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1   /**
2    * Licensed to the Apache Software Foundation (ASF) under one
3    * or more contributor license agreements.  See the NOTICE file
4    * distributed with this work for additional information
5    * regarding copyright ownership.  The ASF licenses this file
6    * to you under the Apache License, Version 2.0 (the
7    * "License"); you may not use this file except in compliance
8    * with the License.  You may obtain a copy of the License at
9    *
10   *     http://www.apache.org/licenses/LICENSE-2.0
11   *
12   * Unless required by applicable law or agreed to in writing, software
13   * distributed under the License is distributed on an "AS IS" BASIS,
14   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
15   * See the License for the specific language governing permissions and
16   * limitations under the License.
17   */
18  package org.apache.hadoop.hbase.master.snapshot;
19  
20  import java.io.FileNotFoundException;
21  import java.io.IOException;
22  import java.util.ArrayList;
23  import java.util.Collections;
24  import java.util.HashMap;
25  import java.util.HashSet;
26  import java.util.Iterator;
27  import java.util.List;
28  import java.util.Map;
29  import java.util.Set;
30  import java.util.concurrent.ThreadPoolExecutor;
31  
32  import org.apache.commons.logging.Log;
33  import org.apache.commons.logging.LogFactory;
34  import org.apache.hadoop.hbase.classification.InterfaceAudience;
35  import org.apache.hadoop.hbase.classification.InterfaceStability;
36  import org.apache.hadoop.conf.Configuration;
37  import org.apache.hadoop.fs.FSDataInputStream;
38  import org.apache.hadoop.fs.FileStatus;
39  import org.apache.hadoop.fs.FileSystem;
40  import org.apache.hadoop.fs.Path;
41  import org.apache.hadoop.hbase.TableName;
42  import org.apache.hadoop.hbase.HBaseInterfaceAudience;
43  import org.apache.hadoop.hbase.HConstants;
44  import org.apache.hadoop.hbase.HTableDescriptor;
45  import org.apache.hadoop.hbase.Stoppable;
46  import org.apache.hadoop.hbase.MetaTableAccessor;
47  import org.apache.hadoop.hbase.errorhandling.ForeignException;
48  import org.apache.hadoop.hbase.executor.ExecutorService;
49  import org.apache.hadoop.hbase.master.AssignmentManager;
50  import org.apache.hadoop.hbase.master.MasterCoprocessorHost;
51  import org.apache.hadoop.hbase.master.MasterFileSystem;
52  import org.apache.hadoop.hbase.master.MasterServices;
53  import org.apache.hadoop.hbase.master.MetricsMaster;
54  import org.apache.hadoop.hbase.master.SnapshotSentinel;
55  import org.apache.hadoop.hbase.master.cleaner.HFileCleaner;
56  import org.apache.hadoop.hbase.master.cleaner.HFileLinkCleaner;
57  import org.apache.hadoop.hbase.procedure.MasterProcedureManager;
58  import org.apache.hadoop.hbase.procedure.Procedure;
59  import org.apache.hadoop.hbase.procedure.ProcedureCoordinator;
60  import org.apache.hadoop.hbase.procedure.ProcedureCoordinatorRpcs;
61  import org.apache.hadoop.hbase.procedure.ZKProcedureCoordinatorRpcs;
62  import org.apache.hadoop.hbase.protobuf.generated.HBaseProtos.NameStringPair;
63  import org.apache.hadoop.hbase.protobuf.generated.HBaseProtos.ProcedureDescription;
64  import org.apache.hadoop.hbase.protobuf.generated.HBaseProtos.SnapshotDescription;
65  import org.apache.hadoop.hbase.protobuf.generated.HBaseProtos.SnapshotDescription.Type;
66  import org.apache.hadoop.hbase.protobuf.generated.ZooKeeperProtos;
67  import org.apache.hadoop.hbase.snapshot.ClientSnapshotDescriptionUtils;
68  import org.apache.hadoop.hbase.snapshot.HBaseSnapshotException;
69  import org.apache.hadoop.hbase.snapshot.RestoreSnapshotException;
70  import org.apache.hadoop.hbase.snapshot.RestoreSnapshotHelper;
71  import org.apache.hadoop.hbase.snapshot.SnapshotCreationException;
72  import org.apache.hadoop.hbase.snapshot.SnapshotDescriptionUtils;
73  import org.apache.hadoop.hbase.snapshot.SnapshotDoesNotExistException;
74  import org.apache.hadoop.hbase.snapshot.SnapshotExistsException;
75  import org.apache.hadoop.hbase.snapshot.SnapshotManifest;
76  import org.apache.hadoop.hbase.snapshot.SnapshotReferenceUtil;
77  import org.apache.hadoop.hbase.snapshot.TablePartiallyOpenException;
78  import org.apache.hadoop.hbase.snapshot.UnknownSnapshotException;
79  import org.apache.hadoop.hbase.util.EnvironmentEdgeManager;
80  import org.apache.hadoop.hbase.util.FSUtils;
81  import org.apache.zookeeper.KeeperException;
82  
83  /**
84   * This class manages the procedure of taking and restoring snapshots. There is only one
85   * SnapshotManager for the master.
86   * <p>
87   * The class provides methods for monitoring in-progress snapshot actions.
88   * <p>
89   * Note: Currently there can only be one snapshot being taken at a time over the cluster. This is a
90   * simplification in the current implementation.
91   */
92  @InterfaceAudience.LimitedPrivate(HBaseInterfaceAudience.CONFIG)
93  @InterfaceStability.Unstable
94  public class SnapshotManager extends MasterProcedureManager implements Stoppable {
95    private static final Log LOG = LogFactory.getLog(SnapshotManager.class);
96  
97    /** By default, check to see if the snapshot is complete every WAKE MILLIS (ms) */
98    private static final int SNAPSHOT_WAKE_MILLIS_DEFAULT = 500;
99  
100   /**
101    * Wait time before removing a finished sentinel from the in-progress map
102    *
103    * NOTE: This is used as a safety auto cleanup.
104    * The snapshot and restore handlers map entries are removed when a user asks if a snapshot or
105    * restore is completed. This operation is part of the HBaseAdmin snapshot/restore API flow.
