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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.BufferedInputStream;
22  import java.io.FileNotFoundException;
23  import java.io.DataInput;
24  import java.io.DataOutput;
25  import java.io.IOException;
26  import java.io.InputStream;
27  import java.util.ArrayList;
28  import java.util.Collections;
29  import java.util.Comparator;
30  import java.util.LinkedList;
31  import java.util.List;
32  import java.util.Random;
33  
34  import org.apache.commons.logging.Log;
35  import org.apache.commons.logging.LogFactory;
36  import org.apache.hadoop.hbase.classification.InterfaceAudience;
37  import org.apache.hadoop.hbase.classification.InterfaceStability;
38  import org.apache.hadoop.conf.Configuration;
39  import org.apache.hadoop.conf.Configured;
40  import org.apache.hadoop.fs.FSDataInputStream;
41  import org.apache.hadoop.fs.FSDataOutputStream;
42  import org.apache.hadoop.fs.FileChecksum;
43  import org.apache.hadoop.fs.FileStatus;
44  import org.apache.hadoop.fs.FileSystem;
45  import org.apache.hadoop.fs.FileUtil;
46  import org.apache.hadoop.fs.Path;
47  import org.apache.hadoop.fs.permission.FsPermission;
48  import org.apache.hadoop.hbase.TableName;
49  import org.apache.hadoop.hbase.HBaseConfiguration;
50  import org.apache.hadoop.hbase.HConstants;
51  import org.apache.hadoop.hbase.HRegionInfo;
52  import org.apache.hadoop.hbase.io.FileLink;
53  import org.apache.hadoop.hbase.io.HFileLink;
54  import org.apache.hadoop.hbase.io.WALLink;
55  import org.apache.hadoop.hbase.mapreduce.TableMapReduceUtil;
56  import org.apache.hadoop.hbase.protobuf.generated.HBaseProtos.SnapshotDescription;
57  import org.apache.hadoop.hbase.protobuf.generated.SnapshotProtos.SnapshotFileInfo;
58  import org.apache.hadoop.hbase.protobuf.generated.SnapshotProtos.SnapshotRegionManifest;
59  import org.apache.hadoop.hbase.util.FSUtils;
60  import org.apache.hadoop.hbase.util.Pair;
61  import org.apache.hadoop.io.BytesWritable;
62  import org.apache.hadoop.io.IOUtils;
63  import org.apache.hadoop.io.NullWritable;
64  import org.apache.hadoop.io.Writable;
65  import org.apache.hadoop.mapreduce.Job;
66  import org.apache.hadoop.mapreduce.JobContext;
67  import org.apache.hadoop.mapreduce.Mapper;
68  import org.apache.hadoop.mapreduce.InputFormat;
69  import org.apache.hadoop.mapreduce.InputSplit;
70  import org.apache.hadoop.mapreduce.RecordReader;
71  import org.apache.hadoop.mapreduce.TaskAttemptContext;
72  import org.apache.hadoop.mapreduce.lib.output.NullOutputFormat;
73  import org.apache.hadoop.mapreduce.security.TokenCache;
74  import org.apache.hadoop.hbase.io.hadoopbackport.ThrottledInputStream;
75  import org.apache.hadoop.util.StringUtils;
76  import org.apache.hadoop.util.Tool;
77  import org.apache.hadoop.util.ToolRunner;
78  
79  /**
80   * Export the specified snapshot to a given FileSystem.
81   *
82   * The .snapshot/name folder is copied to the destination cluster
83   * and then all the hfiles/wals are copied using a Map-Reduce Job in the .archive/ location.
84   * When everything is done, the second cluster can restore the snapshot.
85   */
86  @InterfaceAudience.Public
87  @InterfaceStability.Evolving
88  public class ExportSnapshot extends Configured implements Tool {
89    public static final String NAME = "exportsnapshot";
90    /** Configuration prefix for overrides for the source filesystem */
91    public static final String CONF_SOURCE_PREFIX = NAME + ".from.";
92    /** Configuration prefix for overrides for the destination filesystem */
93    public static final String CONF_DEST_PREFIX = NAME + ".to.";
94  
95    private static final Log LOG = LogFactory.getLog(ExportSnapshot.class);
96  
97    private static final String MR_NUM_MAPS = "mapreduce.job.maps";
98    private static final String CONF_NUM_SPLITS = "snapshot.export.format.splits";
99    private static final String CONF_SNAPSHOT_NAME = "snapshot.export.format.snapshot.name";
100   private static final String CONF_SNAPSHOT_DIR = "snapshot.export.format.snapshot.dir";
101   private static final String CONF_FILES_USER = "snapshot.export.files.attributes.user";
102   private static final String CONF_FILES_GROUP = "snapshot.export.files.attributes.group";
103   private static final String CONF_FILES_MODE = "snapshot.export.files.attributes.mode";
104   private static final String CONF_CHECKSUM_VERIFY = "snapshot.export.checksum.verify";
105   private static final String CONF_OUTPUT_ROOT = "snapshot.export.output.root";
106   private static final String CONF_INPUT_ROOT = "snapshot.export.input.root";
107   private static final String CONF_BUFFER_SIZE = "snapshot.export.buffer.size";
108   private static final String CONF_MAP_GROUP = "snapshot.export.default.map.group";
109   private static final String CONF_BANDWIDTH_MB = "snapshot.export.map.bandwidth.mb";
110   protected static final String CONF_SKIP_TMP = "snapshot.export.skip.tmp";
111 
112   static final String CONF_TEST_FAILURE = "test.snapshot.export.failure";
113   static final String CONF_TEST_RETRY = "test.snapshot.export.failure.retry";
114 
115   private static final String INPUT_FOLDER_PREFIX = "export-files.";
116 
117   // Export Map-Reduce Counters, to keep track of the progress
