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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  
19  package org.apache.hadoop.hbase.snapshot;
20  
21  import java.io.FileNotFoundException;
22  import java.io.IOException;
23  import java.util.ArrayList;
24  import java.util.Collections;
25  import java.util.Comparator;
26  import java.util.LinkedList;
27  import java.util.List;
28  import java.util.Random;
29  
30  import org.apache.commons.logging.Log;
31  import org.apache.commons.logging.LogFactory;
32  import org.apache.hadoop.classification.InterfaceAudience;
33  import org.apache.hadoop.classification.InterfaceStability;
34  import org.apache.hadoop.conf.Configuration;
35  import org.apache.hadoop.conf.Configured;
36  import org.apache.hadoop.fs.FSDataInputStream;
37  import org.apache.hadoop.fs.FSDataOutputStream;
38  import org.apache.hadoop.fs.FileChecksum;
39  import org.apache.hadoop.fs.FileStatus;
40  import org.apache.hadoop.fs.FileSystem;
41  import org.apache.hadoop.fs.FileUtil;
42  import org.apache.hadoop.fs.Path;
43  import org.apache.hadoop.fs.permission.FsPermission;
44  import org.apache.hadoop.hbase.TableName;
45  import org.apache.hadoop.hbase.HBaseConfiguration;
46  import org.apache.hadoop.hbase.HConstants;
47  import org.apache.hadoop.hbase.io.HFileLink;
48  import org.apache.hadoop.hbase.io.HLogLink;
49  import org.apache.hadoop.hbase.mapreduce.JobUtil;
50  import org.apache.hadoop.hbase.mapreduce.TableMapReduceUtil;
51  import org.apache.hadoop.hbase.protobuf.generated.HBaseProtos.SnapshotDescription;
52  import org.apache.hadoop.hbase.regionserver.StoreFileInfo;
53  import org.apache.hadoop.hbase.security.UserProvider;
54  import org.apache.hadoop.hbase.security.token.FsDelegationToken;
55  import org.apache.hadoop.hbase.util.EnvironmentEdgeManager;
56  import org.apache.hadoop.hbase.util.FSUtils;
57  import org.apache.hadoop.hbase.util.Pair;
58  import org.apache.hadoop.io.NullWritable;
59  import org.apache.hadoop.io.SequenceFile;
60  import org.apache.hadoop.io.Text;
61  import org.apache.hadoop.mapreduce.Job;
62  import org.apache.hadoop.mapreduce.Mapper;
63  import org.apache.hadoop.mapreduce.lib.input.SequenceFileInputFormat;
64  import org.apache.hadoop.mapreduce.lib.output.NullOutputFormat;
65  import org.apache.hadoop.util.StringUtils;
66  import org.apache.hadoop.util.Tool;
67  import org.apache.hadoop.util.ToolRunner;
68  
69  /**
70   * Export the specified snapshot to a given FileSystem.
71   *
72   * The .snapshot/name folder is copied to the destination cluster
73   * and then all the hfiles/hlogs are copied using a Map-Reduce Job in the .archive/ location.
74   * When everything is done, the second cluster can restore the snapshot.
