Examples of HLog

org.apache.hadoop.hbase.HLog
HLog stores all the edits to the HStore. It performs logfile-rolling, so external callers are not aware that the underlying file is being rolled.
A single HLog is used by several HRegions simultaneously.
Each HRegion is identified by a unique long int. HRegions do not need to declare themselves before using the HLog; they simply include their HRegion-id in the {@link #append(Text,Text,Text,TreeMap,long)} or {@link #completeCacheFlush(Text,Text,long)} calls.
An HLog consists of multiple on-disk files, which have a chronological order. As data is flushed to other (better) on-disk structures, the log becomes obsolete. We can destroy all the log messages for a given HRegion-id up to the most-recent CACHEFLUSH message from that HRegion.
It's only practical to delete entire files. Thus, we delete an entire on-disk file F when all of the messages in F have a log-sequence-id that's older (smaller) than the most-recent CACHEFLUSH message for every HRegion that has a message in F.
TODO: Vuk Ercegovac also pointed out that keeping HBase HRegion edit logs in HDFS is currently flawed. HBase writes edits to logs and to a memcache. The 'atomic' write to the log is meant to serve as insurance against abnormal RegionServer exit: on startup, the log is rerun to reconstruct an HRegion's last wholesome state. But files in HDFS do not 'exist' until they are cleanly closed -- something that will not happen if RegionServer exits without running its 'close'.
org.apache.hadoop.hbase.regionserver.HLog
HLog stores all the edits to the HStore. It performs logfile-rolling, so external callers are not aware that the underlying file is being rolled.
A single HLog is used by several HRegions simultaneously.
Each HRegion is identified by a unique long int. HRegions do not need to declare themselves before using the HLog; they simply include their HRegion-id in the append or completeCacheFlush calls.
An HLog consists of multiple on-disk files, which have a chronological order. As data is flushed to other (better) on-disk structures, the log becomes obsolete. We can destroy all the log messages for a given HRegion-id up to the most-recent CACHEFLUSH message from that HRegion.
It's only practical to delete entire files. Thus, we delete an entire on-disk file F when all of the messages in F have a log-sequence-id that's older (smaller) than the most-recent CACHEFLUSH message for every HRegion that has a message in F.
Synchronized methods can never execute in parallel. However, between the start of a cache flush and the completion point, appends are allowed but log rolling is not. To prevent log rolling taking place during this period, a separate reentrant lock is used.
org.apache.hadoop.hbase.regionserver.wal.HLog
HLog stores all the edits to the HStore. Its the hbase write-ahead-log implementation. It performs logfile-rolling, so external callers are not aware that the underlying file is being rolled.
There is one HLog per RegionServer. All edits for all Regions carried by a particular RegionServer are entered first in the HLog.
Each HRegion is identified by a unique long int. HRegions do not need to declare themselves before using the HLog; they simply include their HRegion-id in the append or completeCacheFlush calls.
An HLog consists of multiple on-disk files, which have a chronological order. As data is flushed to other (better) on-disk structures, the log becomes obsolete. We can destroy all the log messages for a given HRegion-id up to the most-recent CACHEFLUSH message from that HRegion.
It's only practical to delete entire files. Thus, we delete an entire on-disk file F when all of the messages in F have a log-sequence-id that's older (smaller) than the most-recent CACHEFLUSH message for every HRegion that has a message in F.
Synchronized methods can never execute in parallel. However, between the start of a cache flush and the completion point, appends are allowed but log rolling is not. To prevent log rolling taking place during this period, a separate reentrant lock is used.
To read an HLog, call {@link #getReader(org.apache.hadoop.fs.FileSystem,org.apache.hadoop.fs.Path,org.apache.hadoop.conf.Configuration)}.

Examples of org.apache.hadoop.hbase.HLog

        " does not exist.";
        LOG.error(message);
        throw new FileNotFoundException(message);
      }


      this.log = new HLog(this.fs, 
          new Path(this.fs.getHomeDirectory(),
              HConstants.HREGION_LOGDIR_NAME + "_" + System.currentTimeMillis()
          ),
          this.conf, null
      );

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Examples of org.apache.hadoop.hbase.regionserver.HLog


    // Create a log that we can reuse when we need to open regions
    Path logPath = new Path("/tmp", HConstants.HREGION_LOGDIR_NAME + "_" +
      System.currentTimeMillis());
    LOG.info("Creating log " + logPath.toString());
    HLog log = new HLog(this.fs, logPath, this.conf, null);
    try {
       // Merge Region 0 and Region 1
      HRegion merged = mergeAndVerify("merging regions 0 and 1",
        this.sourceRegions[0].getRegionNameAsString(),
        this.sourceRegions[1].getRegionNameAsString(), log, 2);


      // Merge the result of merging regions 0 and 1 with region 2
      merged = mergeAndVerify("merging regions 0+1 and 2",
        merged.getRegionInfo().getRegionNameAsString(),
        this.sourceRegions[2].getRegionNameAsString(), log, 3);