118   public enum Counter {
119     MISSING_FILES, FILES_COPIED, FILES_SKIPPED, COPY_FAILED,
120     BYTES_EXPECTED, BYTES_SKIPPED, BYTES_COPIED
121   }
122 
123   private static class ExportMapper extends Mapper<BytesWritable, NullWritable,
124                                                    NullWritable, NullWritable> {
125     final static int REPORT_SIZE = 1 * 1024 * 1024;
126     final static int BUFFER_SIZE = 64 * 1024;
127 
128     private boolean testFailures;
129     private Random random;
130 
131     private boolean verifyChecksum;
132     private String filesGroup;
133     private String filesUser;
134     private short filesMode;
135     private int bufferSize;
136 
137     private FileSystem outputFs;
138     private Path outputArchive;
139     private Path outputRoot;
140 
141     private FileSystem inputFs;
142     private Path inputArchive;
143     private Path inputRoot;
144 
145     @Override
146     public void setup(Context context) throws IOException {
147       Configuration conf = context.getConfiguration();
148       Configuration srcConf = HBaseConfiguration.createClusterConf(conf, null, CONF_SOURCE_PREFIX);
149       Configuration destConf = HBaseConfiguration.createClusterConf(conf, null, CONF_DEST_PREFIX);
150 
151       verifyChecksum = conf.getBoolean(CONF_CHECKSUM_VERIFY, true);
152 
153       filesGroup = conf.get(CONF_FILES_GROUP);
154       filesUser = conf.get(CONF_FILES_USER);
155       filesMode = (short)conf.getInt(CONF_FILES_MODE, 0);
156       outputRoot = new Path(conf.get(CONF_OUTPUT_ROOT));
157       inputRoot = new Path(conf.get(CONF_INPUT_ROOT));
158 
159       inputArchive = new Path(inputRoot, HConstants.HFILE_ARCHIVE_DIRECTORY);
160       outputArchive = new Path(outputRoot, HConstants.HFILE_ARCHIVE_DIRECTORY);
161 
162       testFailures = conf.getBoolean(CONF_TEST_FAILURE, false);
163 
164       try {
165         srcConf.setBoolean("fs." + inputRoot.toUri().getScheme() + ".impl.disable.cache", true);
166         inputFs = FileSystem.get(inputRoot.toUri(), srcConf);
167       } catch (IOException e) {
168         throw new IOException("Could not get the input FileSystem with root=" + inputRoot, e);
169       }
170 
171       try {
172         destConf.setBoolean("fs." + outputRoot.toUri().getScheme() + ".impl.disable.cache", true);
173         outputFs = FileSystem.get(outputRoot.toUri(), destConf);
174       } catch (IOException e) {
175         throw new IOException("Could not get the output FileSystem with root="+ outputRoot, e);
176       }
177 
178       // Use the default block size of the outputFs if bigger
179       int defaultBlockSize = Math.max((int) outputFs.getDefaultBlockSize(outputRoot), BUFFER_SIZE);
180       bufferSize = conf.getInt(CONF_BUFFER_SIZE, defaultBlockSize);
181       LOG.info("Using bufferSize=" + StringUtils.humanReadableInt(bufferSize));
182 
183       for (Counter c : Counter.values()) {
184         context.getCounter(c).increment(0);
185       }
186     }
187 
188     @Override
189     protected void cleanup(Context context) {
190       IOUtils.closeStream(inputFs);
191       IOUtils.closeStream(outputFs);
192     }
193 
194     @Override
195     public void map(BytesWritable key, NullWritable value, Context context)
196         throws InterruptedException, IOException {
197       SnapshotFileInfo inputInfo = SnapshotFileInfo.parseFrom(key.copyBytes());
198       Path outputPath = getOutputPath(inputInfo);
199 
200       copyFile(context, inputInfo, outputPath);
201     }
202 
203     /**
204      * Returns the location where the inputPath will be copied.
205      */
206     private Path getOutputPath(final SnapshotFileInfo inputInfo) throws IOException {
207       Path path = null;
208       switch (inputInfo.getType()) {
209         case HFILE:
210           Path inputPath = new Path(inputInfo.getHfile());
211           String family = inputPath.getParent().getName();
212           TableName table =HFileLink.getReferencedTableName(inputPath.getName());
213           String region = HFileLink.getReferencedRegionName(inputPath.getName());
214           String hfile = HFileLink.getReferencedHFileName(inputPath.getName());
215           path = new Path(FSUtils.getTableDir(new Path("./"), table),
216               new Path(region, new Path(family, hfile)));
217           break;
218         case WAL:
219           LOG.warn("snapshot does not keeps WALs: " + inputInfo);
220           break;
221         default:
222           throw new IOException("Invalid File Type: " + inputInfo.getType().toString());
223       }
224       return new Path(outputArchive, path);
225     }
226 
227     /*
228      * Used by TestExportSnapshot to simulate a failure
229      */
230     private void injectTestFailure(final Context context, final SnapshotFileInfo inputInfo)
231         throws IOException {
232       if (testFailures) {
233         if (context.getConfiguration().getBoolean(CONF_TEST_RETRY, false)) {
234           if (random == null) {
235             random = new Random();
236           }
237 
238           // FLAKY-TEST-WARN: lower is better, we can get some runs without the
239           // retry, but at least we reduce the number of test failures due to
240           // this test exception from the same map task.