75   */
76  @InterfaceAudience.Public
77  @InterfaceStability.Evolving
78  public final class ExportSnapshot extends Configured implements Tool {
79    private static final Log LOG = LogFactory.getLog(ExportSnapshot.class);
80  
81    private static final String CONF_FILES_USER = "snapshot.export.files.attributes.user";
82    private static final String CONF_FILES_GROUP = "snapshot.export.files.attributes.group";
83    private static final String CONF_FILES_MODE = "snapshot.export.files.attributes.mode";
84    private static final String CONF_CHECKSUM_VERIFY = "snapshot.export.checksum.verify";
85    private static final String CONF_OUTPUT_ROOT = "snapshot.export.output.root";
86    private static final String CONF_INPUT_ROOT = "snapshot.export.input.root";
87    private static final String CONF_BUFFER_SIZE = "snapshot.export.buffer.size";
88    private static final String CONF_MAP_GROUP = "snapshot.export.default.map.group";
89  
90    static final String CONF_TEST_FAILURE = "test.snapshot.export.failure";
91    static final String CONF_TEST_RETRY = "test.snapshot.export.failure.retry";
92  
93    private static final String INPUT_FOLDER_PREFIX = "export-files.";
94  
95    // Export Map-Reduce Counters, to keep track of the progress
96    public enum Counter { MISSING_FILES, COPY_FAILED, BYTES_EXPECTED, BYTES_COPIED, FILES_COPIED };
97  
98    private static class ExportMapper extends Mapper<Text, NullWritable, NullWritable, NullWritable> {
99      final static int REPORT_SIZE = 1 * 1024 * 1024;
100     final static int BUFFER_SIZE = 64 * 1024;
101 
102     private boolean testFailures;
103     private Random random;
104 
105     private boolean verifyChecksum;
106     private String filesGroup;
107     private String filesUser;
108     private short filesMode;
109     private int bufferSize;
110 
111     private FileSystem outputFs;
112     private Path outputArchive;
113     private Path outputRoot;
114 
115     private FileSystem inputFs;
116     private Path inputArchive;
117     private Path inputRoot;
118 
119     @Override
120     public void setup(Context context) throws IOException {
121       Configuration conf = context.getConfiguration();
122       verifyChecksum = conf.getBoolean(CONF_CHECKSUM_VERIFY, true);
123 
124       filesGroup = conf.get(CONF_FILES_GROUP);
125       filesUser = conf.get(CONF_FILES_USER);
126       filesMode = (short)conf.getInt(CONF_FILES_MODE, 0);
127       outputRoot = new Path(conf.get(CONF_OUTPUT_ROOT));
128       inputRoot = new Path(conf.get(CONF_INPUT_ROOT));
129 
130       inputArchive = new Path(inputRoot, HConstants.HFILE_ARCHIVE_DIRECTORY);
131       outputArchive = new Path(outputRoot, HConstants.HFILE_ARCHIVE_DIRECTORY);
132 
133       testFailures = conf.getBoolean(CONF_TEST_FAILURE, false);
134 
135       try {
136         inputFs = FileSystem.get(inputRoot.toUri(), conf);
137       } catch (IOException e) {
138         throw new IOException("Could not get the input FileSystem with root=" + inputRoot, e);
139       }
140 
141       try {
142         outputFs = FileSystem.get(outputRoot.toUri(), conf);
143       } catch (IOException e) {
144         throw new IOException("Could not get the output FileSystem with root="+ outputRoot, e);
145       }
146 
147       // Use the default block size of the outputFs if bigger
148       int defaultBlockSize = Math.max((int) outputFs.getDefaultBlockSize(), BUFFER_SIZE);
149       bufferSize = conf.getInt(CONF_BUFFER_SIZE, defaultBlockSize);
150       LOG.info("Using bufferSize=" + StringUtils.humanReadableInt(bufferSize));
151     }
152 
153     @Override
154     public void map(Text key, NullWritable value, Context context)
155         throws InterruptedException, IOException {
156       Path inputPath = new Path(key.toString());
157       Path outputPath = getOutputPath(inputPath);
158 
159       LOG.info("copy file input=" + inputPath + " output=" + outputPath);
160       copyFile(context, inputPath, outputPath);
161     }
162 
163     /**
164      * Returns the location where the inputPath will be copied.
165      *  - hfiles are encoded as hfile links hfile-region-table
166      *  - logs are encoded as serverName/logName
167      */
168     private Path getOutputPath(final Path inputPath) throws IOException {
169       Path path;
170       if (HFileLink.isHFileLink(inputPath) || StoreFileInfo.isReference(inputPath)) {
171         String family = inputPath.getParent().getName();
172         TableName table =
173             HFileLink.getReferencedTableName(inputPath.getName());
174         String region = HFileLink.getReferencedRegionName(inputPath.getName());
175         String hfile = HFileLink.getReferencedHFileName(inputPath.getName());
176         path = new Path(FSUtils.getTableDir(new Path("./"), table),
177             new Path(region, new Path(family, hfile)));
178       } else if (isHLogLinkPath(inputPath)) {
179         String logName = inputPath.getName();
180         path = new Path(new Path(outputRoot, HConstants.HREGION_OLDLOGDIR_NAME), logName);
181       } else {
182         path = inputPath;
183       }
184       return new Path(outputArchive, path);
185     }
186 
187     /*
188      * Used by TestExportSnapshot to simulate a failure
189      */
190     private void injectTestFailure(final Context context, final Path inputPath)
191         throws IOException {
192       if (testFailures) {
193         if (context.getConfiguration().getBoolean(CONF_TEST_RETRY, false)) {
194           if (random == null) {
195             random = new Random();
196           }
197 
198           // FLAKY-TEST-WARN: lower is better, we can get some runs without the
199           // retry, but at least we reduce the number of test failures due to
200           // this test exception from the same map task.
