/**
  * Creates the scanner for flushing snapshot. Also calls coprocessors.
  *
  * @param snapshotScanner
  * @param smallestReadPoint
  * @return The scanner; null if coprocessor is canceling the flush.
  */
 protected InternalScanner createScanner(KeyValueScanner snapshotScanner, long smallestReadPoint)
     throws IOException {
   InternalScanner scanner = null;
   if (store.getCoprocessorHost() != null) {
     scanner = store.getCoprocessorHost().preFlushScannerOpen(store, snapshotScanner);
   }
   if (scanner == null) {
     Scan scan = new Scan();
     scan.setMaxVersions(store.getScanInfo().getMaxVersions());
     scanner =
         new StoreScanner(
             store,
             store.getScanInfo(),
             scan,
             Collections.singletonList(snapshotScanner),
             ScanType.COMPACT_RETAIN_DELETES,
             smallestReadPoint,
             HConstants.OLDEST_TIMESTAMP);
   }
   assert scanner != null;
   if (store.getCoprocessorHost() != null) {
     try {
       return store.getCoprocessorHost().preFlush(store, scanner);
     } catch (IOException ioe) {
       scanner.close();
       throw ioe;
     }
   }
   return scanner;
 }
  private static StripeCompactor createCompactor(StoreFileWritersCapture writers, KeyValue[] input)
      throws Exception {
    Configuration conf = HBaseConfiguration.create();
    final Scanner scanner = new Scanner(input);

    // Create store mock that is satisfactory for compactor.
    HColumnDescriptor col = new HColumnDescriptor(NAME_OF_THINGS);
    ScanInfo si = new ScanInfo(col, Long.MAX_VALUE, 0, CellComparator.COMPARATOR);
    Store store = mock(Store.class);
    when(store.getFamily()).thenReturn(col);
    when(store.getScanInfo()).thenReturn(si);
    when(store.areWritesEnabled()).thenReturn(true);
    when(store.getFileSystem()).thenReturn(mock(FileSystem.class));
    when(store.getRegionInfo()).thenReturn(new HRegionInfo(TABLE_NAME));
    when(store.createWriterInTmp(
            anyLong(), any(Compression.Algorithm.class), anyBoolean(), anyBoolean(), anyBoolean()))
        .thenAnswer(writers);
    when(store.getComparator()).thenReturn(CellComparator.COMPARATOR);

    return new StripeCompactor(conf, store) {
      @Override
      protected InternalScanner createScanner(
          Store store,
          List<StoreFileScanner> scanners,
          long smallestReadPoint,
          long earliestPutTs,
          byte[] dropDeletesFromRow,
          byte[] dropDeletesToRow)
          throws IOException {
        return scanner;
      }

      @Override
      protected InternalScanner createScanner(
          Store store,
          List<StoreFileScanner> scanners,
          ScanType scanType,
          long smallestReadPoint,
          long earliestPutTs)
          throws IOException {
        return scanner;
      }
    };
  }
  /**
   * Do a minor/major compaction on an explicit set of storefiles from a Store.
   *
   * @param request the requested compaction that contains all necessary information to complete the
   *     compaction (i.e. the store, the files, etc.)
   * @return Product of compaction or null if all cells expired or deleted and nothing made it
   *     through the compaction.
   * @throws IOException
   */
  StoreFile.Writer compact(CompactionRequest request, long maxId) throws IOException {
    // Calculate maximum key count after compaction (for blooms)
    // Also calculate earliest put timestamp if major compaction
    int maxKeyCount = 0;
    long earliestPutTs = HConstants.LATEST_TIMESTAMP;
    long maxMVCCReadpoint = 0;

    // pull out the interesting things from the CR for ease later
    final Store store = request.getStore();
    final boolean majorCompaction = request.isMajor();
    final List<StoreFile> filesToCompact = request.getFiles();

