  import org.apache.commons.lang.StringUtils;
41  import org.apache.commons.logging.Log;
42  import org.apache.commons.logging.LogFactory;
43  import org.apache.hadoop.hbase.classification.InterfaceAudience;
44  import org.apache.hadoop.conf.Configuration;
45  import org.apache.hadoop.hbase.HConstants;
46  import org.apache.hadoop.hbase.ServerName;
47  import org.apache.hadoop.hbase.exceptions.DeserializationException;
48  import org.apache.hadoop.hbase.protobuf.ProtobufUtil;
49  import org.apache.hadoop.hbase.protobuf.generated.ZooKeeperProtos;
50  import org.apache.hadoop.hbase.protobuf.generated.ZooKeeperProtos.RegionStoreSequenceIds;
51  import org.apache.hadoop.hbase.util.Bytes;
52  import org.apache.hadoop.hbase.util.Threads;
53  import org.apache.hadoop.hbase.zookeeper.ZKUtil.ZKUtilOp.CreateAndFailSilent;
54  import org.apache.hadoop.hbase.zookeeper.ZKUtil.ZKUtilOp.DeleteNodeFailSilent;
55  import org.apache.hadoop.hbase.zookeeper.ZKUtil.ZKUtilOp.SetData;
56  import org.apache.hadoop.security.SecurityUtil;
57  import org.apache.hadoop.security.authentication.util.KerberosUtil;
58  import org.apache.zookeeper.AsyncCallback;
59  import org.apache.zookeeper.CreateMode;
60  import org.apache.zookeeper.KeeperException;
61  import org.apache.zookeeper.KeeperException.NoNodeException;
62  import org.apache.zookeeper.Op;
63  import org.apache.zookeeper.Watcher;
64  import org.apache.zookeeper.ZooDefs.Ids;
65  import org.apache.zookeeper.ZooDefs.Perms;
66  import org.apache.zookeeper.ZooKeeper;
67  import org.apache.zookeeper.client.ZooKeeperSaslClient;
68  import org.apache.zookeeper.data.ACL;
69  import org.apache.zookeeper.data.Id;
70  import org.apache.zookeeper.data.Stat;
71  import org.apache.zookeeper.proto.CreateRequest;
72  import org.apache.zookeeper.proto.DeleteRequest;
73  import org.apache.zookeeper.proto.SetDataRequest;
74  import org.apache.zookeeper.server.ZooKeeperSaslServer;
75  
76  /**
77   * Internal HBase utility class for ZooKeeper.
78   *
79   * <p>Contains only static methods and constants.
80   *
81   * <p>Methods all throw {@link KeeperException} if there is an unexpected
82   * zookeeper exception, so callers of these methods must handle appropriately.
83   * If ZK is required for the operation, the server will need to be aborted.
84   */
85  @InterfaceAudience.Private
86  public class ZKUtil {
87    private static final Log LOG = LogFactory.getLog(ZKUtil.class);
88  
89    // TODO: Replace this with ZooKeeper constant when ZOOKEEPER-277 is resolved.
90    public static final char ZNODE_PATH_SEPARATOR = '/';
91    private static int zkDumpConnectionTimeOut;
92  
93    /**
94     * Creates a new connection to ZooKeeper, pulling settings and ensemble config
95     * from the specified configuration object using methods from {@link ZKConfig}.
96     *
97     * Sets the connection status monitoring watcher to the specified watcher.
98     *
99     * @param conf configuration to pull ensemble and other settings from
100    * @param watcher watcher to monitor connection changes
101    * @return connection to zookeeper
102    * @throws IOException if unable to connect to zk or config problem
103    */
104   public static RecoverableZooKeeper connect(Configuration conf, Watcher watcher)
105   throws IOException {
106     Properties properties = ZKConfig.makeZKProps(conf);
107     String ensemble = ZKConfig.getZKQuorumServersString(properties);
108     return connect(conf, ensemble, watcher);
109   }
110 
111   public static RecoverableZooKeeper connect(Configuration conf, String ensemble,
112       Watcher watcher)
113   throws IOException {
114     return connect(conf, ensemble, watcher, null);
115   }
116 
117   public static RecoverableZooKeeper connect(Configuration conf, String ensemble,
118       Watcher watcher, final String identifier)
119   throws IOException {
120     if(ensemble == null) {
121       throw new IOException("Unable to determine ZooKeeper ensemble");
122     }
123     int timeout = conf.getInt(HConstants.ZK_SESSION_TIMEOUT,
124         HConstants.DEFAULT_ZK_SESSION_TIMEOUT);
125     if (LOG.isTraceEnabled()) {
126       LOG.trace(identifier + " opening connection to ZooKeeper ensemble=" + ensemble);
127     }
128     int retry = conf.getInt("zookeeper.recovery.retry", 3);
129     int retryIntervalMillis =
130       conf.getInt("zookeeper.recovery.retry.intervalmill", 1000);
131     zkDumpConnectionTimeOut = conf.getInt("zookeeper.dump.connection.timeout",
132         1000);
133     return new RecoverableZooKeeper(ensemble, timeout, watcher,
134         retry, retryIntervalMillis, identifier);
135   }
136 
137   /**
138    * Log in the current zookeeper server process using the given configuration
139    * keys for the credential file and login principal.
140    *
141    * <p><strong>This is only applicable when running on secure hbase</strong>
142    * On regular HBase (without security features), this will safely be ignored.
143    * </p>
144    *
145    * @param conf The configuration data to use
146    * @param keytabFileKey Property key used to configure the path to the credential file
147    * @param userNameKey Property key used to configure the login principal
148    * @param hostname Current hostname to use in any credentials
149    * @throws IOException underlying exception from SecurityUtil.login() call
150    */
151   public static void loginServer(Configuration conf, String keytabFileKey,
152       String userNameKey, String hostname) throws IOException {
153     login(conf, keytabFileKey, userNameKey, hostname,
154           ZooKeeperSaslServer.LOGIN_CONTEXT_NAME_KEY,
155           JaasConfiguration.SERVER_KEYTAB_KERBEROS_CONFIG_NAME);
156   }
157 
158   /**
159    * Log in the current zookeeper client using the given configuration
160    * keys for the credential file and login principal.
161    *
162    * <p><strong>This is only applicable when running on secure hbase</strong>
163    * On regular HBase (without security features), this will safely be ignored.
164    * </p>
165    *
166    * @param conf The configuration data to use
167    * @param keytabFileKey Property key used to configure the path to the credential file
168    * @param userNameKey Property key used to configure the login principal
169    * @param hostname Current hostname to use in any credentials
170    * @throws IOException underlying exception from SecurityUtil.login() call
171    */
172   public static void loginClient(Configuration conf, String keytabFileKey,
173       String userNameKey, String hostname) throws IOException {
174     login(conf, keytabFileKey, userNameKey, hostname,
175           ZooKeeperSaslClient.LOGIN_CONTEXT_NAME_KEY,
176           JaasConfiguration.CLIENT_KEYTAB_KERBEROS_CONFIG_NAME);
177   }
178 
179   /**
180    * Log in the current process using the given configuration keys for the
181    * credential file and login principal.
182    *
183    * <p><strong>This is only applicable when running on secure hbase</strong>
184    * On regular HBase (without security features), this will safely be ignored.
185    * </p>
186    *
187    * @param conf The configuration data to use
188    * @param keytabFileKey Property key used to configure the path to the credential file
189    * @param userNameKey Property key used to configure the login principal
190    * @param hostname Current hostname to use in any credentials
191    * @param loginContextProperty property name to expose the entry name
192    * @param loginContextName jaas entry name
193    * @throws IOException underlying exception from SecurityUtil.login() call
194    */
195   private static void login(Configuration conf, String keytabFileKey,
196       String userNameKey, String hostname,
197       String loginContextProperty, String loginContextName)
198       throws IOException {
199     if (!isSecureZooKeeper(conf))
200       return;
201 
202     // User has specified a jaas.conf, keep this one as the good one.
203     // HBASE_OPTS="-Djava.security.auth.login.config=jaas.conf"
204     if (System.getProperty("java.security.auth.login.config") != null)
205       return;
206 
207     // No keytab specified, no auth
208     String keytabFilename = conf.get(keytabFileKey);
209     if (keytabFilename == null) {
210       LOG.warn("no keytab specified for: " + keytabFileKey);
211       return;
212     }
213 
214     String principalConfig = conf.get(userNameKey, System.getProperty("user.name"));
215     String principalName = SecurityUtil.getServerPrincipal(principalConfig, hostname);
216 
217     // Initialize the "jaas.conf" for keyTab/principal,
218     // If keyTab is not specified use the Ticket Cache.
219     // and set the zookeeper login context name.
220     JaasConfiguration jaasConf = new JaasConfiguration(loginContextName,
221         principalName, keytabFilename);
222     javax.security.auth.login.Configuration.setConfiguration(jaasConf);
223     System.setProperty(loginContextProperty, loginContextName);
224   }
225 
226   /**
227    * A JAAS configuration that defines the login modules that we want to use for login.