201           if (random.nextFloat() < 0.03) {
202             throw new IOException("TEST RETRY FAILURE: Unable to copy input=" + inputPath
203                                   + " time=" + System.currentTimeMillis());
204           }
205         } else {
206           context.getCounter(Counter.COPY_FAILED).increment(1);
207           throw new IOException("TEST FAILURE: Unable to copy input=" + inputPath);
208         }
209       }
210     }
211 
212     private void copyFile(final Context context, final Path inputPath, final Path outputPath)
213         throws IOException {
214       injectTestFailure(context, inputPath);
215 
216       // Get the file information
217       FileStatus inputStat = getSourceFileStatus(context, inputPath);
218 
219       // Verify if the output file exists and is the same that we want to copy
220       if (outputFs.exists(outputPath)) {
221         FileStatus outputStat = outputFs.getFileStatus(outputPath);
222         if (outputStat != null && sameFile(inputStat, outputStat)) {
223           LOG.info("Skip copy " + inputPath + " to " + outputPath + ", same file.");
224           return;
225         }
226       }
227 
228       FSDataInputStream in = openSourceFile(context, inputPath);
229       try {
230         context.getCounter(Counter.BYTES_EXPECTED).increment(inputStat.getLen());
231 
232         // Ensure that the output folder is there and copy the file
233         outputFs.mkdirs(outputPath.getParent());
234         FSDataOutputStream out = outputFs.create(outputPath, true);
235         try {
236           copyData(context, inputPath, in, outputPath, out, inputStat.getLen());
237         } finally {
238           out.close();
239         }
240 
241         // Try to Preserve attributes
242         if (!preserveAttributes(outputPath, inputStat)) {
243           LOG.warn("You may have to run manually chown on: " + outputPath);
244         }
245       } finally {
246         in.close();
247       }
248     }
249 
250     /**
251      * Try to Preserve the files attribute selected by the user copying them from the source file
252      * This is only required when you are exporting as a different user than "hbase" or on a system
253      * that doesn't have the "hbase" user.
254      *
255      * This is not considered a blocking failure since the user can force a chmod with the user
256      * that knows is available on the system.
257      */
258     private boolean preserveAttributes(final Path path, final FileStatus refStat) {
259       FileStatus stat;
260       try {
261         stat = outputFs.getFileStatus(path);
262       } catch (IOException e) {
263         LOG.warn("Unable to get the status for file=" + path);
264         return false;
265       }
266 
267       try {
268         if (filesMode > 0 && stat.getPermission().toShort() != filesMode) {
269           outputFs.setPermission(path, new FsPermission(filesMode));
270         } else if (!stat.getPermission().equals(refStat.getPermission())) {
271           outputFs.setPermission(path, refStat.getPermission());
272         }
273       } catch (IOException e) {
274         LOG.warn("Unable to set the permission for file="+ stat.getPath() +": "+ e.getMessage());
275         return false;
276       }
277 
278       String user = stringIsNotEmpty(filesUser) ? filesUser : refStat.getOwner();
279       String group = stringIsNotEmpty(filesGroup) ? filesGroup : refStat.getGroup();
280       if (stringIsNotEmpty(user) || stringIsNotEmpty(group)) {
281         try {
282           if (!(user.equals(stat.getOwner()) && group.equals(stat.getGroup()))) {
283             outputFs.setOwner(path, user, group);
284           }
285         } catch (IOException e) {
286           LOG.warn("Unable to set the owner/group for file="+ stat.getPath() +": "+ e.getMessage());
287           LOG.warn("The user/group may not exist on the destination cluster: user=" +
288                    user + " group=" + group);
289           return false;
290         }
291       }
292 
293       return true;
294     }
295 
296     private boolean stringIsNotEmpty(final String str) {
297       return str != null && str.length() > 0;
298     }
299 
300     private void copyData(final Context context,
301         final Path inputPath, final FSDataInputStream in,
302         final Path outputPath, final FSDataOutputStream out,
303         final long inputFileSize)
304         throws IOException {
305       final String statusMessage = "copied %s/" + StringUtils.humanReadableInt(inputFileSize) +
306                                    " (%.1f%%)";
307 
308       try {
309         byte[] buffer = new byte[bufferSize];
310         long totalBytesWritten = 0;
