/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.apache.hadoop.hbase.io.hfile;

import java.io.Closeable;
import java.io.DataInput;
import java.io.IOException;
import java.net.InetSocketAddress;
import java.util.ArrayList;
import java.util.List;
import java.util.Optional;
import java.util.concurrent.atomic.LongAdder;
import org.apache.commons.io.IOUtils;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.FSDataOutputStream;
import org.apache.hadoop.fs.FileStatus;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.fs.PathFilter;
import org.apache.hadoop.hbase.Cell;
import org.apache.hadoop.hbase.CellComparator;
import org.apache.hadoop.hbase.HConstants;
import org.apache.hadoop.hbase.io.FSDataInputStreamWrapper;
import org.apache.hadoop.hbase.io.MetricsIO;
import org.apache.hadoop.hbase.io.MetricsIOWrapperImpl;
import org.apache.hadoop.hbase.io.compress.Compression;
import org.apache.hadoop.hbase.io.encoding.DataBlockEncoding;
import org.apache.hadoop.hbase.io.hfile.ReaderContext.ReaderType;
import org.apache.hadoop.hbase.regionserver.CellSink;
import org.apache.hadoop.hbase.regionserver.ShipperListener;
import org.apache.hadoop.hbase.util.BloomFilterWriter;
import org.apache.hadoop.hbase.util.Bytes;
import org.apache.hadoop.hbase.util.FSUtils;
import org.apache.hadoop.io.Writable;
import org.apache.yetus.audience.InterfaceAudience;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import org.apache.hbase.thirdparty.com.google.common.base.Preconditions;

/**
 * File format for hbase. A file of sorted key/value pairs. Both keys and values are byte arrays.
 * <p>
 * The memory footprint of a HFile includes the following (below is taken from the <a
 * href=https://issues.apache.org/jira/browse/HADOOP-3315>TFile</a> documentation but applies also
 * to HFile):
 * <ul>
 * <li>Some constant overhead of reading or writing a compressed block.
 * <ul>
 * <li>Each compressed block requires one compression/decompression codec for I/O.
 * <li>Temporary space to buffer the key.
 * <li>Temporary space to buffer the value.
 * </ul>
 * <li>HFile index, which is proportional to the total number of Data Blocks. The total amount of
 * memory needed to hold the index can be estimated as (56+AvgKeySize)*NumBlocks.
 * </ul>
 * Suggestions on performance optimization.
 * <ul>
 * <li>Minimum block size. We recommend a setting of minimum block size between 8KB to 1MB for
 * general usage. Larger block size is preferred if files are primarily for sequential access.
 * However, it would lead to inefficient random access (because there are more data to decompress).
 * Smaller blocks are good for random access, but require more memory to hold the block index, and
 * may be slower to create (because we must flush the compressor stream at the conclusion of each
 * data block, which leads to an FS I/O flush). Further, due to the internal caching in Compression
 * codec, the smallest possible block size would be around 20KB-30KB.
 * <li>The current implementation does not offer true multi-threading for reading. The
 * implementation uses FSDataInputStream seek()+read(), which is shown to be much faster than
 * positioned-read call in single thread mode. However, it also means that if multiple threads
 * attempt to access the same HFile (using multiple scanners) simultaneously, the actual I/O is
 * carried out sequentially even if they access different DFS blocks (Reexamine! pread seems to be
 * 10% faster than seek+read in my testing -- stack).
 * <li>Compression codec. Use "none" if the data is not very compressable (by compressable, I mean a
 * compression ratio at least 2:1). Generally, use "lzo" as the starting point for experimenting.
 * "gz" overs slightly better compression ratio over "lzo" but requires 4x CPU to compress and 2x
 * CPU to decompress, comparing to "lzo".
 * </ul>
 * For more on the background behind HFile, see <a
 * href=https://issues.apache.org/jira/browse/HBASE-61>HBASE-61</a>.
 * <p>
 * File is made of data blocks followed by meta data blocks (if any), a fileinfo block, data block
 * index, meta data block index, and a fixed size trailer which records the offsets at which file
 * changes content type.
 *
 * <pre>
 * &lt;data blocks&gt;&lt;meta blocks&gt;&lt;fileinfo&gt;&lt;
 * data index&gt;&lt;meta index&gt;&lt;trailer&gt;
 * </pre>
 *
 * Each block has a bit of magic at its start. Block are comprised of key/values. In data blocks,
 * they are both byte arrays. Metadata blocks are a String key and a byte array value. An empty file
 * looks like this:
 *
 * <pre>
 * &lt;fileinfo&gt;&lt;trailer&gt;
 * </pre>
 *
 * . That is, there are not data nor meta blocks present.
 * <p>
 * TODO: Do scanners need to be able to take a start and end row? TODO: Should BlockIndex know the
 * name of its file? Should it have a Path that points at its file say for the case where an index
 * lives apart from an HFile instance?
 */
@InterfaceAudience.Private
public final class HFile {
  // LOG is being used in HFileBlock and CheckSumUtil
  static final Logger LOG = LoggerFactory.getLogger(HFile.class);