241           if (random.nextFloat() < 0.03) {
242             throw new IOException("TEST RETRY FAILURE: Unable to copy input=" + inputInfo
243                                   + " time=" + System.currentTimeMillis());
244           }
245         } else {
246           context.getCounter(Counter.COPY_FAILED).increment(1);
247           throw new IOException("TEST FAILURE: Unable to copy input=" + inputInfo);
248         }
249       }
250     }
251 
252     private void copyFile(final Context context, final SnapshotFileInfo inputInfo,
253         final Path outputPath) throws IOException {
254       injectTestFailure(context, inputInfo);
255 
256       // Get the file information
257       FileStatus inputStat = getSourceFileStatus(context, inputInfo);
258 
259       // Verify if the output file exists and is the same that we want to copy
260       if (outputFs.exists(outputPath)) {
261         FileStatus outputStat = outputFs.getFileStatus(outputPath);
262         if (outputStat != null && sameFile(inputStat, outputStat)) {
263           LOG.info("Skip copy " + inputStat.getPath() + " to " + outputPath + ", same file.");
264           context.getCounter(Counter.FILES_SKIPPED).increment(1);
265           context.getCounter(Counter.BYTES_SKIPPED).increment(inputStat.getLen());
266           return;
267         }
268       }
269 
270       InputStream in = openSourceFile(context, inputInfo);
271       int bandwidthMB = context.getConfiguration().getInt(CONF_BANDWIDTH_MB, 100);
272       if (Integer.MAX_VALUE != bandwidthMB) {
273         in = new ThrottledInputStream(new BufferedInputStream(in), bandwidthMB * 1024L * 1024L);
274       }
275 
276       try {
277         context.getCounter(Counter.BYTES_EXPECTED).increment(inputStat.getLen());
278 
279         // Ensure that the output folder is there and copy the file
280         createOutputPath(outputPath.getParent());
281         FSDataOutputStream out = outputFs.create(outputPath, true);
282         try {
283           copyData(context, inputStat.getPath(), in, outputPath, out, inputStat.getLen());
284         } finally {
285           out.close();
286         }
287 
288         // Try to Preserve attributes
289         if (!preserveAttributes(outputPath, inputStat)) {
290           LOG.warn("You may have to run manually chown on: " + outputPath);
291         }
292       } finally {
293         in.close();
294       }
295     }
296 
297     /**
298      * Create the output folder and optionally set ownership.
299      */
300     private void createOutputPath(final Path path) throws IOException {
301       if (filesUser == null && filesGroup == null) {
302         outputFs.mkdirs(path);
303       } else {
304         Path parent = path.getParent();
305         if (!outputFs.exists(parent) && !parent.isRoot()) {
306           createOutputPath(parent);
307         }
308         outputFs.mkdirs(path);
309         if (filesUser != null || filesGroup != null) {
310           // override the owner when non-null user/group is specified
311           outputFs.setOwner(path, filesUser, filesGroup);
312         }
313         if (filesMode > 0) {
314           outputFs.setPermission(path, new FsPermission(filesMode));
315         }
316       }
317     }
318 
319     /**
320      * Try to Preserve the files attribute selected by the user copying them from the source file
321      * This is only required when you are exporting as a different user than "hbase" or on a system
322      * that doesn't have the "hbase" user.
323      *
324      * This is not considered a blocking failure since the user can force a chmod with the user
325      * that knows is available on the system.
326      */
327     private boolean preserveAttributes(final Path path, final FileStatus refStat) {
328       FileStatus stat;
329       try {
330         stat = outputFs.getFileStatus(path);
331       } catch (IOException e) {
332         LOG.warn("Unable to get the status for file=" + path);
333         return false;
334       }
335 
336       try {
337         if (filesMode > 0 && stat.getPermission().toShort() != filesMode) {
338           outputFs.setPermission(path, new FsPermission(filesMode));
339         } else if (refStat != null && !stat.getPermission().equals(refStat.getPermission())) {
340           outputFs.setPermission(path, refStat.getPermission());
341         }
342       } catch (IOException e) {
343         LOG.warn("Unable to set the permission for file="+ stat.getPath() +": "+ e.getMessage());
344         return false;
345       }
346 
347       boolean hasRefStat = (refStat != null);
348       String user = stringIsNotEmpty(filesUser) || !hasRefStat ? filesUser : refStat.getOwner();
349       String group = stringIsNotEmpty(filesGroup) || !hasRefStat ? filesGroup : refStat.getGroup();
350       if (stringIsNotEmpty(user) || stringIsNotEmpty(group)) {
351         try {
352           if (!(user.equals(stat.getOwner()) && group.equals(stat.getGroup()))) {
353             outputFs.setOwner(path, user, group);
354           }
355         } catch (IOException e) {
356           LOG.warn("Unable to set the owner/group for file="+ stat.getPath() +": "+ e.getMessage());
357           LOG.warn("The user/group may not exist on the destination cluster: user=" +
358                    user + " group=" + group);
359           return false;
360         }
361       }
362 
363       return true;
364     }
365 
366     private boolean stringIsNotEmpty(final String str) {
367       return str != null && str.length() > 0;
368     }
369 
370     private void copyData(final Context context,
371         final Path inputPath, final InputStream in,
372         final Path outputPath, final FSDataOutputStream out,
373         final long inputFileSize)
374         throws IOException {
375       final String statusMessage = "copied %s/" + StringUtils.humanReadableInt(inputFileSize) +
376                                    " (%.1f%%)";
377 
378       try {
379         byte[] buffer = new byte[bufferSize];
380         long totalBytesWritten = 0;
381         int reportBytes = 0;
382         int bytesRead;
383 
384         long stime = System.currentTimeMillis();
385         while ((bytesRead = in.read(buffer)) > 0) {
386           out.write(buffer, 0, bytesRead);
387           totalBytesWritten += bytesRead;
388           reportBytes += bytesRead;
389 
390           if (reportBytes >= REPORT_SIZE) {
391             context.getCounter(Counter.BYTES_COPIED).increment(reportBytes);
392             context.setStatus(String.format(statusMessage,
393                               StringUtils.humanReadableInt(totalBytesWritten),
394                               (totalBytesWritten/(float)inputFileSize) * 100.0f) +
395                               " from " + inputPath + " to " + outputPath);
396             reportBytes = 0;
397           }
398         }
399         long etime = System.currentTimeMillis();
400 
401         context.getCounter(Counter.BYTES_COPIED).increment(reportBytes);
402         context.setStatus(String.format(statusMessage,
403                           StringUtils.humanReadableInt(totalBytesWritten),
404                           (totalBytesWritten/(float)inputFileSize) * 100.0f) +
405                           " from " + inputPath + " to " + outputPath);
406 
407         // Verify that the written size match
408         if (totalBytesWritten != inputFileSize) {
409           String msg = "number of bytes copied not matching copied=" + totalBytesWritten +
410                        " expected=" + inputFileSize + " for file=" + inputPath;
411           throw new IOException(msg);
412         }
413 
414         LOG.info("copy completed for input=" + inputPath + " output=" + outputPath);
415         LOG.info("size=" + totalBytesWritten +
416             " (" + StringUtils.humanReadableInt(totalBytesWritten) + ")" +
417             " time=" + StringUtils.formatTimeDiff(etime, stime) +
418             String.format(" %.3fM/sec", (totalBytesWritten / ((etime - stime)/1000.0))/1048576.0));
419         context.getCounter(Counter.FILES_COPIED).increment(1);
420       } catch (IOException e) {
421         LOG.error("Error copying " + inputPath + " to " + outputPath, e);
422         context.getCounter(Counter.COPY_FAILED).increment(1);
423         throw e;
424       }
425     }
426 
427     /**
428      * Try to open the "source" file.