311         int reportBytes = 0;
312         int bytesRead;
313 
314         long stime = System.currentTimeMillis();
315         while ((bytesRead = in.read(buffer)) > 0) {
316           out.write(buffer, 0, bytesRead);
317           totalBytesWritten += bytesRead;
318           reportBytes += bytesRead;
319 
320           if (reportBytes >= REPORT_SIZE) {
321             context.getCounter(Counter.BYTES_COPIED).increment(reportBytes);
322             context.setStatus(String.format(statusMessage,
323                               StringUtils.humanReadableInt(totalBytesWritten),
324                               (totalBytesWritten/(float)inputFileSize) * 100.0f) +
325                               " from " + inputPath + " to " + outputPath);
326             reportBytes = 0;
327           }
328         }
329         long etime = System.currentTimeMillis();
330 
331         context.getCounter(Counter.BYTES_COPIED).increment(reportBytes);
332         context.setStatus(String.format(statusMessage,
333                           StringUtils.humanReadableInt(totalBytesWritten),
334                           (totalBytesWritten/(float)inputFileSize) * 100.0f) +
335                           " from " + inputPath + " to " + outputPath);
336 
337         // Verify that the written size match
338         if (totalBytesWritten != inputFileSize) {
339           String msg = "number of bytes copied not matching copied=" + totalBytesWritten +
340                        " expected=" + inputFileSize + " for file=" + inputPath;
341           throw new IOException(msg);
342         }
343 
344         LOG.info("copy completed for input=" + inputPath + " output=" + outputPath);
345         LOG.info("size=" + totalBytesWritten +
346             " (" + StringUtils.humanReadableInt(totalBytesWritten) + ")" +
347             " time=" + StringUtils.formatTimeDiff(etime, stime) +
348             String.format(" %.3fM/sec", (totalBytesWritten / ((etime - stime)/1000.0))/1048576.0));
349         context.getCounter(Counter.FILES_COPIED).increment(1);
350       } catch (IOException e) {
351         LOG.error("Error copying " + inputPath + " to " + outputPath, e);
352         context.getCounter(Counter.COPY_FAILED).increment(1);
353         throw e;
354       }
355     }
356 
357     /**
358      * Try to open the "source" file.
359      * Throws an IOException if the communication with the inputFs fail or
360      * if the file is not found.
361      */
362     private FSDataInputStream openSourceFile(Context context, final Path path) throws IOException {
363       try {
364         if (HFileLink.isHFileLink(path) || StoreFileInfo.isReference(path)) {
365           return new HFileLink(inputRoot, inputArchive, path).open(inputFs);
366         } else if (isHLogLinkPath(path)) {
367           String serverName = path.getParent().getName();
368           String logName = path.getName();
369           return new HLogLink(inputRoot, serverName, logName).open(inputFs);
370         }
371         return inputFs.open(path);
372       } catch (IOException e) {
373         context.getCounter(Counter.MISSING_FILES).increment(1);
374         LOG.error("Unable to open source file=" + path, e);
375         throw e;
376       }
377     }
378 
379     private FileStatus getSourceFileStatus(Context context, final Path path) throws IOException {
380       try {
381         if (HFileLink.isHFileLink(path) || StoreFileInfo.isReference(path)) {
382           HFileLink link = new HFileLink(inputRoot, inputArchive, path);
383           return link.getFileStatus(inputFs);
384         } else if (isHLogLinkPath(path)) {
385           String serverName = path.getParent().getName();
386           String logName = path.getName();
387           return new HLogLink(inputRoot, serverName, logName).getFileStatus(inputFs);
388         }
389         return inputFs.getFileStatus(path);
390       } catch (FileNotFoundException e) {
391         context.getCounter(Counter.MISSING_FILES).increment(1);
392         LOG.error("Unable to get the status for source file=" + path, e);
393         throw e;
394       } catch (IOException e) {
395         LOG.error("Unable to get the status for source file=" + path, e);
396         throw e;
397       }
398     }
399 
400     private FileChecksum getFileChecksum(final FileSystem fs, final Path path) {
401       try {
402         return fs.getFileChecksum(path);
403       } catch (IOException e) {
404         LOG.warn("Unable to get checksum for file=" + path, e);
405         return null;
406       }
407     }
408 
409     /**
410      * Check if the two files are equal by looking at the file length,
411      * and at the checksum (if user has specified the verifyChecksum flag).