106    * In case something fails on the client side and the snapshot/restore state is not reclaimed
107    * after a default timeout, the entry is removed from the in-progress map.
108    * At this point, if the user asks for the snapshot/restore status, the result will be
109    * snapshot done if exists or failed if it doesn't exists.
110    */
111   private static final int SNAPSHOT_SENTINELS_CLEANUP_TIMEOUT = 60 * 1000;
112 
113   /** Enable or disable snapshot support */
114   public static final String HBASE_SNAPSHOT_ENABLED = "hbase.snapshot.enabled";
115 
116   /**
117    * Conf key for # of ms elapsed between checks for snapshot errors while waiting for
118    * completion.
119    */
120   private static final String SNAPSHOT_WAKE_MILLIS_KEY = "hbase.snapshot.master.wakeMillis";
121 
122   /** By default, check to see if the snapshot is complete (ms) */
123   private static final int SNAPSHOT_TIMEOUT_MILLIS_DEFAULT = 60000;
124 
125   /**
126    * Conf key for # of ms elapsed before injecting a snapshot timeout error when waiting for
127    * completion.
128    */
129   private static final String SNAPSHOT_TIMEOUT_MILLIS_KEY = "hbase.snapshot.master.timeoutMillis";
130 
131   /** Name of the operation to use in the controller */
132   public static final String ONLINE_SNAPSHOT_CONTROLLER_DESCRIPTION = "online-snapshot";
133 
134   /** Conf key for # of threads used by the SnapshotManager thread pool */
135   private static final String SNAPSHOT_POOL_THREADS_KEY = "hbase.snapshot.master.threads";
136 
137   /** number of current operations running on the master */
138   private static final int SNAPSHOT_POOL_THREADS_DEFAULT = 1;
139 
140   private boolean stopped;
141   private MasterServices master;  // Needed by TableEventHandlers
142   private ProcedureCoordinator coordinator;
143 
144   // Is snapshot feature enabled?
145   private boolean isSnapshotSupported = false;
146 
147   // Snapshot handlers map, with table name as key.
148   // The map is always accessed and modified under the object lock using synchronized.
149   // snapshotTable() will insert an Handler in the table.
150   // isSnapshotDone() will remove the handler requested if the operation is finished.
151   private Map<TableName, SnapshotSentinel> snapshotHandlers =
152       new HashMap<TableName, SnapshotSentinel>();
153 
154   // Restore Sentinels map, with table name as key.
155   // The map is always accessed and modified under the object lock using synchronized.
156   // restoreSnapshot()/cloneSnapshot() will insert an Handler in the table.
157   // isRestoreDone() will remove the handler requested if the operation is finished.
158   private Map<TableName, SnapshotSentinel> restoreHandlers =
159       new HashMap<TableName, SnapshotSentinel>();
160 
161   private Path rootDir;
162   private ExecutorService executorService;
163 
164   public SnapshotManager() {}
165 
166   /**
167    * Fully specify all necessary components of a snapshot manager. Exposed for testing.
168    * @param master services for the master where the manager is running
169    * @param coordinator procedure coordinator instance.  exposed for testing.
170    * @param pool HBase ExecutorServcie instance, exposed for testing.
171    */
172   public SnapshotManager(final MasterServices master, final MetricsMaster metricsMaster,
173       ProcedureCoordinator coordinator, ExecutorService pool)
174       throws IOException, UnsupportedOperationException {
175     this.master = master;
176 
177     this.rootDir = master.getMasterFileSystem().getRootDir();
178     checkSnapshotSupport(master.getConfiguration(), master.getMasterFileSystem());
179 
180     this.coordinator = coordinator;
181     this.executorService = pool;
182     resetTempDir();
183   }
184 
185   /**
186    * Gets the list of all completed snapshots.
187    * @return list of SnapshotDescriptions
188    * @throws IOException File system exception
189    */
190   public List<SnapshotDescription> getCompletedSnapshots() throws IOException {
191     return getCompletedSnapshots(SnapshotDescriptionUtils.getSnapshotsDir(rootDir));
192   }
193 
194   /**
195    * Gets the list of all completed snapshots.
196    * @param snapshotDir snapshot directory
197    * @return list of SnapshotDescriptions
198    * @throws IOException File system exception
199    */
200   private List<SnapshotDescription> getCompletedSnapshots(Path snapshotDir) throws IOException {
201     List<SnapshotDescription> snapshotDescs = new ArrayList<SnapshotDescription>();
202     // first create the snapshot root path and check to see if it exists
203     FileSystem fs = master.getMasterFileSystem().getFileSystem();
204     if (snapshotDir == null) snapshotDir = SnapshotDescriptionUtils.getSnapshotsDir(rootDir);
205 
206     // if there are no snapshots, return an empty list
207     if (!fs.exists(snapshotDir)) {
208       return snapshotDescs;
209     }
210 
211     // ignore all the snapshots in progress
212     FileStatus[] snapshots = fs.listStatus(snapshotDir,
213       new SnapshotDescriptionUtils.CompletedSnaphotDirectoriesFilter(fs));
214     // loop through all the completed snapshots
215     for (FileStatus snapshot : snapshots) {
216       Path info = new Path(snapshot.getPath(), SnapshotDescriptionUtils.SNAPSHOTINFO_FILE);
217       // if the snapshot is bad
218       if (!fs.exists(info)) {
219         LOG.error("Snapshot information for " + snapshot.getPath() + " doesn't exist");
220         continue;
221       }
222       FSDataInputStream in = null;
223       try {
224         in = fs.open(info);
225         SnapshotDescription desc = SnapshotDescription.parseFrom(in);
226         snapshotDescs.add(desc);
227       } catch (IOException e) {
228         LOG.warn("Found a corrupted snapshot " + snapshot.getPath(), e);
229       } finally {
230         if (in != null) {
231           in.close();
232         }
233       }
234     }
235     return snapshotDescs;
236   }
237 
238   /**
239    * Cleans up any snapshots in the snapshot/.tmp directory that were left from failed
240    * snapshot attempts.