  /**
   * Maximum length of key in HFile.
   */
  public final static int MAXIMUM_KEY_LENGTH = Integer.MAX_VALUE;

  /**
   * Default compression: none.
   */
  public final static Compression.Algorithm DEFAULT_COMPRESSION_ALGORITHM =
    Compression.Algorithm.NONE;

  /** Minimum supported HFile format version */
  public static final int MIN_FORMAT_VERSION = 2;

  /**
   * Maximum supported HFile format version
   */
  public static final int MAX_FORMAT_VERSION = 3;

  /**
   * Minimum HFile format version with support for persisting cell tags
   */
  public static final int MIN_FORMAT_VERSION_WITH_TAGS = 3;

  /** Default compression name: none. */
  public final static String DEFAULT_COMPRESSION = DEFAULT_COMPRESSION_ALGORITHM.getName();

  /** Meta data block name for bloom filter bits. */
  public static final String BLOOM_FILTER_DATA_KEY = "BLOOM_FILTER_DATA";

  /**
   * We assume that HFile path ends with ROOT_DIR/TABLE_NAME/REGION_NAME/CF_NAME/HFILE, so it has at
   * least this many levels of nesting. This is needed for identifying table and CF name from an
   * HFile path.
   */
  public final static int MIN_NUM_HFILE_PATH_LEVELS = 5;

  /**
   * The number of bytes per checksum.
   */
  public static final int DEFAULT_BYTES_PER_CHECKSUM = 16 * 1024;

  // For measuring number of checksum failures
  static final LongAdder CHECKSUM_FAILURES = new LongAdder();

  // For tests. Gets incremented when we read a block whether from HDFS or from Cache.
  public static final LongAdder DATABLOCK_READ_COUNT = new LongAdder();

  /** Static instance for the metrics so that HFileReaders access the same instance */
  static final MetricsIO metrics = new MetricsIO(new MetricsIOWrapperImpl());

  /**
   * Shutdown constructor.
   */
  private HFile() {
  }

  /**
   * Number of checksum verification failures. It also clears the counter.
   */
  public static final long getAndResetChecksumFailuresCount() {
    return CHECKSUM_FAILURES.sumThenReset();
  }

  /**
   * Number of checksum verification failures. It also clears the counter.
   */
  public static final long getChecksumFailuresCount() {
    return CHECKSUM_FAILURES.sum();
  }

  public static final void updateReadLatency(long latencyMillis, boolean pread) {
    if (pread) {
      metrics.updateFsPreadTime(latencyMillis);
    } else {
      metrics.updateFsReadTime(latencyMillis);
    }
  }

  public static final void updateWriteLatency(long latencyMillis) {
    metrics.updateFsWriteTime(latencyMillis);
  }

  /** API required to write an {@link HFile} */
  public interface Writer extends Closeable, CellSink, ShipperListener {
    /** Max memstore (mvcc) timestamp in FileInfo */
    public static final byte[] MAX_MEMSTORE_TS_KEY = Bytes.toBytes("MAX_MEMSTORE_TS_KEY");

    /** Add an element to the file info map. */
    void appendFileInfo(byte[] key, byte[] value) throws IOException;

