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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.snapshot;
19  
20  import java.io.IOException;
21  
22  import org.apache.commons.logging.Log;
23  import org.apache.commons.logging.LogFactory;
24  import org.apache.hadoop.conf.Configuration;
25  import org.apache.hadoop.fs.FSDataInputStream;
26  import org.apache.hadoop.fs.FSDataOutputStream;
27  import org.apache.hadoop.fs.FileSystem;
28  import org.apache.hadoop.fs.Path;
29  import org.apache.hadoop.fs.permission.FsPermission;
30  import org.apache.hadoop.hbase.HConstants;
31  import org.apache.hadoop.hbase.exceptions.CorruptedSnapshotException;
32  import org.apache.hadoop.hbase.exceptions.SnapshotCreationException;
33  import org.apache.hadoop.hbase.protobuf.generated.HBaseProtos.SnapshotDescription;
34  import org.apache.hadoop.hbase.util.EnvironmentEdgeManager;
35  import org.apache.hadoop.hbase.util.FSUtils;
36  
37  /**
38   * Utility class to help manage {@link SnapshotDescription SnapshotDesriptions}.
39   * <p>
40   * Snapshots are laid out on disk like this:
41   *
42   * <pre>
43   * /hbase/.snapshots
44   *          /.tmp                <---- working directory
45   *          /[snapshot name]     <----- completed snapshot
46   * </pre>
47   *
48   * A completed snapshot named 'completed' then looks like (multiple regions, servers, files, etc.
49   * signified by '...' on the same directory depth).
50   *
51   * <pre>
52   * /hbase/.snapshots/completed
53   *                   .snapshotinfo          <--- Description of the snapshot
54   *                   .tableinfo             <--- Copy of the tableinfo
55   *                    /.logs
56   *                        /[server_name]
57   *                            /... [log files]
58   *                         ...
59   *                   /[region name]           <---- All the region's information
60   *                   .regioninfo              <---- Copy of the HRegionInfo
61   *                      /[column family name]
62   *                          /[hfile name]     <--- name of the hfile in the real region
63   *                          ...
64   *                      ...
65   *                    ...
66   * </pre>
67   *
68   * Utility methods in this class are useful for getting the correct locations for different parts of
69   * the snapshot, as well as moving completed snapshots into place (see
70   * {@link #completeSnapshot}, and writing the
71   * {@link SnapshotDescription} to the working snapshot directory.
72   */
73  public class SnapshotDescriptionUtils {
74  
75    /**
76     * Filter that only accepts completed snapshot directories
77     */
78    public static class CompletedSnaphotDirectoriesFilter extends FSUtils.DirFilter {
79  
80      /**
81       * @param fs
82       */
83      public CompletedSnaphotDirectoriesFilter(FileSystem fs) {
84        super(fs);
85      }
86  
87      @Override
88      public boolean accept(Path path) {
89        // only accept directories that aren't the tmp directory
90        if (super.accept(path)) {
91          return !path.getName().equals(SNAPSHOT_TMP_DIR_NAME);
92        }
93        return false;
94      }
95  
96    }
97  
98    private static final Log LOG = LogFactory.getLog(SnapshotDescriptionUtils.class);
99    /**
100    * Version of the fs layout for a snapshot. Future snapshots may have different file layouts,
101    * which we may need to read in differently.
102    */
103   public static final int SNAPSHOT_LAYOUT_VERSION = 0;
104 
105   // snapshot directory constants
106   /**
107    * The file contains the snapshot basic information and it is under the directory of a snapshot.
108    */
109   public static final String SNAPSHOTINFO_FILE = ".snapshotinfo";
110 
111   /** Temporary directory under the snapshot directory to store in-progress snapshots */
112   public static final String SNAPSHOT_TMP_DIR_NAME = ".tmp";
113   // snapshot operation values
114   /** Default value if no start time is specified */
115   public static final long NO_SNAPSHOT_START_TIME_SPECIFIED = 0;
116 
117   public static final String MASTER_SNAPSHOT_TIMEOUT_MILLIS = "hbase.snapshot.master.timeout.millis";
118 
119   /** By default, wait 60 seconds for a snapshot to complete */
120   public static final long DEFAULT_MAX_WAIT_TIME = 60000;
121 
122   private SnapshotDescriptionUtils() {
123     // private constructor for utility class
124   }
125 
126   /**
127    * @param conf {@link Configuration} from which to check for the timeout
128    * @param type type of snapshot being taken
129    * @param defaultMaxWaitTime Default amount of time to wait, if none is in the configuration
130    * @return the max amount of time the master should wait for a snapshot to complete
131    */
132   public static long getMaxMasterTimeout(Configuration conf, SnapshotDescription.Type type,
133       long defaultMaxWaitTime) {
134     String confKey;
135     switch (type) {
136     case DISABLED:
137     default:
138       confKey = MASTER_SNAPSHOT_TIMEOUT_MILLIS;
139     }
140     return conf.getLong(confKey, defaultMaxWaitTime);
141   }
142 
143   /**
144    * Get the snapshot root directory. All the snapshots are kept under this directory, i.e.