228    */
229   private static class JaasConfiguration extends javax.security.auth.login.Configuration {
230     private static final String SERVER_KEYTAB_KERBEROS_CONFIG_NAME =
231       "zookeeper-server-keytab-kerberos";
232     private static final String CLIENT_KEYTAB_KERBEROS_CONFIG_NAME =
233       "zookeeper-client-keytab-kerberos";
234 
235     private static final Map<String, String> BASIC_JAAS_OPTIONS =
236       new HashMap<String,String>();
237     static {
238       String jaasEnvVar = System.getenv("HBASE_JAAS_DEBUG");
239       if (jaasEnvVar != null && "true".equalsIgnoreCase(jaasEnvVar)) {
240         BASIC_JAAS_OPTIONS.put("debug", "true");
241       }
242     }
243 
244     private static final Map<String,String> KEYTAB_KERBEROS_OPTIONS =
245       new HashMap<String,String>();
246     static {
247       KEYTAB_KERBEROS_OPTIONS.put("doNotPrompt", "true");
248       KEYTAB_KERBEROS_OPTIONS.put("storeKey", "true");
249       KEYTAB_KERBEROS_OPTIONS.put("refreshKrb5Config", "true");
250       KEYTAB_KERBEROS_OPTIONS.putAll(BASIC_JAAS_OPTIONS);
251     }
252 
253     private static final AppConfigurationEntry KEYTAB_KERBEROS_LOGIN =
254       new AppConfigurationEntry(KerberosUtil.getKrb5LoginModuleName(),
255                                 LoginModuleControlFlag.REQUIRED,
256                                 KEYTAB_KERBEROS_OPTIONS);
257 
258     private static final AppConfigurationEntry[] KEYTAB_KERBEROS_CONF =
259       new AppConfigurationEntry[]{KEYTAB_KERBEROS_LOGIN};
260 
261     private javax.security.auth.login.Configuration baseConfig;
262     private final String loginContextName;
263     private final boolean useTicketCache;
264     private final String keytabFile;
265     private final String principal;
266 
267     public JaasConfiguration(String loginContextName, String principal) {
268       this(loginContextName, principal, null, true);
269     }
270 
271     public JaasConfiguration(String loginContextName, String principal, String keytabFile) {
272       this(loginContextName, principal, keytabFile, keytabFile == null || keytabFile.length() == 0);
273     }
274 
275     private JaasConfiguration(String loginContextName, String principal,
276                              String keytabFile, boolean useTicketCache) {
277       try {
278         this.baseConfig = javax.security.auth.login.Configuration.getConfiguration();
279       } catch (SecurityException e) {
280         this.baseConfig = null;
281       }
282       this.loginContextName = loginContextName;
283       this.useTicketCache = useTicketCache;
284       this.keytabFile = keytabFile;
285       this.principal = principal;
286       LOG.info("JaasConfiguration loginContextName=" + loginContextName +
287                " principal=" + principal + " useTicketCache=" + useTicketCache +
288                " keytabFile=" + keytabFile);
289     }
290 
291     @Override
292     public AppConfigurationEntry[] getAppConfigurationEntry(String appName) {
293       if (loginContextName.equals(appName)) {
294         if (!useTicketCache) {
295           KEYTAB_KERBEROS_OPTIONS.put("keyTab", keytabFile);
296           KEYTAB_KERBEROS_OPTIONS.put("useKeyTab", "true");
297         }
298         KEYTAB_KERBEROS_OPTIONS.put("principal", principal);
299         KEYTAB_KERBEROS_OPTIONS.put("useTicketCache", useTicketCache ? "true" : "false");
300         return KEYTAB_KERBEROS_CONF;
301       }
302       if (baseConfig != null) return baseConfig.getAppConfigurationEntry(appName);
303       return(null);
304     }
305   }
306 
307   //
308   // Helper methods
309   //
310 
311   /**
312    * Join the prefix znode name with the suffix znode name to generate a proper
313    * full znode name.
314    *
315    * Assumes prefix does not end with slash and suffix does not begin with it.
316    *
317    * @param prefix beginning of znode name
318    * @param suffix ending of znode name
319    * @return result of properly joining prefix with suffix
320    */
321   public static String joinZNode(String prefix, String suffix) {
322     return prefix + ZNODE_PATH_SEPARATOR + suffix;
323   }
324 
325   /**
326    * Returns the full path of the immediate parent of the specified node.
327    * @param node path to get parent of
328    * @return parent of path, null if passed the root node or an invalid node
329    */
330   public static String getParent(String node) {
331     int idx = node.lastIndexOf(ZNODE_PATH_SEPARATOR);
332     return idx <= 0 ? null : node.substring(0, idx);
333   }
334 
335   /**
336    * Get the name of the current node from the specified fully-qualified path.
337    * @param path fully-qualified path
338    * @return name of the current node
339    */
340   public static String getNodeName(String path) {
341     return path.substring(path.lastIndexOf("/")+1);
342   }
343 
344   /**
345    * Get the key to the ZK ensemble for this configuration without
346    * adding a name at the end
347    * @param conf Configuration to use to build the key
348    * @return ensemble key without a name
349    */
350   public static String getZooKeeperClusterKey(Configuration conf) {
351     return getZooKeeperClusterKey(conf, null);
352   }
353 
354   /**
355    * Get the key to the ZK ensemble for this configuration and append
356    * a name at the end
357    * @param conf Configuration to use to build the key
358    * @param name Name that should be appended at the end if not empty or null
359    * @return ensemble key with a name (if any)
360    */
361   public static String getZooKeeperClusterKey(Configuration conf, String name) {
362     String ensemble = conf.get(HConstants.ZOOKEEPER_QUORUM.replaceAll(
363         "[\\t\\n\\x0B\\f\\r]", ""));
364     StringBuilder builder = new StringBuilder(ensemble);
365     builder.append(":");
366     builder.append(conf.get(HConstants.ZOOKEEPER_CLIENT_PORT));
367     builder.append(":");
368     builder.append(conf.get(HConstants.ZOOKEEPER_ZNODE_PARENT));
369     if (name != null && !name.isEmpty()) {
370       builder.append(",");
371       builder.append(name);
372     }
373     return builder.toString();
374   }
375 
376   /**
377    * Apply the settings in the given key to the given configuration, this is
378    * used to communicate with distant clusters
379    * @param conf configuration object to configure
380    * @param key string that contains the 3 required configuratins
381    * @throws IOException
382    */
383   public static void applyClusterKeyToConf(Configuration conf, String key)
384       throws IOException{
385     String[] parts = transformClusterKey(key);
386     conf.set(HConstants.ZOOKEEPER_QUORUM, parts[0]);
387     conf.set(HConstants.ZOOKEEPER_CLIENT_PORT, parts[1]);
388     conf.set(HConstants.ZOOKEEPER_ZNODE_PARENT, parts[2]);
389   }
390 
391   /**
392    * Separate the given key into the three configurations it should contain:
393    * hbase.zookeeper.quorum, hbase.zookeeper.client.port
394    * and zookeeper.znode.parent
395    * @param key
396    * @return the three configuration in the described order
397    * @throws IOException
398    */
399   public static String[] transformClusterKey(String key) throws IOException {
400     String[] parts = key.split(":");
401     if (parts.length != 3) {
402       throw new IOException("Cluster key passed " + key + " is invalid, the format should be:" +
403           HConstants.ZOOKEEPER_QUORUM + ":hbase.zookeeper.client.port:"
404           + HConstants.ZOOKEEPER_ZNODE_PARENT);
405     }
406     return parts;
407   }
408 
409   //
410   // Existence checks and watches
411   //
412 
413   /**
414    * Watch the specified znode for delete/create/change events.  The watcher is
415    * set whether or not the node exists.  If the node already exists, the method
416    * returns true.  If the node does not exist, the method returns false.
417    *
418    * @param zkw zk reference
419    * @param znode path of node to watch
420    * @return true if znode exists, false if does not exist or error
421    * @throws KeeperException if unexpected zookeeper exception
422    */
423   public static boolean watchAndCheckExists(ZooKeeperWatcher zkw, String znode)
424   throws KeeperException {
425     try {
426       Stat s = zkw.getRecoverableZooKeeper().exists(znode, zkw);
427       boolean exists = s != null ? true : false;
428       if (exists) {
429         LOG.debug(zkw.prefix("Set watcher on existing znode=" + znode));
430       } else {
431         LOG.debug(zkw.prefix("Set watcher on znode that does not yet exist, " + znode));
432       }
433       return exists;
434     } catch (KeeperException e) {
435       LOG.warn(zkw.prefix("Unable to set watcher on znode " + znode), e);
436       zkw.keeperException(e);
437       return false;
438     } catch (InterruptedException e) {
439       LOG.warn(zkw.prefix("Unable to set watcher on znode " + znode), e);
440       zkw.interruptedException(e);
441       return false;
442     }
443   }
444 
445   /**
446    * Watch the specified znode, but only if exists. Useful when watching
447    * for deletions. Uses .getData() (and handles NoNodeException) instead
448    * of .exists() to accomplish this, as .getData() will only set a watch if
449    * the znode exists.
450    * @param zkw zk reference
451    * @param znode path of node to watch
452    * @return true if the watch is set, false if node does not exists
453    * @throws KeeperException if unexpected zookeeper exception
454    */
455   public static boolean setWatchIfNodeExists(ZooKeeperWatcher zkw, String znode)
456       throws KeeperException {
457     try {
458       zkw.getRecoverableZooKeeper().getData(znode, true, null);
459       return true;
460     } catch (NoNodeException e) {
461       return false;
462     } catch (InterruptedException e) {
463       LOG.warn(zkw.prefix("Unable to set watcher on znode " + znode), e);
464       zkw.interruptedException(e);
465       return false;
466     }
467   }
468 
469   /**
470    * Check if the specified node exists.  Sets no watches.
471    *
472    * @param zkw zk reference
473    * @param znode path of node to watch
474    * @return version of the node if it exists, -1 if does not exist
475    * @throws KeeperException if unexpected zookeeper exception
476    */
477   public static int checkExists(ZooKeeperWatcher zkw, String znode)
478   throws KeeperException {
479     try {
480       Stat s = zkw.getRecoverableZooKeeper().exists(znode, null);
481       return s != null ? s.getVersion() : -1;
482     } catch (KeeperException e) {
483       LOG.warn(zkw.prefix("Unable to set watcher on znode (" + znode + ")"), e);
484       zkw.keeperException(e);
485       return -1;
486     } catch (InterruptedException e) {
487       LOG.warn(zkw.prefix("Unable to set watcher on znode (" + znode + ")"), e);
488       zkw.interruptedException(e);
489       return -1;
490     }
491   }
492 
493   //
494   // Znode listings
495   //
496 
497   /**
498    * Lists the children znodes of the specified znode.  Also sets a watch on
499    * the specified znode which will capture a NodeDeleted event on the specified
500    * znode as well as NodeChildrenChanged if any children of the specified znode
501    * are created or deleted.
502    *
503    * Returns null if the specified node does not exist.  Otherwise returns a
504    * list of children of the specified node.  If the node exists but it has no
505    * children, an empty list will be returned.
506    *
507    * @param zkw zk reference
508    * @param znode path of node to list and watch children of
509    * @return list of children of the specified node, an empty list if the node
510    *          exists but has no children, and null if the node does not exist
511    * @throws KeeperException if unexpected zookeeper exception
512    */
513   public static List<String> listChildrenAndWatchForNewChildren(
514       ZooKeeperWatcher zkw, String znode)
515   throws KeeperException {
516     try {
517       List<String> children = zkw.getRecoverableZooKeeper().getChildren(znode, zkw);
518       return children;
519     } catch(KeeperException.NoNodeException ke) {
520       LOG.debug(zkw.prefix("Unable to list children of znode " + znode + " " +
521           "because node does not exist (not an error)"));
522       return null;
523     } catch (KeeperException e) {
524       LOG.warn(zkw.prefix("Unable to list children of znode " + znode + " "), e);
525       zkw.keeperException(e);
526       return null;
527     } catch (InterruptedException e) {
528       LOG.warn(zkw.prefix("Unable to list children of znode " + znode + " "), e);
529       zkw.interruptedException(e);
530       return null;
531     }
532   }
533 
534   /**
535    * List all the children of the specified znode, setting a watch for children
536    * changes and also setting a watch on every individual child in order to get
537    * the NodeCreated and NodeDeleted events.