429      * Throws an IOException if the communication with the inputFs fail or
430      * if the file is not found.
431      */
432     private FSDataInputStream openSourceFile(Context context, final SnapshotFileInfo fileInfo)
433             throws IOException {
434       try {
435         Configuration conf = context.getConfiguration();
436         FileLink link = null;
437         switch (fileInfo.getType()) {
438           case HFILE:
439             Path inputPath = new Path(fileInfo.getHfile());
440             link = HFileLink.buildFromHFileLinkPattern(conf, inputPath);
441             break;
442           case WAL:
443             String serverName = fileInfo.getWalServer();
444             String logName = fileInfo.getWalName();
445             link = new WALLink(inputRoot, serverName, logName);
446             break;
447           default:
448             throw new IOException("Invalid File Type: " + fileInfo.getType().toString());
449         }
450         return link.open(inputFs);
451       } catch (IOException e) {
452         context.getCounter(Counter.MISSING_FILES).increment(1);
453         LOG.error("Unable to open source file=" + fileInfo.toString(), e);
454         throw e;
455       }
456     }
457 
458     private FileStatus getSourceFileStatus(Context context, final SnapshotFileInfo fileInfo)
459         throws IOException {
460       try {
461         Configuration conf = context.getConfiguration();
462         FileLink link = null;
463         switch (fileInfo.getType()) {
464           case HFILE:
465             Path inputPath = new Path(fileInfo.getHfile());
466             link = HFileLink.buildFromHFileLinkPattern(conf, inputPath);
467             break;
468           case WAL:
469             link = new WALLink(inputRoot, fileInfo.getWalServer(), fileInfo.getWalName());
470             break;
471           default:
472             throw new IOException("Invalid File Type: " + fileInfo.getType().toString());
473         }
474         return link.getFileStatus(inputFs);
475       } catch (FileNotFoundException e) {
476         context.getCounter(Counter.MISSING_FILES).increment(1);
477         LOG.error("Unable to get the status for source file=" + fileInfo.toString(), e);
478         throw e;
479       } catch (IOException e) {
480         LOG.error("Unable to get the status for source file=" + fileInfo.toString(), e);
481         throw e;
482       }
483     }
484 
485     private FileChecksum getFileChecksum(final FileSystem fs, final Path path) {
486       try {
487         return fs.getFileChecksum(path);
488       } catch (IOException e) {
489         LOG.warn("Unable to get checksum for file=" + path, e);
490         return null;
491       }
492     }
493 
494     /**
495      * Check if the two files are equal by looking at the file length,
496      * and at the checksum (if user has specified the verifyChecksum flag).
497      */
498     private boolean sameFile(final FileStatus inputStat, final FileStatus outputStat) {
499       // Not matching length
500       if (inputStat.getLen() != outputStat.getLen()) return false;
501 
502       // Mark files as equals, since user asked for no checksum verification
503       if (!verifyChecksum) return true;
504 
505       // If checksums are not available, files are not the same.
506       FileChecksum inChecksum = getFileChecksum(inputFs, inputStat.getPath());
507       if (inChecksum == null) return false;
508 
509       FileChecksum outChecksum = getFileChecksum(outputFs, outputStat.getPath());
510       if (outChecksum == null) return false;
511 
512       return inChecksum.equals(outChecksum);
513     }
514   }
515 
516   // ==========================================================================
517   //  Input Format
518   // ==========================================================================
519 
520   /**
521    * Extract the list of files (HFiles/WALs) to copy using Map-Reduce.
522    * @return list of files referenced by the snapshot (pair of path and size)
523    */
524   private static List<Pair<SnapshotFileInfo, Long>> getSnapshotFiles(final Configuration conf,
525       final FileSystem fs, final Path snapshotDir) throws IOException {
526     SnapshotDescription snapshotDesc = SnapshotDescriptionUtils.readSnapshotInfo(fs, snapshotDir);
527 
528     final List<Pair<SnapshotFileInfo, Long>> files = new ArrayList<Pair<SnapshotFileInfo, Long>>();
529     final TableName table = TableName.valueOf(snapshotDesc.getTable());
530 
531     // Get snapshot files
532     LOG.info("Loading Snapshot '" + snapshotDesc.getName() + "' hfile list");
533     SnapshotReferenceUtil.visitReferencedFiles(conf, fs, snapshotDir, snapshotDesc,
534       new SnapshotReferenceUtil.SnapshotVisitor() {
535         @Override
536         public void storeFile(final HRegionInfo regionInfo, final String family,
537             final SnapshotRegionManifest.StoreFile storeFile) throws IOException {
538           if (storeFile.hasReference()) {
539             // copied as part of the manifest
540           } else {
541             String region = regionInfo.getEncodedName();
542             String hfile = storeFile.getName();
543             Path path = HFileLink.createPath(table, region, family, hfile);
544 
545             SnapshotFileInfo fileInfo = SnapshotFileInfo.newBuilder()
546               .setType(SnapshotFileInfo.Type.HFILE)
547               .setHfile(path.toString())
548               .build();
549 
550             long size;
551             if (storeFile.hasFileSize()) {
552               size = storeFile.getFileSize();
553             } else {
554               size = HFileLink.buildFromHFileLinkPattern(conf, path).getFileStatus(fs).getLen();
555             }
556             files.add(new Pair<SnapshotFileInfo, Long>(fileInfo, size));
557           }
558         }
559     });
560 
561     return files;
562   }
563 
564   /**
565    * Given a list of file paths and sizes, create around ngroups in as balanced a way as possible.