241    *
242    * @throws IOException if we can't reach the filesystem
243    */
244   void resetTempDir() throws IOException {
245     // cleanup any existing snapshots.
246     Path tmpdir = SnapshotDescriptionUtils.getWorkingSnapshotDir(rootDir);
247     if (master.getMasterFileSystem().getFileSystem().exists(tmpdir)) {
248       if (!master.getMasterFileSystem().getFileSystem().delete(tmpdir, true)) {
249         LOG.warn("Couldn't delete working snapshot directory: " + tmpdir);
250       }
251     }
252   }
253 
254   /**
255    * Delete the specified snapshot
256    * @param snapshot
257    * @throws SnapshotDoesNotExistException If the specified snapshot does not exist.
258    * @throws IOException For filesystem IOExceptions
259    */
260   public void deleteSnapshot(SnapshotDescription snapshot) throws SnapshotDoesNotExistException, IOException {
261 
262     // call coproc pre hook
263     MasterCoprocessorHost cpHost = master.getMasterCoprocessorHost();
264     if (cpHost != null) {
265       cpHost.preDeleteSnapshot(snapshot);
266     }
267 
268     // check to see if it is completed
269     if (!isSnapshotCompleted(snapshot)) {
270       throw new SnapshotDoesNotExistException(snapshot);
271     }
272 
273     String snapshotName = snapshot.getName();
274     LOG.debug("Deleting snapshot: " + snapshotName);
275     // first create the snapshot description and check to see if it exists
276     MasterFileSystem fs = master.getMasterFileSystem();
277     Path snapshotDir = SnapshotDescriptionUtils.getCompletedSnapshotDir(snapshotName, rootDir);
278 
279     // delete the existing snapshot
280     if (!fs.getFileSystem().delete(snapshotDir, true)) {
281       throw new HBaseSnapshotException("Failed to delete snapshot directory: " + snapshotDir);
282     }
283 
284     // call coproc post hook
285     if (cpHost != null) {
286       cpHost.postDeleteSnapshot(snapshot);
287     }
288 
289   }
290 
291   /**
292    * Check if the specified snapshot is done
293    *
294    * @param expected
295    * @return true if snapshot is ready to be restored, false if it is still being taken.
296    * @throws IOException IOException if error from HDFS or RPC
297    * @throws UnknownSnapshotException if snapshot is invalid or does not exist.
298    */
299   public boolean isSnapshotDone(SnapshotDescription expected) throws IOException {
300     // check the request to make sure it has a snapshot
301     if (expected == null) {
302       throw new UnknownSnapshotException(
303          "No snapshot name passed in request, can't figure out which snapshot you want to check.");
304     }
305 
306     String ssString = ClientSnapshotDescriptionUtils.toString(expected);
307 
308     // check to see if the sentinel exists,
309     // and if the task is complete removes it from the in-progress snapshots map.
310     SnapshotSentinel handler = removeSentinelIfFinished(this.snapshotHandlers, expected);
311 
312     // stop tracking "abandoned" handlers
313     cleanupSentinels();
314 
315     if (handler == null) {
316       // If there's no handler in the in-progress map, it means one of the following:
317       //   - someone has already requested the snapshot state
318       //   - the requested snapshot was completed long time ago (cleanupSentinels() timeout)
319       //   - the snapshot was never requested
320       // In those cases returns to the user the "done state" if the snapshots exists on disk,
321       // otherwise raise an exception saying that the snapshot is not running and doesn't exist.
322       if (!isSnapshotCompleted(expected)) {
323         throw new UnknownSnapshotException("Snapshot " + ssString
324             + " is not currently running or one of the known completed snapshots.");
325       }
326       // was done, return true;
327       return true;
328     }
329 
330     // pass on any failure we find in the sentinel
331     try {
332       handler.rethrowExceptionIfFailed();
333     } catch (ForeignException e) {
334       // Give some procedure info on an exception.
335       String status;
336       Procedure p = coordinator.getProcedure(expected.getName());
337       if (p != null) {
338         status = p.getStatus();
339       } else {
340         status = expected.getName() + " not found in proclist " + coordinator.getProcedureNames();
341       }
342       throw new HBaseSnapshotException("Snapshot " + ssString +  " had an error.  " + status, e,
343           expected);
344     }
345 
346     // check to see if we are done
347     if (handler.isFinished()) {
348       LOG.debug("Snapshot '" + ssString + "' has completed, notifying client.");
349       return true;
350     } else if (LOG.isDebugEnabled()) {
351       LOG.debug("Snapshoting '" + ssString + "' is still in progress!");
352     }
353     return false;
354   }
355 
356   /**
357    * Check to see if there is a snapshot in progress with the same name or on the same table.
358    * Currently we have a limitation only allowing a single snapshot per table at a time. Also we
359    * don't allow snapshot with the same name.
360    * @param snapshot description of the snapshot being checked.
361    * @return <tt>true</tt> if there is a snapshot in progress with the same name or on the same
362    *         table.
363    */
364   synchronized boolean isTakingSnapshot(final SnapshotDescription snapshot) {
365     TableName snapshotTable = TableName.valueOf(snapshot.getTable());
366     if (isTakingSnapshot(snapshotTable)) {
367       return true;
368     }
369     Iterator<Map.Entry<TableName, SnapshotSentinel>> it = this.snapshotHandlers.entrySet().iterator();
370     while (it.hasNext()) {
371       Map.Entry<TableName, SnapshotSentinel> entry = it.next();
372       SnapshotSentinel sentinel = entry.getValue();
373       if (snapshot.getName().equals(sentinel.getSnapshot().getName()) && !sentinel.isFinished()) {
374         return true;
375       }
376     }
377     return false;
378   }
379 
380   /**
381    * Check to see if the specified table has a snapshot in progress.  Currently we have a
382    * limitation only allowing a single snapshot per table at a time.
383    * @param tableName name of the table being snapshotted.
384    * @return <tt>true</tt> if there is a snapshot in progress on the specified table.
385    */
386   synchronized boolean isTakingSnapshot(final TableName tableName) {
387     SnapshotSentinel handler = this.snapshotHandlers.get(tableName);
388     return handler != null && !handler.isFinished();
389   }
390 
391   /**
392    * Check to make sure that we are OK to run the passed snapshot. Checks to make sure that we
393    * aren't already running a snapshot or restore on the requested table.
