View Javadoc

1   /**
2    * Copyright 2010 The Apache Software Foundation
3    *
4    * Licensed to the Apache Software Foundation (ASF) under one
5    * or more contributor license agreements.  See the NOTICE file
6    * distributed with this work for additional information
7    * regarding copyright ownership.  The ASF licenses this file
8    * to you under the Apache License, Version 2.0 (the
9    * "License"); you may not use this file except in compliance
10   * with the License.  You may obtain a copy of the License at
11   *
12   *     http://www.apache.org/licenses/LICENSE-2.0
13   *
14   * Unless required by applicable law or agreed to in writing, software
15   * distributed under the License is distributed on an "AS IS" BASIS,
16   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
17   * See the License for the specific language governing permissions and
18   * limitations under the License.
19   */
20  package org.apache.hadoop.hbase.master;
21  
22  import java.io.DataInput;
23  import java.io.DataOutput;
24  import java.io.IOException;
25  import java.util.ArrayList;
26  import java.util.Arrays;
27  import java.util.Collections;
28  import java.util.Date;
29  import java.util.HashMap;
30  import java.util.HashSet;
31  import java.util.Iterator;
32  import java.util.List;
33  import java.util.Map;
34  import java.util.NavigableMap;
35  import java.util.Set;
36  import java.util.SortedMap;
37  import java.util.TreeMap;
38  import java.util.TreeSet;
39  import java.util.concurrent.ConcurrentSkipListMap;
40  import java.util.concurrent.ConcurrentSkipListSet;
41  import java.util.concurrent.Executors;
42  import java.util.concurrent.atomic.AtomicInteger;
43  import java.util.concurrent.atomic.AtomicLong;
44  
45  import org.apache.commons.logging.Log;
46  import org.apache.commons.logging.LogFactory;
47  import org.apache.hadoop.conf.Configuration;
48  import org.apache.hadoop.hbase.Chore;
49  import org.apache.hadoop.hbase.HConstants;
50  import org.apache.hadoop.hbase.HRegionInfo;
51  import org.apache.hadoop.hbase.HServerLoad;
52  import org.apache.hadoop.hbase.NotServingRegionException;
53  import org.apache.hadoop.hbase.Server;
54  import org.apache.hadoop.hbase.ServerName;
55  import org.apache.hadoop.hbase.Stoppable;
56  import org.apache.hadoop.hbase.TableNotFoundException;
57  import org.apache.hadoop.hbase.catalog.CatalogTracker;
58  import org.apache.hadoop.hbase.catalog.MetaReader;
59  import org.apache.hadoop.hbase.catalog.RootLocationEditor;
60  import org.apache.hadoop.hbase.client.Result;
61  import org.apache.hadoop.hbase.executor.EventHandler;
62  import org.apache.hadoop.hbase.executor.EventHandler.EventType;
63  import org.apache.hadoop.hbase.executor.ExecutorService;
64  import org.apache.hadoop.hbase.executor.RegionTransitionData;
65  import org.apache.hadoop.hbase.ipc.ServerNotRunningYetException;
66  import org.apache.hadoop.hbase.master.AssignmentManager.RegionState.State;
67  import org.apache.hadoop.hbase.master.handler.ClosedRegionHandler;
68  import org.apache.hadoop.hbase.master.handler.DisableTableHandler;
69  import org.apache.hadoop.hbase.master.handler.EnableTableHandler;
70  import org.apache.hadoop.hbase.master.handler.OpenedRegionHandler;
71  import org.apache.hadoop.hbase.master.handler.ServerShutdownHandler;
72  import org.apache.hadoop.hbase.master.handler.SplitRegionHandler;
73  import org.apache.hadoop.hbase.regionserver.RegionAlreadyInTransitionException;
74  import org.apache.hadoop.hbase.regionserver.RegionOpeningState;
75  import org.apache.hadoop.hbase.regionserver.RegionServerStoppedException;
76  import org.apache.hadoop.hbase.util.Bytes;
77  import org.apache.hadoop.hbase.util.Pair;
78  import org.apache.hadoop.hbase.util.Threads;
79  import org.apache.hadoop.hbase.util.Writables;
80  import org.apache.hadoop.hbase.zookeeper.ZKAssign;
81  import org.apache.hadoop.hbase.zookeeper.ZKTable;
82  import org.apache.hadoop.hbase.zookeeper.ZKUtil;
83  import org.apache.hadoop.hbase.zookeeper.ZooKeeperListener;
84  import org.apache.hadoop.hbase.zookeeper.ZooKeeperWatcher;
85  import org.apache.hadoop.ipc.RemoteException;
86  import org.apache.zookeeper.AsyncCallback;
87  import org.apache.zookeeper.KeeperException;
88  import org.apache.zookeeper.KeeperException.NoNodeException;
89  import org.apache.zookeeper.KeeperException.NodeExistsException;
90  import org.apache.zookeeper.data.Stat;
91  
92  /**
93   * Manages and performs region assignment.
94   * <p>
95   * Monitors ZooKeeper for events related to regions in transition.
96   * <p>
97   * Handles existing regions in transition during master failover.
98   */
99  public class AssignmentManager extends ZooKeeperListener {
100 
101   private static final Log LOG = LogFactory.getLog(AssignmentManager.class);
102 
103   protected Server master;
104 
105   private ServerManager serverManager;
106 
107   private CatalogTracker catalogTracker;
108 
109   private TimeoutMonitor timeoutMonitor;
110 
111   private TimerUpdater timerUpdater;
112 
113   private LoadBalancer balancer;
114 
115   /**
116    * Map of regions to reopen after the schema of a table is changed. Key -
117    * encoded region name, value - HRegionInfo
118    */
119   private final Map <String, HRegionInfo> regionsToReopen;
120 
121   /*
122    * Maximum times we recurse an assignment.  See below in {@link #assign()}.
123    */
124   private final int maximumAssignmentAttempts;
125 
126   /**
127    * Regions currently in transition.  Map of encoded region names to the master
128    * in-memory state for that region.
129    */
130   final ConcurrentSkipListMap<String, RegionState> regionsInTransition =
131     new ConcurrentSkipListMap<String, RegionState>();
132 
133   /** Plans for region movement. Key is the encoded version of a region name*/
134   // TODO: When do plans get cleaned out?  Ever? In server open and in server
135   // shutdown processing -- St.Ack
136   // All access to this Map must be synchronized.
137   final NavigableMap<String, RegionPlan> regionPlans =
138     new TreeMap<String, RegionPlan>();
139 
140   private final ZKTable zkTable;
141 
142   // store all the table names in disabling state
143   Set<String> disablingTables = new HashSet<String>(1);
144   // store all the enabling state table names and corresponding online servers' regions.
145   // This may be needed to avoid calling assign twice for the regions of the ENABLING table
146   // that could have been assigned through processRIT.
147   Map<String, List<HRegionInfo>> enablingTables = new HashMap<String, List<HRegionInfo>>(1);
148   /**
149    * Server to regions assignment map.
150    * Contains the set of regions currently assigned to a given server.
151    * This Map and {@link #regions} are tied.  Always update this in tandem
152    * with the other under a lock on {@link #regions}.
153    * @see #regions
154    */
155   private final NavigableMap<ServerName, Set<HRegionInfo>> servers =
156     new TreeMap<ServerName, Set<HRegionInfo>>();
157 
158   /**
159    * Contains the server which need to update timer, these servers will be
160    * handled by {@link TimerUpdater}
161    */
162   private final ConcurrentSkipListSet<ServerName> serversInUpdatingTimer = 
163     new ConcurrentSkipListSet<ServerName>();
164 
165   /**
166    * Region to server assignment map.
167    * Contains the server a given region is currently assigned to.
168    * This Map and {@link #servers} are tied.  Always update this in tandem
169    * with the other under a lock on {@link #regions}.
170    * @see #servers
171    */
172   private final SortedMap<HRegionInfo, ServerName> regions =
173     new TreeMap<HRegionInfo, ServerName>();
174 
175   private final ExecutorService executorService;
176 
177   //Thread pool executor service for timeout monitor
178   private java.util.concurrent.ExecutorService threadPoolExecutorService;
179   
180   private List<EventType> ignoreStatesRSOffline = Arrays.asList(new EventType[]{
181       EventType.RS_ZK_REGION_FAILED_OPEN, EventType.RS_ZK_REGION_CLOSED });
182 
183   /**
184    * Set when we are doing master failover processing; cleared when failover
185    * completes.
186    */
187   private volatile boolean failover = false;
188 
189   // Set holding all the regions which got processed while RIT was not 
190   // populated during master failover. 
191   private Map<String, HRegionInfo> failoverProcessedRegions =
192     new HashMap<String, HRegionInfo>();
193 
194   /**
195    * Constructs a new assignment manager.
196    *
197    * @param master
198    * @param serverManager
199    * @param catalogTracker
200    * @param service
201    * @throws KeeperException
202    * @throws IOException 
203    */
204   public AssignmentManager(Server master, ServerManager serverManager,
205       CatalogTracker catalogTracker, final LoadBalancer balancer,
206       final ExecutorService service) throws KeeperException, IOException {
207     super(master.getZooKeeper());
208     this.master = master;
209     this.serverManager = serverManager;
210     this.catalogTracker = catalogTracker;
211     this.executorService = service;
212     this.regionsToReopen = Collections.synchronizedMap
213                            (new HashMap<String, HRegionInfo> ());
214     Configuration conf = master.getConfiguration();
215     this.timeoutMonitor = new TimeoutMonitor(
216       conf.getInt("hbase.master.assignment.timeoutmonitor.period", 10000),
217       master, serverManager,
218       conf.getInt("hbase.master.assignment.timeoutmonitor.timeout", 1800000));
219     this.timerUpdater = new TimerUpdater(conf.getInt(
220         "hbase.master.assignment.timerupdater.period", 10000), master);
221     Threads.setDaemonThreadRunning(timerUpdater.getThread(),
222         master.getServerName() + ".timerUpdater");
223     this.zkTable = new ZKTable(this.master.getZooKeeper());
224     this.maximumAssignmentAttempts =
225       this.master.getConfiguration().getInt("hbase.assignment.maximum.attempts", 10);
226     this.balancer = balancer;
227     this.threadPoolExecutorService = Executors.newCachedThreadPool();
228   }
229   
230   void startTimeOutMonitor() {
231     Threads.setDaemonThreadRunning(timeoutMonitor.getThread(), master.getServerName()
232         + ".timeoutMonitor");
233   }
234 
235   /**
236    * Compute the average load across all region servers.
237    * Currently, this uses a very naive computation - just uses the number of
238    * regions being served, ignoring stats about number of requests.
239    * @return the average load
240    */
241   double getAverageLoad() {
242     int totalLoad = 0;
243     int numServers = 0;
244     // Sync on this.regions because access to this.servers always synchronizes
245     // in this order.
246     synchronized (this.regions) {
247       for (Map.Entry<ServerName, Set<HRegionInfo>> e: servers.entrySet()) {
248         numServers++;
249         totalLoad += e.getValue().size();
250       }
251     }
252     return (double)totalLoad / (double)numServers;
253   }
254 
255   /**
256    * @return Instance of ZKTable.
257    */
258   public ZKTable getZKTable() {
259     // These are 'expensive' to make involving trip to zk ensemble so allow
260     // sharing.
261     return this.zkTable;
262   }
263   /**
264    * Returns the RegionServer to which hri is assigned.
265    *
266    * @param hri
267    *          HRegion for which this function returns the region server
268    * @return HServerInfo The region server to which hri belongs
269    */
270   public ServerName getRegionServerOfRegion(HRegionInfo hri) {
271     synchronized (this.regions ) {
272       return regions.get(hri);
273     }
274   }
275 
276   /**
277    * Checks whether the region is assigned.
278    * @param hri HRegion for which this function returns the result
279    * @return True iff assigned.
280    */
281   public boolean isRegionAssigned(HRegionInfo hri) {
282     synchronized (this.regions ) {
283       return regions.containsKey(hri);
284     }
285   }
286 
287   /**
288    * Gives enabling table regions.
289    * 
290    * @param tableName
291    * @return list of regionInfos
292    */
293   public List<HRegionInfo> getEnablingTableRegions(String tableName){
294     return this.enablingTables.get(tableName);
295   }
296 
297   /**
298    * Add a regionPlan for the specified region.
299    * @param encodedName 
300    * @param plan 
301    */
302   public void addPlan(String encodedName, RegionPlan plan) {
303     synchronized (regionPlans) {
304       regionPlans.put(encodedName, plan);
305     }
306   }
307 
308   /**
309    * Add a map of region plans.
310    */
311   public void addPlans(Map<String, RegionPlan> plans) {
312     synchronized (regionPlans) {
313       regionPlans.putAll(plans);
314     }
315   }
316 
317   /**
318    * Set the list of regions that will be reopened
319    * because of an update in table schema
320    *
321    * @param regions
322    *          list of regions that should be tracked for reopen
323    */
324   public void setRegionsToReopen(List <HRegionInfo> regions) {
325     for(HRegionInfo hri : regions) {
326       regionsToReopen.put(hri.getEncodedName(), hri);
327     }
328   }
329 
330   /**
331    * Used by the client to identify if all regions have the schema updates
332    *
333    * @param tableName
334    * @return Pair indicating the status of the alter command
335    * @throws IOException
336    */
337   public Pair<Integer, Integer> getReopenStatus(byte[] tableName)
338   throws IOException {
339     List <HRegionInfo> hris =
340       MetaReader.getTableRegions(this.master.getCatalogTracker(), tableName);
341     Integer pending = 0;
342     for(HRegionInfo hri : hris) {
343       String name = hri.getEncodedName();
344       if (regionsToReopen.containsKey(name) || regionsInTransition.containsKey(name)) {
345         pending++;
346       }
347     }
348     return new Pair<Integer, Integer>(pending, hris.size());
349   }
350   /**
351    * Reset all unassigned znodes.  Called on startup of master.
352    * Call {@link #assignAllUserRegions()} after root and meta have been assigned.
353    * @throws IOException
354    * @throws KeeperException
355    */
356   void cleanoutUnassigned() throws IOException, KeeperException {
357     // Cleanup any existing ZK nodes and start watching
358     ZKAssign.deleteAllNodes(watcher);
359     ZKUtil.listChildrenAndWatchForNewChildren(this.watcher,
360       this.watcher.assignmentZNode);
361   }
362 
363   /**
364    * Called on startup.
365    * Figures whether a fresh cluster start of we are joining extant running cluster.
366    * @throws IOException
367    * @throws KeeperException
368    * @throws InterruptedException
369    */
370   void joinCluster() throws IOException,
371       KeeperException, InterruptedException {
372     // Concurrency note: In the below the accesses on regionsInTransition are
373     // outside of a synchronization block where usually all accesses to RIT are
374     // synchronized.  The presumption is that in this case it is safe since this
375     // method is being played by a single thread on startup.
376 
377     // TODO: Regions that have a null location and are not in regionsInTransitions
378     // need to be handled.
379 
380     // Scan META to build list of existing regions, servers, and assignment
381     // Returns servers who have not checked in (assumed dead) and their regions
382     Map<ServerName, List<Pair<HRegionInfo, Result>>> deadServers = rebuildUserRegions();
383 
384     processDeadServersAndRegionsInTransition(deadServers);
385 
386     // Recover the tables that were not fully moved to DISABLED state.
387     // These tables are in DISABLING state when the master restarted/switched.
388     boolean isWatcherCreated = recoverTableInDisablingState(this.disablingTables);
389     recoverTableInEnablingState(this.enablingTables.keySet(), isWatcherCreated);
390     this.enablingTables.clear();
391     this.disablingTables.clear();
392   }
393 
394   /**
395    * Process all regions that are in transition up in zookeeper.  Used by
396    * master joining an already running cluster.
397    * @throws KeeperException
398    * @throws IOException
399    * @throws InterruptedException
400    */
401   void processDeadServersAndRegionsInTransition()
402   throws KeeperException, IOException, InterruptedException {
403     // Pass null to signify no dead servers in this context.
404     processDeadServersAndRegionsInTransition(null);
405   }
406 
407   /**
408    * Process all regions that are in transition in zookeeper and also
409    * processes the list of dead servers by scanning the META. 
410    * Used by master joining an cluster.
411    * @param deadServers
412    *          Map of dead servers and their regions. Can be null.
413    * @throws KeeperException
414    * @throws IOException
415    * @throws InterruptedException
416    */
417   void processDeadServersAndRegionsInTransition(
418       final Map<ServerName, List<Pair<HRegionInfo, Result>>> deadServers)
419   throws KeeperException, IOException, InterruptedException {
420     List<String> nodes = ZKUtil.listChildrenAndWatchForNewChildren(watcher,
421       watcher.assignmentZNode);
422     
423     if (nodes == null) {
424       String errorMessage = "Failed to get the children from ZK";
425       master.abort(errorMessage, new IOException(errorMessage));
426       return;
427     }
428     // Run through all regions.  If they are not assigned and not in RIT, then
429     // its a clean cluster startup, else its a failover.
430     synchronized (this.regions) {
431       for (Map.Entry<HRegionInfo, ServerName> e : this.regions.entrySet()) {
432         if (!e.getKey().isMetaTable() && e.getValue() != null) {
433           LOG.debug("Found " + e + " out on cluster");
434           this.failover = true;
435           break;
436         }
437         if (nodes.contains(e.getKey().getEncodedName())) {
438           LOG.debug("Found " + e.getKey().getRegionNameAsString() + " in RITs");
439           // Could be a meta region.
440           this.failover = true;
441           break;
442         }
443       }
444     }
445 
446     // Remove regions in RIT, they are possibly being processed by
447     // ServerShutdownHandler.
448     synchronized (regionsInTransition) {
449       nodes.removeAll(regionsInTransition.keySet());
450     }
451 
452     // If some dead servers are processed by ServerShutdownHandler, we shouldn't
453     // assign all user regions( some would be assigned by
454     // ServerShutdownHandler), consider it as a failover
455     if (!this.serverManager.getDeadServers().isEmpty()) {
456       this.failover = true;
457     }
458 
459     // If we found user regions out on cluster, its a failover.
460     if (this.failover) {
461       LOG.info("Found regions out on cluster or in RIT; failover");
462       // Process list of dead servers and regions in RIT.
463       // See HBASE-4580 for more information.
464       processDeadServersAndRecoverLostRegions(deadServers, nodes);
465       this.failover = false;
466       failoverProcessedRegions.clear();
467     } else {
468       // Fresh cluster startup.