566    * The groups created will have similar amounts of bytes.
567    * <p>
568    * The algorithm used is pretty straightforward; the file list is sorted by size,
569    * and then each group fetch the bigger file available, iterating through groups
570    * alternating the direction.
571    */
572   static List<List<Pair<SnapshotFileInfo, Long>>> getBalancedSplits(
573       final List<Pair<SnapshotFileInfo, Long>> files, final int ngroups) {
574     // Sort files by size, from small to big
575     Collections.sort(files, new Comparator<Pair<SnapshotFileInfo, Long>>() {
576       public int compare(Pair<SnapshotFileInfo, Long> a, Pair<SnapshotFileInfo, Long> b) {
577         long r = a.getSecond() - b.getSecond();
578         return (r < 0) ? -1 : ((r > 0) ? 1 : 0);
579       }
580     });
581 
582     // create balanced groups
583     List<List<Pair<SnapshotFileInfo, Long>>> fileGroups =
584       new LinkedList<List<Pair<SnapshotFileInfo, Long>>>();
585     long[] sizeGroups = new long[ngroups];
586     int hi = files.size() - 1;
587     int lo = 0;
588 
589     List<Pair<SnapshotFileInfo, Long>> group;
590     int dir = 1;
591     int g = 0;
592 
593     while (hi >= lo) {
594       if (g == fileGroups.size()) {
595         group = new LinkedList<Pair<SnapshotFileInfo, Long>>();
596         fileGroups.add(group);
597       } else {
598         group = fileGroups.get(g);
599       }
600 
601       Pair<SnapshotFileInfo, Long> fileInfo = files.get(hi--);
602 
603       // add the hi one
604       sizeGroups[g] += fileInfo.getSecond();
605       group.add(fileInfo);
606 
607       // change direction when at the end or the beginning
608       g += dir;
609       if (g == ngroups) {
610         dir = -1;
611         g = ngroups - 1;
612       } else if (g < 0) {
613         dir = 1;
614         g = 0;
615       }
616     }
617 
618     if (LOG.isDebugEnabled()) {
619       for (int i = 0; i < sizeGroups.length; ++i) {
620         LOG.debug("export split=" + i + " size=" + StringUtils.humanReadableInt(sizeGroups[i]));
621       }
622     }
623 
624     return fileGroups;
625   }
626 
627   private static class ExportSnapshotInputFormat extends InputFormat<BytesWritable, NullWritable> {
628     @Override
629     public RecordReader<BytesWritable, NullWritable> createRecordReader(InputSplit split,
630         TaskAttemptContext tac) throws IOException, InterruptedException {
631       return new ExportSnapshotRecordReader(((ExportSnapshotInputSplit)split).getSplitKeys());
632     }
633 
634     @Override
635     public List<InputSplit> getSplits(JobContext context) throws IOException, InterruptedException {
636       Configuration conf = context.getConfiguration();
637       Path snapshotDir = new Path(conf.get(CONF_SNAPSHOT_DIR));
638       FileSystem fs = FileSystem.get(snapshotDir.toUri(), conf);
639 
640       List<Pair<SnapshotFileInfo, Long>> snapshotFiles = getSnapshotFiles(conf, fs, snapshotDir);
641       int mappers = conf.getInt(CONF_NUM_SPLITS, 0);
642       if (mappers == 0 && snapshotFiles.size() > 0) {
643         mappers = 1 + (snapshotFiles.size() / conf.getInt(CONF_MAP_GROUP, 10));
644         mappers = Math.min(mappers, snapshotFiles.size());
645         conf.setInt(CONF_NUM_SPLITS, mappers);
646         conf.setInt(MR_NUM_MAPS, mappers);
647       }
648 
649       List<List<Pair<SnapshotFileInfo, Long>>> groups = getBalancedSplits(snapshotFiles, mappers);
650       List<InputSplit> splits = new ArrayList(groups.size());
651       for (List<Pair<SnapshotFileInfo, Long>> files: groups) {
652         splits.add(new ExportSnapshotInputSplit(files));
653       }
654       return splits;
655     }
656 
657     private static class ExportSnapshotInputSplit extends InputSplit implements Writable {
658       private List<Pair<BytesWritable, Long>> files;
659       private long length;
660 
661       public ExportSnapshotInputSplit() {
662         this.files = null;
663       }
664 
665       public ExportSnapshotInputSplit(final List<Pair<SnapshotFileInfo, Long>> snapshotFiles) {
666         this.files = new ArrayList(snapshotFiles.size());
667         for (Pair<SnapshotFileInfo, Long> fileInfo: snapshotFiles) {
668           this.files.add(new Pair<BytesWritable, Long>(
669             new BytesWritable(fileInfo.getFirst().toByteArray()), fileInfo.getSecond()));
670           this.length += fileInfo.getSecond();
671         }
672       }
673 
674       private List<Pair<BytesWritable, Long>> getSplitKeys() {
675         return files;
676       }
677 
678       @Override
679       public long getLength() throws IOException, InterruptedException {
680         return length;
681       }
682 
683       @Override
684       public String[] getLocations() throws IOException, InterruptedException {
685         return new String[] {};
686       }
687 
688       @Override
689       public void readFields(DataInput in) throws IOException {
690         int count = in.readInt();
691         files = new ArrayList<Pair<BytesWritable, Long>>(count);
692         length = 0;
693         for (int i = 0; i < count; ++i) {