538    * @param zkw zookeeper reference
539    * @param znode node to get children of and watch
540    * @return list of znode names, null if the node doesn't exist
541    * @throws KeeperException
542    */
543   public static List<String> listChildrenAndWatchThem(ZooKeeperWatcher zkw,
544       String znode) throws KeeperException {
545     List<String> children = listChildrenAndWatchForNewChildren(zkw, znode);
546     if (children == null) {
547       return null;
548     }
549     for (String child : children) {
550       watchAndCheckExists(zkw, joinZNode(znode, child));
551     }
552     return children;
553   }
554 
555   /**
556    * Lists the children of the specified znode without setting any watches.
557    *
558    * Sets no watches at all, this method is best effort.
559    *
560    * Returns an empty list if the node has no children.  Returns null if the
561    * parent node itself does not exist.
562    *
563    * @param zkw zookeeper reference
564    * @param znode node to get children
565    * @return list of data of children of specified znode, empty if no children,
566    *         null if parent does not exist
567    * @throws KeeperException if unexpected zookeeper exception
568    */
569   public static List<String> listChildrenNoWatch(ZooKeeperWatcher zkw, String znode)
570   throws KeeperException {
571     List<String> children = null;
572     try {
573       // List the children without watching
574       children = zkw.getRecoverableZooKeeper().getChildren(znode, null);
575     } catch(KeeperException.NoNodeException nne) {
576       return null;
577     } catch(InterruptedException ie) {
578       zkw.interruptedException(ie);
579     }
580     return children;
581   }
582 
583   /**
584    * Simple class to hold a node path and node data.
585    * @deprecated Unused
586    */
587   @Deprecated
588   public static class NodeAndData {
589     private String node;
590     private byte [] data;
591     public NodeAndData(String node, byte [] data) {
592       this.node = node;
593       this.data = data;
594     }
595     public String getNode() {
596       return node;
597     }
598     public byte [] getData() {
599       return data;
600     }
601     @Override
602     public String toString() {
603       return node;
604     }
605     public boolean isEmpty() {
606       return (data == null || data.length == 0);
607     }
608   }
609 
610   /**
611    * Checks if the specified znode has any children.  Sets no watches.
612    *
613    * Returns true if the node exists and has children.  Returns false if the
614    * node does not exist or if the node does not have any children.
615    *
616    * Used during master initialization to determine if the master is a
617    * failed-over-to master or the first master during initial cluster startup.
618    * If the directory for regionserver ephemeral nodes is empty then this is
619    * a cluster startup, if not then it is not cluster startup.
620    *
621    * @param zkw zk reference
622    * @param znode path of node to check for children of
623    * @return true if node has children, false if not or node does not exist
624    * @throws KeeperException if unexpected zookeeper exception
625    */
626   public static boolean nodeHasChildren(ZooKeeperWatcher zkw, String znode)
627   throws KeeperException {
628     try {
629       return !zkw.getRecoverableZooKeeper().getChildren(znode, null).isEmpty();
630     } catch(KeeperException.NoNodeException ke) {
631       LOG.debug(zkw.prefix("Unable to list children of znode " + znode + " " +
632       "because node does not exist (not an error)"));
633       return false;
634     } catch (KeeperException e) {
635       LOG.warn(zkw.prefix("Unable to list children of znode " + znode), e);
636       zkw.keeperException(e);
637       return false;
638     } catch (InterruptedException e) {
639       LOG.warn(zkw.prefix("Unable to list children of znode " + znode), e);
640       zkw.interruptedException(e);
641       return false;
642     }
643   }
644 
645   /**
646    * Get the number of children of the specified node.
647    *
648    * If the node does not exist or has no children, returns 0.
649    *
650    * Sets no watches at all.
651    *
652    * @param zkw zk reference
653    * @param znode path of node to count children of
654    * @return number of children of specified node, 0 if none or parent does not
655    *         exist
656    * @throws KeeperException if unexpected zookeeper exception
657    */
658   public static int getNumberOfChildren(ZooKeeperWatcher zkw, String znode)
659   throws KeeperException {
660     try {
661       Stat stat = zkw.getRecoverableZooKeeper().exists(znode, null);
662       return stat == null ? 0 : stat.getNumChildren();
663     } catch(KeeperException e) {
664       LOG.warn(zkw.prefix("Unable to get children of node " + znode));
665       zkw.keeperException(e);
666     } catch(InterruptedException e) {
667       zkw.interruptedException(e);
668     }
669     return 0;
670   }
671 
672   //
673   // Data retrieval
674   //
675 
676   /**
677    * Get znode data. Does not set a watcher.
678    * @return ZNode data, null if the node does not exist or if there is an
679    *  error.
680    */
681   public static byte [] getData(ZooKeeperWatcher zkw, String znode)
682   throws KeeperException {
683     try {
684       byte [] data = zkw.getRecoverableZooKeeper().getData(znode, null, null);
685       logRetrievedMsg(zkw, znode, data, false);
686       return data;
687     } catch (KeeperException.NoNodeException e) {
688       LOG.debug(zkw.prefix("Unable to get data of znode " + znode + " " +
689         "because node does not exist (not an error)"));
690       return null;
691     } catch (KeeperException e) {
692       LOG.warn(zkw.prefix("Unable to get data of znode " + znode), e);
693       zkw.keeperException(e);
694       return null;
695     } catch (InterruptedException e) {
696       LOG.warn(zkw.prefix("Unable to get data of znode " + znode), e);
697       zkw.interruptedException(e);
698       return null;
699     }
700   }
701 
702   /**
703    * Get the data at the specified znode and set a watch.
704    *
705    * Returns the data and sets a watch if the node exists.  Returns null and no
706    * watch is set if the node does not exist or there is an exception.
707    *
708    * @param zkw zk reference
709    * @param znode path of node
710    * @return data of the specified znode, or null
711    * @throws KeeperException if unexpected zookeeper exception
712    */
713   public static byte [] getDataAndWatch(ZooKeeperWatcher zkw, String znode)
714   throws KeeperException {
715     return getDataInternal(zkw, znode, null, true);
716   }
717 
718   /**
719    * Get the data at the specified znode and set a watch.
720    *
721    * Returns the data and sets a watch if the node exists.  Returns null and no
722    * watch is set if the node does not exist or there is an exception.
723    *
724    * @param zkw zk reference
725    * @param znode path of node
726    * @param stat object to populate the version of the znode
727    * @return data of the specified znode, or null
728    * @throws KeeperException if unexpected zookeeper exception
729    */
730   public static byte[] getDataAndWatch(ZooKeeperWatcher zkw, String znode,
731       Stat stat) throws KeeperException {
732     return getDataInternal(zkw, znode, stat, true);
733   }
734 
735   private static byte[] getDataInternal(ZooKeeperWatcher zkw, String znode, Stat stat,
736       boolean watcherSet)
737       throws KeeperException {
738     try {
739       byte [] data = zkw.getRecoverableZooKeeper().getData(znode, zkw, stat);
740       logRetrievedMsg(zkw, znode, data, watcherSet);
741       return data;
742     } catch (KeeperException.NoNodeException e) {
743       // This log can get pretty annoying when we cycle on 100ms waits.
744       // Enable trace if you really want to see it.
745       LOG.trace(zkw.prefix("Unable to get data of znode " + znode + " " +
746         "because node does not exist (not an error)"));
747       return null;
748     } catch (KeeperException e) {
749       LOG.warn(zkw.prefix("Unable to get data of znode " + znode), e);
750       zkw.keeperException(e);
751       return null;
752     } catch (InterruptedException e) {
753       LOG.warn(zkw.prefix("Unable to get data of znode " + znode), e);
754       zkw.interruptedException(e);
755       return null;
756     }
757   }
758 
759   /**
760    * Get the data at the specified znode without setting a watch.
761    *
762    * Returns the data if the node exists.  Returns null if the node does not
763    * exist.
764    *
765    * Sets the stats of the node in the passed Stat object.  Pass a null stat if
766    * not interested.
767    *
768    * @param zkw zk reference
769    * @param znode path of node
770    * @param stat node status to get if node exists
771    * @return data of the specified znode, or null if node does not exist
772    * @throws KeeperException if unexpected zookeeper exception
773    */
774   public static byte [] getDataNoWatch(ZooKeeperWatcher zkw, String znode,
775       Stat stat)
776   throws KeeperException {
777     try {
778       byte [] data = zkw.getRecoverableZooKeeper().getData(znode, null, stat);
779       logRetrievedMsg(zkw, znode, data, false);
780       return data;
781     } catch (KeeperException.NoNodeException e) {
782       LOG.debug(zkw.prefix("Unable to get data of znode " + znode + " " +
783           "because node does not exist (not necessarily an error)"));
784       return null;
785     } catch (KeeperException e) {
786       LOG.warn(zkw.prefix("Unable to get data of znode " + znode), e);
787       zkw.keeperException(e);
788       return null;
789     } catch (InterruptedException e) {
790       LOG.warn(zkw.prefix("Unable to get data of znode " + znode), e);
791       zkw.interruptedException(e);
792       return null;
793     }
794   }
795 
796   /**
797    * Returns the date of child znodes of the specified znode.  Also sets a watch on
798    * the specified znode which will capture a NodeDeleted event on the specified
799    * znode as well as NodeChildrenChanged if any children of the specified znode
800    * are created or deleted.
801    *
802    * Returns null if the specified node does not exist.  Otherwise returns a
803    * list of children of the specified node.  If the node exists but it has no
804    * children, an empty list will be returned.
805    *
806    * @param zkw zk reference
807    * @param baseNode path of node to list and watch children of
808    * @return list of data of children of the specified node, an empty list if the node
809    *          exists but has no children, and null if the node does not exist
810    * @throws KeeperException if unexpected zookeeper exception
811    * @deprecated Unused
812    */
813   public static List<NodeAndData> getChildDataAndWatchForNewChildren(
814       ZooKeeperWatcher zkw, String baseNode) throws KeeperException {
815     List<String> nodes =
816       ZKUtil.listChildrenAndWatchForNewChildren(zkw, baseNode);
817     List<NodeAndData> newNodes = new ArrayList<NodeAndData>();
818     if (nodes != null) {
819       for (String node : nodes) {
820         String nodePath = ZKUtil.joinZNode(baseNode, node);
821         byte[] data = ZKUtil.getDataAndWatch(zkw, nodePath);
822         newNodes.add(new NodeAndData(nodePath, data));
823       }
824     }
825     return newNodes;
826   }
827 
828   /**
829    * Update the data of an existing node with the expected version to have the
830    * specified data.
831    *
832    * Throws an exception if there is a version mismatch or some other problem.
833    *
834    * Sets no watches under any conditions.