469       LOG.info("Clean cluster startup. Assigning userregions");
470       cleanoutUnassigned();
471       assignAllUserRegions();
472     }
473   }
474 
475   /**
476    * If region is up in zk in transition, then do fixup and block and wait until
477    * the region is assigned and out of transition.  Used on startup for
478    * catalog regions.
479    * @param hri Region to look for.
480    * @return True if we processed a region in transition else false if region
481    * was not up in zk in transition.
482    * @throws InterruptedException
483    * @throws KeeperException
484    * @throws IOException
485    */
486   boolean processRegionInTransitionAndBlockUntilAssigned(final HRegionInfo hri)
487   throws InterruptedException, KeeperException, IOException {
488     boolean intransistion =
489       processRegionInTransition(hri.getEncodedName(), hri, null);
490     if (!intransistion) return intransistion;
491     LOG.debug("Waiting on " + HRegionInfo.prettyPrint(hri.getEncodedName()));
492     synchronized(this.regionsInTransition) {
493       while (!this.master.isStopped() &&
494           this.regionsInTransition.containsKey(hri.getEncodedName())) {
495         // We expect a notify, but by security we set a timout
496         this.regionsInTransition.wait(100);
497       }
498     }
499     return intransistion;
500   }
501 
502   /**
503    * Process failover of new master for region <code>encodedRegionName</code>
504    * up in zookeeper.
505    * @param encodedRegionName Region to process failover for.
506    * @param regionInfo If null we'll go get it from meta table.
507    * @param deadServers Can be null 
508    * @return True if we processed <code>regionInfo</code> as a RIT.
509    * @throws KeeperException
510    * @throws IOException
511    */
512   boolean processRegionInTransition(final String encodedRegionName,
513       final HRegionInfo regionInfo,
514       final Map<ServerName,List<Pair<HRegionInfo,Result>>> deadServers)
515   throws KeeperException, IOException {
516     Stat stat = new Stat();
517     RegionTransitionData data = ZKAssign.getDataAndWatch(watcher,
518         encodedRegionName, stat);
519     if (data == null) return false;
520     HRegionInfo hri = regionInfo;
521     if (hri == null) {
522       if ((hri = getHRegionInfo(data)) == null) return false; 
523     }
524     processRegionsInTransition(data, hri, deadServers, stat.getVersion());
525     return true;
526   }
527 
528   void processRegionsInTransition(final RegionTransitionData data,
529       final HRegionInfo regionInfo,
530       final Map<ServerName, List<Pair<HRegionInfo, Result>>> deadServers,
531       int expectedVersion)
532   throws KeeperException {
533     String encodedRegionName = regionInfo.getEncodedName();
534     LOG.info("Processing region " + regionInfo.getRegionNameAsString() +
535       " in state " + data.getEventType());
536     List<HRegionInfo> hris = this.enablingTables.get(regionInfo.getTableNameAsString());
537     if (hris != null && !hris.isEmpty()) {
538       hris.remove(regionInfo);
539     }
540     synchronized (regionsInTransition) {
541       RegionState regionState = regionsInTransition.get(encodedRegionName);
542       if (regionState != null ||
543           failoverProcessedRegions.containsKey(encodedRegionName)) {
544         // Just return
545         return;
546       }
547       switch (data.getEventType()) {
548       case M_ZK_REGION_CLOSING:
549         // If zk node of the region was updated by a live server skip this
550         // region and just add it into RIT.
551         if (isOnDeadServer(regionInfo, deadServers) &&
552             (data.getOrigin() == null || !serverManager.isServerOnline(data.getOrigin()))) {
553           // If was on dead server, its closed now. Force to OFFLINE and this
554           // will get it reassigned if appropriate
555           forceOffline(regionInfo, data);
556         } else {
557           // Just insert region into RIT.
558           // If this never updates the timeout will trigger new assignment
559           regionsInTransition.put(encodedRegionName, new RegionState(
560             regionInfo, RegionState.State.CLOSING,
561             data.getStamp(), data.getOrigin()));
562         }
563         failoverProcessedRegions.put(encodedRegionName, regionInfo);
564         break;
565 
566       case RS_ZK_REGION_CLOSED:
567       case RS_ZK_REGION_FAILED_OPEN:
568         // Region is closed, insert into RIT and handle it
569         addToRITandCallClose(regionInfo, RegionState.State.CLOSED, data);
570         failoverProcessedRegions.put(encodedRegionName, regionInfo);
571         break;
572 
573       case M_ZK_REGION_OFFLINE:
574         // If zk node of the region was updated by a live server skip this
575         // region and just add it into RIT.
576         if (isOnDeadServer(regionInfo, deadServers) &&
577             (data.getOrigin() == null ||
578               !serverManager.isServerOnline(data.getOrigin()))) {
579           // Region is offline, insert into RIT and handle it like a closed
580           addToRITandCallClose(regionInfo, RegionState.State.OFFLINE, data);
581         } else if (data.getOrigin() != null &&
582             !serverManager.isServerOnline(data.getOrigin())) {
583           // to handle cases where offline node is created but sendRegionOpen
584           // RPC is not yet sent
585           addToRITandCallClose(regionInfo, RegionState.State.OFFLINE, data);
586         } else {
587           regionsInTransition.put(encodedRegionName, new RegionState(
588               regionInfo, RegionState.State.PENDING_OPEN, data.getStamp(), data
589                   .getOrigin()));
590         }
591         failoverProcessedRegions.put(encodedRegionName, regionInfo);
592         break;
593 
594       case RS_ZK_REGION_OPENING:
595         // TODO: Could check if it was on deadServers.  If it was, then we could
596         // do what happens in TimeoutMonitor when it sees this condition.
597 
598         // Just insert region into RIT
599         // If this never updates the timeout will trigger new assignment
600         if (regionInfo.isMetaTable()) {
601           regionsInTransition.put(encodedRegionName, new RegionState(
602               regionInfo, RegionState.State.OPENING, data.getStamp(), data
603                   .getOrigin()));
604           // If ROOT or .META. table is waiting for timeout monitor to assign
605           // it may take lot of time when the assignment.timeout.period is
606           // the default value which may be very long.  We will not be able
607           // to serve any request during this time.
608           // So we will assign the ROOT and .META. region immediately.
609           processOpeningState(regionInfo);
610           break;
611         }
612         regionsInTransition.put(encodedRegionName, new RegionState(regionInfo,
613             RegionState.State.OPENING, data.getStamp(), data.getOrigin()));
614         failoverProcessedRegions.put(encodedRegionName, regionInfo);
615         break;
616 
617       case RS_ZK_REGION_OPENED:
618         // Region is opened, insert into RIT and handle it
619         regionsInTransition.put(encodedRegionName, new RegionState(
620             regionInfo, RegionState.State.OPEN,
621             data.getStamp(), data.getOrigin()));
622         ServerName sn = data.getOrigin() == null? null: data.getOrigin();
623         // sn could be null if this server is no longer online.  If
624         // that is the case, just let this RIT timeout; it'll be assigned
625         // to new server then.
626         if (sn == null) {
627           LOG.warn("Region in transition " + regionInfo.getEncodedName() +
628             " references a null server; letting RIT timeout so will be " +
629             "assigned elsewhere");
630         } else if (!serverManager.isServerOnline(sn)
631             && (isOnDeadServer(regionInfo, deadServers)
632                 || regionInfo.isMetaRegion() || regionInfo.isRootRegion())) {
633           forceOffline(regionInfo, data);
634         } else {
635           new OpenedRegionHandler(master, this, regionInfo, sn, expectedVersion)
636               .process();
637         }
638         failoverProcessedRegions.put(encodedRegionName, regionInfo);
639         break;
640       }
641     }
642   }
643   
644 
645   /**
646    * Put the region <code>hri</code> into an offline state up in zk.
647    * @param hri
648    * @param oldData
649    * @throws KeeperException
650    */
651   private void forceOffline(final HRegionInfo hri,
652       final RegionTransitionData oldData)
653   throws KeeperException {
654     // If was on dead server, its closed now.  Force to OFFLINE and then
655     // handle it like a close; this will get it reassigned if appropriate
656     LOG.debug("RIT " + hri.getEncodedName() + " in state=" +
657       oldData.getEventType() + " was on deadserver; forcing offline");
658     ZKAssign.createOrForceNodeOffline(this.watcher, hri,
659       this.master.getServerName());
660     addToRITandCallClose(hri, RegionState.State.OFFLINE, oldData);
661   }
662 
663   /**
664    * Add to the in-memory copy of regions in transition and then call close
665    * handler on passed region <code>hri</code>
666    * @param hri
667    * @param state
668    * @param oldData
669    */
670   private void addToRITandCallClose(final HRegionInfo hri,
671       final RegionState.State state, final RegionTransitionData oldData) {
672     this.regionsInTransition.put(hri.getEncodedName(),
673       new RegionState(hri, state, oldData.getStamp(), oldData.getOrigin()));
674     new ClosedRegionHandler(this.master, this, hri).process();
675   }
676 
677   /**
678    * When a region is closed, it should be removed from the regionsToReopen
679    * @param hri HRegionInfo of the region which was closed
680    */
681   public void removeClosedRegion(HRegionInfo hri) {
682     if (!regionsToReopen.isEmpty()) {
683       if (regionsToReopen.remove(hri.getEncodedName()) != null) {
684           LOG.debug("Removed region from reopening regions because it was closed");
685       }
686     }
687   }
688 
689   /**
690    * @param regionInfo
691    * @param deadServers Map of deadServers and the regions they were carrying;
692    * can be null.
693    * @return True if the passed regionInfo in the passed map of deadServers?
694    */
695   private boolean isOnDeadServer(final HRegionInfo regionInfo,
696       final Map<ServerName, List<Pair<HRegionInfo, Result>>> deadServers) {
697     if (deadServers == null) return false;
698     for (Map.Entry<ServerName, List<Pair<HRegionInfo, Result>>> deadServer:
699         deadServers.entrySet()) {
700       for (Pair<HRegionInfo, Result> e: deadServer.getValue()) {
701         if (e.getFirst().equals(regionInfo)) return true;
702       }
703     }
704     return false;
705   }
706 
707   /**
708    * Handles various states an unassigned node can be in.
709    * <p>
710    * Method is called when a state change is suspected for an unassigned node.
711    * <p>
712    * This deals with skipped transitions (we got a CLOSED but didn't see CLOSING
713    * yet).
714    * @param data
715    * @param expectedVersion
716    */
717   private void handleRegion(final RegionTransitionData data, int expectedVersion) {
718     synchronized(regionsInTransition) {
719       HRegionInfo hri = null;
720       if (data == null || data.getOrigin() == null) {
721         LOG.warn("Unexpected NULL input " + data);
722         return;
723       }
724       ServerName sn = data.getOrigin();
725       // Check if this is a special HBCK transition
726       if (sn.equals(HConstants.HBCK_CODE_SERVERNAME)) {
727         handleHBCK(data);
728         return;
729       }
730       String encodedName = HRegionInfo.encodeRegionName(data.getRegionName());
731       String prettyPrintedRegionName = HRegionInfo.prettyPrint(encodedName);
732       // Verify this is a known server
733       if (!serverManager.isServerOnline(sn) &&
734           !this.master.getServerName().equals(sn)
735           && !ignoreStatesRSOffline.contains(data.getEventType())) {
736         LOG.warn("Attempted to handle region transition for server but " +
737           "server is not online: " + prettyPrintedRegionName);
738         return;
739       }
740       // Printing if the event was created a long time ago helps debugging
741       boolean lateEvent = data.getStamp() <
742           (System.currentTimeMillis() - 15000);
743       LOG.debug("Handling transition=" + data.getEventType() +
744         ", server=" + data.getOrigin() + ", region=" +
745           (prettyPrintedRegionName == null? "null": prettyPrintedRegionName)  +
746           (lateEvent? ", which is more than 15 seconds late" : ""));
747       RegionState regionState = regionsInTransition.get(encodedName);
748       switch (data.getEventType()) {
749         case M_ZK_REGION_OFFLINE:
750           // Nothing to do.
751           break;
752 
753         case RS_ZK_REGION_SPLITTING:
754           if (!isInStateForSplitting(regionState)) break;
755           addSplittingToRIT(sn, encodedName);
756           break;
757 
758         case RS_ZK_REGION_SPLIT:
759           // RegionState must be null, or SPLITTING or PENDING_CLOSE.
760           if (!isInStateForSplitting(regionState)) break;
761           // If null, add SPLITTING state before going to SPLIT
762           if (regionState == null) {
763             regionState = addSplittingToRIT(sn, encodedName);
764             String message = "Received SPLIT for region " + prettyPrintedRegionName +
765               " from server " + sn;
766             // If still null, it means we cannot find it and it was already processed
767             if (regionState == null) {
768               LOG.warn(message + " but it doesn't exist anymore," +
769                   " probably already processed its split");
770               break;
771             }
772             LOG.info(message +
773                 " but region was not first in SPLITTING state; continuing");
774           }
775           // Check it has daughters.
776           byte [] payload = data.getPayload();
777           List<HRegionInfo> daughters = null;
778           try {
779             daughters = Writables.getHRegionInfos(payload, 0, payload.length);
780           } catch (IOException e) {
781             LOG.error("Dropped split! Failed reading split payload for " +
782               prettyPrintedRegionName);
783             break;
784           }
785           assert daughters.size() == 2;
786           // Assert that we can get a serverinfo for this server.
787           if (!this.serverManager.isServerOnline(sn)) {
788             LOG.error("Dropped split! ServerName=" + sn + " unknown.");
789             break;
790           }
791           // Run handler to do the rest of the SPLIT handling.
792           this.executorService.submit(new SplitRegionHandler(master, this,
793             regionState.getRegion(), sn, daughters));
794           break;
795 
796         case M_ZK_REGION_CLOSING:
797           hri = checkIfInFailover(regionState, encodedName, data);
798           if (hri != null) {
799             regionState = new RegionState(hri, RegionState.State.CLOSING, data
800                .getStamp(), data.getOrigin());
801             regionsInTransition.put(encodedName, regionState);
802             failoverProcessedRegions.put(encodedName, hri);
803             break;
804           }
805           // Should see CLOSING after we have asked it to CLOSE or additional
806           // times after already being in state of CLOSING
807           if (regionState == null ||
808               (!regionState.isPendingClose() && !regionState.isClosing())) {
809             LOG.warn("Received CLOSING for region " + prettyPrintedRegionName +
810               " from server " + data.getOrigin() + " but region was in " +
811               " the state " + regionState + " and not " +
812               "in expected PENDING_CLOSE or CLOSING states");
813             return;
814           }
815           // Transition to CLOSING (or update stamp if already CLOSING)
816           regionState.update(RegionState.State.CLOSING,
817               data.getStamp(), data.getOrigin());
818           break;
819 
820         case RS_ZK_REGION_CLOSED:
821           hri = checkIfInFailover(regionState, encodedName, data);
822           if (hri != null) {
823             regionState = new RegionState(hri, RegionState.State.CLOSED, data
824                 .getStamp(), data.getOrigin());
825             regionsInTransition.put(encodedName, regionState);
826             removeClosedRegion(regionState.getRegion());
827             new ClosedRegionHandler(master, this, regionState.getRegion())
828               .process();
829             failoverProcessedRegions.put(encodedName, hri);
830             break;
831           }
832           // Should see CLOSED after CLOSING but possible after PENDING_CLOSE
833           if (regionState == null ||
834               (!regionState.isPendingClose() && !regionState.isClosing())) {
835             LOG.warn("Received CLOSED for region " + prettyPrintedRegionName +
836                 " from server " + data.getOrigin() + " but region was in " +
837                 " the state " + regionState + " and not " +
838                 "in expected PENDING_CLOSE or CLOSING states");
839             return;
840           }
841           // Handle CLOSED by assigning elsewhere or stopping if a disable
842           // If we got here all is good.  Need to update RegionState -- else
843           // what follows will fail because not in expected state.
844           regionState.update(RegionState.State.CLOSED,
845               data.getStamp(), data.getOrigin());
846           removeClosedRegion(regionState.getRegion());
847           this.executorService.submit(new ClosedRegionHandler(master,
848             this, regionState.getRegion()));
849           break;
850           
851         case RS_ZK_REGION_FAILED_OPEN:
852           hri = checkIfInFailover(regionState, encodedName, data);
853           if (hri != null) {
854             regionState = new RegionState(hri, RegionState.State.CLOSED, data
855                 .getStamp(), data.getOrigin());
856             regionsInTransition.put(encodedName, regionState);
857             new ClosedRegionHandler(master, this, regionState.getRegion())
858               .process();
859             failoverProcessedRegions.put(encodedName, hri);
860             break;
861           }
862           if (regionState == null ||
863               (!regionState.isOffline() && !regionState.isPendingOpen() && !regionState.isOpening())) {
864             LOG.warn("Received FAILED_OPEN for region " + prettyPrintedRegionName +
865                 " from server " + data.getOrigin() + " but region was in " +
866                 " the state " + regionState + " and not in OFFLINE, PENDING_OPEN or OPENING");
867             return;
868           }
869           // Handle this the same as if it were opened and then closed.
870           regionState.update(RegionState.State.CLOSED,
871               data.getStamp(), data.getOrigin());
872           // When there are more than one region server a new RS is selected as the 
873           // destination and the same is updated in the regionplan. (HBASE-5546)
874           getRegionPlan(regionState, sn, true);
875           this.executorService.submit(new ClosedRegionHandler(master,
876             this, regionState.getRegion()));
877           break;
878 
879         case RS_ZK_REGION_OPENING:
880           hri = checkIfInFailover(regionState, encodedName, data);       
881           if (hri != null) {
882             regionState = new RegionState(hri, RegionState.State.OPENING, data
883                 .getStamp(), data.getOrigin());
884             regionsInTransition.put(encodedName, regionState);
885             failoverProcessedRegions.put(encodedName, hri);
886             break;
887           }
888           if (regionState == null ||
889               (!regionState.isOffline() && !regionState.isPendingOpen() &&
890                   !regionState.isOpening())) {
891               LOG.warn("Received OPENING for region " + prettyPrintedRegionName +  " from server " +
892                 sn + " but region was in " + " the state " + regionState + " and not " +
893                 "in expected OFFLINE, PENDING_OPEN or OPENING states");
894               return;
895           }
896           // Transition to OPENING (or update stamp if already OPENING)
897           regionState.update(RegionState.State.OPENING,
898               data.getStamp(), data.getOrigin());
899           break;
900 
901         case RS_ZK_REGION_OPENED:
902           hri = checkIfInFailover(regionState, encodedName, data);
903           if (hri != null) {
904             regionState = new RegionState(hri, RegionState.State.OPEN, data
905                 .getStamp(), data.getOrigin());
906             regionsInTransition.put(encodedName, regionState);
907             new OpenedRegionHandler(master, this, regionState.getRegion(), data
908               .getOrigin(), expectedVersion).process();
909             failoverProcessedRegions.put(encodedName, hri);
910             break;
911           }
912           // Should see OPENED after OPENING but possible after PENDING_OPEN
913           if (regionState == null ||
914               (!regionState.isOffline() && !regionState.isPendingOpen() && !regionState.isOpening())) {
915             LOG.warn("Received OPENED for region " +
916                 prettyPrintedRegionName +
917                 " from server " + data.getOrigin() + " but region was in " +
918                 " the state " + regionState + " and not " +
919                 "in expected OFFLINE, PENDING_OPEN or OPENING states");
920             return;
921           }
922           // Handle OPENED by removing from transition and deleted zk node
923           regionState.update(RegionState.State.OPEN,
924               data.getStamp(), data.getOrigin());
925           this.executorService.submit(
926             new OpenedRegionHandler(master, this, regionState.getRegion(),
927               data.getOrigin(), expectedVersion));
928           break;
929       }
930     }
931   }
932 
933   /**
934    * Checks whether the callback came while RIT was not yet populated during
935    * master failover.