694           BytesWritable fileInfo = new BytesWritable();
695           fileInfo.readFields(in);
696           long size = in.readLong();
697           files.add(new Pair<BytesWritable, Long>(fileInfo, size));
698           length += size;
699         }
700       }
701 
702       @Override
703       public void write(DataOutput out) throws IOException {
704         out.writeInt(files.size());
705         for (final Pair<BytesWritable, Long> fileInfo: files) {
706           fileInfo.getFirst().write(out);
707           out.writeLong(fileInfo.getSecond());
708         }
709       }
710     }
711 
712     private static class ExportSnapshotRecordReader
713         extends RecordReader<BytesWritable, NullWritable> {
714       private final List<Pair<BytesWritable, Long>> files;
715       private long totalSize = 0;
716       private long procSize = 0;
717       private int index = -1;
718 
719       ExportSnapshotRecordReader(final List<Pair<BytesWritable, Long>> files) {
720         this.files = files;
721         for (Pair<BytesWritable, Long> fileInfo: files) {
722           totalSize += fileInfo.getSecond();
723         }
724       }
725 
726       @Override
727       public void close() { }
728 
729       @Override
730       public BytesWritable getCurrentKey() { return files.get(index).getFirst(); }
731 
732       @Override
733       public NullWritable getCurrentValue() { return NullWritable.get(); }
734 
735       @Override
736       public float getProgress() { return (float)procSize / totalSize; }
737 
738       @Override
739       public void initialize(InputSplit split, TaskAttemptContext tac) { }
740 
741       @Override
742       public boolean nextKeyValue() {
743         if (index >= 0) {
744           procSize += files.get(index).getSecond();
745         }
746         return(++index < files.size());
747       }
748     }
749   }
750 
751   // ==========================================================================
752   //  Tool
753   // ==========================================================================
754 
755   /**
756    * Run Map-Reduce Job to perform the files copy.
757    */
758   private void runCopyJob(final Path inputRoot, final Path outputRoot,
759       final String snapshotName, final Path snapshotDir, final boolean verifyChecksum,
760       final String filesUser, final String filesGroup, final int filesMode,
761       final int mappers, final int bandwidthMB)
762           throws IOException, InterruptedException, ClassNotFoundException {
763     Configuration conf = getConf();
764     if (filesGroup != null) conf.set(CONF_FILES_GROUP, filesGroup);
765     if (filesUser != null) conf.set(CONF_FILES_USER, filesUser);
766     if (mappers > 0) {
767       conf.setInt(CONF_NUM_SPLITS, mappers);
768       conf.setInt(MR_NUM_MAPS, mappers);
769     }
770     conf.setInt(CONF_FILES_MODE, filesMode);
771     conf.setBoolean(CONF_CHECKSUM_VERIFY, verifyChecksum);
772     conf.set(CONF_OUTPUT_ROOT, outputRoot.toString());
773     conf.set(CONF_INPUT_ROOT, inputRoot.toString());
774     conf.setInt(CONF_BANDWIDTH_MB, bandwidthMB);
775     conf.set(CONF_SNAPSHOT_NAME, snapshotName);
776     conf.set(CONF_SNAPSHOT_DIR, snapshotDir.toString());
777 
778     Job job = new Job(conf);
779     job.setJobName("ExportSnapshot-" + snapshotName);
780     job.setJarByClass(ExportSnapshot.class);
781     TableMapReduceUtil.addDependencyJars(job);
782     job.setMapperClass(ExportMapper.class);
783     job.setInputFormatClass(ExportSnapshotInputFormat.class);
784     job.setOutputFormatClass(NullOutputFormat.class);
785     job.setMapSpeculativeExecution(false);
786     job.setNumReduceTasks(0);
787 
788     // Acquire the delegation Tokens
789     Configuration srcConf = HBaseConfiguration.createClusterConf(conf, null, CONF_SOURCE_PREFIX);
790     TokenCache.obtainTokensForNamenodes(job.getCredentials(),
791       new Path[] { inputRoot }, srcConf);
792     Configuration destConf = HBaseConfiguration.createClusterConf(conf, null, CONF_DEST_PREFIX);
793     TokenCache.obtainTokensForNamenodes(job.getCredentials(),
794         new Path[] { outputRoot }, destConf);
795 
796     // Run the MR Job
797     if (!job.waitForCompletion(true)) {
798       // TODO: Replace the fixed string with job.getStatus().getFailureInfo()
799       // when it will be available on all the supported versions.
800       throw new ExportSnapshotException("Copy Files Map-Reduce Job failed");
801     }
802   }
803 
804   private void verifySnapshot(final Configuration baseConf,
805       final FileSystem fs, final Path rootDir, final Path snapshotDir) throws IOException {
806     // Update the conf with the current root dir, since may be a different cluster
807     Configuration conf = new Configuration(baseConf);
808     FSUtils.setRootDir(conf, rootDir);
809     FSUtils.setFsDefault(conf, FSUtils.getRootDir(conf));
810     SnapshotDescription snapshotDesc = SnapshotDescriptionUtils.readSnapshotInfo(fs, snapshotDir);
811     SnapshotReferenceUtil.verifySnapshot(conf, fs, snapshotDir, snapshotDesc);
812   }
813 
814   /**
815    * Set path ownership.