835    *
836    * @param zkw zk reference
837    * @param znode
838    * @param data
839    * @param expectedVersion
840    * @throws KeeperException if unexpected zookeeper exception
841    * @throws KeeperException.BadVersionException if version mismatch
842    * @deprecated Unused
843    */
844   public static void updateExistingNodeData(ZooKeeperWatcher zkw, String znode,
845       byte [] data, int expectedVersion)
846   throws KeeperException {
847     try {
848       zkw.getRecoverableZooKeeper().setData(znode, data, expectedVersion);
849     } catch(InterruptedException ie) {
850       zkw.interruptedException(ie);
851     }
852   }
853 
854   //
855   // Data setting
856   //
857 
858   /**
859    * Sets the data of the existing znode to be the specified data.  Ensures that
860    * the current data has the specified expected version.
861    *
862    * <p>If the node does not exist, a {@link NoNodeException} will be thrown.
863    *
864    * <p>If their is a version mismatch, method returns null.
865    *
866    * <p>No watches are set but setting data will trigger other watchers of this
867    * node.
868    *
869    * <p>If there is another problem, a KeeperException will be thrown.
870    *
871    * @param zkw zk reference
872    * @param znode path of node
873    * @param data data to set for node
874    * @param expectedVersion version expected when setting data
875    * @return true if data set, false if version mismatch
876    * @throws KeeperException if unexpected zookeeper exception
877    */
878   public static boolean setData(ZooKeeperWatcher zkw, String znode,
879       byte [] data, int expectedVersion)
880   throws KeeperException, KeeperException.NoNodeException {
881     try {
882       return zkw.getRecoverableZooKeeper().setData(znode, data, expectedVersion) != null;
883     } catch (InterruptedException e) {
884       zkw.interruptedException(e);
885       return false;
886     }
887   }
888 
889   /**
890    * Set data into node creating node if it doesn't yet exist.
891    * Does not set watch.
892    *
893    * @param zkw zk reference
894    * @param znode path of node
895    * @param data data to set for node
896    * @throws KeeperException
897    */
898   public static void createSetData(final ZooKeeperWatcher zkw, final String znode,
899       final byte [] data)
900   throws KeeperException {
901     if (checkExists(zkw, znode) == -1) {
902       ZKUtil.createWithParents(zkw, znode, data);
903     } else {
904       ZKUtil.setData(zkw, znode, data);
905     }
906   }
907 
908   /**
909    * Sets the data of the existing znode to be the specified data.  The node
910    * must exist but no checks are done on the existing data or version.
911    *
912    * <p>If the node does not exist, a {@link NoNodeException} will be thrown.
913    *
914    * <p>No watches are set but setting data will trigger other watchers of this
915    * node.
916    *
917    * <p>If there is another problem, a KeeperException will be thrown.
918    *
919    * @param zkw zk reference
920    * @param znode path of node
921    * @param data data to set for node
922    * @throws KeeperException if unexpected zookeeper exception
923    */
924   public static void setData(ZooKeeperWatcher zkw, String znode, byte [] data)
925   throws KeeperException, KeeperException.NoNodeException {
926     setData(zkw, (SetData)ZKUtilOp.setData(znode, data));
927   }
928 
929   private static void setData(ZooKeeperWatcher zkw, SetData setData)
930   throws KeeperException, KeeperException.NoNodeException {
931     SetDataRequest sd = (SetDataRequest)toZooKeeperOp(zkw, setData).toRequestRecord();
932     setData(zkw, sd.getPath(), sd.getData(), sd.getVersion());
933   }
934 
935   /**
936    * Returns whether or not secure authentication is enabled
937    * (whether <code>hbase.security.authentication</code> is set to
938    * <code>kerberos</code>.
939    */
940   public static boolean isSecureZooKeeper(Configuration conf) {
941     // Detection for embedded HBase client with jaas configuration
942     // defined for third party programs.
943     try {
944       javax.security.auth.login.Configuration testConfig =
945           javax.security.auth.login.Configuration.getConfiguration();
946       if (testConfig.getAppConfigurationEntry("Client") == null
947           && testConfig.getAppConfigurationEntry(
948             JaasConfiguration.CLIENT_KEYTAB_KERBEROS_CONFIG_NAME) == null
949           && testConfig.getAppConfigurationEntry(
950               JaasConfiguration.SERVER_KEYTAB_KERBEROS_CONFIG_NAME) == null) {
951         return false;
952       }
953     } catch(Exception e) {
954       // No Jaas configuration defined.
955       return false;
956     }
957 
958     // Master & RSs uses hbase.zookeeper.client.*
959     return "kerberos".equalsIgnoreCase(conf.get("hbase.security.authentication"));
960   }
961 
962   private static ArrayList<ACL> createACL(ZooKeeperWatcher zkw, String node) {
963     return createACL(zkw, node, isSecureZooKeeper(zkw.getConfiguration()));
964   }
965 
966   public static ArrayList<ACL> createACL(ZooKeeperWatcher zkw, String node,
967     boolean isSecureZooKeeper) {
968     if (!node.startsWith(zkw.baseZNode)) {
969       return Ids.OPEN_ACL_UNSAFE;
970     }
971     if (isSecureZooKeeper) {
972       String superUser = zkw.getConfiguration().get("hbase.superuser");
973       ArrayList<ACL> acls = new ArrayList<ACL>();
974       // add permission to hbase supper user
975       if (superUser != null) {
976         acls.add(new ACL(Perms.ALL, new Id("auth", superUser)));
977       }
978       // Certain znodes are accessed directly by the client,
979       // so they must be readable by non-authenticated clients
980       if (zkw.isClientReadable(node)) {
981         acls.addAll(Ids.CREATOR_ALL_ACL);
982         acls.addAll(Ids.READ_ACL_UNSAFE);
983       } else {
984         acls.addAll(Ids.CREATOR_ALL_ACL);
985       }
986       return acls;
987     } else {
988       return Ids.OPEN_ACL_UNSAFE;
989     }
990   }
991 
992   //
993   // Node creation
994   //
995 
996   /**
997    *
998    * Set the specified znode to be an ephemeral node carrying the specified
999    * data.
1000    *
1001    * If the node is created successfully, a watcher is also set on the node.
1002    *
1003    * If the node is not created successfully because it already exists, this
1004    * method will also set a watcher on the node.
1005    *
1006    * If there is another problem, a KeeperException will be thrown.
1007    *
1008    * @param zkw zk reference
1009    * @param znode path of node
1010    * @param data data of node
1011    * @return true if node created, false if not, watch set in both cases
1012    * @throws KeeperException if unexpected zookeeper exception
1013    */
1014   public static boolean createEphemeralNodeAndWatch(ZooKeeperWatcher zkw,
1015       String znode, byte [] data)
1016   throws KeeperException {
1017     boolean ret = true;
1018     try {
1019       zkw.getRecoverableZooKeeper().create(znode, data, createACL(zkw, znode),
1020           CreateMode.EPHEMERAL);
1021     } catch (KeeperException.NodeExistsException nee) {
1022       ret = false;
1023     } catch (InterruptedException e) {
1024       LOG.info("Interrupted", e);
1025       Thread.currentThread().interrupt();
1026     }
1027     if(!watchAndCheckExists(zkw, znode)) {
1028       // It did exist but now it doesn't, try again
1029       return createEphemeralNodeAndWatch(zkw, znode, data);
1030     }
1031     return ret;
1032   }
1033 
1034   /**
1035    * Creates the specified znode to be a persistent node carrying the specified
1036    * data.
1037    *
1038    * Returns true if the node was successfully created, false if the node
1039    * already existed.
1040    *
1041    * If the node is created successfully, a watcher is also set on the node.
1042    *
1043    * If the node is not created successfully because it already exists, this
1044    * method will also set a watcher on the node but return false.
1045    *
1046    * If there is another problem, a KeeperException will be thrown.
1047    *
1048    * @param zkw zk reference
1049    * @param znode path of node
1050    * @param data data of node
1051    * @return true if node created, false if not, watch set in both cases
1052    * @throws KeeperException if unexpected zookeeper exception
1053    */
1054   public static boolean createNodeIfNotExistsAndWatch(
1055       ZooKeeperWatcher zkw, String znode, byte [] data)
1056   throws KeeperException {
1057     boolean ret = true;
1058     try {
1059       zkw.getRecoverableZooKeeper().create(znode, data, createACL(zkw, znode),
1060           CreateMode.PERSISTENT);
1061     } catch (KeeperException.NodeExistsException nee) {
1062       ret = false;
1063     } catch (InterruptedException e) {
1064       zkw.interruptedException(e);
1065       return false;
1066     }
1067     try {
1068       zkw.getRecoverableZooKeeper().exists(znode, zkw);
1069     } catch (InterruptedException e) {
1070       zkw.interruptedException(e);
1071       return false;
1072     }
1073     return ret;
1074   }
1075 
1076   /**
1077    * Creates the specified znode with the specified data but does not watch it.
1078    *
1079    * Returns the znode of the newly created node
1080    *
1081    * If there is another problem, a KeeperException will be thrown.
1082    *
1083    * @param zkw zk reference
1084    * @param znode path of node
1085    * @param data data of node
1086    * @param createMode specifying whether the node to be created is ephemeral and/or sequential
1087    * @return true name of the newly created znode or null
1088    * @throws KeeperException if unexpected zookeeper exception
1089    */
1090   public static String createNodeIfNotExistsNoWatch(ZooKeeperWatcher zkw, String znode,
1091       byte[] data, CreateMode createMode) throws KeeperException {
1092 
1093     String createdZNode = null;
1094     try {
1095       createdZNode = zkw.getRecoverableZooKeeper().create(znode, data,
1096           createACL(zkw, znode), createMode);
1097     } catch (KeeperException.NodeExistsException nee) {
1098       return znode;
1099     } catch (InterruptedException e) {
1100       zkw.interruptedException(e);
1101       return null;
1102     }
1103     return createdZNode;
1104   }
1105 
1106   /**
1107    * Creates the specified node with the specified data and watches it.
1108    *
1109    * <p>Throws an exception if the node already exists.
1110    *
1111    * <p>The node created is persistent and open access.
1112    *
1113    * <p>Returns the version number of the created node if successful.
1114    *
1115    * @param zkw zk reference
1116    * @param znode path of node to create
1117    * @param data data of node to create
1118    * @return version of node created
1119    * @throws KeeperException if unexpected zookeeper exception
1120    * @throws KeeperException.NodeExistsException if node already exists
1121    */
1122   public static int createAndWatch(ZooKeeperWatcher zkw,
1123       String znode, byte [] data)
1124   throws KeeperException, KeeperException.NodeExistsException {
1125     try {
1126       zkw.getRecoverableZooKeeper().create(znode, data, createACL(zkw, znode),
1127           CreateMode.PERSISTENT);
1128       Stat stat = zkw.getRecoverableZooKeeper().exists(znode, zkw);
1129       if (stat == null){
1130         // Likely a race condition. Someone deleted the znode.