936    * @param regionState
937    * @param encodedName
938    * @param data
939    * @return hri
940    */
941   private HRegionInfo checkIfInFailover(RegionState regionState,
942       String encodedName, RegionTransitionData data) {
943     if (regionState == null && this.failover &&
944         (failoverProcessedRegions.containsKey(encodedName) == false ||
945           failoverProcessedRegions.get(encodedName) == null)) {
946       HRegionInfo hri = this.failoverProcessedRegions.get(encodedName);
947       if (hri == null) hri = getHRegionInfo(data);
948       return hri;
949     }
950     return null;
951   }
952   
953   /**
954    * Gets the HRegionInfo from the META table
955    * @param  data
956    * @return HRegionInfo hri for the region 
957    */
958   private HRegionInfo getHRegionInfo(RegionTransitionData data) {
959     Pair<HRegionInfo, ServerName> p = null;
960     try {
961       p = MetaReader.getRegion(catalogTracker, data.getRegionName());
962       if (p == null) return null;
963       return p.getFirst();
964     } catch (IOException e) {
965       master.abort("Aborting because error occoured while reading "
966           + data.getRegionName() + " from .META.", e);
967       return null;
968     }
969   }
970 
971   /**
972    * @return Returns true if this RegionState is splittable; i.e. the
973    * RegionState is currently in splitting state or pending_close or
974    * null (Anything else will return false). (Anything else will return false).
975    */
976   private boolean isInStateForSplitting(final RegionState rs) {
977     if (rs == null) return true;
978     if (rs.isSplitting()) return true;
979     if (convertPendingCloseToSplitting(rs)) return true;
980     LOG.warn("Dropped region split! Not in state good for SPLITTING; rs=" + rs);
981     return false;
982   }
983 
984   /**
985    * If the passed regionState is in PENDING_CLOSE, clean up PENDING_CLOSE
986    * state and convert it to SPLITTING instead.
987    * This can happen in case where master wants to close a region at same time
988    * a regionserver starts a split.  The split won.  Clean out old PENDING_CLOSE
989    * state.
990    * @param rs
991    * @return True if we converted from PENDING_CLOSE to SPLITTING
992    */
993   private boolean convertPendingCloseToSplitting(final RegionState rs) {
994     if (!rs.isPendingClose()) return false;
995     LOG.debug("Converting PENDING_CLOSE to SPLITING; rs=" + rs);
996     rs.update(RegionState.State.SPLITTING);
997     // Clean up existing state.  Clear from region plans seems all we
998     // have to do here by way of clean up of PENDING_CLOSE.
999     clearRegionPlan(rs.getRegion());
1000     return true;
1001   }
1002 
1003   /**
1004    * @param serverName
1005    * @param encodedName
1006    * @return The SPLITTING RegionState we added to RIT for the passed region
1007    * <code>encodedName</code>
1008    */
1009   private RegionState addSplittingToRIT(final ServerName serverName,
1010       final String encodedName) {
1011     RegionState regionState = null;
1012     synchronized (this.regions) {
1013       regionState = findHRegionInfoThenAddToRIT(serverName, encodedName);
1014       if (regionState != null) {
1015         regionState.update(RegionState.State.SPLITTING,
1016           System.currentTimeMillis(), serverName);
1017       }
1018     }
1019     return regionState;
1020   }
1021 
1022   /**
1023    * Caller must hold lock on <code>this.regions</code>.
1024    * @param serverName
1025    * @param encodedName
1026    * @return The instance of RegionState that was added to RIT or null if error.
1027    */
1028   private RegionState findHRegionInfoThenAddToRIT(final ServerName serverName,
1029       final String encodedName) {
1030     HRegionInfo hri = findHRegionInfo(serverName, encodedName);
1031     if (hri == null) {
1032       LOG.warn("Region " + encodedName + " not found on server " + serverName +
1033         "; failed processing");
1034       return null;
1035     }
1036     // Add to regions in transition, then update state to SPLITTING.
1037     return addToRegionsInTransition(hri);
1038   }
1039 
1040   /**
1041    * Caller must hold lock on <code>this.regions</code>.
1042    * @param serverName
1043    * @param encodedName
1044    * @return Found HRegionInfo or null.
1045    */
1046   private HRegionInfo findHRegionInfo(final ServerName sn,
1047       final String encodedName) {
1048     if (!this.serverManager.isServerOnline(sn)) return null;
1049     Set<HRegionInfo> hris = this.servers.get(sn);
1050     HRegionInfo foundHri = null;
1051     for (HRegionInfo hri: hris) {
1052       if (hri.getEncodedName().equals(encodedName)) {
1053         foundHri = hri;
1054         break;
1055       }
1056     }
1057     return foundHri;
1058   }
1059 
1060   /**
1061    * Handle a ZK unassigned node transition triggered by HBCK repair tool.
1062    * <p>
1063    * This is handled in a separate code path because it breaks the normal rules.
1064    * @param data
1065    */
1066   private void handleHBCK(RegionTransitionData data) {
1067     String encodedName = HRegionInfo.encodeRegionName(data.getRegionName());
1068     LOG.info("Handling HBCK triggered transition=" + data.getEventType() +
1069       ", server=" + data.getOrigin() + ", region=" +
1070       HRegionInfo.prettyPrint(encodedName));
1071     RegionState regionState = regionsInTransition.get(encodedName);
1072     switch (data.getEventType()) {
1073       case M_ZK_REGION_OFFLINE:
1074         HRegionInfo regionInfo = null;
1075         if (regionState != null) {
1076           regionInfo = regionState.getRegion();
1077         } else {
1078           try {
1079             byte[] name = data.getRegionName();
1080             Pair<HRegionInfo, ServerName> p = MetaReader.getRegion(catalogTracker, name);
1081             regionInfo = p.getFirst();
1082           } catch (IOException e) {
1083             LOG.info("Exception reading META doing HBCK repair operation", e);
1084             return;
1085           }
1086         }
1087         LOG.info("HBCK repair is triggering assignment of region=" +
1088             regionInfo.getRegionNameAsString());
1089         // trigger assign, node is already in OFFLINE so don't need to update ZK
1090         assign(regionInfo, false);
1091         break;
1092 
1093       default:
1094         LOG.warn("Received unexpected region state from HBCK (" +
1095             data.getEventType() + ")");
1096         break;
1097     }
1098   }
1099 
1100   // ZooKeeper events
1101 
1102   /**
1103    * New unassigned node has been created.
1104    *
1105    * <p>This happens when an RS begins the OPENING or CLOSING of a region by
1106    * creating an unassigned node.
1107    *
1108    * <p>When this happens we must:
1109    * <ol>
1110    *   <li>Watch the node for further events</li>
1111    *   <li>Read and handle the state in the node</li>
1112    * </ol>
1113    */
1114   @Override
1115   public void nodeCreated(String path) {
1116     if(path.startsWith(watcher.assignmentZNode)) {
1117       try {
1118         Stat stat = new Stat();
1119         RegionTransitionData data = ZKAssign.getDataAndWatch(watcher, path, stat);
1120         if (data == null) {
1121           return;
1122         }
1123         handleRegion(data, stat.getVersion());
1124       } catch (KeeperException e) {
1125         master.abort("Unexpected ZK exception reading unassigned node data", e);
1126       }
1127     }
1128   }
1129 
1130   /**
1131    * Existing unassigned node has had data changed.
1132    *
1133    * <p>This happens when an RS transitions from OFFLINE to OPENING, or between
1134    * OPENING/OPENED and CLOSING/CLOSED.
1135    *
1136    * <p>When this happens we must:
1137    * <ol>
1138    *   <li>Watch the node for further events</li>
1139    *   <li>Read and handle the state in the node</li>
1140    * </ol>
1141    */
1142   @Override
1143   public void nodeDataChanged(String path) {
1144     if(path.startsWith(watcher.assignmentZNode)) {
1145       try {
1146         Stat stat = new Stat();
1147         RegionTransitionData data = ZKAssign.getDataAndWatch(watcher, path, stat);
1148         if (data == null) {
1149           return;
1150         }
1151         handleRegion(data, stat.getVersion());
1152       } catch (KeeperException e) {
1153         master.abort("Unexpected ZK exception reading unassigned node data", e);
1154       }
1155     }
1156   }
1157 
1158   @Override
1159   public void nodeDeleted(final String path) {
1160     if (path.startsWith(this.watcher.assignmentZNode)) {
1161       String regionName = ZKAssign.getRegionName(this.master.getZooKeeper(), path);
1162       RegionState rs = this.regionsInTransition.get(regionName);
1163       if (rs != null) {
1164         HRegionInfo regionInfo = rs.getRegion();
1165         if (rs.isSplit()) {
1166           LOG.debug("Ephemeral node deleted, regionserver crashed?, offlining the region"
1167               + rs.getRegion() + " clearing from RIT;");
1168           regionOffline(rs.getRegion());
1169         } else if (rs.isSplitting()) {
1170           LOG.debug("Ephemeral node deleted.  Found in SPLITTING state. " + "Removing from RIT "
1171               + rs.getRegion());
1172           synchronized(this.regionsInTransition) {
1173             this.regionsInTransition.remove(regionName);
1174           }
1175         } else {
1176           LOG.debug("The znode of region " + regionInfo.getRegionNameAsString()
1177               + " has been deleted.");
1178           if (rs.isOpened()) {
1179             makeRegionOnline(rs, regionInfo);
1180           }
1181         }
1182       }
1183     }
1184   }
1185 
1186   private void makeRegionOnline(RegionState rs, HRegionInfo regionInfo) {
1187     regionOnline(regionInfo, rs.serverName);
1188     LOG.info("The master has opened the region "
1189         + regionInfo.getRegionNameAsString() + " that was online on "
1190         + rs.serverName);
1191     if (this.getZKTable().isDisablingOrDisabledTable(
1192         regionInfo.getTableNameAsString())) {
1193       LOG.debug("Opened region "
1194           + regionInfo.getRegionNameAsString() + " but "
1195           + "this table is disabled, triggering close of region");
1196       unassign(regionInfo);
1197     }
1198   }
1199 
1200   /**
1201    * New unassigned node has been created.
1202    *
1203    * <p>This happens when an RS begins the OPENING, SPLITTING or CLOSING of a
1204    * region by creating a znode.
1205    *
1206    * <p>When this happens we must:
1207    * <ol>
1208    *   <li>Watch the node for further children changed events</li>
1209    *   <li>Watch all new children for changed events</li>
1210    * </ol>
1211    */
1212   @Override
1213   public void nodeChildrenChanged(String path) {
1214     if(path.equals(watcher.assignmentZNode)) {
1215       try {
1216         List<String> children = ZKUtil.listChildrenAndWatchForNewChildren(watcher,
1217             watcher.assignmentZNode);
1218         if (children != null) {
1219           Stat stat = new Stat();
1220           for (String child : children) {
1221             stat.setVersion(0);
1222             RegionTransitionData data = ZKAssign.getDataAndWatch(watcher,
1223                 ZKUtil.joinZNode(watcher.assignmentZNode, child), stat);
1224             // See HBASE-7551, handle splitting here as well, in case we miss the node change event
1225             if (stat.getVersion() > 0 && data.getEventType() == EventType.RS_ZK_REGION_SPLITTING) {
1226               handleRegion(data, stat.getVersion());
1227             }
1228           }
1229         }
1230       } catch(KeeperException e) {
1231         master.abort("Unexpected ZK exception reading unassigned children", e);
1232       }
1233     }
1234   }
1235 
1236   /**
1237    * Marks the region as online.  Removes it from regions in transition and
1238    * updates the in-memory assignment information.
1239    * <p>
1240    * Used when a region has been successfully opened on a region server.
1241    * @param regionInfo
1242    * @param sn
1243    */
1244   void regionOnline(HRegionInfo regionInfo, ServerName sn) {
1245     synchronized (this.regionsInTransition) {
1246       RegionState rs =
1247         this.regionsInTransition.remove(regionInfo.getEncodedName());
1248       if (rs != null) {
1249         this.regionsInTransition.notifyAll();
1250       }
1251     }
1252     synchronized (this.regions) {
1253       // Add check
1254       ServerName oldSn = this.regions.get(regionInfo);
1255       if (oldSn != null) LOG.warn("Overwriting " + regionInfo.getEncodedName() +
1256         " on " + oldSn + " with " + sn);
1257       
1258       if (isServerOnline(sn)) {
1259         this.regions.put(regionInfo, sn);
1260         addToServers(sn, regionInfo);
1261         this.regions.notifyAll();
1262       } else {
1263         LOG.info("The server is not in online servers, ServerName=" + 
1264           sn.getServerName() + ", region=" + regionInfo.getEncodedName());
1265       }
1266     }
1267     // Remove plan if one.
1268     clearRegionPlan(regionInfo);
1269     // Add the server to serversInUpdatingTimer
1270     addToServersInUpdatingTimer(sn);
1271   }
1272 
1273   /**
1274    * Add the server to the set serversInUpdatingTimer, then {@link TimerUpdater}
1275    * will update timers for this server in background
1276    * @param sn
1277    */
1278   private void addToServersInUpdatingTimer(final ServerName sn) {
1279     this.serversInUpdatingTimer.add(sn);
1280   }
1281 
1282   /**
1283    * Touch timers for all regions in transition that have the passed
1284    * <code>sn</code> in common.
1285    * Call this method whenever a server checks in.  Doing so helps the case where
1286    * a new regionserver has joined the cluster and its been given 1k regions to
1287    * open.  If this method is tickled every time the region reports in a
1288    * successful open then the 1k-th region won't be timed out just because its
1289    * sitting behind the open of 999 other regions.  This method is NOT used
1290    * as part of bulk assign -- there we have a different mechanism for extending
1291    * the regions in transition timer (we turn it off temporarily -- because
1292    * there is no regionplan involved when bulk assigning.
1293    * @param sn
1294    */
1295   private void updateTimers(final ServerName sn) {
1296     // This loop could be expensive.
1297     // First make a copy of current regionPlan rather than hold sync while
1298     // looping because holding sync can cause deadlock.  Its ok in this loop
1299     // if the Map we're going against is a little stale
1300     Map<String, RegionPlan> copy = new HashMap<String, RegionPlan>();
1301     synchronized(this.regionPlans) {
1302       copy.putAll(this.regionPlans);
1303     }
1304     for (Map.Entry<String, RegionPlan> e: copy.entrySet()) {
1305       if (e.getValue() == null || e.getValue().getDestination() == null) continue;
1306       if (!e.getValue().getDestination().equals(sn)) continue;
1307       RegionState rs = null;
1308       synchronized (this.regionsInTransition) {
1309         rs = this.regionsInTransition.get(e.getKey());
1310       }
1311       if (rs == null) continue;
1312       rs.updateTimestampToNow();
1313     }
1314   }
1315 
1316   /**
1317    * Marks the region as offline.  Removes it from regions in transition and
1318    * removes in-memory assignment information.
1319    * <p>
1320    * Used when a region has been closed and should remain closed.
1321    * @param regionInfo
1322    */
1323   public void regionOffline(final HRegionInfo regionInfo) {
1324     // remove the region plan as well just in case.
1325     clearRegionPlan(regionInfo);
1326     setOffline(regionInfo);
1327 
1328     synchronized(this.regionsInTransition) {
1329       if (this.regionsInTransition.remove(regionInfo.getEncodedName()) != null) {
1330         this.regionsInTransition.notifyAll();
1331       }
1332     }
1333   }
1334 
1335   /**
1336    * Sets the region as offline by removing in-memory assignment information but
1337    * retaining transition information.
1338    * <p>
1339    * Used when a region has been closed but should be reassigned.
1340    * @param regionInfo
1341    */
1342   public void setOffline(HRegionInfo regionInfo) {
1343     synchronized (this.regions) {
1344       ServerName sn = this.regions.remove(regionInfo);
1345       if (sn == null) return;
1346       Set<HRegionInfo> serverRegions = this.servers.get(sn);
1347       if (!serverRegions.remove(regionInfo)) {
1348         LOG.warn("No " + regionInfo + " on " + sn);
1349       }
1350     }
1351   }
1352 
1353   public void offlineDisabledRegion(HRegionInfo regionInfo) {
1354     // Disabling so should not be reassigned, just delete the CLOSED node
1355     LOG.debug("Table being disabled so deleting ZK node and removing from " +
1356         "regions in transition, skipping assignment of region " +
1357           regionInfo.getRegionNameAsString());
1358     try {
1359       if (!ZKAssign.deleteClosedNode(watcher, regionInfo.getEncodedName())) {
1360         // Could also be in OFFLINE mode
1361         ZKAssign.deleteOfflineNode(watcher, regionInfo.getEncodedName());
1362       }
1363     } catch (KeeperException.NoNodeException nne) {
1364       LOG.debug("Tried to delete closed node for " + regionInfo + " but it " +
1365           "does not exist so just offlining");
1366     } catch (KeeperException e) {
1367       this.master.abort("Error deleting CLOSED node in ZK", e);
1368     }
1369     regionOffline(regionInfo);
1370   }
1371 
1372   // Assignment methods
1373 
1374   /**
1375    * Assigns the specified region.
1376    * <p>
1377    * If a RegionPlan is available with a valid destination then it will be used
1378    * to determine what server region is assigned to.  If no RegionPlan is
1379    * available, region will be assigned to a random available server.
1380    * <p>
1381    * Updates the RegionState and sends the OPEN RPC.