412      */
413     private boolean sameFile(final FileStatus inputStat, final FileStatus outputStat) {
414       // Not matching length
415       if (inputStat.getLen() != outputStat.getLen()) return false;
416 
417       // Mark files as equals, since user asked for no checksum verification
418       if (!verifyChecksum) return true;
419 
420       // If checksums are not available, files are not the same.
421       FileChecksum inChecksum = getFileChecksum(inputFs, inputStat.getPath());
422       if (inChecksum == null) return false;
423 
424       FileChecksum outChecksum = getFileChecksum(outputFs, outputStat.getPath());
425       if (outChecksum == null) return false;
426 
427       return inChecksum.equals(outChecksum);
428     }
429 
430     /**
431      * HLog files are encoded as serverName/logName
432      * and since all the other files should be in /hbase/table/..path..
433      * we can rely on the depth, for now.
434      */
435     private static boolean isHLogLinkPath(final Path path) {
436       return path.depth() == 2;
437     }
438   }
439 
440   /**
441    * Extract the list of files (HFiles/HLogs) to copy using Map-Reduce.
442    * @return list of files referenced by the snapshot (pair of path and size)
443    */
444   private List<Pair<Path, Long>> getSnapshotFiles(final FileSystem fs, final Path snapshotDir)
445       throws IOException {
446     SnapshotDescription snapshotDesc = SnapshotDescriptionUtils.readSnapshotInfo(fs, snapshotDir);
447 
448     final List<Pair<Path, Long>> files = new ArrayList<Pair<Path, Long>>();
449     final TableName table =
450         TableName.valueOf(snapshotDesc.getTable());
451     final Configuration conf = getConf();
452 
453     // Get snapshot files
454     SnapshotReferenceUtil.visitReferencedFiles(fs, snapshotDir,
455       new SnapshotReferenceUtil.FileVisitor() {
456         public void storeFile (final String region, final String family, final String hfile)
457             throws IOException {
458           Path path = HFileLink.createPath(table, region, family, hfile);
459           long size = new HFileLink(conf, path).getFileStatus(fs).getLen();
460           files.add(new Pair<Path, Long>(path, size));
461         }
462 
463         public void recoveredEdits (final String region, final String logfile)
464             throws IOException {
465           // copied with the snapshot referenecs
466         }
467 
468         public void logFile (final String server, final String logfile)
469             throws IOException {
470           long size = new HLogLink(conf, server, logfile).getFileStatus(fs).getLen();
471           files.add(new Pair<Path, Long>(new Path(server, logfile), size));
472         }
473     });
474 
475     return files;
476   }
477 
478   /**
479    * Given a list of file paths and sizes, create around ngroups in as balanced a way as possible.
480    * The groups created will have similar amounts of bytes.
481    * <p>
482    * The algorithm used is pretty straightforward; the file list is sorted by size,
483    * and then each group fetch the bigger file available, iterating through groups
484    * alternating the direction.