    /** Returns the path to this {@link HFile} */
    Path getPath();

    /**
     * Adds an inline block writer such as a multi-level block index writer or a compound Bloom
     * filter writer.
     */
    void addInlineBlockWriter(InlineBlockWriter bloomWriter);

    // The below three methods take Writables. We'd like to undo Writables but undoing the below
    // would be pretty painful. Could take a byte [] or a Message but we want to be backward
    // compatible around hfiles so would need to map between Message and Writable or byte [] and
    // current Writable serialization. This would be a bit of work to little gain. Thats my
    // thinking at moment. St.Ack 20121129

    void appendMetaBlock(String bloomFilterMetaKey, Writable metaWriter);

    /**
     * Store general Bloom filter in the file. This does not deal with Bloom filter internals but is
     * necessary, since Bloom filters are stored differently in HFile version 1 and version 2.
     */
    void addGeneralBloomFilter(BloomFilterWriter bfw);

    /**
     * Store delete family Bloom filter in the file, which is only supported in HFile V2.
     */
    void addDeleteFamilyBloomFilter(BloomFilterWriter bfw) throws IOException;

    /**
     * Return the file context for the HFile this writer belongs to
     */
    HFileContext getFileContext();
  }

  /**
   * This variety of ways to construct writers is used throughout the code, and we want to be able
   * to swap writer implementations.
   */
  public static class WriterFactory {
    protected final Configuration conf;
    protected final CacheConfig cacheConf;
    protected FileSystem fs;
    protected Path path;
    protected FSDataOutputStream ostream;
    protected InetSocketAddress[] favoredNodes;
    private HFileContext fileContext;
    protected boolean shouldDropBehind = false;

    WriterFactory(Configuration conf, CacheConfig cacheConf) {
      this.conf = conf;
      this.cacheConf = cacheConf;
    }

    public WriterFactory withPath(FileSystem fs, Path path) {
      Preconditions.checkNotNull(fs);
      Preconditions.checkNotNull(path);
      this.fs = fs;
      this.path = path;
      return this;
    }

    public WriterFactory withOutputStream(FSDataOutputStream ostream) {
      Preconditions.checkNotNull(ostream);
      this.ostream = ostream;
      return this;
    }

    public WriterFactory withFavoredNodes(InetSocketAddress[] favoredNodes) {
      // Deliberately not checking for null here.
      this.favoredNodes = favoredNodes;
      return this;
    }

    public WriterFactory withFileContext(HFileContext fileContext) {
      this.fileContext = fileContext;
      return this;
    }

    public WriterFactory withShouldDropCacheBehind(boolean shouldDropBehind) {
      this.shouldDropBehind = shouldDropBehind;
      return this;
    }

    public Writer create() throws IOException {
      if ((path != null ? 1 : 0) + (ostream != null ? 1 : 0) != 1) {
        throw new AssertionError("Please specify exactly one of " + "filesystem/path or path");
      }
      if (path != null) {
        ostream = HFileWriterImpl.createOutputStream(conf, fs, path, favoredNodes);
        try {
          ostream.setDropBehind(shouldDropBehind && cacheConf.shouldDropBehindCompaction());
        } catch (UnsupportedOperationException uoe) {
          LOG.trace("Unable to set drop behind on {}", path, uoe);
          LOG.debug("Unable to set drop behind on {}", path.getName());
        }
      }
      return new HFileWriterImpl(conf, cacheConf, path, ostream, fileContext);
    }
  }

  /** The configuration key for HFile version to use for new files */
  public static final String FORMAT_VERSION_KEY = "hfile.format.version";

  public static int getFormatVersion(Configuration conf) {
    int version = conf.getInt(FORMAT_VERSION_KEY, MAX_FORMAT_VERSION);
    checkFormatVersion(version);
    return version;
  }

  /**
   * Returns the factory to be used to create {@link HFile} writers. Disables block cache access for
   * all writers created through the returned factory.
   */
  public static final WriterFactory getWriterFactoryNoCache(Configuration conf) {
    return HFile.getWriterFactory(conf, CacheConfig.DISABLED);
  }