    for (StoreFile file : filesToCompact) {
      StoreFile.Reader r = file.getReader();
      if (r == null) {
        LOG.warn("Null reader for " + file.getPath());
        continue;
      }
      // NOTE: getFilterEntries could cause under-sized blooms if the user
      //       switches bloom type (e.g. from ROW to ROWCOL)
      long keyCount =
          (r.getBloomFilterType() == store.getFamily().getBloomFilterType())
              ? r.getFilterEntries()
              : r.getEntries();
      maxKeyCount += keyCount;
      // Calculate the maximum MVCC readpoint used in any of the involved files
      Map<byte[], byte[]> fileInfo = r.loadFileInfo();
      byte[] tmp = fileInfo.get(HFileWriterV2.MAX_MEMSTORE_TS_KEY);
      if (tmp != null) {
        maxMVCCReadpoint = Math.max(maxMVCCReadpoint, Bytes.toLong(tmp));
      }
      // For major compactions calculate the earliest put timestamp
      // of all involved storefiles. This is used to remove
      // family delete marker during the compaction.
      if (majorCompaction) {
        tmp = fileInfo.get(StoreFile.EARLIEST_PUT_TS);
        if (tmp == null) {
          // There's a file with no information, must be an old one
          // assume we have very old puts
          earliestPutTs = HConstants.OLDEST_TIMESTAMP;
        } else {
          earliestPutTs = Math.min(earliestPutTs, Bytes.toLong(tmp));
        }
      }
      if (LOG.isDebugEnabled()) {
        LOG.debug(
            "Compacting "
                + file
                + ", keycount="
                + keyCount
                + ", bloomtype="
                + r.getBloomFilterType().toString()
                + ", size="
                + StringUtils.humanReadableInt(r.length())
                + ", encoding="
                + r.getHFileReader().getEncodingOnDisk()
                + (majorCompaction ? ", earliestPutTs=" + earliestPutTs : ""));
      }
    }

    // keep track of compaction progress
    this.progress = new CompactionProgress(maxKeyCount);
    // Get some configs
    int compactionKVMax = getConf().getInt("hbase.hstore.compaction.kv.max", 10);
    Compression.Algorithm compression = store.getFamily().getCompression();
    // Avoid overriding compression setting for major compactions if the user
    // has not specified it separately
    Compression.Algorithm compactionCompression =
        (store.getFamily().getCompactionCompression() != Compression.Algorithm.NONE)
            ? store.getFamily().getCompactionCompression()
            : compression;

    // For each file, obtain a scanner:
    List<StoreFileScanner> scanners =
        StoreFileScanner.getScannersForStoreFiles(filesToCompact, false, false, true);

    // Make the instantiation lazy in case compaction produces no product; i.e.
    // where all source cells are expired or deleted.
    StoreFile.Writer writer = null;
    // Find the smallest read point across all the Scanners.
    long smallestReadPoint = store.getHRegion().getSmallestReadPoint();
    MultiVersionConsistencyControl.setThreadReadPoint(smallestReadPoint);
    try {
      InternalScanner scanner = null;
      try {
        if (store.getHRegion().getCoprocessorHost() != null) {
          scanner =
              store
                  .getHRegion()
                  .getCoprocessorHost()
                  .preCompactScannerOpen(
                      store,
                      scanners,
                      majorCompaction ? ScanType.MAJOR_COMPACT : ScanType.MINOR_COMPACT,
                      earliestPutTs,
                      request);
        }
        if (scanner == null) {
          Scan scan = new Scan();
          scan.setMaxVersions(store.getFamily().getMaxVersions());
          /* Include deletes, unless we are doing a major compaction */
          scanner =
              new StoreScanner(
                  store,
                  store.getScanInfo(),
                  scan,
                  scanners,
                  majorCompaction ? ScanType.MAJOR_COMPACT : ScanType.MINOR_COMPACT,
                  smallestReadPoint,
                  earliestPutTs);
        }
        if (store.getHRegion().getCoprocessorHost() != null) {
          InternalScanner cpScanner =
              store.getHRegion().getCoprocessorHost().preCompact(store, scanner, request);
          // NULL scanner returned from coprocessor hooks means skip normal processing
          if (cpScanner == null) {
            return null;
          }
          scanner = cpScanner;
        }

        int bytesWritten = 0;
        // since scanner.next() can return 'false' but still be delivering data,
        // we have to use a do/while loop.
        List<KeyValue> kvs = new ArrayList<KeyValue>();
        // Limit to "hbase.hstore.compaction.kv.max" (default 10) to avoid OOME
        boolean hasMore;
        do {
          hasMore = scanner.next(kvs, compactionKVMax);
          if (writer == null && !kvs.isEmpty()) {
            writer =
                store.createWriterInTmp(
                    maxKeyCount,
                    compactionCompression,
                    true,
                    maxMVCCReadpoint >= smallestReadPoint);
          }
          if (writer != null) {
            // output to writer:
            for (KeyValue kv : kvs) {
              if (kv.getMemstoreTS() <= smallestReadPoint) {
                kv.setMemstoreTS(0);
              }
              writer.append(kv);
              // update progress per key
              ++progress.currentCompactedKVs;

              // check periodically to see if a system stop is requested
              if (Store.closeCheckInterval > 0) {
                bytesWritten += kv.getLength();
                if (bytesWritten > Store.closeCheckInterval) {
                  bytesWritten = 0;
                  isInterrupted(store, writer);
                }
              }
            }
          }
          kvs.clear();
        } while (hasMore);
      } finally {
        if (scanner != null) {
          scanner.close();
        }
      }
    } finally {
      if (writer != null) {
        writer.appendMetadata(maxId, majorCompaction);
        writer.close();
      }
    }
    return writer;
  }