1382    * <p>
1383    * This will only succeed if the region is in transition and in a CLOSED or
1384    * OFFLINE state or not in transition (in-memory not zk), and of course, the
1385    * chosen server is up and running (It may have just crashed!).  If the
1386    * in-memory checks pass, the zk node is forced to OFFLINE before assigning.
1387    *
1388    * @param region server to be assigned
1389    * @param setOfflineInZK whether ZK node should be created/transitioned to an
1390    *                       OFFLINE state before assigning the region
1391    */
1392   public void assign(HRegionInfo region, boolean setOfflineInZK) {
1393     assign(region, setOfflineInZK, false);
1394   }
1395 
1396   public void assign(HRegionInfo region, boolean setOfflineInZK,
1397       boolean forceNewPlan) {
1398     assign(region, setOfflineInZK, forceNewPlan, false);
1399   }
1400 
1401   /**
1402    * @param region
1403    * @param setOfflineInZK
1404    * @param forceNewPlan
1405    * @param hijack
1406    *          - true new assignment is needed, false otherwise
1407    */
1408   public void assign(HRegionInfo region, boolean setOfflineInZK,
1409       boolean forceNewPlan, boolean hijack) {
1410     // If hijack is true do not call disableRegionIfInRIT as 
1411     // we have not yet moved the znode to OFFLINE state.
1412     if (!hijack && isDisabledorDisablingRegionInRIT(region)) {
1413       return;
1414     }
1415     if (this.serverManager.isClusterShutdown()) {
1416       LOG.info("Cluster shutdown is set; skipping assign of " +
1417         region.getRegionNameAsString());
1418       return;
1419     }
1420     if (isAssigningSplitParentRegion(region)) {
1421       return;
1422     }
1423     RegionState state = addToRegionsInTransition(region,
1424         hijack);
1425     synchronized (state) {
1426       assign(region, state, setOfflineInZK, forceNewPlan, hijack);
1427     }
1428   }
1429 
1430   /**
1431    * Bulk assign regions to <code>destination</code>.
1432    * @param destination
1433    * @param regions Regions to assign.
1434    */
1435   void assign(final ServerName destination,
1436       final List<HRegionInfo> regions) {
1437     if (regions.size() == 0) {
1438       return;
1439     }
1440     LOG.debug("Bulk assigning " + regions.size() + " region(s) to " +
1441       destination.toString());
1442 
1443     List<RegionState> states = new ArrayList<RegionState>(regions.size());
1444     synchronized (this.regionsInTransition) {
1445       for (HRegionInfo region: regions) {
1446         states.add(forceRegionStateToOffline(region));
1447       }
1448     }
1449     // Add region plans, so we can updateTimers when one region is opened so
1450     // that unnecessary timeout on RIT is reduced.
1451     Map<String, RegionPlan> plans=new HashMap<String, RegionPlan>();
1452     for (HRegionInfo region : regions) {
1453       plans.put(region.getEncodedName(), new RegionPlan(region, null,
1454           destination));
1455     }
1456     this.addPlans(plans);
1457     
1458     // Presumption is that only this thread will be updating the state at this
1459     // time; i.e. handlers on backend won't be trying to set it to OPEN, etc.
1460     AtomicInteger counter = new AtomicInteger(0);
1461     CreateUnassignedAsyncCallback cb =
1462       new CreateUnassignedAsyncCallback(this.watcher, destination, counter);
1463     for (RegionState state: states) {
1464       if (!asyncSetOfflineInZooKeeper(state, cb, state)) {
1465         return;
1466       }
1467     }
1468     // Wait until all unassigned nodes have been put up and watchers set.
1469     int total = regions.size();
1470     for (int oldCounter = 0; true;) {
1471       int count = counter.get();
1472       if (oldCounter != count) {
1473         LOG.info(destination.toString() + " outstanding calls=" + count +
1474           " of total=" + total);
1475         oldCounter = count;
1476       }
1477       if (count == total) break;
1478       Threads.sleep(1);
1479     }
1480     // Check if any failed.
1481     if (cb.hasErrors()) {
1482       // TODO: createOrForceNodeOffline actually handles this condition; whereas this
1483       //       code used to just abort master. Now, it will bail more "gracefully".
1484       LOG.error("Error creating nodes for some of the regions we are trying to bulk assign");
1485       return;
1486     }
1487 
1488     // Move on to open regions.
1489     try {
1490       // Send OPEN RPC. If it fails on a IOE or RemoteException, the
1491       // TimeoutMonitor will pick up the pieces.
1492       long maxWaitTime = System.currentTimeMillis() +
1493         this.master.getConfiguration().
1494           getLong("hbase.regionserver.rpc.startup.waittime", 60000);
1495       while (!this.master.isStopped()) {
1496         try {
1497           this.serverManager.sendRegionOpen(destination, regions);
1498           break;
1499         } catch (RemoteException e) {
1500           IOException decodedException = e.unwrapRemoteException();
1501           if (decodedException instanceof RegionServerStoppedException) {
1502             LOG.warn("The region server was shut down, ", decodedException);
1503             // No need to retry, the region server is a goner.
1504             return;
1505           } else if (decodedException instanceof ServerNotRunningYetException) {
1506             // This is the one exception to retry.  For all else we should just fail
1507             // the startup.
1508             long now = System.currentTimeMillis();
1509             if (now > maxWaitTime) throw e;
1510             LOG.debug("Server is not yet up; waiting up to " +
1511                 (maxWaitTime - now) + "ms", e);
1512             Thread.sleep(1000);
1513           }
1514 
1515           throw decodedException;
1516         }
1517       }
1518     } catch (IOException e) {
1519       // Can be a socket timeout, EOF, NoRouteToHost, etc
1520       LOG.info("Unable to communicate with the region server in order" +
1521           " to assign regions", e);
1522     } catch (InterruptedException e) {
1523       throw new RuntimeException(e);
1524     }
1525     LOG.debug("Bulk assigning done for " + destination.toString());
1526   }
1527 
1528   /**
1529    * Callback handler for create unassigned znodes used during bulk assign.
1530    */
1531   static class CreateUnassignedAsyncCallback implements AsyncCallback.StringCallback {
1532     private final Log LOG = LogFactory.getLog(CreateUnassignedAsyncCallback.class);
1533     private final ZooKeeperWatcher zkw;
1534     private final ServerName destination;
1535     private final AtomicInteger counter;
1536     private final AtomicInteger errorCount = new AtomicInteger(0);
1537 
1538     CreateUnassignedAsyncCallback(final ZooKeeperWatcher zkw,
1539         final ServerName destination, final AtomicInteger counter) {
1540       this.zkw = zkw;
1541       this.destination = destination;
1542       this.counter = counter;
1543     }
1544 
1545     boolean hasErrors() {
1546       return this.errorCount.get() > 0;
1547     }
1548 
1549     @Override
1550     public void processResult(int rc, String path, Object ctx, String name) {
1551       if (rc == KeeperException.Code.NODEEXISTS.intValue()) {
1552         LOG.warn("Node for " + path + " already exists");
1553         reportCompletion(false);
1554         return;
1555       }
1556       if (rc != 0) {
1557         // This is resultcode. If non-zero, we will abort :(
1558         LOG.warn("rc != 0 for " + path + " -- some error, may be retryable connection loss -- "
1559             + "FIX see http://wiki.apache.org/hadoop/ZooKeeper/FAQ#A2");
1560         this.zkw.abort("Some error, may be connection loss writing unassigned at " + path +
1561           ", rc=" + rc, null);
1562         return;
1563       }
1564       LOG.debug("rs=" + (RegionState)ctx + ", server=" + this.destination.toString());
1565       // Async exists to set a watcher so we'll get triggered when
1566       // unassigned node changes.
1567       this.zkw.getRecoverableZooKeeper().getZooKeeper().exists(path, this.zkw,
1568         new ExistsUnassignedAsyncCallback(this, destination), ctx);
1569     }
1570 
1571     void reportCompletion(boolean success) {
1572       if (!success) {
1573         this.errorCount.incrementAndGet();
1574       }
1575       this.counter.incrementAndGet();
1576     }
1577   }
1578 
1579   /**
1580    * Callback handler for the exists call that sets watcher on unassigned znodes.
1581    * Used during bulk assign on startup.
1582    */
1583   static class ExistsUnassignedAsyncCallback implements AsyncCallback.StatCallback {
1584     private final Log LOG = LogFactory.getLog(ExistsUnassignedAsyncCallback.class);
1585     private ServerName destination;
1586     private CreateUnassignedAsyncCallback parent;
1587 
1588     ExistsUnassignedAsyncCallback(
1589         CreateUnassignedAsyncCallback parent, ServerName destination) {
1590       this.parent = parent;
1591       this.destination = destination;
1592     }
1593 
1594     @Override
1595     public void processResult(int rc, String path, Object ctx, Stat stat) {
1596       if (rc != 0) {
1597         // This is resultcode.  If non-zero, need to resubmit.
1598         LOG.warn("rc != 0 for " + path + " -- some error, may be connection loss -- " +
1599           "FIX see http://wiki.apache.org/hadoop/ZooKeeper/FAQ#A2");
1600         parent.reportCompletion(false);
1601         return;
1602       }
1603       RegionState state = (RegionState)ctx;
1604       LOG.debug("rs=" + state);
1605       // Transition RegionState to PENDING_OPEN here in master; means we've
1606       // sent the open.  We're a little ahead of ourselves here since we've not
1607       // yet sent out the actual open but putting this state change after the
1608       // call to open risks our writing PENDING_OPEN after state has been moved
1609       // to OPENING by the regionserver.
1610       state.update(RegionState.State.PENDING_OPEN, System.currentTimeMillis(), destination);
1611       parent.reportCompletion(true);
1612     }
1613   }
1614 
1615   /**
1616    * @param region
1617    * @return The current RegionState
1618    */
1619   private RegionState addToRegionsInTransition(final HRegionInfo region) {
1620     return addToRegionsInTransition(region, false);
1621   }
1622   /**
1623    * @param region
1624    * @param hijack
1625    * @return The current RegionState
1626    */
1627   private RegionState addToRegionsInTransition(final HRegionInfo region,
1628       boolean hijack) {
1629     synchronized (regionsInTransition) {
1630       return forceRegionStateToOffline(region, hijack);
1631     }
1632   }
1633   /**
1634    * Sets regions {@link RegionState} to {@link RegionState.State#OFFLINE}.
1635    * Caller must hold lock on this.regionsInTransition.
1636    * @param region
1637    * @return Amended RegionState.
1638    */
1639   private RegionState forceRegionStateToOffline(final HRegionInfo region) {
1640     return forceRegionStateToOffline(region, false);
1641   }
1642 
1643   /**
1644    * Sets regions {@link RegionState} to {@link RegionState.State#OFFLINE}.
1645    * Caller must hold lock on this.regionsInTransition.
1646    * @param region
1647    * @param hijack
1648    * @return Amended RegionState.
1649    */
1650   private RegionState forceRegionStateToOffline(final HRegionInfo region,
1651       boolean hijack) {
1652     String encodedName = region.getEncodedName();
1653     RegionState state = this.regionsInTransition.get(encodedName);
1654     if (state == null) {
1655       state = new RegionState(region, RegionState.State.OFFLINE);
1656       this.regionsInTransition.put(encodedName, state);
1657     } else {
1658       // If we are reassigning the node do not force in-memory state to OFFLINE.
1659       // Based on the znode state we will decide if to change in-memory state to
1660       // OFFLINE or not. It will be done before setting znode to OFFLINE state.
1661 
1662       // We often get here with state == CLOSED because ClosedRegionHandler will
1663       // assign on its tail as part of the handling of a region close.
1664       if (!hijack) {
1665         LOG.debug("Forcing OFFLINE; was=" + state);
1666         state.update(RegionState.State.OFFLINE);
1667       }
1668     }
1669     return state;
1670   }
1671 
1672   /**
1673    * Caller must hold lock on the passed <code>state</code> object.
1674    * @param state
1675    * @param setOfflineInZK
1676    * @param forceNewPlan
1677    * @param hijack
1678    */
1679   private void assign(final HRegionInfo region, final RegionState state,
1680       final boolean setOfflineInZK, final boolean forceNewPlan,
1681       boolean hijack) {
1682     boolean regionAlreadyInTransitionException = false;
1683     boolean serverNotRunningYet = false;
1684     long maxRegionServerStartupWaitTime = -1;
1685     for (int i = 0; i < this.maximumAssignmentAttempts; i++) {
1686       int versionOfOfflineNode = -1;
1687       if (setOfflineInZK) {
1688         // get the version of the znode after setting it to OFFLINE.
1689         // versionOfOfflineNode will be -1 if the znode was not set to OFFLINE
1690         versionOfOfflineNode = setOfflineInZooKeeper(state, hijack,
1691             regionAlreadyInTransitionException);
1692         if(versionOfOfflineNode != -1){
1693           if (isDisabledorDisablingRegionInRIT(region)) {
1694             return;
1695           }
1696           // In case of assign from EnableTableHandler table state is ENABLING. Any how
1697           // EnableTableHandler will set ENABLED after assigning all the table regions. If we
1698           // try to set to ENABLED directly then client api may think ENABLE table is completed.
1699           // When we have a case like all the regions are added directly into META and we call
1700           // assignRegion then we need to make the table ENABLED. Hence in such case the table
1701           // will not be in ENABLING or ENABLED state.
1702           String tableName = region.getTableNameAsString();
1703           if (!zkTable.isEnablingTable(tableName) && !zkTable.isEnabledTable(tableName)) {
1704             LOG.debug("Setting table " + tableName + " to ENABLED state.");
1705             setEnabledTable(region);
1706           }
1707         }
1708       }
1709       
1710       if (setOfflineInZK && versionOfOfflineNode == -1) {
1711         return;
1712       }
1713       
1714       if (this.master.isStopped()) {
1715         LOG.debug("Server stopped; skipping assign of " + state);
1716         return;
1717       }
1718       RegionPlan plan = getRegionPlan(state, !regionAlreadyInTransitionException
1719           && !serverNotRunningYet && forceNewPlan);
1720       if (plan == null) {
1721         LOG.debug("Unable to determine a plan to assign " + state);
1722         this.timeoutMonitor.setAllRegionServersOffline(true);
1723         return; // Should get reassigned later when RIT times out.
1724       }
1725       try {
1726         LOG.debug("Assigning region " + state.getRegion().getRegionNameAsString() +
1727           " to " + plan.getDestination().toString());
1728         long currentOfflineTimeStamp = state.getStamp();
1729         RegionOpeningState regionOpenState = serverManager.sendRegionOpen(plan.getDestination(),
1730             state.getRegion(), versionOfOfflineNode);
1731         if (regionOpenState == RegionOpeningState.OPENED) {
1732           // Transition RegionState to PENDING_OPEN
1733           // Check if already the offline state has been updated due to a
1734           // failure in prev assign
1735           if (state.isOffline() && currentOfflineTimeStamp != state.getStamp()) {
1736             return;
1737           }
1738           if (state.isOffline() && !state.isOpening()) {
1739             state.update(RegionState.State.PENDING_OPEN,
1740                 System.currentTimeMillis(), plan.getDestination());
1741           }
1742           if (state.isOpening()) return;
1743           if (state.isOpened()) return;
1744         } else if (regionOpenState == RegionOpeningState.ALREADY_OPENED) {
1745           // Remove region from in-memory transition and unassigned node from ZK
1746           // While trying to enable the table the regions of the table were
1747           // already enabled.
1748           LOG.debug("ALREADY_OPENED region " + state.getRegion().getRegionNameAsString() +
1749               " to " + plan.getDestination().toString());
1750           String encodedRegionName = state.getRegion()
1751               .getEncodedName();
1752           try {
1753             ZKAssign.deleteOfflineNode(master.getZooKeeper(), encodedRegionName);
1754           } catch (KeeperException.NoNodeException e) {
1755             if(LOG.isDebugEnabled()){
1756               LOG.debug("The unassigned node "+encodedRegionName+" doesnot exist.");
1757             }
1758           } catch (KeeperException e) {
1759             master.abort(
1760                 "Error deleting OFFLINED node in ZK for transition ZK node ("
1761                     + encodedRegionName + ")", e);
1762           }
1763           synchronized (this.regionsInTransition) {
1764             this.regionsInTransition.remove(plan.getRegionInfo()
1765                 .getEncodedName());
1766           }
1767           synchronized (this.regions) {
1768             this.regions.put(plan.getRegionInfo(), plan.getDestination());
1769             addToServers(plan.getDestination(), plan.getRegionInfo());
1770           }
1771         }
1772         break;
1773       } catch (Throwable t) {
1774         if (t instanceof RemoteException) {
1775           t = ((RemoteException) t).unwrapRemoteException();
1776         }
1777         regionAlreadyInTransitionException = false;
1778         serverNotRunningYet = false;
1779         if (t instanceof RegionAlreadyInTransitionException) {
1780           regionAlreadyInTransitionException = true;
1781           if (LOG.isDebugEnabled()) {
1782             LOG.debug("Failed assignment in: " + plan.getDestination() + " due to "
1783                 + t.getMessage());
1784           }
1785         } else if (t instanceof ServerNotRunningYetException) {
1786           if (maxRegionServerStartupWaitTime < 0) {
1787             maxRegionServerStartupWaitTime = System.currentTimeMillis()
1788                 + this.master.getConfiguration().getLong("hbase.regionserver.rpc.startup.waittime",
1789                     60000);
1790           }
1791           try {
1792             long now = System.currentTimeMillis();
1793             if (now < maxRegionServerStartupWaitTime) {
1794               LOG.debug("Server is not yet up; waiting up to "
1795                   + (maxRegionServerStartupWaitTime - now) + "ms", t);
1796               serverNotRunningYet = true;
1797               Thread.sleep(100);
1798               i--; // reset the try count
1799             } else {
1800               LOG.debug("Server is not up for a while; try a new one", t);
1801             }
1802           } catch (InterruptedException ie) {
1803             LOG.warn("Failed to assign " + state.getRegion().getRegionNameAsString()
1804                 + " since interrupted", ie);
1805             Thread.currentThread().interrupt();
1806             return;
1807           }
1808         } else if (t instanceof java.net.SocketTimeoutException 
1809             && this.serverManager.isServerOnline(plan.getDestination())) {
1810           LOG.warn("Call openRegion() to " + plan.getDestination()
1811               + " has timed out when trying to assign "
1812               + region.getRegionNameAsString()
1813               + ", but the region might already be opened on "
1814               + plan.getDestination() + ".", t);
1815           return;
1816         }
1817         LOG.warn("Failed assignment of "
1818           + state.getRegion().getRegionNameAsString()
1819           + " to "
1820           + plan.getDestination()
1821           + ", trying to assign "
1822           + (regionAlreadyInTransitionException || serverNotRunningYet
1823             ? "to the same region server because of "
1824             + "RegionAlreadyInTransitionException/ServerNotRunningYetException;"
1825             : "elsewhere instead; ")
1826           + "retry=" + i, t);
1827         // Clean out plan we failed execute and one that doesn't look like it'll
1828         // succeed anyways; we need a new plan!