816    */
817   private void setOwner(final FileSystem fs, final Path path, final String user,
818       final String group, final boolean recursive) throws IOException {
819     if (user != null || group != null) {
820       if (recursive && fs.isDirectory(path)) {
821         for (FileStatus child : fs.listStatus(path)) {
822           setOwner(fs, child.getPath(), user, group, recursive);
823         }
824       }
825       fs.setOwner(path, user, group);
826     }
827   }
828 
829   /**
830    * Set path permission.
831    */
832   private void setPermission(final FileSystem fs, final Path path, final short filesMode,
833       final boolean recursive) throws IOException {
834     if (filesMode > 0) {
835       FsPermission perm = new FsPermission(filesMode);
836       if (recursive && fs.isDirectory(path)) {
837         for (FileStatus child : fs.listStatus(path)) {
838           setPermission(fs, child.getPath(), filesMode, recursive);
839         }
840       }
841       fs.setPermission(path, perm);
842     }
843   }
844 
845   /**
846    * Execute the export snapshot by copying the snapshot metadata, hfiles and wals.
847    * @return 0 on success, and != 0 upon failure.
848    */
849   @Override
850   public int run(String[] args) throws IOException {
851     boolean verifyTarget = true;
852     boolean verifyChecksum = true;
853     String snapshotName = null;
854     String targetName = null;
855     boolean overwrite = false;
856     String filesGroup = null;
857     String filesUser = null;
858     Path outputRoot = null;
859     int bandwidthMB = Integer.MAX_VALUE;
860     int filesMode = 0;
861     int mappers = 0;
862 
863     Configuration conf = getConf();
864     Path inputRoot = FSUtils.getRootDir(conf);
865 
866     // Process command line args
867     for (int i = 0; i < args.length; i++) {
868       String cmd = args[i];
869       if (cmd.equals("-snapshot")) {
870         snapshotName = args[++i];
871       } else if (cmd.equals("-target")) {
872         targetName = args[++i];
873       } else if (cmd.equals("-copy-to")) {
874         outputRoot = new Path(args[++i]);
875       } else if (cmd.equals("-copy-from")) {
876         inputRoot = new Path(args[++i]);
877         FSUtils.setRootDir(conf, inputRoot);
878       } else if (cmd.equals("-no-checksum-verify")) {
879         verifyChecksum = false;
880       } else if (cmd.equals("-no-target-verify")) {
881         verifyTarget = false;
882       } else if (cmd.equals("-mappers")) {
883         mappers = Integer.parseInt(args[++i]);
884       } else if (cmd.equals("-chuser")) {
885         filesUser = args[++i];
886       } else if (cmd.equals("-chgroup")) {
887         filesGroup = args[++i];
888       } else if (cmd.equals("-bandwidth")) {
889         bandwidthMB = Integer.parseInt(args[++i]);
890       } else if (cmd.equals("-chmod")) {
891         filesMode = Integer.parseInt(args[++i], 8);
892       } else if (cmd.equals("-overwrite")) {
893         overwrite = true;
894       } else if (cmd.equals("-h") || cmd.equals("--help")) {
895         printUsageAndExit();
896       } else {
897         System.err.println("UNEXPECTED: " + cmd);
898         printUsageAndExit();
899       }
900     }
901 
902     // Check user options
903     if (snapshotName == null) {
904       System.err.println("Snapshot name not provided.");
905       printUsageAndExit();
906     }
907 
908     if (outputRoot == null) {
909       System.err.println("Destination file-system not provided.");
910       printUsageAndExit();
911     }
912 
913     if (targetName == null) {
914       targetName = snapshotName;
915     }
916 
917     Configuration srcConf = HBaseConfiguration.createClusterConf(conf, null, CONF_SOURCE_PREFIX);
918     srcConf.setBoolean("fs." + inputRoot.toUri().getScheme() + ".impl.disable.cache", true);
919     FileSystem inputFs = FileSystem.get(inputRoot.toUri(), srcConf);
920     LOG.debug("inputFs=" + inputFs.getUri().toString() + " inputRoot=" + inputRoot);
921     Configuration destConf = HBaseConfiguration.createClusterConf(conf, null, CONF_DEST_PREFIX);
922     destConf.setBoolean("fs." + outputRoot.toUri().getScheme() + ".impl.disable.cache", true);
923     FileSystem outputFs = FileSystem.get(outputRoot.toUri(), destConf);
924     LOG.debug("outputFs=" + outputFs.getUri().toString() + " outputRoot=" + outputRoot.toString());
925 
926     boolean skipTmp = conf.getBoolean(CONF_SKIP_TMP, false);
927 
928     Path snapshotDir = SnapshotDescriptionUtils.getCompletedSnapshotDir(snapshotName, inputRoot);
929     Path snapshotTmpDir = SnapshotDescriptionUtils.getWorkingSnapshotDir(targetName, outputRoot);
930     Path outputSnapshotDir = SnapshotDescriptionUtils.getCompletedSnapshotDir(targetName, outputRoot);
931     Path initialOutputSnapshotDir = skipTmp ? outputSnapshotDir : snapshotTmpDir;
932 
933     // Check if the snapshot already exists
934     if (outputFs.exists(outputSnapshotDir)) {
935       if (overwrite) {
936         if (!outputFs.delete(outputSnapshotDir, true)) {
937           System.err.println("Unable to remove existing snapshot directory: " + outputSnapshotDir);
938           return 1;
939         }
940       } else {
941         System.err.println("The snapshot '" + targetName +
942           "' already exists in the destination: " + outputSnapshotDir);
943         return 1;
944       }
945     }
946 
947     if (!skipTmp) {
948       // Check if the snapshot already in-progress
949       if (outputFs.exists(snapshotTmpDir)) {
950         if (overwrite) {
951           if (!outputFs.delete(snapshotTmpDir, true)) {
952             System.err.println("Unable to remove existing snapshot tmp directory: "+snapshotTmpDir);
953             return 1;
954           }
955         } else {
956           System.err.println("A snapshot with the same name '"+ targetName +"' may be in-progress");
957           System.err.println("Please check "+snapshotTmpDir+". If the snapshot has completed, ");
958           System.err.println("consider removing "+snapshotTmpDir+" by using the -overwrite option");
959           return 1;
960         }
961       }
962     }
963 
964     // Step 1 - Copy fs1:/.snapshot/<snapshot> to  fs2:/.snapshot/.tmp/<snapshot>
965     // The snapshot references must be copied before the hfiles otherwise the cleaner
966     // will remove them because they are unreferenced.