394    * @param snapshot description of the snapshot we want to start
395    * @throws HBaseSnapshotException if the filesystem could not be prepared to start the snapshot
396    */
397   private synchronized void prepareToTakeSnapshot(SnapshotDescription snapshot)
398       throws HBaseSnapshotException {
399     FileSystem fs = master.getMasterFileSystem().getFileSystem();
400     Path workingDir = SnapshotDescriptionUtils.getWorkingSnapshotDir(snapshot, rootDir);
401     TableName snapshotTable =
402         TableName.valueOf(snapshot.getTable());
403 
404     // make sure we aren't already running a snapshot
405     if (isTakingSnapshot(snapshot)) {
406       SnapshotSentinel handler = this.snapshotHandlers.get(snapshotTable);
407       throw new SnapshotCreationException("Rejected taking "
408           + ClientSnapshotDescriptionUtils.toString(snapshot)
409           + " because we are already running another snapshot "
410           + (handler != null ? ("on the same table " +
411               ClientSnapshotDescriptionUtils.toString(handler.getSnapshot()))
412               : "with the same name"), snapshot);
413     }
414 
415     // make sure we aren't running a restore on the same table
416     if (isRestoringTable(snapshotTable)) {
417       SnapshotSentinel handler = restoreHandlers.get(snapshotTable);
418       throw new SnapshotCreationException("Rejected taking "
419           + ClientSnapshotDescriptionUtils.toString(snapshot)
420           + " because we are already have a restore in progress on the same snapshot "
421           + ClientSnapshotDescriptionUtils.toString(handler.getSnapshot()), snapshot);
422     }
423 
424     try {
425       // delete the working directory, since we aren't running the snapshot. Likely leftovers
426       // from a failed attempt.
427       fs.delete(workingDir, true);
428 
429       // recreate the working directory for the snapshot
430       if (!fs.mkdirs(workingDir)) {
431         throw new SnapshotCreationException("Couldn't create working directory (" + workingDir
432             + ") for snapshot" , snapshot);
433       }
434     } catch (HBaseSnapshotException e) {
435       throw e;
436     } catch (IOException e) {
437       throw new SnapshotCreationException(
438           "Exception while checking to see if snapshot could be started.", e, snapshot);
439     }
440   }
441 
442   /**
443    * Take a snapshot of a disabled table.
444    * @param snapshot description of the snapshot to take. Modified to be {@link Type#DISABLED}.
445    * @throws HBaseSnapshotException if the snapshot could not be started
446    */
447   private synchronized void snapshotDisabledTable(SnapshotDescription snapshot)
448       throws HBaseSnapshotException {
449     // setup the snapshot
450     prepareToTakeSnapshot(snapshot);
451 
452     // set the snapshot to be a disabled snapshot, since the client doesn't know about that
453     snapshot = snapshot.toBuilder().setType(Type.DISABLED).build();
454 
455     // Take the snapshot of the disabled table
456     DisabledTableSnapshotHandler handler =
457         new DisabledTableSnapshotHandler(snapshot, master);
458     snapshotTable(snapshot, handler);
459   }
460 
461   /**
462    * Take a snapshot of an enabled table.
463    * @param snapshot description of the snapshot to take.
464    * @throws HBaseSnapshotException if the snapshot could not be started
465    */
466   private synchronized void snapshotEnabledTable(SnapshotDescription snapshot)
467       throws HBaseSnapshotException {
468     // setup the snapshot
469     prepareToTakeSnapshot(snapshot);
470 
471     // Take the snapshot of the enabled table
472     EnabledTableSnapshotHandler handler =
473         new EnabledTableSnapshotHandler(snapshot, master, this);
474     snapshotTable(snapshot, handler);
475   }
476 
477   /**
478    * Take a snapshot using the specified handler.
479    * On failure the snapshot temporary working directory is removed.
480    * NOTE: prepareToTakeSnapshot() called before this one takes care of the rejecting the
481    *       snapshot request if the table is busy with another snapshot/restore operation.
482    * @param snapshot the snapshot description
483    * @param handler the snapshot handler
484    */
485   private synchronized void snapshotTable(SnapshotDescription snapshot,
486       final TakeSnapshotHandler handler) throws HBaseSnapshotException {
487     try {
488       handler.prepare();
489       this.executorService.submit(handler);
490       this.snapshotHandlers.put(TableName.valueOf(snapshot.getTable()), handler);
491     } catch (Exception e) {
492       // cleanup the working directory by trying to delete it from the fs.
493       Path workingDir = SnapshotDescriptionUtils.getWorkingSnapshotDir(snapshot, rootDir);
494       try {
495         if (!this.master.getMasterFileSystem().getFileSystem().delete(workingDir, true)) {
496           LOG.error("Couldn't delete working directory (" + workingDir + " for snapshot:" +
497               ClientSnapshotDescriptionUtils.toString(snapshot));
498         }
499       } catch (IOException e1) {
500         LOG.error("Couldn't delete working directory (" + workingDir + " for snapshot:" +
501             ClientSnapshotDescriptionUtils.toString(snapshot));
502       }
503       // fail the snapshot
504       throw new SnapshotCreationException("Could not build snapshot handler", e, snapshot);
505     }
506   }
507 
508   /**
509    * Take a snapshot based on the enabled/disabled state of the table.
510    *
511    * @param snapshot
512    * @throws HBaseSnapshotException when a snapshot specific exception occurs.
513    * @throws IOException when some sort of generic IO exception occurs.