1131         throw KeeperException.create(KeeperException.Code.SYSTEMERROR,
1132             "ZK.exists returned null (i.e.: znode does not exist) for znode=" + znode);
1133       }
1134      return stat.getVersion();
1135     } catch (InterruptedException e) {
1136       zkw.interruptedException(e);
1137       return -1;
1138     }
1139   }
1140 
1141   /**
1142    * Async creates the specified node with the specified data.
1143    *
1144    * <p>Throws an exception if the node already exists.
1145    *
1146    * <p>The node created is persistent and open access.
1147    *
1148    * @param zkw zk reference
1149    * @param znode path of node to create
1150    * @param data data of node to create
1151    * @param cb
1152    * @param ctx
1153    * @throws KeeperException if unexpected zookeeper exception
1154    * @throws KeeperException.NodeExistsException if node already exists
1155    */
1156   public static void asyncCreate(ZooKeeperWatcher zkw,
1157       String znode, byte [] data, final AsyncCallback.StringCallback cb,
1158       final Object ctx) {
1159     zkw.getRecoverableZooKeeper().getZooKeeper().create(znode, data,
1160         createACL(zkw, znode), CreateMode.PERSISTENT, cb, ctx);
1161   }
1162 
1163   /**
1164    * Creates the specified node, iff the node does not exist.  Does not set a
1165    * watch and fails silently if the node already exists.
1166    *
1167    * The node created is persistent and open access.
1168    *
1169    * @param zkw zk reference
1170    * @param znode path of node
1171    * @throws KeeperException if unexpected zookeeper exception
1172    */
1173   public static void createAndFailSilent(ZooKeeperWatcher zkw,
1174       String znode) throws KeeperException {
1175     createAndFailSilent(zkw, znode, new byte[0]);
1176   }
1177 
1178   /**
1179    * Creates the specified node containing specified data, iff the node does not exist.  Does
1180    * not set a watch and fails silently if the node already exists.
1181    *
1182    * The node created is persistent and open access.
1183    *
1184    * @param zkw zk reference
1185    * @param znode path of node
1186    * @param data a byte array data to store in the znode
1187    * @throws KeeperException if unexpected zookeeper exception
1188    */
1189   public static void createAndFailSilent(ZooKeeperWatcher zkw,
1190       String znode, byte[] data)
1191   throws KeeperException {
1192     createAndFailSilent(zkw,
1193         (CreateAndFailSilent)ZKUtilOp.createAndFailSilent(znode, data));
1194   }
1195   
1196   private static void createAndFailSilent(ZooKeeperWatcher zkw, CreateAndFailSilent cafs)
1197   throws KeeperException {
1198     CreateRequest create = (CreateRequest)toZooKeeperOp(zkw, cafs).toRequestRecord();
1199     String znode = create.getPath();
1200     try {
1201       RecoverableZooKeeper zk = zkw.getRecoverableZooKeeper();
1202       if (zk.exists(znode, false) == null) {
1203         zk.create(znode, create.getData(), create.getAcl(), CreateMode.fromFlag(create.getFlags()));
1204       }
1205     } catch(KeeperException.NodeExistsException nee) {
1206     } catch(KeeperException.NoAuthException nee){
1207       try {
1208         if (null == zkw.getRecoverableZooKeeper().exists(znode, false)) {
1209           // If we failed to create the file and it does not already exist.
1210           throw(nee);
1211         }
1212       } catch (InterruptedException ie) {
1213         zkw.interruptedException(ie);
1214       }
1215 
1216     } catch(InterruptedException ie) {
1217       zkw.interruptedException(ie);
1218     }
1219   }
1220 
1221   /**
1222    * Creates the specified node and all parent nodes required for it to exist.
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)
1233   throws KeeperException {
1234     createWithParents(zkw, znode, new byte[0]);
1235   }
1236 
1237   /**
1238    * Creates the specified node and all parent nodes required for it to exist.  The creation of
1239    * parent znodes is not atomic with the leafe znode creation but the data is written atomically
1240    * when the leaf node is created.
1241    *
1242    * No watches are set and no errors are thrown if the node already exists.
1243    *
1244    * The nodes created are persistent and open access.
1245    *
1246    * @param zkw zk reference
1247    * @param znode path of node
1248    * @throws KeeperException if unexpected zookeeper exception
1249    */
1250   public static void createWithParents(ZooKeeperWatcher zkw, String znode, byte[] data)
1251   throws KeeperException {
1252     try {
1253       if(znode == null) {
1254         return;
1255       }
1256       zkw.getRecoverableZooKeeper().create(znode, data, createACL(zkw, znode),
1257           CreateMode.PERSISTENT);
1258     } catch(KeeperException.NodeExistsException nee) {
1259       return;
1260     } catch(KeeperException.NoNodeException nne) {
1261       createWithParents(zkw, getParent(znode));
1262       createWithParents(zkw, znode, data);
1263     } catch(InterruptedException ie) {
1264       zkw.interruptedException(ie);
1265     }
1266   }
1267 
1268   //
1269   // Deletes
1270   //
1271 
1272   /**
1273    * Delete the specified node.  Sets no watches.  Throws all exceptions.
1274    */
1275   public static void deleteNode(ZooKeeperWatcher zkw, String node)
1276   throws KeeperException {
1277     deleteNode(zkw, node, -1);
1278   }
1279 
1280   /**
1281    * Delete the specified node with the specified version.  Sets no watches.
1282    * Throws all exceptions.
1283    */
1284   public static boolean deleteNode(ZooKeeperWatcher zkw, String node,
1285       int version)
1286   throws KeeperException {
1287     try {
1288       zkw.getRecoverableZooKeeper().delete(node, version);
1289       return true;
1290     } catch(KeeperException.BadVersionException bve) {
1291       return false;
1292     } catch(InterruptedException ie) {
1293       zkw.interruptedException(ie);
1294       return false;
1295     }
1296   }
1297 
1298   /**
1299    * Deletes the specified node.  Fails silent if the node does not exist.
1300    * @param zkw
1301    * @param node
1302    * @throws KeeperException
1303    */
1304   public static void deleteNodeFailSilent(ZooKeeperWatcher zkw, String node)
1305   throws KeeperException {
1306     deleteNodeFailSilent(zkw,
1307       (DeleteNodeFailSilent)ZKUtilOp.deleteNodeFailSilent(node));
1308   }
1309 
1310   private static void deleteNodeFailSilent(ZooKeeperWatcher zkw,
1311       DeleteNodeFailSilent dnfs) throws KeeperException {
1312     DeleteRequest delete = (DeleteRequest)toZooKeeperOp(zkw, dnfs).toRequestRecord();
1313     try {
1314       zkw.getRecoverableZooKeeper().delete(delete.getPath(), delete.getVersion());
1315     } catch(KeeperException.NoNodeException nne) {
1316     } catch(InterruptedException ie) {
1317       zkw.interruptedException(ie);
1318     }
1319   }
1320 
1321 
1322   /**
1323    * Delete the specified node and all of it's children.
1324    * <p>
1325    * If the node does not exist, just returns.
1326    * <p>
1327    * Sets no watches. Throws all exceptions besides dealing with deletion of
1328    * children.
1329    */
1330   public static void deleteNodeRecursively(ZooKeeperWatcher zkw, String node)
1331   throws KeeperException {
1332     deleteNodeRecursivelyMultiOrSequential(zkw, true, node);
1333   }
1334 
1335   /**
1336    * Delete all the children of the specified node but not the node itself.
1337    *
1338    * Sets no watches.  Throws all exceptions besides dealing with deletion of
1339    * children.
1340    *
1341    * If hbase.zookeeper.useMulti is true, use ZooKeeper's multi-update functionality.
1342    * Otherwise, run the list of operations sequentially.
1343    *
1344    * @throws KeeperException
1345    */
1346   public static void deleteChildrenRecursively(ZooKeeperWatcher zkw, String node)
1347       throws KeeperException {
1348     deleteChildrenRecursivelyMultiOrSequential(zkw, true, node);
1349   }
1350 
1351   /**
1352    * Delete all the children of the specified node but not the node itself. This
1353    * will first traverse the znode tree for listing the children and then delete
1354    * these znodes using multi-update api or sequential based on the specified
1355    * configurations.
1356    * <p>
1357    * Sets no watches. Throws all exceptions besides dealing with deletion of
1358    * children.
1359    * <p>
1360    * If hbase.zookeeper.useMulti is true, use ZooKeeper's multi-update
1361    * functionality. Otherwise, run the list of operations sequentially.
1362    * <p>
1363    * If all of the following are true:
1364    * <ul>
1365    * <li>runSequentialOnMultiFailure is true
1366    * <li>hbase.zookeeper.useMulti is true
1367    * </ul>
1368    * on calling multi, we get a ZooKeeper exception that can be handled by a
1369    * sequential call(*), we retry the operations one-by-one (sequentially).
1370    *
1371    * @param zkw
1372    *          - zk reference
1373    * @param runSequentialOnMultiFailure
1374    *          - if true when we get a ZooKeeper exception that could retry the
1375    *          operations one-by-one (sequentially)
1376    * @param pathRoots
1377    *          - path of the parent node(s)
1378    * @throws KeeperException.NotEmptyException
1379    *           if node has children while deleting
1380    * @throws KeeperException
1381    *           if unexpected ZooKeeper exception
1382    * @throws IllegalArgumentException
1383    *           if an invalid path is specified
1384    */
1385   public static void deleteChildrenRecursivelyMultiOrSequential(
1386       ZooKeeperWatcher zkw, boolean runSequentialOnMultiFailure,
1387       String... pathRoots) throws KeeperException {
1388     if (pathRoots == null || pathRoots.length <= 0) {
1389       LOG.warn("Given path is not valid!");
1390       return;
1391     }
1392     List<ZKUtilOp> ops = new ArrayList<ZKUtil.ZKUtilOp>();
1393     for (String eachRoot : pathRoots) {
1394       List<String> children = listChildrenBFSNoWatch(zkw, eachRoot);
1395       // Delete the leaves first and eventually get rid of the root
1396       for (int i = children.size() - 1; i >= 0; --i) {
1397         ops.add(ZKUtilOp.deleteNodeFailSilent(children.get(i)));
1398       }
1399     }
1400     // atleast one element should exist
1401     if (ops.size() > 0) {
1402       multiOrSequential(zkw, ops, runSequentialOnMultiFailure);
1403     }
1404   }
1405 
1406   /**
1407    * Delete the specified node and its children. This traverse the
1408    * znode tree for listing the children and then delete
1409    * these znodes including the parent using multi-update api or
1410    * sequential based on the specified configurations.