      // Merge the result of merging regions 0, 1 and 2 with region 3
      merged = mergeAndVerify("merging regions 0+1+2 and 3",
        merged.getRegionInfo().getRegionNameAsString(),
        this.sourceRegions[3].getRegionNameAsString(), log, 4);
      
      // Merge the result of merging regions 0, 1, 2 and 3 with region 4
      merged = mergeAndVerify("merging regions 0+1+2+3 and 4",
        merged.getRegionInfo().getRegionNameAsString(),
        this.sourceRegions[4].getRegionNameAsString(), log, rows.length);
    } finally {
      log.closeAndDelete();
    }
  }

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Examples of org.apache.hadoop.hbase.regionserver.wal.HLog

   * @param oldLogDir
   * @return WAL instance.
   * @throws IOException
   */
  protected HLog instantiateHLog(Path logdir, Path oldLogDir) throws IOException {
    return new HLog(this.fs.getBackingFs(), logdir, oldLogDir, this.conf,
      getWALActionListeners(), this.serverNameFromMasterPOV.toString());
  }

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Examples of org.apache.hadoop.hbase.regionserver.wal.HLog

    return c.getBlockCacheColumnFamilySummaries(this.conf);
  }


  @Override
  public byte[][] rollHLogWriter() throws IOException, FailedLogCloseException {
    HLog wal = this.getWAL();
    return wal.rollWriter(true);
  }

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Examples of org.apache.hadoop.hbase.regionserver.wal.HLog

    Path regionDir = HRegion.getRegionDir(tableDir, info.getEncodedName());
    FileSystem fs = FileSystem.get(conf);
    fs.mkdirs(regionDir);
    // Write HRI to a file in case we need to recover .META.
    writeRegioninfoOnFilesystem(info, regionDir, fs, conf);
    HLog effectiveHLog = hlog;
    if (hlog == null && !ignoreHLog) {
      effectiveHLog = new HLog(fs, new Path(regionDir, HConstants.HREGION_LOGDIR_NAME),
          new Path(regionDir, HConstants.HREGION_OLDLOGDIR_NAME), conf);
    }
    HRegion region = HRegion.newHRegion(tableDir,
        effectiveHLog, fs, conf, info, hTableDescriptor, null);
    if (initialize) {

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Examples of org.apache.hadoop.hbase.regionserver.wal.HLog

      listPaths(fs, b.getRegionDir());
    }


    Configuration conf = a.getConf();
    HTableDescriptor tabledesc = a.getTableDesc();
    HLog log = a.getLog();
    Path tableDir = a.getTableDir();
    // Presume both are of same region type -- i.e. both user or catalog
    // table regions.  This way can use comparator.
    final byte[] startKey =
      (a.comparator.matchingRows(a.getStartKey(), 0, a.getStartKey().length,

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Examples of org.apache.hadoop.hbase.regionserver.wal.HLog

    final Path logdir = new Path(c.get("hbase.tmp.dir"),
        "hlog" + tableDir.getName()
        + EnvironmentEdgeManager.currentTimeMillis());
    final Path oldLogDir = new Path(c.get("hbase.tmp.dir"),
        HConstants.HREGION_OLDLOGDIR_NAME);
    final HLog log = new HLog(fs, logdir, oldLogDir, c);
    try {
      processTable(fs, tableDir, log, c, majorCompact);
    } finally {
       log.close();
       // TODO: is this still right?
       BlockCache bc = new CacheConfig(c).getBlockCache();
       if (bc != null) bc.shutdown();
    }
  }

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Examples of org.apache.hadoop.hbase.regionserver.wal.HLog


    fs.delete(logdir, true);


    htd.addFamily(hcd);
    HRegionInfo info = new HRegionInfo(htd.getTableName(), null, null, false);
    HLog hlog = HLogFactory.createHLog(fs, basedir, logName, conf);
    HRegion region = new HRegion(tableDir, hlog, fs, conf, info, htd, null);


    store = new HStore(region, hcd, conf);
  }

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Examples of org.apache.hadoop.hbase.regionserver.wal.HLog

    TEST_UTIL.createTable(tableName, "cf");
    try {
      HTable table = new HTable(TEST_UTIL.getConfiguration(), tableName);
      try {
        HRegionServer server = TEST_UTIL.getRSForFirstRegionInTable(Bytes.toBytes(tableName));
        HLog log = server.getWAL();
        checkMinLogRolls(log, 5);
      } finally {
        table.close();
      }
    } finally {

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Examples of org.apache.hadoop.hbase.regionserver.wal.HLog

    final String family = "cf";


    TEST_UTIL.createTable(tableName, family);
    try {
      HRegionServer server = TEST_UTIL.getRSForFirstRegionInTable(Bytes.toBytes(tableName));
      HLog log = server.getWAL();
      final HTable table = new HTable(TEST_UTIL.getConfiguration(), tableName);


      Thread writerThread = new Thread("writer") {
        @Override
        public void run() {

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