514    */
515   public void takeSnapshot(SnapshotDescription snapshot) throws IOException {
516     // check to see if we already completed the snapshot
517     if (isSnapshotCompleted(snapshot)) {
518       throw new SnapshotExistsException("Snapshot '" + snapshot.getName()
519           + "' already stored on the filesystem.", snapshot);
520     }
521 
522     LOG.debug("No existing snapshot, attempting snapshot...");
523 
524     // stop tracking "abandoned" handlers
525     cleanupSentinels();
526 
527     // check to see if the table exists
528     HTableDescriptor desc = null;
529     try {
530       desc = master.getTableDescriptors().get(
531           TableName.valueOf(snapshot.getTable()));
532     } catch (FileNotFoundException e) {
533       String msg = "Table:" + snapshot.getTable() + " info doesn't exist!";
534       LOG.error(msg);
535       throw new SnapshotCreationException(msg, e, snapshot);
536     } catch (IOException e) {
537       throw new SnapshotCreationException("Error while geting table description for table "
538           + snapshot.getTable(), e, snapshot);
539     }
540     if (desc == null) {
541       throw new SnapshotCreationException("Table '" + snapshot.getTable()
542           + "' doesn't exist, can't take snapshot.", snapshot);
543     }
544 
545     // if not specified, set the snapshot format
546     if (!snapshot.hasVersion()) {
547       snapshot = snapshot.toBuilder()
548           .setVersion(SnapshotDescriptionUtils.SNAPSHOT_LAYOUT_VERSION)
549           .build();
550     }
551 
552     // call pre coproc hook
553     MasterCoprocessorHost cpHost = master.getMasterCoprocessorHost();
554     if (cpHost != null) {
555       cpHost.preSnapshot(snapshot, desc);
556     }
557 
558     // if the table is enabled, then have the RS run actually the snapshot work
559     TableName snapshotTable = TableName.valueOf(snapshot.getTable());
560     AssignmentManager assignmentMgr = master.getAssignmentManager();
561     if (assignmentMgr.getTableStateManager().isTableState(snapshotTable,
562         ZooKeeperProtos.Table.State.ENABLED)) {
563       LOG.debug("Table enabled, starting distributed snapshot.");
564       snapshotEnabledTable(snapshot);
565       LOG.debug("Started snapshot: " + ClientSnapshotDescriptionUtils.toString(snapshot));
566     }
567     // For disabled table, snapshot is created by the master
568     else if (assignmentMgr.getTableStateManager().isTableState(snapshotTable,
569         ZooKeeperProtos.Table.State.DISABLED)) {
570       LOG.debug("Table is disabled, running snapshot entirely on master.");
571       snapshotDisabledTable(snapshot);
572       LOG.debug("Started snapshot: " + ClientSnapshotDescriptionUtils.toString(snapshot));
573     } else {
574       LOG.error("Can't snapshot table '" + snapshot.getTable()
575           + "', isn't open or closed, we don't know what to do!");
576       TablePartiallyOpenException tpoe = new TablePartiallyOpenException(snapshot.getTable()
577           + " isn't fully open.");
578       throw new SnapshotCreationException("Table is not entirely open or closed", tpoe, snapshot);
579     }
580 
581     // call post coproc hook
582     if (cpHost != null) {
583       cpHost.postSnapshot(snapshot, desc);
584     }
585   }
586 
587   /**
588    * Set the handler for the current snapshot
589    * <p>
590    * Exposed for TESTING
591    * @param tableName
592    * @param handler handler the master should use
593    *
594    * TODO get rid of this if possible, repackaging, modify tests.
595    */
596   public synchronized void setSnapshotHandlerForTesting(
597       final TableName tableName,
598       final SnapshotSentinel handler) {
599     if (handler != null) {
600       this.snapshotHandlers.put(tableName, handler);
601     } else {
602       this.snapshotHandlers.remove(tableName);
603     }
604   }
605 
606   /**
607    * @return distributed commit coordinator for all running snapshots
608    */
609   ProcedureCoordinator getCoordinator() {
610     return coordinator;
611   }
612 
613   /**
614    * Check to see if the snapshot is one of the currently completed snapshots
615    * Returns true if the snapshot exists in the "completed snapshots folder".
616    *
617    * @param snapshot expected snapshot to check
618    * @return <tt>true</tt> if the snapshot is stored on the {@link FileSystem}, <tt>false</tt> if is
619    *         not stored
620    * @throws IOException if the filesystem throws an unexpected exception,
621    * @throws IllegalArgumentException if snapshot name is invalid.
622    */
623   private boolean isSnapshotCompleted(SnapshotDescription snapshot) throws IOException {
624     try {
625       final Path snapshotDir = SnapshotDescriptionUtils.getCompletedSnapshotDir(snapshot, rootDir);
626       FileSystem fs = master.getMasterFileSystem().getFileSystem();
627       // check to see if the snapshot already exists
628       return fs.exists(snapshotDir);
629     } catch (IllegalArgumentException iae) {
630       throw new UnknownSnapshotException("Unexpected exception thrown", iae);
631     }
632   }
633 
634   /**
635    * Clone the specified snapshot into a new table.
636    * The operation will fail if the destination table has a snapshot or restore in progress.