485    */
486   static List<List<Path>> getBalancedSplits(final List<Pair<Path, Long>> files, int ngroups) {
487     // Sort files by size, from small to big
488     Collections.sort(files, new Comparator<Pair<Path, Long>>() {
489       public int compare(Pair<Path, Long> a, Pair<Path, Long> b) {
490         long r = a.getSecond() - b.getSecond();
491         return (r < 0) ? -1 : ((r > 0) ? 1 : 0);
492       }
493     });
494 
495     // create balanced groups
496     List<List<Path>> fileGroups = new LinkedList<List<Path>>();
497     long[] sizeGroups = new long[ngroups];
498     int hi = files.size() - 1;
499     int lo = 0;
500 
501     List<Path> group;
502     int dir = 1;
503     int g = 0;
504 
505     while (hi >= lo) {
506       if (g == fileGroups.size()) {
507         group = new LinkedList<Path>();
508         fileGroups.add(group);
509       } else {
510         group = fileGroups.get(g);
511       }
512 
513       Pair<Path, Long> fileInfo = files.get(hi--);
514 
515       // add the hi one
516       sizeGroups[g] += fileInfo.getSecond();
517       group.add(fileInfo.getFirst());
518 
519       // change direction when at the end or the beginning
520       g += dir;
521       if (g == ngroups) {
522         dir = -1;
523         g = ngroups - 1;
524       } else if (g < 0) {
525         dir = 1;
526         g = 0;
527       }
528     }
529 
530     if (LOG.isDebugEnabled()) {
531       for (int i = 0; i < sizeGroups.length; ++i) {
532         LOG.debug("export split=" + i + " size=" + StringUtils.humanReadableInt(sizeGroups[i]));
533       }
534     }
535 
536     return fileGroups;
537   }
538 
539   private static Path getInputFolderPath(Configuration conf)
540       throws IOException, InterruptedException {
541     Path stagingDir = JobUtil.getStagingDir(conf);
542     return new Path(stagingDir, INPUT_FOLDER_PREFIX +
543       String.valueOf(EnvironmentEdgeManager.currentTimeMillis()));
544   }
545 
546   /**
547    * Create the input files, with the path to copy, for the MR job.
548    * Each input files contains n files, and each input file has a similar amount data to copy.
549    * The number of input files created are based on the number of mappers provided as argument
550    * and the number of the files to copy.
551    */
552   private static Path[] createInputFiles(final Configuration conf,
553       final List<Pair<Path, Long>> snapshotFiles, int mappers)
554       throws IOException, InterruptedException {
555     Path inputFolderPath = getInputFolderPath(conf);
556     FileSystem fs = inputFolderPath.getFileSystem(conf);
557     LOG.debug("Input folder location: " + inputFolderPath);
558 
559     List<List<Path>> splits = getBalancedSplits(snapshotFiles, mappers);
560     Path[] inputFiles = new Path[splits.size()];
561 
562     Text key = new Text();
563     for (int i = 0; i < inputFiles.length; i++) {
564       List<Path> files = splits.get(i);
565       inputFiles[i] = new Path(inputFolderPath, String.format("export-%d.seq", i));
566       SequenceFile.Writer writer = SequenceFile.createWriter(fs, conf, inputFiles[i],
567         Text.class, NullWritable.class);
568       LOG.debug("Input split: " + i);
569       try {
570         for (Path file: files) {
571           LOG.debug(file.toString());
572           key.set(file.toString());
573           writer.append(key, NullWritable.get());
574         }
575       } finally {
576         writer.close();
577       }
578     }
579 
580     return inputFiles;
581   }
582 
583   /**
584    * Run Map-Reduce Job to perform the files copy.
585    */
586   private void runCopyJob(final FileSystem inputFs, final Path inputRoot,
587       final FileSystem outputFs, final Path outputRoot,
588       final List<Pair<Path, Long>> snapshotFiles, final boolean verifyChecksum,
589       final String filesUser, final String filesGroup, final int filesMode,
590       final int mappers) throws IOException, InterruptedException, ClassNotFoundException {
591     Configuration conf = getConf();
592     if (filesGroup != null) conf.set(CONF_FILES_GROUP, filesGroup);
593     if (filesUser != null) conf.set(CONF_FILES_USER, filesUser);
594     conf.setInt(CONF_FILES_MODE, filesMode);
595     conf.setBoolean(CONF_CHECKSUM_VERIFY, verifyChecksum);
596     conf.set(CONF_OUTPUT_ROOT, outputRoot.toString());
597     conf.set(CONF_INPUT_ROOT, inputRoot.toString());
598     conf.setInt("mapreduce.job.maps", mappers);
599 
600     Job job = new Job(conf);
601     job.setJobName("ExportSnapshot");
602     job.setJarByClass(ExportSnapshot.class);
603     TableMapReduceUtil.addDependencyJars(job);
604     job.setMapperClass(ExportMapper.class);
605     job.setInputFormatClass(SequenceFileInputFormat.class);
606     job.setOutputFormatClass(NullOutputFormat.class);
607     job.setMapSpeculativeExecution(false);
608     job.setNumReduceTasks(0);
609     for (Path path: createInputFiles(conf, snapshotFiles, mappers)) {
610       LOG.debug("Add Input Path=" + path);
611       SequenceFileInputFormat.addInputPath(job, path);
612     }
613 
614     UserProvider userProvider = UserProvider.instantiate(job.getConfiguration());
615     FsDelegationToken inputFsToken = new FsDelegationToken(userProvider, "irenewer");
616     FsDelegationToken outputFsToken = new FsDelegationToken(userProvider, "orenewer");
617     try {
618       // Acquire the delegation Tokens
619       inputFsToken.acquireDelegationToken(inputFs);
620       outputFsToken.acquireDelegationToken(outputFs);
621 
622       // Run the MR Job
623       if (!job.waitForCompletion(true)) {
624         // TODO: Replace the fixed string with job.getStatus().getFailureInfo()
625         // when it will be available on all the supported versions.