1829         // Transition back to OFFLINE
1830         state.update(RegionState.State.OFFLINE);
1831         // If region opened on destination of present plan, reassigning to new
1832         // RS may cause double assignments. In case of RegionAlreadyInTransitionException
1833         // reassigning to same RS.
1834         RegionPlan newPlan = plan;
1835         if (!regionAlreadyInTransitionException && !serverNotRunningYet) {
1836           // Force a new plan and reassign. Will return null if no servers.
1837           // The new plan could be the same as the existing plan since we don't
1838           // exclude the server of the original plan, which should not be
1839           // excluded since it could be the only server up now.
1840           newPlan = getRegionPlan(state, true);
1841         }
1842         if (newPlan == null) {
1843           this.timeoutMonitor.setAllRegionServersOffline(true);
1844           LOG.warn("Unable to find a viable location to assign region " +
1845             state.getRegion().getRegionNameAsString());
1846           return;
1847         }
1848       }
1849     }
1850   }
1851 
1852   private static boolean isAssigningSplitParentRegion(final HRegionInfo region) {
1853     if (region.isSplitParent()) {
1854       LOG.info("Skipping assign of " + region.getRegionNameAsString()
1855         + ", already split, or still splitting");
1856       return true;
1857     }
1858     return false;
1859   }
1860 
1861   private boolean isDisabledorDisablingRegionInRIT(final HRegionInfo region) {
1862     String tableName = region.getTableNameAsString();
1863     boolean disabled = this.zkTable.isDisabledTable(tableName);
1864     if (disabled || this.zkTable.isDisablingTable(tableName)) {
1865       LOG.info("Table " + tableName + (disabled ? " disabled;" : " disabling;") +
1866         " skipping assign of " + region.getRegionNameAsString());
1867       offlineDisabledRegion(region);
1868       return true;
1869     }
1870     return false;
1871   }
1872 
1873   /**
1874    * Set region as OFFLINED up in zookeeper
1875    * 
1876    * @param state
1877    * @param hijack
1878    *          - true if needs to be hijacked and reassigned, false otherwise.
1879    * @param regionAlreadyInTransitionException  
1880    *          - true if we need to retry assignment because of RegionAlreadyInTransitionException.       
1881    * @return the version of the offline node if setting of the OFFLINE node was
1882    *         successful, -1 otherwise.
1883    */
1884   int setOfflineInZooKeeper(final RegionState state, boolean hijack,
1885       boolean regionAlreadyInTransitionException) {
1886     // In case of reassignment the current state in memory need not be
1887     // OFFLINE. 
1888     if (!hijack && !state.isClosed() && !state.isOffline()) {
1889       if (!regionAlreadyInTransitionException ) {
1890         LOG.warn("Unexpected state : " + state + " .. Cannot transit it to OFFLINE.");
1891         return -1;
1892       } 
1893       LOG.debug("Unexpected state : " + state
1894           + " but retrying to assign because RegionAlreadyInTransitionException.");
1895     }
1896     boolean allowZNodeCreation = false;
1897     // Under reassignment if the current state is PENDING_OPEN
1898     // or OPENING then refresh the in-memory state to PENDING_OPEN. This is
1899     // important because if the region was in 
1900     // RS_OPENING state for a long time the master will try to force the znode
1901     // to OFFLINE state meanwhile the RS could have opened the corresponding
1902     // region and the state in znode will be RS_ZK_REGION_OPENED.
1903     // For all other cases we can change the in-memory state to OFFLINE.
1904     if (hijack &&
1905         (state.getState().equals(RegionState.State.PENDING_OPEN) || 
1906             state.getState().equals(RegionState.State.OPENING))) {
1907       state.update(RegionState.State.PENDING_OPEN);
1908       allowZNodeCreation = false;
1909     } else {
1910       state.update(RegionState.State.OFFLINE);
1911       allowZNodeCreation = true;
1912     }
1913     int versionOfOfflineNode = -1;
1914     try {
1915       // get the version after setting the znode to OFFLINE
1916       versionOfOfflineNode = ZKAssign.createOrForceNodeOffline(master.getZooKeeper(), 
1917           state.getRegion(), this.master.getServerName(),
1918           hijack, allowZNodeCreation);
1919       if (versionOfOfflineNode == -1) {
1920         LOG.warn("Attempted to create/force node into OFFLINE state before "
1921             + "completing assignment but failed to do so for " + state);
1922         return -1;
1923       }
1924     } catch (KeeperException e) {
1925       master.abort("Unexpected ZK exception creating/setting node OFFLINE", e);
1926       return -1;
1927     }
1928     return versionOfOfflineNode;
1929   }
1930 
1931   /**
1932    * Set region as OFFLINED up in zookeeper asynchronously.
1933    * @param state
1934    * @return True if we succeeded, false otherwise (State was incorrect or failed
1935    * updating zk).
1936    */
1937   boolean asyncSetOfflineInZooKeeper(final RegionState state,
1938       final AsyncCallback.StringCallback cb, final Object ctx) {
1939     if (!state.isClosed() && !state.isOffline()) {
1940         new RuntimeException("Unexpected state trying to OFFLINE; " + state);
1941       this.master.abort("Unexpected state trying to OFFLINE; " + state,
1942         new IllegalStateException());
1943       return false;
1944     }
1945     state.update(RegionState.State.OFFLINE);
1946     try {
1947       ZKAssign.asyncCreateNodeOffline(master.getZooKeeper(), state.getRegion(),
1948         this.master.getServerName(), cb, ctx);
1949     } catch (KeeperException e) {
1950       // TODO: this error handling will never execute, as the callback is async.
1951       if (e instanceof NodeExistsException) {
1952         LOG.warn("Node for " + state.getRegion() + " already exists");
1953       } else { 
1954         master.abort("Unexpected ZK exception creating/setting node OFFLINE", e);
1955       }
1956       return false;
1957     }
1958     return true;
1959   }
1960 
1961   /**
1962    * @param state
1963    * @return Plan for passed <code>state</code> (If none currently, it creates one or
1964    * if no servers to assign, it returns null).
1965    */
1966   RegionPlan getRegionPlan(final RegionState state,
1967       final boolean forceNewPlan) {
1968     return getRegionPlan(state, null, forceNewPlan);
1969   }
1970 
1971   /**
1972    * @param state
1973    * @param serverToExclude Server to exclude (we know its bad). Pass null if
1974    * all servers are thought to be assignable.
1975    * @param forceNewPlan If true, then if an existing plan exists, a new plan
1976    * will be generated.
1977    * @return Plan for passed <code>state</code> (If none currently, it creates one or
1978    * if no servers to assign, it returns null).
1979    */
1980   RegionPlan getRegionPlan(final RegionState state,
1981       final ServerName serverToExclude, final boolean forceNewPlan) {
1982     // Pickup existing plan or make a new one
1983     final String encodedName = state.getRegion().getEncodedName();
1984     final List<ServerName> servers = this.serverManager.getOnlineServersList();
1985     final List<ServerName> drainingServers = this.serverManager.getDrainingServersList();
1986 
1987 
1988     if (serverToExclude != null) servers.remove(serverToExclude);
1989 
1990     // Loop through the draining server list and remove them from the server
1991     // list.
1992     if (!drainingServers.isEmpty()) {
1993       for (final ServerName server: drainingServers) {
1994         LOG.debug("Removing draining server: " + server +
1995             " from eligible server pool.");
1996         servers.remove(server);
1997       }
1998     }
1999 
2000     // Remove the deadNotExpired servers from the server list.
2001     removeDeadNotExpiredServers(servers);
2002 
2003 
2004 
2005     if (servers.isEmpty()) return null;
2006 
2007     RegionPlan randomPlan = null;
2008     boolean newPlan = false;
2009     RegionPlan existingPlan = null;
2010 
2011     synchronized (this.regionPlans) {
2012       existingPlan = this.regionPlans.get(encodedName);
2013 
2014       if (existingPlan != null && existingPlan.getDestination() != null) {
2015         LOG.debug("Found an existing plan for " +
2016             state.getRegion().getRegionNameAsString() +
2017        " destination server is " + existingPlan.getDestination().toString());
2018       }
2019 
2020       if (forceNewPlan
2021           || existingPlan == null
2022           || existingPlan.getDestination() == null
2023           || drainingServers.contains(existingPlan.getDestination())) {
2024         newPlan = true;
2025         randomPlan = new RegionPlan(state.getRegion(), null, balancer
2026             .randomAssignment(servers));
2027         this.regionPlans.put(encodedName, randomPlan);
2028       }
2029     }
2030 
2031     if (newPlan) {
2032       LOG.debug("No previous transition plan was found (or we are ignoring " +
2033         "an existing plan) for " + state.getRegion().getRegionNameAsString() +
2034         " so generated a random one; " + randomPlan + "; " +
2035         serverManager.countOfRegionServers() +
2036                " (online=" + serverManager.getOnlineServers().size() +
2037                ", available=" + servers.size() + ") available servers");
2038         return randomPlan;
2039       }
2040     LOG.debug("Using pre-existing plan for region " +
2041                state.getRegion().getRegionNameAsString() + "; plan=" + existingPlan);
2042       return existingPlan;
2043   }
2044 
2045   /**
2046    * Loop through the deadNotExpired server list and remove them from the
2047    * servers.
2048    * @param servers
2049    */
2050   public void removeDeadNotExpiredServers(List<ServerName> servers) {
2051     Set<ServerName> deadNotExpiredServers = this.serverManager
2052         .getDeadNotExpiredServers();
2053     if (!deadNotExpiredServers.isEmpty()) {
2054       for (ServerName server : deadNotExpiredServers) {
2055         LOG.debug("Removing dead but not expired server: " + server
2056             + " from eligible server pool.");
2057         servers.remove(server);
2058       }
2059     }
2060   }
2061 
2062   /**
2063    * Unassign the list of regions. Configuration knobs:
2064    * hbase.bulk.waitbetween.reopen indicates the number of milliseconds to
2065    * wait before unassigning another region from this region server
2066    *
2067    * @param regions
2068    * @throws InterruptedException
2069    */
2070   public void unassign(List<HRegionInfo> regions) {
2071     int waitTime = this.master.getConfiguration().getInt(
2072         "hbase.bulk.waitbetween.reopen", 0);
2073     for (HRegionInfo region : regions) {
2074       if (isRegionInTransition(region) != null)
2075         continue;
2076       unassign(region, false);
2077       while (isRegionInTransition(region) != null) {
2078         try {
2079           Thread.sleep(10);
2080         } catch (InterruptedException e) {
2081           // Do nothing, continue
2082         }
2083       }
2084       if (waitTime > 0)
2085         try {
2086           Thread.sleep(waitTime);
2087         } catch (InterruptedException e) {
2088           // Do nothing, continue
2089         }
2090     }
2091   }
2092 
2093   /**
2094    * Unassigns the specified region.
2095    * <p>
2096    * Updates the RegionState and sends the CLOSE RPC unless region is being
2097    * split by regionserver; then the unassign fails (silently) because we
2098    * presume the region being unassigned no longer exists (its been split out
2099    * of existence). TODO: What to do if split fails and is rolled back and
2100    * parent is revivified?
2101    * <p>
2102    * If a RegionPlan is already set, it will remain.
2103    *
2104    * @param region server to be unassigned
2105    */
2106   public void unassign(HRegionInfo region) {
2107     unassign(region, false);
2108   }
2109 
2110   /**
2111    * Unassigns the specified region.
2112    * <p>
2113    * Updates the RegionState and sends the CLOSE RPC unless region is being
2114    * split by regionserver; then the unassign fails (silently) because we
2115    * presume the region being unassigned no longer exists (its been split out
2116    * of existence). TODO: What to do if split fails and is rolled back and
2117    * parent is revivified?
2118    * <p>
2119    * If a RegionPlan is already set, it will remain.
2120    *
2121    * @param region server to be unassigned
2122    * @param force if region should be closed even if already closing
2123    */
2124   public void unassign(HRegionInfo region, boolean force) {
2125     // TODO: Method needs refactoring.  Ugly buried returns throughout.  Beware!
2126     LOG.debug("Starting unassignment of region " +
2127       region.getRegionNameAsString() + " (offlining)");
2128 
2129     synchronized (this.regions) {
2130       // Check if this region is currently assigned
2131       if (!regions.containsKey(region)) {
2132         LOG.debug("Attempted to unassign region " +
2133           region.getRegionNameAsString() + " but it is not " +
2134           "currently assigned anywhere");
2135         return;
2136       }
2137     }
2138     String encodedName = region.getEncodedName();
2139     // Grab the state of this region and synchronize on it
2140     RegionState state;
2141     int versionOfClosingNode = -1;
2142     synchronized (regionsInTransition) {
2143       state = regionsInTransition.get(encodedName);
2144       if (state == null) {
2145          // Create the znode in CLOSING state
2146         try {
2147           versionOfClosingNode = ZKAssign.createNodeClosing(
2148             master.getZooKeeper(), region, master.getServerName());
2149           if (versionOfClosingNode == -1) {
2150             LOG.debug("Attempting to unassign region " +
2151                 region.getRegionNameAsString() + " but ZK closing node "
2152                 + "can't be created.");
2153             return;
2154           }
2155         } catch (KeeperException e) {
2156           if (e instanceof NodeExistsException) {
2157             // Handle race between master initiated close and regionserver
2158             // orchestrated splitting. See if existing node is in a
2159             // SPLITTING or SPLIT state.  If so, the regionserver started
2160             // an op on node before we could get our CLOSING in.  Deal.
2161             NodeExistsException nee = (NodeExistsException)e;
2162             String path = nee.getPath();
2163             try {
2164               if (isSplitOrSplitting(path)) {
2165                 LOG.debug(path + " is SPLIT or SPLITTING; " +
2166                   "skipping unassign because region no longer exists -- its split");
2167                 return;
2168               }
2169             } catch (KeeperException.NoNodeException ke) {
2170               LOG.warn("Failed getData on SPLITTING/SPLIT at " + path +
2171                 "; presuming split and that the region to unassign, " +
2172                 encodedName + ", no longer exists -- confirm", ke);
2173               return;
2174             } catch (KeeperException ke) {
2175               LOG.error("Unexpected zk state", ke);
2176               ke = e;
2177             }
2178           }
2179           // If we get here, don't understand whats going on -- abort.
2180           master.abort("Unexpected ZK exception creating node CLOSING", e);
2181           return;
2182         }
2183         state = new RegionState(region, RegionState.State.PENDING_CLOSE);
2184         regionsInTransition.put(encodedName, state);
2185       } else if (force && (state.isPendingClose() || state.isClosing())) {
2186         LOG.debug("Attempting to unassign region " + region.getRegionNameAsString() + 
2187           " which is already " + state.getState()  + 
2188           " but forcing to send a CLOSE RPC again ");
2189         state.update(state.getState());
2190       } else {
2191         LOG.debug("Attempting to unassign region " +
2192           region.getRegionNameAsString() + " but it is " +
2193           "already in transition (" + state.getState() + ", force=" + force + ")");
2194         return;
2195       }
2196     } 
2197     // Send CLOSE RPC
2198     ServerName server = null;
2199     synchronized (this.regions) {
2200       server = regions.get(region);
2201     }
2202     // ClosedRegionhandler can remove the server from this.regions
2203     if (server == null) {
2204       // Possibility of disable flow removing from RIT.
2205       synchronized (regionsInTransition) {
2206         state = regionsInTransition.get(encodedName);
2207         if (state != null) {
2208           // remove only if the state is PENDING_CLOSE or CLOSING
2209           State presentState = state.getState();
2210           if (presentState == State.PENDING_CLOSE
2211               || presentState == State.CLOSING) {
2212             this.regionsInTransition.remove(encodedName);
2213           }
2214         }
2215       }
2216       // delete the node. if no node exists need not bother.
2217       deleteClosingOrClosedNode(region);
2218       return;
2219     }
2220     try {
2221       // TODO: We should consider making this look more like it does for the
2222       // region open where we catch all throwables and never abort
2223       if (serverManager.sendRegionClose(server, state.getRegion(),
2224         versionOfClosingNode)) {
2225         LOG.debug("Sent CLOSE to " + server + " for region " +
2226           region.getRegionNameAsString());
2227         return;
2228       }
2229       // This never happens. Currently regionserver close always return true.
2230       LOG.warn("Server " + server + " region CLOSE RPC returned false for " +
2231         region.getRegionNameAsString());
2232     } catch (NotServingRegionException nsre) {
2233       LOG.info("Server " + server + " returned " + nsre + " for " +
2234         region.getRegionNameAsString());
2235       // Presume that master has stale data.  Presume remote side just split.
2236       // Presume that the split message when it comes in will fix up the master's
2237       // in memory cluster state.
2238     } catch (Throwable t) {
2239       if (t instanceof RemoteException) {
2240         t = ((RemoteException)t).unwrapRemoteException();
2241         if (t instanceof NotServingRegionException) {
2242           if (checkIfRegionBelongsToDisabling(region)
2243               || checkIfRegionBelongsToDisabled(region)) {
2244             // Remove from the regionsinTransition map
2245             LOG.info("While trying to recover the table "
2246                 + region.getTableNameAsString()
2247                 + " to DISABLED state the region " + region
2248                 + " was offlined but the table was in DISABLING state");
2249             synchronized (this.regionsInTransition) {
2250               this.regionsInTransition.remove(region.getEncodedName());
2251             }
2252             // Remove from the regionsMap
2253             synchronized (this.regions) {
2254               ServerName sn = this.regions.remove(region);
2255               if (sn != null) {
2256                 Set<HRegionInfo> serverRegions = this.servers.get(sn);
2257                 if (serverRegions == null || !serverRegions.remove(region)) {
2258                   LOG.warn("No " + region + " on " + sn);
2259                 }
2260               }
2261             }
2262             deleteClosingOrClosedNode(region);
2263           }
2264         }
2265         // RS is already processing this region, only need to update the timestamp
2266         if (t instanceof RegionAlreadyInTransitionException) {
2267           LOG.debug("update " + state + " the timestamp.");
2268           state.update(state.getState());
2269         }
2270       }
2271       LOG.info("Server " + server + " returned " + t + " for " +
2272         region.getEncodedName());
2273       // Presume retry or server will expire.