145    * ${hbase.rootdir}/.snapshot
146    * @param rootDir hbase root directory
147    * @return the base directory in which all snapshots are kept
148    */
149   public static Path getSnapshotRootDir(final Path rootDir) {
150     return new Path(rootDir, HConstants.SNAPSHOT_DIR_NAME);
151   }
152 
153   /**
154    * Get the directory for a specified snapshot. This directory is a sub-directory of snapshot root
155    * directory and all the data files for a snapshot are kept under this directory.
156    * @param snapshot snapshot being taken
157    * @param rootDir hbase root directory
158    * @return the final directory for the completed snapshot
159    */
160   public static Path getCompletedSnapshotDir(final SnapshotDescription snapshot, final Path rootDir) {
161     return getCompletedSnapshotDir(snapshot.getName(), rootDir);
162   }
163 
164   /**
165    * Get the directory for a completed snapshot. This directory is a sub-directory of snapshot root
166    * directory and all the data files for a snapshot are kept under this directory.
167    * @param snapshotName name of the snapshot being taken
168    * @param rootDir hbase root directory
169    * @return the final directory for the completed snapshot
170    */
171   public static Path getCompletedSnapshotDir(final String snapshotName, final Path rootDir) {
172     return getCompletedSnapshotDir(getSnapshotsDir(rootDir), snapshotName);
173   }
174 
175   /**
176    * Get the general working directory for snapshots - where they are built, where they are
177    * temporarily copied on export, etc.
178    * @param rootDir root directory of the HBase installation
179    * @return Path to the snapshot tmp directory, relative to the passed root directory
180    */
181   public static Path getWorkingSnapshotDir(final Path rootDir) {
182     return new Path(getSnapshotsDir(rootDir), SNAPSHOT_TMP_DIR_NAME);
183   }
184 
185   /**
186    * Get the directory to build a snapshot, before it is finalized
187    * @param snapshot snapshot that will be built
188    * @param rootDir root directory of the hbase installation
189    * @return {@link Path} where one can build a snapshot
190    */
191   public static Path getWorkingSnapshotDir(SnapshotDescription snapshot, final Path rootDir) {
192     return getCompletedSnapshotDir(getWorkingSnapshotDir(rootDir), snapshot.getName());
193   }
194 
195   /**
196    * Get the directory to build a snapshot, before it is finalized
197    * @param snapshotName name of the snapshot
198    * @param rootDir root directory of the hbase installation
199    * @return {@link Path} where one can build a snapshot
200    */
201   public static Path getWorkingSnapshotDir(String snapshotName, final Path rootDir) {
202     return getCompletedSnapshotDir(getWorkingSnapshotDir(rootDir), snapshotName);
203   }
204 
205   /**
206    * Get the directory to store the snapshot instance
207    * @param snapshotsDir hbase-global directory for storing all snapshots
208    * @param snapshotName name of the snapshot to take
209    * @return the final directory for the completed snapshot
210    */
211   private static final Path getCompletedSnapshotDir(final Path snapshotsDir, String snapshotName) {
212     return new Path(snapshotsDir, snapshotName);
213   }
214 
215   /**
216    * @param rootDir hbase root directory
217    * @return the directory for all completed snapshots;
218    */
219   public static final Path getSnapshotsDir(Path rootDir) {
220     return new Path(rootDir, HConstants.SNAPSHOT_DIR_NAME);
221   }
222 
223   /**
224    * Convert the passed snapshot description into a 'full' snapshot description based on default
225    * parameters, if none have been supplied. This resolves any 'optional' parameters that aren't
226    * supplied to their default values.
227    * @param snapshot general snapshot descriptor
228    * @param conf Configuration to read configured snapshot defaults if snapshot is not complete
229    * @return a valid snapshot description
230    * @throws IllegalArgumentException if the {@link SnapshotDescription} is not a complete
231    *           {@link SnapshotDescription}.