1411    * <p>
1412    * Sets no watches. Throws all exceptions besides dealing with deletion of
1413    * children.
1414    * <p>
1415    * If hbase.zookeeper.useMulti is true, use ZooKeeper's multi-update
1416    * functionality. Otherwise, run the list of operations sequentially.
1417    * <p>
1418    * If all of the following are true:
1419    * <ul>
1420    * <li>runSequentialOnMultiFailure is true
1421    * <li>hbase.zookeeper.useMulti is true
1422    * </ul>
1423    * on calling multi, we get a ZooKeeper exception that can be handled by a
1424    * sequential call(*), we retry the operations one-by-one (sequentially).
1425    *
1426    * @param zkw
1427    *          - zk reference
1428    * @param runSequentialOnMultiFailure
1429    *          - if true when we get a ZooKeeper exception that could retry the
1430    *          operations one-by-one (sequentially)
1431    * @param pathRoots
1432    *          - path of the parent node(s)
1433    * @throws KeeperException.NotEmptyException
1434    *           if node has children while deleting
1435    * @throws KeeperException
1436    *           if unexpected ZooKeeper exception
1437    * @throws IllegalArgumentException
1438    *           if an invalid path is specified
1439    */
1440   public static void deleteNodeRecursivelyMultiOrSequential(ZooKeeperWatcher zkw,
1441       boolean runSequentialOnMultiFailure, String... pathRoots) throws KeeperException {
1442     if (pathRoots == null || pathRoots.length <= 0) {
1443       LOG.warn("Given path is not valid!");
1444       return;
1445     }
1446     List<ZKUtilOp> ops = new ArrayList<ZKUtil.ZKUtilOp>();
1447     for (String eachRoot : pathRoots) {
1448       // Zookeeper Watches are one time triggers; When children of parent nodes are deleted
1449       // recursively, must set another watch, get notified of delete node
1450       List<String> children = listChildrenBFSAndWatchThem(zkw, eachRoot);
1451       // Delete the leaves first and eventually get rid of the root
1452       for (int i = children.size() - 1; i >= 0; --i) {
1453         ops.add(ZKUtilOp.deleteNodeFailSilent(children.get(i)));
1454       }
1455       try {
1456         if (zkw.getRecoverableZooKeeper().exists(eachRoot, zkw) != null) {
1457           ops.add(ZKUtilOp.deleteNodeFailSilent(eachRoot));
1458         }
1459       } catch (InterruptedException e) {
1460         zkw.interruptedException(e);
1461       }
1462     }
1463     // atleast one element should exist
1464     if (ops.size() > 0) {
1465       multiOrSequential(zkw, ops, runSequentialOnMultiFailure);
1466     }
1467   }
1468 
1469   /**
1470    * BFS Traversal of all the children under path, with the entries in the list,
1471    * in the same order as that of the traversal. Lists all the children without
1472    * setting any watches.
1473    *
1474    * @param zkw
1475    *          - zk reference
1476    * @param znode
1477    *          - path of node
1478    * @return list of children znodes under the path
1479    * @throws KeeperException
1480    *           if unexpected ZooKeeper exception
1481    */
1482   private static List<String> listChildrenBFSNoWatch(ZooKeeperWatcher zkw,
1483       final String znode) throws KeeperException {
1484     Deque<String> queue = new LinkedList<String>();
1485     List<String> tree = new ArrayList<String>();
1486     queue.add(znode);
1487     while (true) {
1488       String node = queue.pollFirst();
1489       if (node == null) {
1490         break;
1491       }
1492       List<String> children = listChildrenNoWatch(zkw, node);
1493       if (children == null) {
1494         continue;
1495       }
1496       for (final String child : children) {
1497         final String childPath = node + "/" + child;
1498         queue.add(childPath);
1499         tree.add(childPath);
1500       }
1501     }
1502     return tree;
1503   }
1504 
1505   /**
1506    * BFS Traversal of all the children under path, with the entries in the list,
1507    * in the same order as that of the traversal.
1508    * Lists all the children and set watches on to them.
1509    *
1510    * @param zkw
1511    *          - zk reference
1512    * @param znode
1513    *          - path of node
1514    * @return list of children znodes under the path
1515    * @throws KeeperException
1516    *           if unexpected ZooKeeper exception
1517    */
1518   private static List<String> listChildrenBFSAndWatchThem(ZooKeeperWatcher zkw, final String znode)
1519       throws KeeperException {
1520     Deque<String> queue = new LinkedList<String>();
1521     List<String> tree = new ArrayList<String>();
1522     queue.add(znode);
1523     while (true) {
1524       String node = queue.pollFirst();
1525       if (node == null) {
1526         break;
1527       }
1528       List<String> children = listChildrenAndWatchThem(zkw, node);
1529       if (children == null) {
1530         continue;
1531       }
1532       for (final String child : children) {
1533         final String childPath = node + "/" + child;
1534         queue.add(childPath);
1535         tree.add(childPath);
1536       }
1537     }
1538     return tree;
1539   }
1540 
1541   /**
1542    * Represents an action taken by ZKUtil, e.g. createAndFailSilent.
1543    * These actions are higher-level than ZKOp actions, which represent
1544    * individual actions in the ZooKeeper API, like create.
1545    */
1546   public abstract static class ZKUtilOp {
1547     private String path;
1548 
1549     private ZKUtilOp(String path) {
1550       this.path = path;
1551     }
1552 
1553     /**
1554      * @return a createAndFailSilent ZKUtilOp
1555      */
1556     public static ZKUtilOp createAndFailSilent(String path, byte[] data) {
1557       return new CreateAndFailSilent(path, data);
1558     }
1559 
1560     /**
1561      * @return a deleteNodeFailSilent ZKUtilOP
1562      */
1563     public static ZKUtilOp deleteNodeFailSilent(String path) {
1564       return new DeleteNodeFailSilent(path);
1565     }
1566 
1567     /**
1568      * @return a setData ZKUtilOp
1569      */
1570     public static ZKUtilOp setData(String path, byte [] data) {
1571       return new SetData(path, data);
1572     }
1573 
1574     /**
1575      * @return path to znode where the ZKOp will occur
1576      */
1577     public String getPath() {
1578       return path;
1579     }
1580 
1581     /**
1582      * ZKUtilOp representing createAndFailSilent in ZooKeeper
1583      * (attempt to create node, ignore error if already exists)
1584      */
1585     public static class CreateAndFailSilent extends ZKUtilOp {
1586       private byte [] data;
1587 
1588       private CreateAndFailSilent(String path, byte [] data) {
1589         super(path);
1590         this.data = data;
1591       }
1592 
1593       public byte[] getData() {
1594         return data;
1595       }
1596 
1597       @Override
1598       public boolean equals(Object o) {
1599         if (this == o) return true;
1600         if (!(o instanceof CreateAndFailSilent)) return false;
1601 
1602         CreateAndFailSilent op = (CreateAndFailSilent) o;
1603         return getPath().equals(op.getPath()) && Arrays.equals(data, op.data);
1604       }
1605 
1606       @Override
1607       public int hashCode() {
1608         int ret = 17 + getPath().hashCode() * 31;
1609         return ret * 31 + Bytes.hashCode(data);
1610       }
1611     }
1612 
1613     /**
1614      * ZKUtilOp representing deleteNodeFailSilent in ZooKeeper
1615      * (attempt to delete node, ignore error if node doesn't exist)
1616      */
1617     public static class DeleteNodeFailSilent extends ZKUtilOp {
1618       private DeleteNodeFailSilent(String path) {
1619         super(path);
1620       }
1621 
1622       @Override
1623       public boolean equals(Object o) {
1624         if (this == o) return true;
1625         if (!(o instanceof DeleteNodeFailSilent)) return false;
1626 
1627         return super.equals(o);
1628       }
1629 
1630       @Override
1631       public int hashCode() {
1632         return getPath().hashCode();
1633       }
1634     }
1635 
1636     /**
1637      * ZKUtilOp representing setData in ZooKeeper
1638      */
1639     public static class SetData extends ZKUtilOp {
1640       private byte [] data;
1641 
1642       private SetData(String path, byte [] data) {
1643         super(path);
1644         this.data = data;
1645       }
1646 
1647       public byte[] getData() {
1648         return data;
1649       }
1650 
1651       @Override
1652       public boolean equals(Object o) {
1653         if (this == o) return true;
1654         if (!(o instanceof SetData)) return false;
1655 
1656         SetData op = (SetData) o;
1657         return getPath().equals(op.getPath()) && Arrays.equals(data, op.data);
1658       }
1659 
1660       @Override
1661       public int hashCode() {
1662         int ret = getPath().hashCode();
1663         return ret * 31 + Bytes.hashCode(data);
1664       }
1665     }
1666   }
1667 
1668   /**
1669    * Convert from ZKUtilOp to ZKOp
1670    */
1671   private static Op toZooKeeperOp(ZooKeeperWatcher zkw, ZKUtilOp op)
1672   throws UnsupportedOperationException {
1673     if(op == null) return null;
1674 
1675     if (op instanceof CreateAndFailSilent) {
1676       CreateAndFailSilent cafs = (CreateAndFailSilent)op;
1677       return Op.create(cafs.getPath(), cafs.getData(), createACL(zkw, cafs.getPath()),
1678         CreateMode.PERSISTENT);
1679     } else if (op instanceof DeleteNodeFailSilent) {
1680       DeleteNodeFailSilent dnfs = (DeleteNodeFailSilent)op;
1681       return Op.delete(dnfs.getPath(), -1);
1682     } else if (op instanceof SetData) {
1683       SetData sd = (SetData)op;
1684       return Op.setData(sd.getPath(), sd.getData(), -1);
1685     } else {
1686       throw new UnsupportedOperationException("Unexpected ZKUtilOp type: "
1687         + op.getClass().getName());
1688     }
1689   }
1690 
1691   /**
1692    * If hbase.zookeeper.useMulti is true, use ZooKeeper's multi-update functionality.
1693    * Otherwise, run the list of operations sequentially.
1694    *
1695    * If all of the following are true:
1696    * - runSequentialOnMultiFailure is true
1697    * - hbase.zookeeper.useMulti is true
1698    * - on calling multi, we get a ZooKeeper exception that can be handled by a sequential call(*)
1699    * Then:
1700    * - we retry the operations one-by-one (sequentially)
1701    *
1702    * Note *: an example is receiving a NodeExistsException from a "create" call.  Without multi,
1703    * a user could call "createAndFailSilent" to ensure that a node exists if they don't care who
1704    * actually created the node (i.e. the NodeExistsException from ZooKeeper is caught).
1705    * This will cause all operations in the multi to fail, however, because
1706    * the NodeExistsException that zk.create throws will fail the multi transaction.
