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From: anew <git@git.apache.org>
To: dev@tephra.incubator.apache.org
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Subject: [GitHub] incubator-tephra pull request #20: Compute global prune upper bound using co...
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Message-Id: <20161203162142.69042EEE33@git1-us-west.apache.org>
Date: Sat,  3 Dec 2016 16:21:42 +0000 (UTC)
archived-at: Sat, 03 Dec 2016 16:21:50 -0000

Github user anew commented on a diff in the pull request:

    https://github.com/apache/incubator-tephra/pull/20#discussion_r90759321
  
    --- Diff: tephra-hbase-compat-1.1-base/src/main/java/org/apache/tephra/hbase/coprocessor/janitor/DataJanitorState.java ---
    @@ -58,10 +110,248 @@ public long getPruneUpperBound(byte[] regionId) throws IOException {
         }
       }
     
    +  /**
    +   * Get latest prune upper bounds for given regions. This is a batch operation of method
    +   * {@link #getPruneUpperBoundForRegion(byte[])}
    +   *
    +   * @param regions a set of regions
    +   * @return a map containing region id and its latest prune upper bound value
    +   * @throws IOException when not able to read the data from HBase
    +   */
    +  public Map<byte[], Long> getPruneUpperBoundForRegions(SortedSet<byte[]> regions) throws IOException {
    +    Map<byte[], Long> resultMap = new TreeMap<>(Bytes.BYTES_COMPARATOR);
    +    try (Table stateTable = stateTableSupplier.get()) {
    +      byte[] startRow = makeRegionKey(EMPTY_BYTE_ARRAY);
    +      Scan scan = new Scan(startRow, REGION_KEY_PREFIX_STOP);
    +      scan.addColumn(FAMILY, PRUNE_UPPER_BOUND_COL);
    +
    +      try (ResultScanner scanner = stateTable.getScanner(scan)) {
    +        Result next;
    +        while ((next = scanner.next()) != null) {
    +          byte[] region = getRegionFromKey(next.getRow());
    +          if (regions.contains(region)) {
    +            byte[] timeBytes = next.getValue(FAMILY, PRUNE_UPPER_BOUND_COL);
    +            if (timeBytes != null) {
    +              long pruneUpperBoundRegion = Bytes.toLong(timeBytes);
    +              resultMap.put(region, pruneUpperBoundRegion);
    +            }
    +          }
    +        }
    +      }
    +      return resultMap;
    +    }
    +  }
    +
    +  /**
    +   * Delete all regions that are not in the given exclude set and whose prune upper bound is less than a given value.
    +   * After the invalid list is pruned up to deletionPruneUpperBound, we do not need entries for regions that have
    +   * prune upper bound less than deletionPruneUpperBound. We however limit the deletion to only regions that are
    +   * no longer in existence (due to deletion, etc.), to avoid update/delete race conditions.
    +   *
    +   * @param deletionPruneUpperBound prune upper bound below which regions will be deleted
    +   * @param excludeRegions set of regions that should not be deleted
    +   * @throws IOException when not able to delete data in HBase
    +   */
    +  public void deleteRegionsWithPruneUpperBoundBefore(long deletionPruneUpperBound, SortedSet<byte[]> excludeRegions)
    +    throws IOException {
    +    try (Table stateTable = stateTableSupplier.get()) {
    +      byte[] startRow = makeRegionKey(EMPTY_BYTE_ARRAY);
    +      Scan scan = new Scan(startRow, REGION_KEY_PREFIX_STOP);
    +      scan.addColumn(FAMILY, PRUNE_UPPER_BOUND_COL);
    +
    +      try (ResultScanner scanner = stateTable.getScanner(scan)) {
    +        Result next;
    +        while ((next = scanner.next()) != null) {
    +          byte[] region = getRegionFromKey(next.getRow());
    +          if (!excludeRegions.contains(region)) {
    +            byte[] timeBytes = next.getValue(FAMILY, PRUNE_UPPER_BOUND_COL);
    +            if (timeBytes != null) {
    +              long pruneUpperBoundRegion = Bytes.toLong(timeBytes);
    +              if (pruneUpperBoundRegion < deletionPruneUpperBound) {
    +                stateTable.delete(new Delete(next.getRow()));
    +              }
    +            }
    +          }
    +        }
    +      }
    +    }
    +  }
    +
    +  // ---------------------------------------------------
    +  // ------- Methods for regions at a given time -------
    +  // ---------------------------------------------------
    +  // Key: 0x2<time><region-id>
    +  // Col 't': <empty byte array>
    +  // ---------------------------------------------------
    +
    +  /**
    +   * Persist the regions for the given time. {@link HBaseTransactionPruningPlugin} saves the set of
    +   * transactional regions existing in the HBase instance periodically.
    +   *
    +   * @param time timestamp in milliseconds
    +   * @param regions set of regions at the time
    +   * @throws IOException when not able to persist the data to HBase
    +   */
    +  public void saveRegionsForTime(long time, Set<byte[]> regions) throws IOException {
    +    byte[] timeBytes = Bytes.toBytes(getInvertedTime(time));
    +    try (Table stateTable = stateTableSupplier.get()) {
    +      for (byte[] region : regions) {
    +        Put put = new Put(makeTimeRegionKey(timeBytes, region));
    +        put.addColumn(FAMILY, REGION_TIME_COL, EMPTY_BYTE_ARRAY);
    +        stateTable.put(put);
    +      }
    +    }
    +  }
    +
    +  /**
    +   * Return the set of regions saved for the time just before the given time. This method finds the greatest time
    --- End diff --
    
    Seems that this is the set of regions at or before the given time. (time itself is included in the scan). 


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