2274     }
2275   }
2276   
2277   /**
2278    * 
2279    * @param region regioninfo of znode to be deleted.
2280    */
2281   public void deleteClosingOrClosedNode(HRegionInfo region) {
2282     try {
2283       if (!ZKAssign.deleteNode(master.getZooKeeper(), region.getEncodedName(),
2284           EventHandler.EventType.M_ZK_REGION_CLOSING)) {
2285         boolean deleteNode = ZKAssign.deleteNode(master.getZooKeeper(), region
2286             .getEncodedName(), EventHandler.EventType.RS_ZK_REGION_CLOSED);
2287         // TODO : We don't abort if the delete node returns false. Is there any
2288         // such corner case?
2289         if (!deleteNode) {
2290           LOG.error("The deletion of the CLOSED node for the region "
2291               + region.getEncodedName() + " returned " + deleteNode);
2292         }
2293       }
2294     } catch (NoNodeException e) {
2295       LOG.debug("CLOSING/CLOSED node for the region " + region.getEncodedName()
2296           + " already deleted");
2297     } catch (KeeperException ke) {
2298       master.abort(
2299           "Unexpected ZK exception deleting node CLOSING/CLOSED for the region "
2300               + region.getEncodedName(), ke);
2301       return;
2302     }
2303   }
2304 
2305   /**
2306    * @param path
2307    * @return True if znode is in SPLIT or SPLITTING state.
2308    * @throws KeeperException Can happen if the znode went away in meantime.
2309    */
2310   private boolean isSplitOrSplitting(final String path) throws KeeperException {
2311     boolean result = false;
2312     // This may fail if the SPLIT or SPLITTING znode gets cleaned up before we
2313     // can get data from it.
2314     RegionTransitionData data = ZKAssign.getData(master.getZooKeeper(), path);
2315     EventType evt = data.getEventType();
2316     switch (evt) {
2317     case RS_ZK_REGION_SPLIT:
2318     case RS_ZK_REGION_SPLITTING:
2319       result = true;
2320       break;
2321     default:
2322       break;
2323     }
2324     return result;
2325   }
2326 
2327   /**
2328    * Waits until the specified region has completed assignment.
2329    * <p>
2330    * If the region is already assigned, returns immediately.  Otherwise, method
2331    * blocks until the region is assigned.
2332    * @param regionInfo region to wait on assignment for
2333    * @throws InterruptedException
2334    */
2335   public void waitForAssignment(HRegionInfo regionInfo)
2336   throws InterruptedException {
2337     synchronized(regions) {
2338       while (!this.master.isStopped() && !regions.containsKey(regionInfo)) {
2339         // We should receive a notification, but it's
2340         //  better to have a timeout to recheck the condition here:
2341         //  it lowers the impact of a race condition if any
2342         regions.wait(100);
2343       }
2344     }
2345   }
2346 
2347   /**
2348    * Assigns the ROOT region.
2349    * <p>
2350    * Assumes that ROOT is currently closed and is not being actively served by
2351    * any RegionServer.
2352    * <p>
2353    * Forcibly unsets the current root region location in ZooKeeper and assigns
2354    * ROOT to a random RegionServer.
2355    * @throws KeeperException
2356    */
2357   public void assignRoot() throws KeeperException {
2358     RootLocationEditor.deleteRootLocation(this.master.getZooKeeper());
2359     assign(HRegionInfo.ROOT_REGIONINFO, true);
2360   }
2361 
2362   /**
2363    * Assigns the META region.
2364    * <p>
2365    * Assumes that META is currently closed and is not being actively served by
2366    * any RegionServer.
2367    * <p>
2368    * Forcibly assigns META to a random RegionServer.
2369    */
2370   public void assignMeta() {
2371     // Force assignment to a random server
2372     assign(HRegionInfo.FIRST_META_REGIONINFO, true);
2373   }
2374 
2375   /**
2376    * Assigns all user regions to online servers. Use round-robin assignment.
2377    * 
2378    * @param regions
2379    * @throws IOException
2380    * @throws InterruptedException
2381    */
2382   public void assignUserRegionsToOnlineServers(List<HRegionInfo> regions)
2383       throws IOException,
2384       InterruptedException {
2385     List<ServerName> servers = this.serverManager.getOnlineServersList();
2386     removeDeadNotExpiredServers(servers);
2387     assignUserRegions(regions, servers);
2388   }
2389 
2390   /**
2391    * Assigns all user regions, if any.  Used during cluster startup.
2392    * <p>
2393    * This is a synchronous call and will return once every region has been
2394    * assigned.  If anything fails, an exception is thrown
2395    * @throws InterruptedException
2396    * @throws IOException
2397    */
2398   public void assignUserRegions(List<HRegionInfo> regions, List<ServerName> servers)
2399   throws IOException, InterruptedException {
2400     if (regions == null)
2401       return;
2402     Map<ServerName, List<HRegionInfo>> bulkPlan = null;
2403     // Generate a round-robin bulk assignment plan
2404     bulkPlan = balancer.roundRobinAssignment(regions, servers);
2405     LOG.info("Bulk assigning " + regions.size() + " region(s) round-robin across " +
2406                servers.size() + " server(s)");
2407     // Use fixed count thread pool assigning.
2408     BulkAssigner ba = new StartupBulkAssigner(this.master, bulkPlan, this);
2409     ba.bulkAssign();
2410     LOG.info("Bulk assigning done");
2411   }
2412 
2413   private void setEnabledTable(HRegionInfo hri) {
2414     String tableName = hri.getTableNameAsString();
2415     boolean isTableEnabled = this.zkTable.isEnabledTable(tableName);
2416     if (!isTableEnabled) {
2417       setEnabledTable(tableName);
2418     }    
2419   }
2420 
2421   /**
2422    * Assigns all user regions, if any exist.  Used during cluster startup.
2423    * <p>
2424    * This is a synchronous call and will return once every region has been
2425    * assigned.  If anything fails, an exception is thrown and the cluster
2426    * should be shutdown.
2427    * @throws InterruptedException
2428    * @throws IOException
2429    */
2430   public void assignAllUserRegions() throws IOException, InterruptedException {
2431     // Skip assignment for regions of tables in DISABLING state also because
2432     // during clean cluster startup no RS is alive and regions map also doesn't
2433     // have any information about the regions. See HBASE-6281.
2434     Set<String> disablingDisabledAndEnablingTables = new HashSet<String>(this.disablingTables);
2435     disablingDisabledAndEnablingTables.addAll(this.zkTable.getDisabledTables());
2436     disablingDisabledAndEnablingTables.addAll(this.enablingTables.keySet());
2437     // Scan META for all user regions, skipping any disabled tables
2438     Map<HRegionInfo, ServerName> allRegions = MetaReader.fullScan(catalogTracker,
2439         disablingDisabledAndEnablingTables, true);
2440     if (allRegions == null || allRegions.isEmpty()) return;
2441 
2442     // Get all available servers
2443     List<ServerName> servers = serverManager.getOnlineServersList();
2444 
2445     // Remove the deadNotExpired servers from the server list.
2446     removeDeadNotExpiredServers(servers);
2447 
2448     // If there are no servers we need not proceed with region assignment.
2449     if(servers.isEmpty()) return;
2450 
2451     // Determine what type of assignment to do on startup
2452     boolean retainAssignment = master.getConfiguration().
2453       getBoolean("hbase.master.startup.retainassign", true);
2454 
2455     Map<ServerName, List<HRegionInfo>> bulkPlan = null;
2456     if (retainAssignment) {
2457       // Reuse existing assignment info
2458       bulkPlan = balancer.retainAssignment(allRegions, servers);
2459     } else {
2460       // assign regions in round-robin fashion
2461       assignUserRegions(new ArrayList<HRegionInfo>(allRegions.keySet()), servers);
2462       for (HRegionInfo hri : allRegions.keySet()) {
2463         setEnabledTable(hri);
2464       }
2465       return;
2466     }
2467     LOG.info("Bulk assigning " + allRegions.size() + " region(s) across " +
2468       servers.size() + " server(s), retainAssignment=" + retainAssignment);
2469 
2470     // Use fixed count thread pool assigning.
2471     BulkAssigner ba = new StartupBulkAssigner(this.master, bulkPlan, this);
2472     ba.bulkAssign();
2473     for (HRegionInfo hri : allRegions.keySet()) {
2474       setEnabledTable(hri);
2475     }
2476     LOG.info("Bulk assigning done");
2477   }
2478 
2479   /**
2480    * Run bulk assign on startup.  Does one RCP per regionserver passing a
2481    * batch of reginons using {@link SingleServerBulkAssigner}.
2482    * Uses default {@link #getUncaughtExceptionHandler()}
2483    * which will abort the Server if exception.
2484    */
2485   static class StartupBulkAssigner extends BulkAssigner {
2486     final Map<ServerName, List<HRegionInfo>> bulkPlan;
2487     final AssignmentManager assignmentManager;
2488 
2489     StartupBulkAssigner(final Server server,
2490         final Map<ServerName, List<HRegionInfo>> bulkPlan,
2491         final AssignmentManager am) {
2492       super(server);
2493       this.bulkPlan = bulkPlan;
2494       this.assignmentManager = am;
2495     }
2496 
2497     @Override
2498     public boolean bulkAssign(boolean sync) throws InterruptedException,
2499         IOException {
2500       // Disable timing out regions in transition up in zk while bulk assigning.
2501       this.assignmentManager.timeoutMonitor.bulkAssign(true);
2502       try {
2503         return super.bulkAssign(sync);
2504       } finally {
2505         // Reenable timing out regions in transition up in zi.
2506         this.assignmentManager.timeoutMonitor.bulkAssign(false);
2507       }
2508     }
2509 
2510     @Override
2511     protected String getThreadNamePrefix() {
2512       return this.server.getServerName() + "-StartupBulkAssigner";
2513     }
2514 
2515     @Override
2516     protected void populatePool(java.util.concurrent.ExecutorService pool) {
2517       for (Map.Entry<ServerName, List<HRegionInfo>> e: this.bulkPlan.entrySet()) {
2518         pool.execute(new SingleServerBulkAssigner(e.getKey(), e.getValue(),
2519           this.assignmentManager));
2520       }
2521     }
2522 
2523     protected boolean waitUntilDone(final long timeout)
2524     throws InterruptedException {
2525       Set<HRegionInfo> regionSet = new HashSet<HRegionInfo>();
2526       for (List<HRegionInfo> regionList : bulkPlan.values()) {
2527         regionSet.addAll(regionList);
2528       }
2529       return this.assignmentManager.waitUntilNoRegionsInTransition(timeout, regionSet);
2530     }
2531 
2532     @Override
2533     protected long getTimeoutOnRIT() {
2534       // Guess timeout.  Multiply the number of regions on a random server
2535       // by how long we thing one region takes opening.
2536       long perRegionOpenTimeGuesstimate =
2537         this.server.getConfiguration().getLong("hbase.bulk.assignment.perregion.open.time", 1000);
2538       int regionsPerServer =
2539         this.bulkPlan.entrySet().iterator().next().getValue().size();
2540       long timeout = perRegionOpenTimeGuesstimate * regionsPerServer;
2541       LOG.debug("Timeout-on-RIT=" + timeout);
2542       return timeout;
2543     }
2544   }
2545 
2546   /**
2547    * Manage bulk assigning to a server.
2548    */
2549   static class SingleServerBulkAssigner implements Runnable {
2550     private final ServerName regionserver;
2551     private final List<HRegionInfo> regions;
2552     private final AssignmentManager assignmentManager;
2553 
2554     SingleServerBulkAssigner(final ServerName regionserver,
2555         final List<HRegionInfo> regions, final AssignmentManager am) {
2556       for (Iterator<HRegionInfo> it = regions.iterator(); it.hasNext(); ) {
2557         if (isAssigningSplitParentRegion(it.next())) {
2558           it.remove();
2559         }
2560       }
2561       this.regionserver = regionserver;
2562       this.regions = regions;
2563       this.assignmentManager = am;
2564     }
2565     @Override
2566     public void run() {
2567       this.assignmentManager.assign(this.regionserver, this.regions);
2568     }
2569   }
2570 
2571   /**
2572    * Wait until no regions in transition.
2573    * @param timeout How long to wait.
2574    * @return True if nothing in regions in transition.
2575    * @throws InterruptedException
2576    */
2577   boolean waitUntilNoRegionsInTransition(final long timeout)
2578   throws InterruptedException {
2579     // Blocks until there are no regions in transition. It is possible that
2580     // there
2581     // are regions in transition immediately after this returns but guarantees
2582     // that if it returns without an exception that there was a period of time
2583     // with no regions in transition from the point-of-view of the in-memory
2584     // state of the Master.
2585     long startTime = System.currentTimeMillis();
2586     long remaining = timeout;
2587     synchronized (regionsInTransition) {
2588       while (regionsInTransition.size() > 0 && !this.master.isStopped()
2589           && remaining > 0) {
2590         regionsInTransition.wait(remaining);
2591         remaining = timeout - (System.currentTimeMillis() - startTime);
2592       }
2593     }
2594     return regionsInTransition.isEmpty();
2595   }
2596 
2597   /**
2598    * Wait until no regions from set regions are in transition.
2599    * @param timeout How long to wait.
2600    * @param regions set of regions to wait for
2601    * @return True if nothing in regions in transition.
2602    * @throws InterruptedException
2603    */
2604   boolean waitUntilNoRegionsInTransition(final long timeout, Set<HRegionInfo> regions)
2605   throws InterruptedException {
2606     // Blocks until there are no regions in transition.
2607     long startTime = System.currentTimeMillis();
2608     long remaining = timeout;
2609     boolean stillInTransition = true;
2610     synchronized (regionsInTransition) {
2611       while (regionsInTransition.size() > 0 && !this.master.isStopped() &&
2612           remaining > 0 && stillInTransition) {
2613         int count = 0;
2614         for (RegionState rs : regionsInTransition.values()) {
2615           if (regions.contains(rs.getRegion())) {
2616             count++;
2617             break;
2618           }
2619         }
2620         if (count == 0) {
2621           stillInTransition = false;
2622           break;
2623         }
2624         regionsInTransition.wait(remaining);
2625         remaining = timeout - (System.currentTimeMillis() - startTime);
2626       }
2627     }
2628     return stillInTransition;
2629   }
2630 
2631   /**
2632    * Rebuild the list of user regions and assignment information.
2633    * <p>
2634    * Returns a map of servers that are not found to be online and the regions
2635    * they were hosting.
2636    * @return map of servers not online to their assigned regions, as stored
2637    *         in META
2638    * @throws IOException
2639    */
2640   Map<ServerName, List<Pair<HRegionInfo, Result>>> rebuildUserRegions() throws IOException,
2641       KeeperException {
2642     // Region assignment from META
2643     List<Result> results = MetaReader.fullScan(this.catalogTracker);
2644     // Get any new but slow to checkin region server that joined the cluster
2645     Set<ServerName> onlineServers = serverManager.getOnlineServers().keySet();    
2646     // Map of offline servers and their regions to be returned
2647     Map<ServerName, List<Pair<HRegionInfo,Result>>> offlineServers =
2648       new TreeMap<ServerName, List<Pair<HRegionInfo, Result>>>();
2649     // Iterate regions in META
2650     for (Result result : results) {
2651       boolean disabled = false;
2652       boolean disablingOrEnabling = false;
2653       Pair<HRegionInfo, ServerName> region = MetaReader.parseCatalogResult(result);
2654       if (region == null) continue;
2655       HRegionInfo regionInfo = region.getFirst();
2656       ServerName regionLocation = region.getSecond();
2657       if (regionInfo == null) continue;
2658       String tableName = regionInfo.getTableNameAsString();
2659       if (regionLocation == null) {
2660         // regionLocation could be null if createTable didn't finish properly.
2661         // When createTable is in progress, HMaster restarts.
2662         // Some regions have been added to .META., but have not been assigned.
2663         // When this happens, the region's table must be in ENABLING state.
2664         // It can't be in ENABLED state as that is set when all regions are
2665         // assigned.
2666         // It can't be in DISABLING state, because DISABLING state transitions
2667         // from ENABLED state when application calls disableTable.
2668         // It can't be in DISABLED state, because DISABLED states transitions
2669         // from DISABLING state.
2670         boolean enabling = checkIfRegionsBelongsToEnabling(regionInfo);
2671         addTheTablesInPartialState(regionInfo);
2672         if (enabling) {
2673           addToEnablingTableRegions(regionInfo);
2674         } else {
2675           LOG.warn("Region " + regionInfo.getEncodedName() + " has null regionLocation."
2676               + " But its table " + tableName + " isn't in ENABLING state.");
2677         }
2678       } else if (!onlineServers.contains(regionLocation)) {
2679         // Region is located on a server that isn't online
2680         List<Pair<HRegionInfo, Result>> offlineRegions =
2681           offlineServers.get(regionLocation);
2682         if (offlineRegions == null) {
2683           offlineRegions = new ArrayList<Pair<HRegionInfo,Result>>(1);
2684           offlineServers.put(regionLocation, offlineRegions);
2685         }
2686         offlineRegions.add(new Pair<HRegionInfo,Result>(regionInfo, result));
2687         disabled = checkIfRegionBelongsToDisabled(regionInfo);
2688         disablingOrEnabling = addTheTablesInPartialState(regionInfo);
2689         // need to enable the table if not disabled or disabling or enabling
2690         // this will be used in rolling restarts
2691         enableTableIfNotDisabledOrDisablingOrEnabling(disabled,
2692             disablingOrEnabling, tableName);
2693       } else {
2694         // If region is in offline and split state check the ZKNode
2695         if (regionInfo.isOffline() && regionInfo.isSplit()) {
2696           String node = ZKAssign.getNodeName(this.watcher, regionInfo
2697               .getEncodedName());
2698           Stat stat = new Stat();
2699           byte[] data = ZKUtil.getDataNoWatch(this.watcher, node, stat);
2700           // If znode does not exist dont consider this region
2701           if (data == null) {
2702             LOG.debug("Region "+ regionInfo.getRegionNameAsString() + " split is completed. " 
2703                 + "Hence need not add to regions list");
2704             continue;
2705           }
2706         }
2707         // Region is being served and on an active server
2708         // add only if region not in disabled and enabling table
2709         boolean enabling = checkIfRegionsBelongsToEnabling(regionInfo);
2710         disabled = checkIfRegionBelongsToDisabled(regionInfo);
2711         if (!enabling && !disabled) {
2712           synchronized (this.regions) {
2713             regions.put(regionInfo, regionLocation);
2714             addToServers(regionLocation, regionInfo);
2715           }
2716         }
2717         disablingOrEnabling = addTheTablesInPartialState(regionInfo);
2718         if (enabling) {
2719           addToEnablingTableRegions(regionInfo);
2720         }
2721         // need to enable the table if not disabled or disabling or enabling
2722         // this will be used in rolling restarts
2723         enableTableIfNotDisabledOrDisablingOrEnabling(disabled,
2724             disablingOrEnabling, tableName);
2725       }
2726     }
2727     return offlineServers;
2728   }
2729 
2730   private void addToEnablingTableRegions(HRegionInfo regionInfo) {
2731     String tableName = regionInfo.getTableNameAsString();
2732     List<HRegionInfo> hris = this.enablingTables.get(tableName);
2733     if (!hris.contains(regionInfo)) {
2734       if (LOG.isDebugEnabled()) {
2735         LOG.debug("Adding region" + regionInfo.getRegionNameAsString()
2736             + " to enabling table " + tableName + ".");
2737       }
2738       hris.add(regionInfo);
2739     }
2740   }
2741   
2742   private void enableTableIfNotDisabledOrDisablingOrEnabling(boolean disabled,
2743       boolean disablingOrEnabling, String tableName) {
2744     if (!disabled && !disablingOrEnabling
2745         && !getZKTable().isEnabledTable(tableName)) {
2746       setEnabledTable(tableName);
2747     }
2748   }
2749 
2750   private Boolean addTheTablesInPartialState(HRegionInfo regionInfo) {
2751     String tableName = regionInfo.getTableNameAsString();
2752     if (checkIfRegionBelongsToDisabling(regionInfo)) {
2753       this.disablingTables.add(tableName);
2754       return true;
2755     } else if (checkIfRegionsBelongsToEnabling(regionInfo)) {
2756       if (!this.enablingTables.containsKey(tableName)) {
2757         this.enablingTables.put(tableName, new ArrayList<HRegionInfo>());
2758       } 
2759       return true;
2760     } 
2761     return false;
2762   }
2763 
2764   /**
2765    * Recover the tables that were not fully moved to DISABLED state. These
2766    * tables are in DISABLING state when the master restarted/switched.