232    */
233   public static SnapshotDescription validate(SnapshotDescription snapshot, Configuration conf)
234       throws IllegalArgumentException {
235     if (!snapshot.hasTable()) {
236       throw new IllegalArgumentException(
237         "Descriptor doesn't apply to a table, so we can't build it.");
238     }
239 
240     // set the creation time, if one hasn't been set
241     long time = snapshot.getCreationTime();
242     if (time == SnapshotDescriptionUtils.NO_SNAPSHOT_START_TIME_SPECIFIED) {
243       time = EnvironmentEdgeManager.currentTimeMillis();
244       LOG.debug("Creation time not specified, setting to:" + time + " (current time:"
245           + EnvironmentEdgeManager.currentTimeMillis() + ").");
246       SnapshotDescription.Builder builder = snapshot.toBuilder();
247       builder.setCreationTime(time);
248       snapshot = builder.build();
249     }
250     return snapshot;
251   }
252 
253   /**
254    * Write the snapshot description into the working directory of a snapshot
255    * @param snapshot description of the snapshot being taken
256    * @param workingDir working directory of the snapshot
257    * @param fs {@link FileSystem} on which the snapshot should be taken
258    * @throws IOException if we can't reach the filesystem and the file cannot be cleaned up on
259    *           failure
260    */
261   public static void writeSnapshotInfo(SnapshotDescription snapshot, Path workingDir, FileSystem fs)
262       throws IOException {
263     FsPermission perms = FSUtils.getFilePermissions(fs, fs.getConf(),
264       HConstants.DATA_FILE_UMASK_KEY);
265     Path snapshotInfo = new Path(workingDir, SnapshotDescriptionUtils.SNAPSHOTINFO_FILE);
266     try {
267       FSDataOutputStream out = FSUtils.create(fs, snapshotInfo, perms, true);
268       try {
269         snapshot.writeTo(out);
270       } finally {
271         out.close();
272       }
273     } catch (IOException e) {
274       // if we get an exception, try to remove the snapshot info
275       if (!fs.delete(snapshotInfo, false)) {
276         String msg = "Couldn't delete snapshot info file: " + snapshotInfo;
277         LOG.error(msg);
278         throw new IOException(msg);
279       }
280     }
281   }
282 
283   /**
284    * Read in the {@link SnapshotDescription} stored for the snapshot in the passed directory
285    * @param fs filesystem where the snapshot was taken
286    * @param snapshotDir directory where the snapshot was stored
287    * @return the stored snapshot description
288    * @throws org.apache.hadoop.hbase.exceptions.CorruptedSnapshotException if the snapshot cannot be read
289    */
290   public static SnapshotDescription readSnapshotInfo(FileSystem fs, Path snapshotDir)
291       throws CorruptedSnapshotException {
292     Path snapshotInfo = new Path(snapshotDir, SNAPSHOTINFO_FILE);
293     try {
294       FSDataInputStream in = null;
295       try {
296         in = fs.open(snapshotInfo);
297         return SnapshotDescription.parseFrom(in);
298       } finally {
299         if (in != null) in.close();
300       }
301     } catch (IOException e) {
302       throw new CorruptedSnapshotException("Couldn't read snapshot info from:" + snapshotInfo, e);
303     }
304   }
305 
306   /**
307    * Move the finished snapshot to its final, publicly visible directory - this marks the snapshot
308    * as 'complete'.
309    * @param snapshot description of the snapshot being tabken
310    * @param rootdir root directory of the hbase installation
311    * @param workingDir directory where the in progress snapshot was built
312    * @param fs {@link FileSystem} where the snapshot was built
313    * @throws org.apache.hadoop.hbase.exceptions.SnapshotCreationException if the snapshot could not be moved
314    * @throws IOException the filesystem could not be reached
315    */
316   public static void completeSnapshot(SnapshotDescription snapshot, Path rootdir, Path workingDir,
317       FileSystem fs) throws SnapshotCreationException, IOException {
318     Path finishedDir = getCompletedSnapshotDir(snapshot, rootdir);
319     LOG.debug("Snapshot is done, just moving the snapshot from " + workingDir + " to "
320         + finishedDir);
321     if (!fs.rename(workingDir, finishedDir)) {
322       throw new SnapshotCreationException("Failed to move working directory(" + workingDir
323           + ") to completed directory(" + finishedDir + ").", snapshot);
324     }
325   }
326 
327 }