626         throw new ExportSnapshotException("Copy Files Map-Reduce Job failed");
627       }
628     } finally {
629       inputFsToken.releaseDelegationToken();
630       outputFsToken.releaseDelegationToken();
631     }
632   }
633 
634   /**
635    * Execute the export snapshot by copying the snapshot metadata, hfiles and hlogs.
636    * @return 0 on success, and != 0 upon failure.
637    */
638   @Override
639   public int run(String[] args) throws IOException {
640     boolean verifyChecksum = true;
641     String snapshotName = null;
642     boolean overwrite = false;
643     String filesGroup = null;
644     String filesUser = null;
645     Path outputRoot = null;
646     int filesMode = 0;
647     int mappers = 0;
648 
649     // Process command line args
650     for (int i = 0; i < args.length; i++) {
651       String cmd = args[i];
652       try {
653         if (cmd.equals("-snapshot")) {
654           snapshotName = args[++i];
655         } else if (cmd.equals("-copy-to")) {
656           outputRoot = new Path(args[++i]);
657         } else if (cmd.equals("-no-checksum-verify")) {
658           verifyChecksum = false;
659         } else if (cmd.equals("-mappers")) {
660           mappers = Integer.parseInt(args[++i]);
661         } else if (cmd.equals("-chuser")) {
662           filesUser = args[++i];
663         } else if (cmd.equals("-chgroup")) {
664           filesGroup = args[++i];
665         } else if (cmd.equals("-chmod")) {
666           filesMode = Integer.parseInt(args[++i], 8);
667         } else if (cmd.equals("-overwrite")) {
668           overwrite = true;
669         } else if (cmd.equals("-h") || cmd.equals("--help")) {
670           printUsageAndExit();
671         } else {
672           System.err.println("UNEXPECTED: " + cmd);
673           printUsageAndExit();
674         }
675       } catch (Exception e) {
676         printUsageAndExit();
677       }
678     }
679 
680     // Check user options
681     if (snapshotName == null) {
682       System.err.println("Snapshot name not provided.");
683       printUsageAndExit();
684     }
685 
686     if (outputRoot == null) {
687       System.err.println("Destination file-system not provided.");
688       printUsageAndExit();
689     }
690 
691     Configuration conf = getConf();
692     Path inputRoot = FSUtils.getRootDir(conf);
693     FileSystem inputFs = FileSystem.get(conf);
694     FileSystem outputFs = FileSystem.get(outputRoot.toUri(), conf);
695 
696     Path snapshotDir = SnapshotDescriptionUtils.getCompletedSnapshotDir(snapshotName, inputRoot);
697     Path snapshotTmpDir = SnapshotDescriptionUtils.getWorkingSnapshotDir(snapshotName, outputRoot);
698     Path outputSnapshotDir = SnapshotDescriptionUtils.getCompletedSnapshotDir(snapshotName, outputRoot);
699 
700     // Check if the snapshot already exists
701     if (outputFs.exists(outputSnapshotDir)) {
702       if (overwrite) {
703         if (!outputFs.delete(outputSnapshotDir, true)) {
704           System.err.println("Unable to remove existing snapshot directory: " + outputSnapshotDir);
705           return 1;
706         }
707       } else {
708         System.err.println("The snapshot '" + snapshotName +
709           "' already exists in the destination: " + outputSnapshotDir);
710         return 1;
711       }
712     }
713 
714     // Check if the snapshot already in-progress
715     if (outputFs.exists(snapshotTmpDir)) {
716       if (overwrite) {
717         if (!outputFs.delete(snapshotTmpDir, true)) {
718           System.err.println("Unable to remove existing snapshot tmp directory: " + snapshotTmpDir);
719           return 1;
720         }
721       } else {
722         System.err.println("A snapshot with the same name '"+ snapshotName +"' may be in-progress");
723         System.err.println("Please check " + snapshotTmpDir + ". If the snapshot has completed, ");
724         System.err.println("consider removing " + snapshotTmpDir + " before retrying export");
725         return 1;
726       }
727     }
728 
729     // Step 0 - Extract snapshot files to copy
730     final List<Pair<Path, Long>> files = getSnapshotFiles(inputFs, snapshotDir);
731     if (mappers == 0 && files.size() > 0) {
732       mappers = 1 + (files.size() / conf.getInt(CONF_MAP_GROUP, 10));
733       mappers = Math.min(mappers, files.size());
734     }
735 
736     // Step 1 - Copy fs1:/.snapshot/<snapshot> to  fs2:/.snapshot/.tmp/<snapshot>
737     // The snapshot references must be copied before the hfiles otherwise the cleaner
738     // will remove them because they are unreferenced.