2767    * 
2768    * @param disablingTables
2769    * @return
2770    * @throws KeeperException
2771    * @throws TableNotFoundException
2772    * @throws IOException
2773    */
2774   private boolean recoverTableInDisablingState(Set<String> disablingTables)
2775       throws KeeperException, TableNotFoundException, IOException {
2776     boolean isWatcherCreated = false;
2777     if (disablingTables.size() != 0) {
2778       // Create a watcher on the zookeeper node
2779       ZKUtil.listChildrenAndWatchForNewChildren(watcher,
2780           watcher.assignmentZNode);
2781       isWatcherCreated = true;
2782       for (String tableName : disablingTables) {
2783         // Recover by calling DisableTableHandler
2784         LOG.info("The table " + tableName
2785             + " is in DISABLING state.  Hence recovering by moving the table"
2786             + " to DISABLED state.");
2787         new DisableTableHandler(this.master, tableName.getBytes(),
2788             catalogTracker, this, true).process();
2789       }
2790     }
2791     return isWatcherCreated;
2792   }
2793 
2794   /**
2795    * Recover the tables that are not fully moved to ENABLED state. These tables
2796    * are in ENABLING state when the master restarted/switched
2797    * 
2798    * @param enablingTables
2799    * @param isWatcherCreated
2800    * @throws KeeperException
2801    * @throws TableNotFoundException
2802    * @throws IOException
2803    */
2804   private void recoverTableInEnablingState(Set<String> enablingTables,
2805       boolean isWatcherCreated) throws KeeperException, TableNotFoundException,
2806       IOException {
2807     if (enablingTables.size() != 0) {
2808       if (false == isWatcherCreated) {
2809         ZKUtil.listChildrenAndWatchForNewChildren(watcher,
2810             watcher.assignmentZNode);
2811       }
2812       for (String tableName : enablingTables) {
2813         // Recover by calling EnableTableHandler
2814         LOG.info("The table " + tableName
2815             + " is in ENABLING state.  Hence recovering by moving the table"
2816             + " to ENABLED state.");
2817         // enableTable in sync way during master startup,
2818         // no need to invoke coprocessor
2819         EnableTableHandler eth = null;
2820         try {
2821           eth =
2822               new EnableTableHandler(this.master, tableName.getBytes(), catalogTracker, this, true);
2823         } catch (TableNotFoundException e) {
2824           LOG.warn("Table " + tableName + " not found in .META. to recover.");
2825           continue;
2826         }
2827         if (eth != null) eth.process();
2828       }
2829     }
2830   }
2831 
2832   private boolean checkIfRegionsBelongsToEnabling(HRegionInfo regionInfo) {
2833     String tableName = regionInfo.getTableNameAsString();
2834     return getZKTable().isEnablingTable(tableName);
2835   }
2836 
2837   private boolean checkIfRegionBelongsToDisabled(HRegionInfo regionInfo) {
2838     String tableName = regionInfo.getTableNameAsString();
2839     return getZKTable().isDisabledTable(tableName);
2840   }
2841 
2842   private boolean checkIfRegionBelongsToDisabling(HRegionInfo regionInfo) {
2843     String tableName = regionInfo.getTableNameAsString();
2844     return getZKTable().isDisablingTable(tableName);
2845   }
2846 
2847   /**
2848    * Processes list of dead servers from result of META scan and regions in RIT
2849    * <p>
2850    * This is used for failover to recover the lost regions that belonged to
2851    * RegionServers which failed while there was no active master or regions 
2852    * that were in RIT.
2853    * <p>
2854    * 
2855    * @param deadServers
2856    *          The list of dead servers which failed while there was no active
2857    *          master. Can be null.
2858    * @param nodes
2859    *          The regions in RIT
2860    * @throws IOException
2861    * @throws KeeperException
2862    */
2863   private void processDeadServersAndRecoverLostRegions(
2864       Map<ServerName, List<Pair<HRegionInfo, Result>>> deadServers,
2865       List<String> nodes) throws IOException, KeeperException {
2866     if (null != deadServers) {
2867       Set<ServerName> actualDeadServers = this.serverManager.getDeadServers();
2868       for (Map.Entry<ServerName, List<Pair<HRegionInfo, Result>>> deadServer : 
2869         deadServers.entrySet()) {
2870         // skip regions of dead servers because SSH will process regions during rs expiration.
2871         // see HBASE-5916
2872         if (actualDeadServers.contains(deadServer.getKey())) {
2873           for (Pair<HRegionInfo, Result> deadRegion : deadServer.getValue()) {
2874             HRegionInfo hri = deadRegion.getFirst();
2875             // Delete znode of region in transition if table is disabled or disabling. If a region
2876             // server went down during master initialization then SSH cannot handle the regions of
2877             // partially disabled tables because in memory region state information may not be
2878             // available with master.
2879             deleteNodeAndOfflineRegion(hri);
2880             nodes.remove(deadRegion.getFirst().getEncodedName());
2881           }
2882           continue;
2883         }
2884         List<Pair<HRegionInfo, Result>> regions = deadServer.getValue();
2885         for (Pair<HRegionInfo, Result> region : regions) {
2886           HRegionInfo regionInfo = region.getFirst();
2887           Result result = region.getSecond();
2888           // If region was in transition (was in zk) force it offline for
2889           // reassign
2890           try {
2891             RegionTransitionData data = ZKAssign.getData(watcher,
2892                 regionInfo.getEncodedName());
2893 
2894             // If zk node of this region has been updated by a live server,
2895             // we consider that this region is being handled.
2896             // So we should skip it and process it in
2897             // processRegionsInTransition.
2898             if (data != null && data.getOrigin() != null && 
2899                 serverManager.isServerOnline(data.getOrigin())) {
2900               LOG.info("The region " + regionInfo.getEncodedName()
2901                   + "is being handled on " + data.getOrigin());
2902               continue;
2903             }
2904             // Process with existing RS shutdown code
2905             boolean assign = ServerShutdownHandler.processDeadRegion(
2906                 regionInfo, result, this, this.catalogTracker);
2907             if (assign) {
2908               ZKAssign.createOrForceNodeOffline(watcher, regionInfo,
2909                   master.getServerName());
2910               if (!nodes.contains(regionInfo.getEncodedName())) {
2911                 nodes.add(regionInfo.getEncodedName());
2912               }
2913             }
2914           } catch (KeeperException.NoNodeException nne) {
2915             // This is fine
2916           }
2917         }
2918       }
2919     }
2920 
2921     if (!nodes.isEmpty()) {
2922       for (String encodedRegionName : nodes) {
2923         processRegionInTransition(encodedRegionName, null, deadServers);
2924       }
2925     }
2926   }
2927 
2928   /**
2929    * Delete znode of region in transition if table is disabling/disabled and offline the region.
2930    * @param hri region to offline.
2931    */
2932   public void deleteNodeAndOfflineRegion(HRegionInfo hri) {
2933     if (zkTable.isDisablingOrDisabledTable(hri.getTableNameAsString())) {
2934       try {
2935         // If table is partially disabled then delete znode if exists in any state.
2936         ZKAssign.deleteNodeFailSilent(this.master.getZooKeeper(), hri);
2937       } catch (KeeperException ke) {
2938         this.master.abort("Unexpected ZK exception deleting unassigned node " + hri, ke);
2939       }
2940       regionOffline(hri);
2941     }
2942   }
2943 
2944   /*
2945    * Presumes caller has taken care of necessary locking modifying servers Map.
2946    * @param hsi
2947    * @param hri
2948    */
2949   private void addToServers(final ServerName sn, final HRegionInfo hri) {
2950     Set<HRegionInfo> hris = servers.get(sn);
2951     if (hris == null) {
2952       hris = new ConcurrentSkipListSet<HRegionInfo>();
2953       servers.put(sn, hris);
2954     }
2955     if (!hris.contains(hri)) hris.add(hri);
2956   }
2957 
2958   /**
2959    * @return A copy of the Map of regions currently in transition.
2960    */
2961   public NavigableMap<String, RegionState> getRegionsInTransition() {
2962     synchronized (this.regionsInTransition) {
2963       return new TreeMap<String, RegionState>(this.regionsInTransition);
2964     }
2965   }
2966 
2967   /**
2968    * @return True if regions in transition.
2969    */
2970   public boolean isRegionsInTransition() {
2971     synchronized (this.regionsInTransition) {
2972       return !this.regionsInTransition.isEmpty();
2973     }
2974   }
2975 
2976   /**
2977    * @param hri Region to check.
2978    * @return Returns null if passed region is not in transition else the current
2979    * RegionState
2980    */
2981   public RegionState isRegionInTransition(final HRegionInfo hri) {
2982     synchronized (this.regionsInTransition) {
2983       return this.regionsInTransition.get(hri.getEncodedName());
2984     }
2985   }
2986 
2987   /**
2988    * Clears the specified region from being in transition.
2989    * <p>
2990    * @param hri Region to remove.
2991    * @deprecated This is a dupe of {@link #regionOffline(HRegionInfo)}.
2992    *   Please use that method instead.
2993    */
2994   public void clearRegionFromTransition(HRegionInfo hri) {
2995     synchronized (this.regionsInTransition) {
2996       this.regionsInTransition.remove(hri.getEncodedName());
2997     }
2998     synchronized (this.regions) {
2999       this.regions.remove(hri);
3000       for (Set<HRegionInfo> regions : this.servers.values()) {
3001         regions.remove(hri);
3002       }
3003     }
3004     clearRegionPlan(hri);
3005   }
3006 
3007   /**
3008    * @param region Region whose plan we are to clear.
3009    */
3010   void clearRegionPlan(final HRegionInfo region) {
3011     synchronized (this.regionPlans) {
3012       this.regionPlans.remove(region.getEncodedName());
3013     }
3014   }
3015 
3016   /**
3017    * Wait on region to clear regions-in-transition.
3018    * @param hri Region to wait on.
3019    * @throws IOException
3020    */
3021   public void waitOnRegionToClearRegionsInTransition(final HRegionInfo hri)
3022   throws IOException {
3023     if (isRegionInTransition(hri) == null) return;
3024     RegionState rs = null;
3025     // There is already a timeout monitor on regions in transition so I
3026     // should not have to have one here too?
3027     while(!this.master.isStopped() && (rs = isRegionInTransition(hri)) != null) {
3028       Threads.sleep(1000);
3029       LOG.info("Waiting on " + rs + " to clear regions-in-transition");
3030     }
3031     if (this.master.isStopped()) {
3032       LOG.info("Giving up wait on regions in " +
3033         "transition because stoppable.isStopped is set");
3034     }
3035   }
3036 
3037 
3038   /**
3039    * Gets the online regions of the specified table.
3040    * This method looks at the in-memory state.  It does not go to <code>.META.</code>.
3041    * Only returns <em>online</em> regions.  If a region on this table has been
3042    * closed during a disable, etc., it will be included in the returned list.
3043    * So, the returned list may not necessarily be ALL regions in this table, its
3044    * all the ONLINE regions in the table.
3045    * @param tableName
3046    * @return Online regions from <code>tableName</code>
3047    */
3048   public List<HRegionInfo> getRegionsOfTable(byte[] tableName) {
3049     List<HRegionInfo> tableRegions = new ArrayList<HRegionInfo>();
3050     // boundary needs to have table's name but regionID 0 so that it is sorted 
3051     // before all table's regions.
3052     HRegionInfo boundary =
3053       new HRegionInfo(tableName, null, null, false, 0L);
3054     synchronized (this.regions) {
3055       for (HRegionInfo regionInfo: this.regions.tailMap(boundary).keySet()) {
3056         if(Bytes.equals(regionInfo.getTableName(), tableName)) {
3057           tableRegions.add(regionInfo);
3058         } else {
3059           break;
3060         }
3061       }
3062     }
3063     return tableRegions;
3064   }
3065 
3066   /**
3067    * Update timers for all regions in transition going against the server in the
3068    * serversInUpdatingTimer.
3069    */
3070   public class TimerUpdater extends Chore {
3071 
3072     public TimerUpdater(final int period, final Stoppable stopper) {
3073       super("AssignmentTimerUpdater", period, stopper);
3074     }
3075 
3076     @Override
3077     protected void chore() {
3078       ServerName serverToUpdateTimer = null;
3079       while (!serversInUpdatingTimer.isEmpty() && !stopper.isStopped()) {
3080         if (serverToUpdateTimer == null) {
3081           serverToUpdateTimer = serversInUpdatingTimer.first();
3082         } else {
3083           serverToUpdateTimer = serversInUpdatingTimer
3084               .higher(serverToUpdateTimer);
3085         }
3086         if (serverToUpdateTimer == null) {
3087           break;
3088         }
3089         updateTimers(serverToUpdateTimer);
3090         serversInUpdatingTimer.remove(serverToUpdateTimer);
3091       }
3092     }
3093   }
3094 
3095   /**
3096    * Monitor to check for time outs on region transition operations
3097    */
3098   public class TimeoutMonitor extends Chore {
3099     private final int timeout;
3100     private boolean bulkAssign = false;
3101     private boolean allRegionServersOffline = false;
3102     private ServerManager serverManager;
3103 
3104     /**
3105      * Creates a periodic monitor to check for time outs on region transition
3106      * operations.  This will deal with retries if for some reason something
3107      * doesn't happen within the specified timeout.
3108      * @param period
3109    * @param stopper When {@link Stoppable#isStopped()} is true, this thread will
3110    * cleanup and exit cleanly.
3111      * @param timeout
3112      */
3113     public TimeoutMonitor(final int period, final Stoppable stopper,
3114         ServerManager serverManager,
3115         final int timeout) {
3116       super("AssignmentTimeoutMonitor", period, stopper);
3117       this.timeout = timeout;
3118       this.serverManager = serverManager;
3119     }
3120 
3121     /**
3122      * @param bulkAssign If true, we'll suspend checking regions in transition
3123      * up in zookeeper.  If false, will reenable check.
3124      * @return Old setting for bulkAssign.
3125      */
3126     public boolean bulkAssign(final boolean bulkAssign) {
3127       boolean result = this.bulkAssign;
3128       this.bulkAssign = bulkAssign;
3129       return result;
3130     }
3131 
3132     private synchronized void setAllRegionServersOffline(
3133       boolean allRegionServersOffline) {
3134       this.allRegionServersOffline = allRegionServersOffline;
3135     }
3136 
3137     @Override
3138     protected void chore() {
3139       // If bulkAssign in progress, suspend checks
3140       if (this.bulkAssign) return;
3141       boolean allRSsOffline = this.serverManager.getOnlineServersList().
3142         isEmpty();
3143 
3144       synchronized (regionsInTransition) {
3145         // Iterate all regions in transition checking for time outs
3146         long now = System.currentTimeMillis();
3147         for (RegionState regionState : regionsInTransition.values()) {
3148           if (regionState.getStamp() + timeout <= now) {
3149            //decide on action upon timeout
3150             actOnTimeOut(regionState);
3151           } else if (this.allRegionServersOffline && !allRSsOffline) {
3152             RegionPlan existingPlan = regionPlans.get(regionState.getRegion().getEncodedName());
3153             if (existingPlan == null
3154                 || !this.serverManager.isServerOnline(existingPlan.getDestination())) {
3155               // if some RSs just came back online, we can start the
3156               // the assignment right away
3157               actOnTimeOut(regionState);
3158             }
3159           }
3160         }
3161       }
3162       setAllRegionServersOffline(allRSsOffline);
3163     }
3164 
3165     private void actOnTimeOut(RegionState regionState) {
3166       HRegionInfo regionInfo = regionState.getRegion();
3167       LOG.info("Regions in transition timed out:  " + regionState);
3168       // Expired! Do a retry.
3169       switch (regionState.getState()) {
3170       case CLOSED:
3171         LOG.info("Region " + regionInfo.getEncodedName()
3172             + " has been CLOSED for too long, waiting on queued "
3173             + "ClosedRegionHandler to run or server shutdown");
3174         // Update our timestamp.