637    *
638    * @param snapshot Snapshot Descriptor
639    * @param hTableDescriptor Table Descriptor of the table to create
640    */
641   synchronized void cloneSnapshot(final SnapshotDescription snapshot,
642       final HTableDescriptor hTableDescriptor) throws HBaseSnapshotException {
643     TableName tableName = hTableDescriptor.getTableName();
644 
645     // make sure we aren't running a snapshot on the same table
646     if (isTakingSnapshot(tableName)) {
647       throw new RestoreSnapshotException("Snapshot in progress on the restore table=" + tableName);
648     }
649 
650     // make sure we aren't running a restore on the same table
651     if (isRestoringTable(tableName)) {
652       throw new RestoreSnapshotException("Restore already in progress on the table=" + tableName);
653     }
654 
655     try {
656       CloneSnapshotHandler handler =
657         new CloneSnapshotHandler(master, snapshot, hTableDescriptor).prepare();
658       this.executorService.submit(handler);
659       this.restoreHandlers.put(tableName, handler);
660     } catch (Exception e) {
661       String msg = "Couldn't clone the snapshot=" + ClientSnapshotDescriptionUtils.toString(snapshot) +
662         " on table=" + tableName;
663       LOG.error(msg, e);
664       throw new RestoreSnapshotException(msg, e);
665     }
666   }
667 
668   /**
669    * Restore the specified snapshot
670    * @param reqSnapshot
671    * @throws IOException
672    */
673   public void restoreSnapshot(SnapshotDescription reqSnapshot) throws IOException {
674     FileSystem fs = master.getMasterFileSystem().getFileSystem();
675     Path snapshotDir = SnapshotDescriptionUtils.getCompletedSnapshotDir(reqSnapshot, rootDir);
676     MasterCoprocessorHost cpHost = master.getMasterCoprocessorHost();
677 
678     // check if the snapshot exists
679     if (!fs.exists(snapshotDir)) {
680       LOG.error("A Snapshot named '" + reqSnapshot.getName() + "' does not exist.");
681       throw new SnapshotDoesNotExistException(reqSnapshot);
682     }
683 
684     // read snapshot information
685     SnapshotDescription fsSnapshot = SnapshotDescriptionUtils.readSnapshotInfo(fs, snapshotDir);
686     SnapshotManifest manifest = SnapshotManifest.open(master.getConfiguration(), fs,
687         snapshotDir, fsSnapshot);
688     HTableDescriptor snapshotTableDesc = manifest.getTableDescriptor();
689     TableName tableName = TableName.valueOf(reqSnapshot.getTable());
690 
691     // stop tracking "abandoned" handlers
692     cleanupSentinels();
693 
694     // Verify snapshot validity
695     SnapshotReferenceUtil.verifySnapshot(master.getConfiguration(), fs, manifest);
696 
697     // Execute the restore/clone operation
698     if (MetaTableAccessor.tableExists(master.getConnection(), tableName)) {
699       if (master.getAssignmentManager().getTableStateManager().isTableState(
700           TableName.valueOf(fsSnapshot.getTable()), ZooKeeperProtos.Table.State.ENABLED)) {
701         throw new UnsupportedOperationException("Table '" +
702             TableName.valueOf(fsSnapshot.getTable()) + "' must be disabled in order to " +
703             "perform a restore operation" +
704             ".");
705       }
706 
707       // call coproc pre hook
708       if (cpHost != null) {
709         cpHost.preRestoreSnapshot(reqSnapshot, snapshotTableDesc);
710       }
711       restoreSnapshot(fsSnapshot, snapshotTableDesc);
712       LOG.info("Restore snapshot=" + fsSnapshot.getName() + " as table=" + tableName);
713 
714       if (cpHost != null) {
715         cpHost.postRestoreSnapshot(reqSnapshot, snapshotTableDesc);
716       }
717     } else {
718       HTableDescriptor htd = RestoreSnapshotHelper.cloneTableSchema(snapshotTableDesc, tableName);
719       if (cpHost != null) {
720         cpHost.preCloneSnapshot(reqSnapshot, htd);
721       }
722       cloneSnapshot(fsSnapshot, htd);
723       LOG.info("Clone snapshot=" + fsSnapshot.getName() + " as table=" + tableName);
724 
725       if (cpHost != null) {
726         cpHost.postCloneSnapshot(reqSnapshot, htd);
727       }
728     }
729   }
730 
731   /**
732    * Restore the specified snapshot.
733    * The restore will fail if the destination table has a snapshot or restore in progress.
734    *
735    * @param snapshot Snapshot Descriptor
736    * @param hTableDescriptor Table Descriptor
737    */
738   private synchronized void restoreSnapshot(final SnapshotDescription snapshot,
739       final HTableDescriptor hTableDescriptor) throws HBaseSnapshotException {
740     TableName tableName = hTableDescriptor.getTableName();
741 
742     // make sure we aren't running a snapshot on the same table
743     if (isTakingSnapshot(tableName)) {
744       throw new RestoreSnapshotException("Snapshot in progress on the restore table=" + tableName);
745     }
746 
747     // make sure we aren't running a restore on the same table
748     if (isRestoringTable(tableName)) {
749       throw new RestoreSnapshotException("Restore already in progress on the table=" + tableName);
750     }
751 
752     try {
753       RestoreSnapshotHandler handler =
754         new RestoreSnapshotHandler(master, snapshot, hTableDescriptor).prepare();
755       this.executorService.submit(handler);
756       restoreHandlers.put(tableName, handler);
757     } catch (Exception e) {
758       String msg = "Couldn't restore the snapshot=" + ClientSnapshotDescriptionUtils.toString(
759           snapshot)  +
760           " on table=" + tableName;
761       LOG.error(msg, e);
762       throw new RestoreSnapshotException(msg, e);
763     }
764   }
765 
766   /**
767    * Verify if the restore of the specified table is in progress.
768    *
769    * @param tableName table under restore
770    * @return <tt>true</tt> if there is a restore in progress of the specified table.
771    */
772   private synchronized boolean isRestoringTable(final TableName tableName) {
773     SnapshotSentinel sentinel = this.restoreHandlers.get(tableName);
774     return(sentinel != null && !sentinel.isFinished());
775   }
776 
777   /**
778    * Returns the status of a restore operation.
779    * If the in-progress restore is failed throws the exception that caused the failure.
780    *
781    * @param snapshot
782    * @return false if in progress, true if restore is completed or not requested.
783    * @throws IOException if there was a failure during the restore
784    */
785   public boolean isRestoreDone(final SnapshotDescription snapshot) throws IOException {
786     // check to see if the sentinel exists,
787     // and if the task is complete removes it from the in-progress restore map.
788     SnapshotSentinel sentinel = removeSentinelIfFinished(this.restoreHandlers, snapshot);
789 
790     // stop tracking "abandoned" handlers
791     cleanupSentinels();
792 
793     if (sentinel == null) {
794       // there is no sentinel so restore is not in progress.
795       return true;
796     }
797 
798     LOG.debug("Verify snapshot=" + snapshot.getName() + " against="
799         + sentinel.getSnapshot().getName() + " table=" +
800         TableName.valueOf(snapshot.getTable()));
801 
802     // If the restore is failed, rethrow the exception
803     sentinel.rethrowExceptionIfFailed();
804 
805     // check to see if we are done
806     if (sentinel.isFinished()) {
807       LOG.debug("Restore snapshot=" + ClientSnapshotDescriptionUtils.toString(snapshot) +
808           " has completed. Notifying the client.");
809       return true;
810     }
811 
812     if (LOG.isDebugEnabled()) {
813       LOG.debug("Sentinel is not yet finished with restoring snapshot=" +
814           ClientSnapshotDescriptionUtils.toString(snapshot));
815     }
816     return false;
817   }
818 
819   /**
820    * Return the handler if it is currently live and has the same snapshot target name.