739     try {
740       FileUtil.copy(inputFs, snapshotDir, outputFs, snapshotTmpDir, false, false, conf);
741     } catch (IOException e) {
742       throw new ExportSnapshotException("Failed to copy the snapshot directory: from=" +
743         snapshotDir + " to=" + snapshotTmpDir);
744     }
745 
746     // Step 2 - Start MR Job to copy files
747     // The snapshot references must be copied before the files otherwise the files gets removed
748     // by the HFileArchiver, since they have no references.
749     try {
750       if (files.size() == 0) {
751         LOG.warn("There are 0 store file to be copied. There may be no data in the table.");
752       } else {
753         runCopyJob(inputFs, inputRoot, outputFs, outputRoot, files, verifyChecksum,
754                    filesUser, filesGroup, filesMode, mappers);
755       }
756 
757       // Step 3 - Rename fs2:/.snapshot/.tmp/<snapshot> fs2:/.snapshot/<snapshot>
758       if (!outputFs.rename(snapshotTmpDir, outputSnapshotDir)) {
759         throw new ExportSnapshotException("Unable to rename snapshot directory from=" +
760           snapshotTmpDir + " to=" + outputSnapshotDir);
761       }
762       return 0;
763     } catch (Exception e) {
764       LOG.error("Snapshot export failed", e);
765       outputFs.delete(snapshotTmpDir, true);
766       outputFs.delete(outputSnapshotDir, true);
767       return 1;
768     }
769   }
770 
771   // ExportSnapshot
772   private void printUsageAndExit() {
773     System.err.printf("Usage: bin/hbase %s [options]%n", getClass().getName());
774     System.err.println(" where [options] are:");
775     System.err.println("  -h|-help                Show this help and exit.");
776     System.err.println("  -snapshot NAME          Snapshot to restore.");
777     System.err.println("  -copy-to NAME           Remote destination hdfs://");
778     System.err.println("  -no-checksum-verify     Do not verify checksum.");
779     System.err.println("  -overwrite              Rewrite the snapshot manifest if already exists");
780     System.err.println("  -chuser USERNAME        Change the owner of the files " +
781         "to the specified one.");
782     System.err.println("  -chgroup GROUP          Change the group of the files to " +
783         "the specified one.");
784     System.err.println("  -chmod MODE             Change the permission of the files " +
785         "to the specified one.");
786     System.err.println("  -mappers                Number of mappers to use during the " +
787         "copy (mapreduce.job.maps).");
788     System.err.println();
789     System.err.println("Examples:");
790     System.err.println("  hbase " + getClass().getName() + " \\");
791     System.err.println("    -snapshot MySnapshot -copy-to hdfs://srv2:8082/hbase \\");
792     System.err.println("    -chuser MyUser -chgroup MyGroup -chmod 700 -mappers 16");
793     System.exit(1);
794   }
795 
796   /**
797    * The guts of the {@link #main} method.
798    * Call this method to avoid the {@link #main(String[])} System.exit.
799    * @param args
800    * @return errCode
801    * @throws Exception
802    */
803   static int innerMain(final Configuration conf, final String [] args) throws Exception {
804     return ToolRunner.run(conf, new ExportSnapshot(), args);
805   }
806 
807   public static void main(String[] args) throws Exception {
808     System.exit(innerMain(HBaseConfiguration.create(), args));
809   }
810 }