3175         regionState.updateTimestampToNow();
3176         break;
3177       case OFFLINE:
3178         LOG.info("Region has been OFFLINE for too long, " + "reassigning "
3179             + regionInfo.getRegionNameAsString() + " to a random server");
3180         invokeAssign(regionInfo);
3181         break;
3182       case PENDING_OPEN:
3183         LOG.info("Region has been PENDING_OPEN for too "
3184             + "long, reassigning region=" + regionInfo.getRegionNameAsString());
3185         invokeAssign(regionInfo);
3186         break;
3187       case OPENING:
3188         processOpeningState(regionInfo);
3189         break;
3190       case OPEN:
3191         LOG.error("Region has been OPEN for too long, " +
3192             "we don't know where region was opened so can't do anything");
3193         synchronized (regionState) {
3194           regionState.updateTimestampToNow();
3195         }
3196         break;
3197 
3198       case PENDING_CLOSE:
3199         LOG.info("Region has been PENDING_CLOSE for too "
3200             + "long, running forced unassign again on region="
3201             + regionInfo.getRegionNameAsString());
3202         invokeUnassign(regionInfo);
3203         break;
3204       case CLOSING:
3205         LOG.info("Region has been CLOSING for too " +
3206           "long, this should eventually complete or the server will " +
3207           "expire, send RPC again");
3208         invokeUnassign(regionInfo);
3209         break;
3210       }
3211     }
3212   }
3213   
3214   private void processOpeningState(HRegionInfo regionInfo) {
3215     LOG.info("Region has been OPENING for too " + "long, reassigning region="
3216         + regionInfo.getRegionNameAsString());
3217     // Should have a ZK node in OPENING state
3218     try {
3219       String node = ZKAssign.getNodeName(watcher, regionInfo.getEncodedName());
3220       Stat stat = new Stat();
3221       RegionTransitionData dataInZNode = ZKAssign.getDataNoWatch(watcher, node,
3222           stat);
3223       if (dataInZNode == null) {
3224         LOG.warn("Data is null, node " + node + " no longer exists");
3225         return;
3226       }
3227       if (dataInZNode.getEventType() == EventType.RS_ZK_REGION_OPENED) {
3228         LOG.debug("Region has transitioned to OPENED, allowing "
3229             + "watched event handlers to process");
3230         return;
3231       } else if (dataInZNode.getEventType() != EventType.RS_ZK_REGION_OPENING &&
3232           dataInZNode.getEventType() != EventType.RS_ZK_REGION_FAILED_OPEN ) {
3233         LOG.warn("While timing out a region in state OPENING, "
3234             + "found ZK node in unexpected state: "
3235             + dataInZNode.getEventType());
3236         return;
3237       }
3238       invokeAssign(regionInfo);
3239     } catch (KeeperException ke) {
3240       LOG.error("Unexpected ZK exception timing out CLOSING region", ke);
3241       return;
3242     }
3243     return;
3244   }
3245 
3246   private void invokeAssign(HRegionInfo regionInfo) {
3247     threadPoolExecutorService.submit(new AssignCallable(this, regionInfo));
3248   }
3249 
3250   private void invokeUnassign(HRegionInfo regionInfo) {
3251     threadPoolExecutorService.submit(new UnAssignCallable(this, regionInfo));
3252   }
3253 
3254   public boolean isCarryingRoot(ServerName serverName) {
3255     return isCarryingRegion(serverName, HRegionInfo.ROOT_REGIONINFO);
3256   }
3257 
3258   public boolean isCarryingMeta(ServerName serverName) {
3259     return isCarryingRegion(serverName, HRegionInfo.FIRST_META_REGIONINFO);
3260   }
3261   /**
3262    * Check if the shutdown server carries the specific region.
3263    * We have a bunch of places that store region location
3264    * Those values aren't consistent. There is a delay of notification.
3265    * The location from zookeeper unassigned node has the most recent data;
3266    * but the node could be deleted after the region is opened by AM.
3267    * The AM's info could be old when OpenedRegionHandler
3268    * processing hasn't finished yet when server shutdown occurs.
3269    * @return whether the serverName currently hosts the region
3270    */
3271   public boolean isCarryingRegion(ServerName serverName, HRegionInfo hri) {
3272     RegionTransitionData data = null;
3273     try {
3274       data = ZKAssign.getData(master.getZooKeeper(), hri.getEncodedName());
3275     } catch (KeeperException e) {
3276       master.abort("Unexpected ZK exception reading unassigned node for region="
3277         + hri.getEncodedName(), e);
3278     }
3279 
3280     ServerName addressFromZK = (data != null && data.getOrigin() != null) ?
3281       data.getOrigin() : null;
3282     if (addressFromZK != null) {
3283       // if we get something from ZK, we will use the data
3284       boolean matchZK = (addressFromZK != null &&
3285         addressFromZK.equals(serverName));
3286       LOG.debug("based on ZK, current region=" + hri.getRegionNameAsString() +
3287           " is on server=" + addressFromZK +
3288           " server being checked=: " + serverName);
3289       return matchZK;
3290     }
3291 
3292     ServerName addressFromAM = getRegionServerOfRegion(hri);
3293     boolean matchAM = (addressFromAM != null &&
3294       addressFromAM.equals(serverName));
3295     LOG.debug("based on AM, current region=" + hri.getRegionNameAsString() +
3296       " is on server=" + (addressFromAM != null ? addressFromAM : "null") +
3297       " server being checked: " + serverName);
3298 
3299     return matchAM;
3300   }
3301 
3302   /**
3303    * Start processing of shutdown server.
3304    * @param sn Server that went down.
3305    * @return Pair that has a set of regions in transition TO the dead server and
3306    * a list of regions that were in transition, and also ON this server.
3307    */
3308   public Pair<Set<HRegionInfo>, List<RegionState>> processServerShutdown(final ServerName sn) {
3309     // Clean out any existing assignment plans for this server
3310     synchronized (this.regionPlans) {
3311       for (Iterator <Map.Entry<String, RegionPlan>> i =
3312           this.regionPlans.entrySet().iterator(); i.hasNext();) {
3313         Map.Entry<String, RegionPlan> e = i.next();
3314         ServerName otherSn = e.getValue().getDestination();
3315         // The name will be null if the region is planned for a random assign.
3316         if (otherSn != null && otherSn.equals(sn)) {
3317           // Use iterator's remove else we'll get CME
3318           i.remove();
3319         }
3320       }
3321     }
3322     // TODO: Do we want to sync on RIT here?
3323     // Remove this server from map of servers to regions, and remove all regions
3324     // of this server from online map of regions.
3325     Set<HRegionInfo> deadRegions = new TreeSet<HRegionInfo>();
3326     synchronized (this.regions) {
3327       Set<HRegionInfo> assignedRegions = this.servers.remove(sn);
3328       if (assignedRegions != null && !assignedRegions.isEmpty()) {
3329         deadRegions.addAll(assignedRegions);
3330         for (HRegionInfo region : deadRegions) {
3331           this.regions.remove(region);
3332         }
3333       }
3334     }
3335     // See if any of the regions that were online on this server were in RIT
3336     // If they are, normal timeouts will deal with them appropriately so
3337     // let's skip a manual re-assignment.
3338     Set<HRegionInfo> ritsGoingToServer = new ConcurrentSkipListSet<HRegionInfo>();
3339     List<RegionState> ritsOnServer = new ArrayList<RegionState>();
3340     synchronized (regionsInTransition) {
3341       for (RegionState state : this.regionsInTransition.values()) {
3342         // If destination server in RegionState is same as dead server then add to regions to assign
3343         // Skip the region in OFFLINE state because destionation server in RegionState is master
3344         // server name. Skip the region if the destionation server in RegionState is other than dead
3345         // server.
3346         if ((state.getServerName() != null) && state.getServerName().equals(sn)) {
3347           ritsGoingToServer.add(state.getRegion());
3348         }
3349         if (deadRegions.contains(state.getRegion())) {
3350           ritsOnServer.add(state);
3351         }
3352       }
3353     }
3354     return new Pair<Set<HRegionInfo>, List<RegionState>>(ritsGoingToServer, ritsOnServer);
3355   }
3356 
3357   /**
3358    * Update inmemory structures.
3359    * @param sn Server that reported the split
3360    * @param parent Parent region that was split
3361    * @param a Daughter region A
3362    * @param b Daughter region B
3363    */
3364   public void handleSplitReport(final ServerName sn, final HRegionInfo parent,
3365       final HRegionInfo a, final HRegionInfo b) {
3366     regionOffline(parent);
3367     regionOnline(a, sn);
3368     regionOnline(b, sn);
3369 
3370     // There's a possibility that the region was splitting while a user asked
3371     // the master to disable, we need to make sure we close those regions in
3372     // that case. This is not racing with the region server itself since RS
3373     // report is done after the split transaction completed.
3374     if (this.zkTable.isDisablingOrDisabledTable(
3375         parent.getTableNameAsString())) {
3376       unassign(a);
3377       unassign(b);
3378     }
3379   }
3380 
3381   /**
3382    * This is an EXPENSIVE clone.  Cloning though is the safest thing to do.
3383    * Can't let out original since it can change and at least the loadbalancer
3384    * wants to iterate this exported list.  We need to synchronize on regions
3385    * since all access to this.servers is under a lock on this.regions.
3386    * 
3387    * @return A clone of current assignments by table.
3388    */
3389   Map<String, Map<ServerName, List<HRegionInfo>>> getAssignmentsByTable() {
3390     Map<String, Map<ServerName, List<HRegionInfo>>> result = null;
3391     synchronized (this.regions) {
3392       result = new HashMap<String, Map<ServerName,List<HRegionInfo>>>();
3393       if (!this.master.getConfiguration().
3394           getBoolean("hbase.master.loadbalance.bytable", true)) {
3395         result.put("ensemble", getAssignments());
3396       } else {
3397         for (Map.Entry<ServerName, Set<HRegionInfo>> e: this.servers.entrySet()) {
3398           for (HRegionInfo hri : e.getValue()) {
3399             if (hri.isMetaRegion() || hri.isRootRegion()) continue;
3400             String tablename = hri.getTableNameAsString();
3401             Map<ServerName, List<HRegionInfo>> svrToRegions = result.get(tablename);
3402             if (svrToRegions == null) {
3403               svrToRegions = new HashMap<ServerName, List<HRegionInfo>>(this.servers.size());
3404               result.put(tablename, svrToRegions);
3405             }
3406             List<HRegionInfo> regions = null;
3407             if (!svrToRegions.containsKey(e.getKey())) {
3408               regions = new ArrayList<HRegionInfo>();
3409               svrToRegions.put(e.getKey(), regions);
3410             } else {
3411               regions = svrToRegions.get(e.getKey());
3412             }
3413             regions.add(hri);
3414           }
3415         }
3416       }
3417     }
3418     Map<ServerName, HServerLoad> onlineSvrs = this.serverManager.getOnlineServers();
3419     // Take care of servers w/o assignments.
3420     for (Map<ServerName,List<HRegionInfo>> map : result.values()) {
3421       for (Map.Entry<ServerName, HServerLoad> svrEntry: onlineSvrs.entrySet()) {
3422         if (!map.containsKey(svrEntry.getKey())) {
3423           map.put(svrEntry.getKey(), new ArrayList<HRegionInfo>());
3424         }
3425       }
3426     }
3427     return result;
3428   }
3429   
3430   /**
3431    * @return A clone of current assignments. Note, this is assignments only.
3432    * If a new server has come in and it has no regions, it will not be included
3433    * in the returned Map.
3434    */
3435   Map<ServerName, List<HRegionInfo>> getAssignments() {
3436     // This is an EXPENSIVE clone.  Cloning though is the safest thing to do.
3437     // Can't let out original since it can change and at least the loadbalancer
3438     // wants to iterate this exported list.  We need to synchronize on regions
3439     // since all access to this.servers is under a lock on this.regions.
3440     Map<ServerName, List<HRegionInfo>> result = null;
3441     synchronized (this.regions) {
3442       result = new HashMap<ServerName, List<HRegionInfo>>(this.servers.size());
3443       for (Map.Entry<ServerName, Set<HRegionInfo>> e: this.servers.entrySet()) {
3444         result.put(e.getKey(), new ArrayList<HRegionInfo>(e.getValue()));
3445       }
3446     }
3447     return result;
3448   }
3449 
3450   /**
3451    * @param encodedRegionName Region encoded name.
3452    * @return Null or a {@link Pair} instance that holds the full {@link HRegionInfo}
3453    * and the hosting servers {@link ServerName}.
3454    */
3455   Pair<HRegionInfo, ServerName> getAssignment(final byte [] encodedRegionName) {
3456     String name = Bytes.toString(encodedRegionName);
3457     synchronized(this.regions) {
3458       for (Map.Entry<HRegionInfo, ServerName> e: this.regions.entrySet()) {
3459         if (e.getKey().getEncodedName().equals(name)) {
3460           return new Pair<HRegionInfo, ServerName>(e.getKey(), e.getValue());
3461         }
3462       }
3463     }
3464     return null;
3465   }
3466 
3467   /**
3468    * @param plan Plan to execute.
3469    */
3470   void balance(final RegionPlan plan) {
3471     synchronized (this.regionPlans) {
3472       this.regionPlans.put(plan.getRegionName(), plan);
3473     }
3474     unassign(plan.getRegionInfo());
3475   }
3476 
3477   /**
3478    * Run through remaining regionservers and unassign all catalog regions.
3479    */
3480   void unassignCatalogRegions() {
3481     synchronized (this.regions) {
3482       for (Map.Entry<ServerName, Set<HRegionInfo>> e: this.servers.entrySet()) {
3483         Set<HRegionInfo> regions = e.getValue();
3484         if (regions == null || regions.isEmpty()) continue;
3485         for (HRegionInfo hri: regions) {
3486           if (hri.isMetaRegion()) {
3487             unassign(hri);
3488           }
3489         }
3490       }
3491     }
3492   }
3493 
3494   /**
3495    * State of a Region while undergoing transitions.
3496    */
3497   public static class RegionState implements org.apache.hadoop.io.Writable {
3498     private HRegionInfo region;
3499 
3500     public enum State {
3501       OFFLINE,        // region is in an offline state
3502       PENDING_OPEN,   // sent rpc to server to open but has not begun
3503       OPENING,        // server has begun to open but not yet done
3504       OPEN,           // server opened region and updated meta
3505       PENDING_CLOSE,  // sent rpc to server to close but has not begun
3506       CLOSING,        // server has begun to close but not yet done
3507       CLOSED,         // server closed region and updated meta
3508       SPLITTING,      // server started split of a region
3509       SPLIT           // server completed split of a region
3510     }
3511 
3512     private State state;
3513     // Many threads can update the state at the stamp at the same time
3514     private final AtomicLong stamp;
3515     private ServerName serverName;
3516 
3517     public RegionState() {
3518       this.stamp = new AtomicLong(System.currentTimeMillis());
3519     }
3520 
3521     RegionState(HRegionInfo region, State state) {
3522       this(region, state, System.currentTimeMillis(), null);
3523     }
3524 
3525     RegionState(HRegionInfo region, State state, long stamp, ServerName serverName) {
3526       this.region = region;
3527       this.state = state;
3528       this.stamp = new AtomicLong(stamp);
3529       this.serverName = serverName;
3530     }
3531 
3532     public void update(State state, long stamp, ServerName serverName) {
3533       this.state = state;
3534       updateTimestamp(stamp);
3535       this.serverName = serverName;
3536     }
3537 
3538     public void update(State state) {
3539       this.state = state;
3540       updateTimestampToNow();
3541       this.serverName = null;
3542     }
3543 
3544     public void updateTimestamp(long stamp) {
3545       this.stamp.set(stamp);
3546     }
3547 
3548     public void updateTimestampToNow() {
3549       this.stamp.set(System.currentTimeMillis());
3550     }
3551 
3552     public State getState() {
3553       return state;
3554     }
3555 
3556     public long getStamp() {
3557       return stamp.get();
3558     }
3559 
3560     public HRegionInfo getRegion() {
3561       return region;
3562     }
3563 
3564     public ServerName getServerName() {
3565       return serverName;
3566     }
3567 
3568     public boolean isClosing() {
3569       return state == State.CLOSING;
3570     }
3571 
3572     public boolean isClosed() {
3573       return state == State.CLOSED;
3574     }
3575 
3576     public boolean isPendingClose() {
3577       return state == State.PENDING_CLOSE;
3578     }
3579 
3580     public boolean isOpening() {
3581       return state == State.OPENING;
3582     }
3583 
3584     public boolean isOpened() {
3585       return state == State.OPEN;
3586     }
3587 
3588     public boolean isPendingOpen() {
3589       return state == State.PENDING_OPEN;
3590     }
3591 
3592     public boolean isOffline() {
3593       return state == State.OFFLINE;
3594     }
3595 
3596     public boolean isSplitting() {
3597       return state == State.SPLITTING;
3598     }
3599  
3600     public boolean isSplit() {
3601       return state == State.SPLIT;
3602     }
3603 
3604     @Override
3605     public String toString() {
3606       return region.getRegionNameAsString()
3607         + " state=" + state
3608         + ", ts=" + stamp
3609         + ", server=" + serverName;
3610     }
3611 
3612     /**
3613      * A slower (but more easy-to-read) stringification 
3614      */
3615     public String toDescriptiveString() {
3616       long lstamp = stamp.get();
3617       long relTime = System.currentTimeMillis() - lstamp;
3618       
3619       return region.getRegionNameAsString()
3620         + " state=" + state
3621         + ", ts=" + new Date(lstamp) + " (" + (relTime/1000) + "s ago)"
3622         + ", server=" + serverName;
3623     }
3624 
3625     @Override
3626     public void readFields(DataInput in) throws IOException {
3627       region = new HRegionInfo();
3628       region.readFields(in);
3629       state = State.valueOf(in.readUTF());
3630       stamp.set(in.readLong());
3631     }
3632 
3633     @Override
3634     public void write(DataOutput out) throws IOException {
3635       region.write(out);
3636       out.writeUTF(state.name());
3637       out.writeLong(stamp.get());
3638     }
3639   }
3640   
3641   public void stop() {
3642     this.timeoutMonitor.interrupt();
3643     this.timerUpdater.interrupt();
3644   }
3645   
3646   /**
3647    * Check whether the RegionServer is online.
3648    * @param serverName 
3649    * @return True if online.
3650    */
3651   public boolean isServerOnline(ServerName serverName) {
3652     return this.serverManager.isServerOnline(serverName);
3653   }
3654   /**
3655    * Shutdown the threadpool executor service
3656    */
3657   public void shutdown() {
3658     if (null != threadPoolExecutorService) {
3659       this.threadPoolExecutorService.shutdown();
3660     }
3661   }
3662 
3663   protected void setEnabledTable(String tableName) {
3664     try {
3665       this.zkTable.setEnabledTable(tableName);
3666     } catch (KeeperException e) {
3667       // here we can abort as it is the start up flow
3668       String errorMsg = "Unable to ensure that the table " + tableName
3669           + " will be" + " enabled because of a ZooKeeper issue";
3670       LOG.error(errorMsg);
3671       this.master.abort(errorMsg, e);
3672     }
3673   }
3674 
3675 }