967     try {
968       LOG.info("Copy Snapshot Manifest");
969       FileUtil.copy(inputFs, snapshotDir, outputFs, initialOutputSnapshotDir, false, false, conf);
970       if (filesUser != null || filesGroup != null) {
971         setOwner(outputFs, snapshotTmpDir, filesUser, filesGroup, true);
972       }
973       if (filesMode > 0) {
974         setPermission(outputFs, snapshotTmpDir, (short)filesMode, true);
975       }
976     } catch (IOException e) {
977       throw new ExportSnapshotException("Failed to copy the snapshot directory: from=" +
978         snapshotDir + " to=" + initialOutputSnapshotDir, e);
979     }
980 
981     // Write a new .snapshotinfo if the target name is different from the source name
982     if (!targetName.equals(snapshotName)) {
983       SnapshotDescription snapshotDesc =
984         SnapshotDescriptionUtils.readSnapshotInfo(inputFs, snapshotDir)
985           .toBuilder()
986           .setName(targetName)
987           .build();
988       SnapshotDescriptionUtils.writeSnapshotInfo(snapshotDesc, snapshotTmpDir, outputFs);
989     }
990 
991     // Step 2 - Start MR Job to copy files
992     // The snapshot references must be copied before the files otherwise the files gets removed
993     // by the HFileArchiver, since they have no references.
994     try {
995       runCopyJob(inputRoot, outputRoot, snapshotName, snapshotDir, verifyChecksum,
996                  filesUser, filesGroup, filesMode, mappers, bandwidthMB);
997 
998       LOG.info("Finalize the Snapshot Export");
999       if (!skipTmp) {
1000         // Step 3 - Rename fs2:/.snapshot/.tmp/<snapshot> fs2:/.snapshot/<snapshot>
1001         if (!outputFs.rename(snapshotTmpDir, outputSnapshotDir)) {
1002           throw new ExportSnapshotException("Unable to rename snapshot directory from=" +
1003             snapshotTmpDir + " to=" + outputSnapshotDir);
1004         }
1005       }
1006 
1007       // Step 4 - Verify snapshot integrity
1008       if (verifyTarget) {
1009         LOG.info("Verify snapshot integrity");
1010         verifySnapshot(destConf, outputFs, outputRoot, outputSnapshotDir);
1011       }
1012 
1013       LOG.info("Export Completed: " + targetName);
1014       return 0;
1015     } catch (Exception e) {
1016       LOG.error("Snapshot export failed", e);
1017       if (!skipTmp) {
1018         outputFs.delete(snapshotTmpDir, true);
1019       }
1020       outputFs.delete(outputSnapshotDir, true);
1021       return 1;
1022     } finally {
1023       IOUtils.closeStream(inputFs);
1024       IOUtils.closeStream(outputFs);
1025     }
1026   }
1027 
1028   // ExportSnapshot
1029   private void printUsageAndExit() {
1030     System.err.printf("Usage: bin/hbase %s [options]%n", getClass().getName());
1031     System.err.println(" where [options] are:");
1032     System.err.println("  -h|-help                Show this help and exit.");
1033     System.err.println("  -snapshot NAME          Snapshot to restore.");
1034     System.err.println("  -copy-to NAME           Remote destination hdfs://");
1035     System.err.println("  -copy-from NAME         Input folder hdfs:// (default hbase.rootdir)");
1036     System.err.println("  -no-checksum-verify     Do not verify checksum, use name+length only.");
1037     System.err.println("  -no-target-verify       Do not verify the integrity of the \\" +
1038         "exported snapshot.");
1039     System.err.println("  -overwrite              Rewrite the snapshot manifest if already exists");
1040     System.err.println("  -chuser USERNAME        Change the owner of the files " +
1041         "to the specified one.");
1042     System.err.println("  -chgroup GROUP          Change the group of the files to " +
1043         "the specified one.");
1044     System.err.println("  -chmod MODE             Change the permission of the files " +
1045         "to the specified one.");
1046     System.err.println("  -mappers                Number of mappers to use during the " +
1047         "copy (mapreduce.job.maps).");
1048     System.err.println("  -bandwidth              Limit bandwidth to this value in MB/second.");
1049     System.err.println();
1050     System.err.println("Examples:");
1051     System.err.println("  hbase snapshot export \\");
1052     System.err.println("    -snapshot MySnapshot -copy-to hdfs://srv2:8082/hbase \\");
1053     System.err.println("    -chuser MyUser -chgroup MyGroup -chmod 700 -mappers 16");
1054     System.err.println();
1055     System.err.println("  hbase snapshot export \\");
1056     System.err.println("    -snapshot MySnapshot -copy-from hdfs://srv2:8082/hbase \\");
1057     System.err.println("    -copy-to hdfs://srv1:50070/hbase \\");
1058     System.exit(1);
1059   }
1060 
1061   /**
1062    * The guts of the {@link #main} method.
1063    * Call this method to avoid the {@link #main(String[])} System.exit.
1064    * @param args
1065    * @return errCode
1066    * @throws Exception
1067    */
1068   static int innerMain(final Configuration conf, final String [] args) throws Exception {
1069     return ToolRunner.run(conf, new ExportSnapshot(), args);
1070   }
1071 
1072   public static void main(String[] args) throws Exception {
1073     System.exit(innerMain(HBaseConfiguration.create(), args));
1074   }
1075 }