1707    * In this case, if the previous conditions hold, the commands are run sequentially, which should
1708    * result in the correct final state, but means that the operations will not run atomically.
1709    *
1710    * @throws KeeperException
1711    */
1712   public static void multiOrSequential(ZooKeeperWatcher zkw, List<ZKUtilOp> ops,
1713       boolean runSequentialOnMultiFailure) throws KeeperException {
1714     if (ops == null) return;
1715     boolean useMulti = zkw.getConfiguration().getBoolean(HConstants.ZOOKEEPER_USEMULTI, false);
1716 
1717     if (useMulti) {
1718       List<Op> zkOps = new LinkedList<Op>();
1719       for (ZKUtilOp op : ops) {
1720         zkOps.add(toZooKeeperOp(zkw, op));
1721       }
1722       try {
1723         zkw.getRecoverableZooKeeper().multi(zkOps);
1724       } catch (KeeperException ke) {
1725        switch (ke.code()) {
1726          case NODEEXISTS:
1727          case NONODE:
1728          case BADVERSION:
1729          case NOAUTH:
1730            // if we get an exception that could be solved by running sequentially
1731            // (and the client asked us to), then break out and run sequentially
1732            if (runSequentialOnMultiFailure) {
1733              LOG.info("On call to ZK.multi, received exception: " + ke.toString() + "."
1734                + "  Attempting to run operations sequentially because"
1735                + " runSequentialOnMultiFailure is: " + runSequentialOnMultiFailure + ".");
1736              processSequentially(zkw, ops);
1737              break;
1738            }
1739           default:
1740             throw ke;
1741         }
1742       } catch (InterruptedException ie) {
1743         zkw.interruptedException(ie);
1744       }
1745     } else {
1746       // run sequentially
1747       processSequentially(zkw, ops);
1748     }
1749 
1750   }
1751 
1752   private static void processSequentially(ZooKeeperWatcher zkw, List<ZKUtilOp> ops)
1753       throws KeeperException, NoNodeException {
1754     for (ZKUtilOp op : ops) {
1755       if (op instanceof CreateAndFailSilent) {
1756         createAndFailSilent(zkw, (CreateAndFailSilent) op);
1757       } else if (op instanceof DeleteNodeFailSilent) {
1758         deleteNodeFailSilent(zkw, (DeleteNodeFailSilent) op);
1759       } else if (op instanceof SetData) {
1760         setData(zkw, (SetData) op);
1761       } else {
1762         throw new UnsupportedOperationException("Unexpected ZKUtilOp type: "
1763             + op.getClass().getName());
1764       }
1765     }
1766   }
1767 
1768   //
1769   // ZooKeeper cluster information
1770   //
1771 
1772   /** @return String dump of everything in ZooKeeper. */
1773   public static String dump(ZooKeeperWatcher zkw) {
1774     StringBuilder sb = new StringBuilder();
1775     try {
1776       sb.append("HBase is rooted at ").append(zkw.baseZNode);
1777       sb.append("\nActive master address: ");
1778       try {
1779         sb.append(MasterAddressTracker.getMasterAddress(zkw));
1780       } catch (IOException e) {
1781         sb.append("<<FAILED LOOKUP: " + e.getMessage() + ">>");
1782       }
1783       sb.append("\nBackup master addresses:");
1784       for (String child : listChildrenNoWatch(zkw,
1785                                               zkw.backupMasterAddressesZNode)) {
1786         sb.append("\n ").append(child);
1787       }
1788       sb.append("\nRegion server holding hbase:meta: " + MetaRegionTracker.getMetaRegionLocation(zkw));
1789       sb.append("\nRegion servers:");
1790       for (String child : listChildrenNoWatch(zkw, zkw.rsZNode)) {
1791         sb.append("\n ").append(child);
1792       }
1793       try {
1794         getReplicationZnodesDump(zkw, sb);
1795       } catch (KeeperException ke) {
1796         LOG.warn("Couldn't get the replication znode dump", ke);
1797       }
1798       sb.append("\nQuorum Server Statistics:");
1799       String[] servers = zkw.getQuorum().split(",");
1800       for (String server : servers) {
1801         sb.append("\n ").append(server);
1802         try {
1803           String[] stat = getServerStats(server, ZKUtil.zkDumpConnectionTimeOut);
1804 
1805           if (stat == null) {
1806             sb.append("[Error] invalid quorum server: " + server);
1807             break;
1808           }
1809 
1810           for (String s : stat) {
1811             sb.append("\n  ").append(s);
1812           }
1813         } catch (Exception e) {
1814           sb.append("\n  ERROR: ").append(e.getMessage());
1815         }
1816       }
1817     } catch (KeeperException ke) {
1818       sb.append("\nFATAL ZooKeeper Exception!\n");
1819       sb.append("\n" + ke.getMessage());
1820     }
1821     return sb.toString();
1822   }
1823 
1824   /**
1825    * Appends replication znodes to the passed StringBuilder.
1826    * @param zkw
1827    * @param sb
1828    * @throws KeeperException
1829    */
1830   private static void getReplicationZnodesDump(ZooKeeperWatcher zkw, StringBuilder sb)
1831       throws KeeperException {
1832     String replicationZNodeName = zkw.getConfiguration().get("zookeeper.znode.replication",
1833       "replication");
1834     String replicationZnode = joinZNode(zkw.baseZNode, replicationZNodeName);
1835     if (ZKUtil.checkExists(zkw, replicationZnode) == -1) return;
1836     // do a ls -r on this znode
1837     sb.append("\n").append(replicationZnode).append(": ");
1838     List<String> children = ZKUtil.listChildrenNoWatch(zkw, replicationZnode);
1839     for (String child : children) {
1840       String znode = joinZNode(replicationZnode, child);
1841       if (child.equals(zkw.getConfiguration().get("zookeeper.znode.replication.peers", "peers"))) {
1842         appendPeersZnodes(zkw, znode, sb);
1843       } else if (child.equals(zkw.getConfiguration().
1844           get("zookeeper.znode.replication.rs", "rs"))) {
1845         appendRSZnodes(zkw, znode, sb);
1846       }
1847     }
1848   }
1849 
1850   private static void appendRSZnodes(ZooKeeperWatcher zkw, String znode, StringBuilder sb)
1851       throws KeeperException {
1852     List<String> stack = new LinkedList<String>();
1853     stack.add(znode);
1854     do {
1855       String znodeToProcess = stack.remove(stack.size() - 1);
1856       sb.append("\n").append(znodeToProcess).append(": ");
1857       byte[] data = ZKUtil.getData(zkw, znodeToProcess);
1858       if (data != null && data.length > 0) { // log position
1859         long position = 0;
1860         try {
1861           position = ZKUtil.parseHLogPositionFrom(ZKUtil.getData(zkw, znodeToProcess));
1862           sb.append(position);
1863         } catch (Exception e) {
1864         }
1865       }
1866       for (String zNodeChild : ZKUtil.listChildrenNoWatch(zkw, znodeToProcess)) {
1867         stack.add(ZKUtil.joinZNode(znodeToProcess, zNodeChild));
1868       }
1869     } while (stack.size() > 0);
1870   }
1871 
1872   private static void appendPeersZnodes(ZooKeeperWatcher zkw, String peersZnode,
1873     StringBuilder sb) throws KeeperException {
1874     int pblen = ProtobufUtil.lengthOfPBMagic();
1875     sb.append("\n").append(peersZnode).append(": ");
1876     for (String peerIdZnode : ZKUtil.listChildrenNoWatch(zkw, peersZnode)) {
1877       String znodeToProcess = ZKUtil.joinZNode(peersZnode, peerIdZnode);
1878       byte[] data = ZKUtil.getData(zkw, znodeToProcess);
1879       // parse the data of the above peer znode.
1880       try {
1881         ZooKeeperProtos.ReplicationPeer.Builder builder =
1882           ZooKeeperProtos.ReplicationPeer.newBuilder();
1883         ProtobufUtil.mergeFrom(builder, data, pblen, data.length - pblen);
1884         String clusterKey = builder.getClusterkey();
1885         sb.append("\n").append(znodeToProcess).append(": ").append(clusterKey);
1886         // add the peer-state.
1887         appendPeerState(zkw, znodeToProcess, sb);
1888       } catch (IOException ipbe) {
1889         LOG.warn("Got Exception while parsing peer: " + znodeToProcess, ipbe);
1890       }
1891     }
1892   }
1893 
1894   private static void appendPeerState(ZooKeeperWatcher zkw, String znodeToProcess,
1895       StringBuilder sb) throws KeeperException, IOException {
1896     String peerState = zkw.getConfiguration().get("zookeeper.znode.replication.peers.state",
1897       "peer-state");
1898     int pblen = ProtobufUtil.lengthOfPBMagic();
1899     for (String child : ZKUtil.listChildrenNoWatch(zkw, znodeToProcess)) {
1900       if (!child.equals(peerState)) continue;
1901       String peerStateZnode = ZKUtil.joinZNode(znodeToProcess, child);
1902       sb.append("\n").append(peerStateZnode).append(": ");
1903       byte[] peerStateData = ZKUtil.getData(zkw, peerStateZnode);
1904       ZooKeeperProtos.ReplicationState.Builder builder = 
1905         ZooKeeperProtos.ReplicationState.newBuilder();
1906       ProtobufUtil.mergeFrom(builder, peerStateData, pblen, peerStateData.length - pblen);
1907       sb.append(builder.getState().name());
1908     }
1909   }
1910 
1911   /**
1912    * Gets the statistics from the given server.
1913    *
1914    * @param server  The server to get the statistics from.
1915    * @param timeout  The socket timeout to use.
1916    * @return The array of response strings.
1917    * @throws IOException When the socket communication fails.
1918    */
1919   public static String[] getServerStats(String server, int timeout)
1920   throws IOException {
1921     String[] sp = server.split(":");
1922     if (sp == null || sp.length == 0) {
1923       return null;
1924     }
1925 
1926     String host = sp[0];
1927     int port = sp.length > 1 ? Integer.parseInt(sp[1])
1928         : HConstants.DEFAULT_ZOOKEPER_CLIENT_PORT;
1929 
1930     Socket socket = new Socket();
1931     InetSocketAddress sockAddr = new InetSocketAddress(host, port);
1932     socket.connect(sockAddr, timeout);
1933 
1934     socket.setSoTimeout(timeout);
1935     PrintWriter out = new PrintWriter(socket.getOutputStream(), true);
1936     BufferedReader in = new BufferedReader(new InputStreamReader(
1937       socket.getInputStream()));
1938     out.println("stat");
1939     out.flush();
1940     ArrayList<String> res = new ArrayList<String>();
1941     while (true) {
1942       String line = in.readLine();
1943       if (line != null) {
1944         res.add(line);
1945       } else {
1946         break;
1947       }
1948     }
1949     socket.close();
1950     return res.toArray(new String[res.size()]);
1951   }
1952 
1953   private static void logRetrievedMsg(final ZooKeeperWatcher zkw,
1954       final String znode, final byte [] data, final boolean watcherSet) {
1955     if (!LOG.isTraceEnabled()) return;
1956     LOG.trace(zkw.prefix("Retrieved " + ((data == null)? 0: data.length) +
1957       " byte(s) of data from znode " + znode +
1958       (watcherSet? " and set watcher; ": "; data=") +
1959       (data == null? "null": data.length == 0? "empty": (
1960           znode.startsWith(zkw.assignmentZNode)?