821    * The handler is removed from the sentinels map if completed.
822    * @param sentinels live handlers
823    * @param snapshot snapshot description
824    * @return null if doesn't match, else a live handler.
825    */
826   private synchronized SnapshotSentinel removeSentinelIfFinished(
827       final Map<TableName, SnapshotSentinel> sentinels,
828       final SnapshotDescription snapshot) {
829     if (!snapshot.hasTable()) {
830       return null;
831     }
832 
833     TableName snapshotTable = TableName.valueOf(snapshot.getTable());
834     SnapshotSentinel h = sentinels.get(snapshotTable);
835     if (h == null) {
836       return null;
837     }
838 
839     if (!h.getSnapshot().getName().equals(snapshot.getName())) {
840       // specified snapshot is to the one currently running
841       return null;
842     }
843 
844     // Remove from the "in-progress" list once completed
845     if (h.isFinished()) {
846       sentinels.remove(snapshotTable);
847     }
848 
849     return h;
850   }
851 
852   /**
853    * Removes "abandoned" snapshot/restore requests.
854    * As part of the HBaseAdmin snapshot/restore API the operation status is checked until completed,
855    * and the in-progress maps are cleaned up when the status of a completed task is requested.
856    * To avoid having sentinels staying around for long time if something client side is failed,
857    * each operation tries to clean up the in-progress maps sentinels finished from a long time.
858    */
859   private void cleanupSentinels() {
860     cleanupSentinels(this.snapshotHandlers);
861     cleanupSentinels(this.restoreHandlers);
862   }
863 
864   /**
865    * Remove the sentinels that are marked as finished and the completion time
866    * has exceeded the removal timeout.
867    * @param sentinels map of sentinels to clean
868    */
869   private synchronized void cleanupSentinels(final Map<TableName, SnapshotSentinel> sentinels) {
870     long currentTime = EnvironmentEdgeManager.currentTime();
871     Iterator<Map.Entry<TableName, SnapshotSentinel>> it =
872         sentinels.entrySet().iterator();
873     while (it.hasNext()) {
874       Map.Entry<TableName, SnapshotSentinel> entry = it.next();
875       SnapshotSentinel sentinel = entry.getValue();
876       if (sentinel.isFinished() &&
877           (currentTime - sentinel.getCompletionTimestamp()) > SNAPSHOT_SENTINELS_CLEANUP_TIMEOUT)
878       {
879         it.remove();
880       }
881     }
882   }
883 
884   //
885   // Implementing Stoppable interface
886   //
887 
888   @Override
889   public void stop(String why) {
890     // short circuit
891     if (this.stopped) return;
892     // make sure we get stop
893     this.stopped = true;
894     // pass the stop onto take snapshot handlers
895     for (SnapshotSentinel snapshotHandler: this.snapshotHandlers.values()) {
896       snapshotHandler.cancel(why);
897     }
898 
899     // pass the stop onto all the restore handlers
900     for (SnapshotSentinel restoreHandler: this.restoreHandlers.values()) {
901       restoreHandler.cancel(why);
902     }
903     try {
904       if (coordinator != null) {
905         coordinator.close();
906       }
907     } catch (IOException e) {
908       LOG.error("stop ProcedureCoordinator error", e);
909     }
910   }
911 
912   @Override
913   public boolean isStopped() {
914     return this.stopped;
915   }
916 
917   /**
918    * Throws an exception if snapshot operations (take a snapshot, restore, clone) are not supported.
919    * Called at the beginning of snapshot() and restoreSnapshot() methods.
920    * @throws UnsupportedOperationException if snapshot are not supported
921    */
922   public void checkSnapshotSupport() throws UnsupportedOperationException {
923     if (!this.isSnapshotSupported) {
924       throw new UnsupportedOperationException(
925         "To use snapshots, You must add to the hbase-site.xml of the HBase Master: '" +
926           HBASE_SNAPSHOT_ENABLED + "' property with value 'true'.");
927     }
928   }
929 
930   /**
931    * Called at startup, to verify if snapshot operation is supported, and to avoid
932    * starting the master if there're snapshots present but the cleaners needed are missing.
933    * Otherwise we can end up with snapshot data loss.
934    * @param conf The {@link Configuration} object to use
935    * @param mfs The MasterFileSystem to use
936    * @throws IOException in case of file-system operation failure
937    * @throws UnsupportedOperationException in case cleaners are missing and
938    *         there're snapshot in the system
939    */
940   private void checkSnapshotSupport(final Configuration conf, final MasterFileSystem mfs)
941       throws IOException, UnsupportedOperationException {
942     // Verify if snapshot is disabled by the user
943     String enabled = conf.get(HBASE_SNAPSHOT_ENABLED);
944     boolean snapshotEnabled = conf.getBoolean(HBASE_SNAPSHOT_ENABLED, false);
945     boolean userDisabled = (enabled != null && enabled.trim().length() > 0 && !snapshotEnabled);
946 
947     // Extract cleaners from conf
948     Set<String> hfileCleaners = new HashSet<String>();
949     String[] cleaners = conf.getStrings(HFileCleaner.MASTER_HFILE_CLEANER_PLUGINS);
950     if (cleaners != null) Collections.addAll(hfileCleaners, cleaners);
951 
952     Set<String> logCleaners = new HashSet<String>();
953     cleaners = conf.getStrings(HConstants.HBASE_MASTER_LOGCLEANER_PLUGINS);
954     if (cleaners != null) Collections.addAll(logCleaners, cleaners);
955 
956     // check if an older version of snapshot directory was present
957     Path oldSnapshotDir = new Path(mfs.getRootDir(), HConstants.OLD_SNAPSHOT_DIR_NAME);
958     FileSystem fs = mfs.getFileSystem();
959     List<SnapshotDescription> ss = getCompletedSnapshots(new Path(rootDir, oldSnapshotDir));
960     if (ss != null && !ss.isEmpty()) {
961       LOG.error("Snapshots from an earlier release were found under: " + oldSnapshotDir);
962       LOG.error("Please rename the directory as " + HConstants.SNAPSHOT_DIR_NAME);
963     }
964 
965     // If the user has enabled the snapshot, we force the cleaners to be present
966     // otherwise we still need to check if cleaners are enabled or not and verify
967     // that there're no snapshot in the .snapshot folder.
968     if (snapshotEnabled) {
969       // Inject snapshot cleaners, if snapshot.enable is true
970       hfileCleaners.add(SnapshotHFileCleaner.class.getName());
971       hfileCleaners.add(HFileLinkCleaner.class.getName());
972       logCleaners.add(SnapshotLogCleaner.class.getName());
973 
974       // Set cleaners conf
975       conf.setStrings(HFileCleaner.MASTER_HFILE_CLEANER_PLUGINS,
976         hfileCleaners.toArray(new String[hfileCleaners.size()]));
977       conf.setStrings(HConstants.HBASE_MASTER_LOGCLEANER_PLUGINS,
978         logCleaners.toArray(new String[logCleaners.size()]));
979     } else {
980       // Verify if cleaners are present
981       snapshotEnabled = logCleaners.contains(SnapshotLogCleaner.class.getName()) &&
982         hfileCleaners.contains(SnapshotHFileCleaner.class.getName()) &&
983         hfileCleaners.contains(HFileLinkCleaner.class.getName());
984 
985       // Warn if the cleaners are enabled but the snapshot.enabled property is false/not set.
986       if (snapshotEnabled) {
987         LOG.warn("Snapshot log and hfile cleaners are present in the configuration, " +
988           "but the '" + HBASE_SNAPSHOT_ENABLED + "' property " +
989           (userDisabled ? "is set to 'false'." : "is not set."));
990       }
991     }
992 
993     // Mark snapshot feature as enabled if cleaners are present and user has not disabled it.
994     this.isSnapshotSupported = snapshotEnabled && !userDisabled;
995 
996     // If cleaners are not enabled, verify that there're no snapshot in the .snapshot folder
997     // otherwise we end up with snapshot data loss.
998     if (!snapshotEnabled) {
999       LOG.info("Snapshot feature is not enabled, missing log and hfile cleaners.");
1000       Path snapshotDir = SnapshotDescriptionUtils.getSnapshotsDir(mfs.getRootDir());
1001       if (fs.exists(snapshotDir)) {
1002         FileStatus[] snapshots = FSUtils.listStatus(fs, snapshotDir,
1003           new SnapshotDescriptionUtils.CompletedSnaphotDirectoriesFilter(fs));
1004         if (snapshots != null) {
1005           LOG.error("Snapshots are present, but cleaners are not enabled.");
1006           checkSnapshotSupport();
1007         }
1008       }
1009     }
1010   }
1011 
1012   @Override
1013   public void initialize(MasterServices master, MetricsMaster metricsMaster) throws KeeperException,
1014       IOException, UnsupportedOperationException {
1015     this.master = master;
1016 
1017     this.rootDir = master.getMasterFileSystem().getRootDir();
1018     checkSnapshotSupport(master.getConfiguration(), master.getMasterFileSystem());
1019 
1020     // get the configuration for the coordinator
1021     Configuration conf = master.getConfiguration();
1022     long wakeFrequency = conf.getInt(SNAPSHOT_WAKE_MILLIS_KEY, SNAPSHOT_WAKE_MILLIS_DEFAULT);
1023     long timeoutMillis = conf.getLong(SNAPSHOT_TIMEOUT_MILLIS_KEY, SNAPSHOT_TIMEOUT_MILLIS_DEFAULT);
1024     int opThreads = conf.getInt(SNAPSHOT_POOL_THREADS_KEY, SNAPSHOT_POOL_THREADS_DEFAULT);
1025 
1026     // setup the default procedure coordinator
1027     String name = master.getServerName().toString();
1028     ThreadPoolExecutor tpool = ProcedureCoordinator.defaultPool(name, opThreads);
1029     ProcedureCoordinatorRpcs comms = new ZKProcedureCoordinatorRpcs(
1030         master.getZooKeeper(), SnapshotManager.ONLINE_SNAPSHOT_CONTROLLER_DESCRIPTION, name);
1031 
1032     this.coordinator = new ProcedureCoordinator(comms, tpool, timeoutMillis, wakeFrequency);
1033     this.executorService = master.getExecutorService();
1034     resetTempDir();
1035   }
1036 
1037   @Override
1038   public String getProcedureSignature() {
1039     return ONLINE_SNAPSHOT_CONTROLLER_DESCRIPTION;
1040   }
1041 
1042   @Override
1043   public void execProcedure(ProcedureDescription desc) throws IOException {
1044     takeSnapshot(toSnapshotDescription(desc));
1045   }
1046 
1047   @Override
1048   public boolean isProcedureDone(ProcedureDescription desc) throws IOException {
1049     return isSnapshotDone(toSnapshotDescription(desc));
1050   }
1051 
1052   private SnapshotDescription toSnapshotDescription(ProcedureDescription desc)
1053       throws IOException {
1054     SnapshotDescription.Builder builder = SnapshotDescription.newBuilder();
1055     if (!desc.hasInstance()) {
1056       throw new IOException("Snapshot name is not defined: " + desc.toString());
1057     }
1058     String snapshotName = desc.getInstance();
1059     List<NameStringPair> props = desc.getConfigurationList();
1060     String table = null;
1061     for (NameStringPair prop : props) {
1062       if ("table".equalsIgnoreCase(prop.getName())) {
1063         table = prop.getValue();
1064       }
1065     }
1066     if (table == null) {
1067       throw new IOException("Snapshot table is not defined: " + desc.toString());
1068     }
1069     TableName tableName = TableName.valueOf(table);
1070     builder.setTable(tableName.getNameAsString());
1071     builder.setName(snapshotName);
1072     builder.setType(SnapshotDescription.Type.FLUSH);
1073     return builder.build();
1074   }
1075 }