1961             ZKAssign.toString(data): // We should not be doing this reaching into another class
1962           znode.startsWith(zkw.metaServerZNode)?
1963             getServerNameOrEmptyString(data):
1964           znode.startsWith(zkw.backupMasterAddressesZNode)?
1965             getServerNameOrEmptyString(data):
1966           StringUtils.abbreviate(Bytes.toStringBinary(data), 32)))));
1967   }
1968 
1969   private static String getServerNameOrEmptyString(final byte [] data) {
1970     try {
1971       return ServerName.parseFrom(data).toString();
1972     } catch (DeserializationException e) {
1973       return "";
1974     }
1975   }
1976 
1977   /**
1978    * Waits for HBase installation's base (parent) znode to become available.
1979    * @throws IOException on ZK errors
1980    */
1981   public static void waitForBaseZNode(Configuration conf) throws IOException {
1982     LOG.info("Waiting until the base znode is available");
1983     String parentZNode = conf.get(HConstants.ZOOKEEPER_ZNODE_PARENT,
1984         HConstants.DEFAULT_ZOOKEEPER_ZNODE_PARENT);
1985     ZooKeeper zk = new ZooKeeper(ZKConfig.getZKQuorumServersString(conf),
1986         conf.getInt(HConstants.ZK_SESSION_TIMEOUT,
1987         HConstants.DEFAULT_ZK_SESSION_TIMEOUT), EmptyWatcher.instance);
1988 
1989     final int maxTimeMs = 10000;
1990     final int maxNumAttempts = maxTimeMs / HConstants.SOCKET_RETRY_WAIT_MS;
1991 
1992     KeeperException keeperEx = null;
1993     try {
1994       try {
1995         for (int attempt = 0; attempt < maxNumAttempts; ++attempt) {
1996           try {
1997             if (zk.exists(parentZNode, false) != null) {
1998               LOG.info("Parent znode exists: " + parentZNode);
1999               keeperEx = null;
2000               break;
2001             }
2002           } catch (KeeperException e) {
2003             keeperEx = e;
2004           }
2005           Threads.sleepWithoutInterrupt(HConstants.SOCKET_RETRY_WAIT_MS);
2006         }
2007       } finally {
2008         zk.close();
2009       }
2010     } catch (InterruptedException ex) {
2011       Thread.currentThread().interrupt();
2012     }
2013 
2014     if (keeperEx != null) {
2015       throw new IOException(keeperEx);
2016     }
2017   }
2018 
2019 
2020   public static byte[] blockUntilAvailable(
2021     final ZooKeeperWatcher zkw, final String znode, final long timeout)
2022     throws InterruptedException {
2023     if (timeout < 0) throw new IllegalArgumentException();
2024     if (zkw == null) throw new IllegalArgumentException();
2025     if (znode == null) throw new IllegalArgumentException();
2026 
2027     byte[] data = null;
2028     boolean finished = false;
2029     final long endTime = System.currentTimeMillis() + timeout;
2030     while (!finished) {
2031       try {
2032         data = ZKUtil.getData(zkw, znode);
2033       } catch(KeeperException e) {
2034         if (e instanceof KeeperException.SessionExpiredException
2035             || e instanceof KeeperException.AuthFailedException) {
2036           // non-recoverable errors so stop here
2037           throw new InterruptedException("interrupted due to " + e);
2038         }
2039         LOG.warn("Unexpected exception handling blockUntilAvailable", e);
2040       }
2041 
2042       if (data == null && (System.currentTimeMillis() +
2043         HConstants.SOCKET_RETRY_WAIT_MS < endTime)) {
2044         Thread.sleep(HConstants.SOCKET_RETRY_WAIT_MS);
2045       } else {
2046         finished = true;
2047       }
2048     }
2049 
2050     return data;
2051   }
2052 
2053 
2054   /**
2055    * Convert a {@link DeserializationException} to a more palatable {@link KeeperException}.
2056    * Used when can't let a {@link DeserializationException} out w/o changing public API.
2057    * @param e Exception to convert
2058    * @return Converted exception
2059    */
2060   public static KeeperException convert(final DeserializationException e) {
2061     KeeperException ke = new KeeperException.DataInconsistencyException();
2062     ke.initCause(e);
2063     return ke;
2064   }
2065 
2066   /**
2067    * Recursively print the current state of ZK (non-transactional)
2068    * @param root name of the root directory in zk to print
2069    * @throws KeeperException
2070    */
2071   public static void logZKTree(ZooKeeperWatcher zkw, String root) {
2072     if (!LOG.isDebugEnabled()) return;
2073     LOG.debug("Current zk system:");
2074     String prefix = "|-";
2075     LOG.debug(prefix + root);
2076     try {
2077       logZKTree(zkw, root, prefix);
2078     } catch (KeeperException e) {
2079       throw new RuntimeException(e);
2080     }
2081   }
2082 
2083   /**
2084    * Helper method to print the current state of the ZK tree.
2085    * @see #logZKTree(ZooKeeperWatcher, String)
2086    * @throws KeeperException if an unexpected exception occurs
2087    */
2088   protected static void logZKTree(ZooKeeperWatcher zkw, String root, String prefix) throws KeeperException {
2089     List<String> children = ZKUtil.listChildrenNoWatch(zkw, root);
2090     if (children == null) return;
2091     for (String child : children) {
2092       LOG.debug(prefix + child);
2093       String node = ZKUtil.joinZNode(root.equals("/") ? "" : root, child);
2094       logZKTree(zkw, node, prefix + "---");
2095     }
2096   }
2097 
2098   /**
2099    * @param position
2100    * @return Serialized protobuf of <code>position</code> with pb magic prefix prepended suitable
2101    *         for use as content of an hlog position in a replication queue.
2102    */
2103   public static byte[] positionToByteArray(final long position) {
2104     byte[] bytes = ZooKeeperProtos.ReplicationHLogPosition.newBuilder().setPosition(position)
2105         .build().toByteArray();
2106     return ProtobufUtil.prependPBMagic(bytes);
2107   }
2108 
2109   /**
2110    * @param bytes - Content of a HLog position znode.
2111    * @return long - The current HLog position.
2112    * @throws DeserializationException
2113    */
2114   public static long parseHLogPositionFrom(final byte[] bytes) throws DeserializationException {
2115     if (bytes == null) {
2116       throw new DeserializationException("Unable to parse null HLog position.");
2117     }
2118     if (ProtobufUtil.isPBMagicPrefix(bytes)) {
2119       int pblen = ProtobufUtil.lengthOfPBMagic();
2120       ZooKeeperProtos.ReplicationHLogPosition.Builder builder =
2121           ZooKeeperProtos.ReplicationHLogPosition.newBuilder();
2122       ZooKeeperProtos.ReplicationHLogPosition position;
2123       try {
2124         ProtobufUtil.mergeFrom(builder, bytes, pblen, bytes.length - pblen);
2125         position = builder.build();
2126       } catch (IOException e) {
2127         throw new DeserializationException(e);
2128       }
2129       return position.getPosition();
2130     } else {
2131       if (bytes.length > 0) {
2132         return Bytes.toLong(bytes);
2133       }
2134       return 0;
2135     }
2136   }
2137 
2138   /**
2139    * @param regionLastFlushedSequenceId the flushed sequence id of a region which is the min of its
2140    *          store max seq ids
2141    * @param storeSequenceIds column family to sequence Id map
2142    * @return Serialized protobuf of <code>RegionSequenceIds</code> with pb magic prefix prepended
2143    *         suitable for use to filter wal edits in distributedLogReplay mode
2144    */
2145   public static byte[] regionSequenceIdsToByteArray(final Long regionLastFlushedSequenceId,
2146       final Map<byte[], Long> storeSequenceIds) {
2147     ZooKeeperProtos.RegionStoreSequenceIds.Builder regionSequenceIdsBuilder =
2148         ZooKeeperProtos.RegionStoreSequenceIds.newBuilder();
2149     ZooKeeperProtos.StoreSequenceId.Builder storeSequenceIdBuilder =
2150         ZooKeeperProtos.StoreSequenceId.newBuilder();
2151     if (storeSequenceIds != null) {
2152       for (Map.Entry<byte[], Long> e : storeSequenceIds.entrySet()){
2153         byte[] columnFamilyName = e.getKey();
2154         Long curSeqId = e.getValue();
2155         storeSequenceIdBuilder.setFamilyName(ByteStringer.wrap(columnFamilyName));
2156         storeSequenceIdBuilder.setSequenceId(curSeqId);
2157         regionSequenceIdsBuilder.addStoreSequenceId(storeSequenceIdBuilder.build());
2158         storeSequenceIdBuilder.clear();
2159       }
2160     }
2161     regionSequenceIdsBuilder.setLastFlushedSequenceId(regionLastFlushedSequenceId);
2162     byte[] result = regionSequenceIdsBuilder.build().toByteArray();
2163     return ProtobufUtil.prependPBMagic(result);
2164   }
2165 
2166   /**
2167    * @param bytes Content of serialized data of RegionStoreSequenceIds
2168    * @return a RegionStoreSequenceIds object
2169    * @throws DeserializationException
2170    */
2171   public static RegionStoreSequenceIds parseRegionStoreSequenceIds(final byte[] bytes)
2172       throws DeserializationException {
2173     if (bytes == null || !ProtobufUtil.isPBMagicPrefix(bytes)) {
2174       throw new DeserializationException("Unable to parse RegionStoreSequenceIds.");
2175     }
2176     RegionStoreSequenceIds.Builder regionSequenceIdsBuilder =
2177         ZooKeeperProtos.RegionStoreSequenceIds.newBuilder();
2178     int pblen = ProtobufUtil.lengthOfPBMagic();
2179     RegionStoreSequenceIds storeIds = null;
2180     try {
2181       ProtobufUtil.mergeFrom(regionSequenceIdsBuilder, bytes, pblen, bytes.length - pblen);
2182       storeIds = regionSequenceIdsBuilder.build();
2183     } catch (IOException e) {
2184       throw new DeserializationException(e);
2185     }
2186     return storeIds;
2187   }
2188 }