  /**
   * Returns the factory to be used to create {@link HFile} writers
   */
  public static final WriterFactory getWriterFactory(Configuration conf, CacheConfig cacheConf) {
    int version = getFormatVersion(conf);
    switch (version) {
      case 2:
        throw new IllegalArgumentException("This should never happen. "
          + "Did you change hfile.format.version to read v2? This version of the software writes v3"
          + " hfiles only (but it can read v2 files without having to update hfile.format.version "
          + "in hbase-site.xml)");
      case 3:
        return new HFile.WriterFactory(conf, cacheConf);
      default:
        throw new IllegalArgumentException(
          "Cannot create writer for HFile " + "format version " + version);
    }
  }

  /**
   * An abstraction used by the block index. Implementations will check cache for any asked-for
   * block and return cached block if found. Otherwise, after reading from fs, will try and put
   * block into cache before returning.
   */
  public interface CachingBlockReader {
    /**
     * Read in a file block.
     * @param offset                    offset to read.
     * @param onDiskBlockSize           size of the block
     * @param isCompaction              is this block being read as part of a compaction
     * @param expectedBlockType         the block type we are expecting to read with this read
     *                                  operation, or null to read whatever block type is available
     *                                  and avoid checking (that might reduce caching efficiency of
     *                                  encoded data blocks)
     * @param expectedDataBlockEncoding the data block encoding the caller is expecting data blocks
     *                                  to be in, or null to not perform this check and return the
     *                                  block irrespective of the encoding. This check only applies
     *                                  to data blocks and can be set to null when the caller is
     *                                  expecting to read a non-data block and has set
     *                                  expectedBlockType accordingly.
     * @return Block wrapped in a ByteBuffer.
     */
    HFileBlock readBlock(long offset, long onDiskBlockSize, boolean cacheBlock, final boolean pread,
      final boolean isCompaction, final boolean updateCacheMetrics, BlockType expectedBlockType,
      DataBlockEncoding expectedDataBlockEncoding) throws IOException;
  }

  /** An interface used by clients to open and iterate an {@link HFile}. */
  public interface Reader extends Closeable, CachingBlockReader {
    /**
     * Returns this reader's "name". Usually the last component of the path. Needs to be constant as
     * the file is being moved to support caching on write.
     */
    String getName();

    CellComparator getComparator();

    HFileScanner getScanner(Configuration conf, boolean cacheBlocks, boolean pread,
      boolean isCompaction);

    HFileBlock getMetaBlock(String metaBlockName, boolean cacheBlock) throws IOException;

    Optional<Cell> getLastKey();

    Optional<Cell> midKey() throws IOException;

    long length();

    long getEntries();

    Optional<Cell> getFirstKey();

    long indexSize();

    Optional<byte[]> getFirstRowKey();

    Optional<byte[]> getLastRowKey();

    FixedFileTrailer getTrailer();

    void setDataBlockIndexReader(HFileBlockIndex.CellBasedKeyBlockIndexReader reader);

    HFileBlockIndex.CellBasedKeyBlockIndexReader getDataBlockIndexReader();

    void setMetaBlockIndexReader(HFileBlockIndex.ByteArrayKeyBlockIndexReader reader);

    HFileBlockIndex.ByteArrayKeyBlockIndexReader getMetaBlockIndexReader();

    HFileScanner getScanner(Configuration conf, boolean cacheBlocks, boolean pread);

    /**
     * Retrieves general Bloom filter metadata as appropriate for each {@link HFile} version. Knows
     * nothing about how that metadata is structured.
     */
    DataInput getGeneralBloomFilterMetadata() throws IOException;

    /**
     * Retrieves delete family Bloom filter metadata as appropriate for each {@link HFile} version.
     * Knows nothing about how that metadata is structured.
     */
    DataInput getDeleteBloomFilterMetadata() throws IOException;

    Path getPath();

    /** Close method with optional evictOnClose */
    void close(boolean evictOnClose) throws IOException;

    DataBlockEncoding getDataBlockEncoding();

    boolean hasMVCCInfo();

    /**
     * Return the file context of the HFile this reader belongs to
     */
    HFileContext getFileContext();

    boolean isPrimaryReplicaReader();

    DataBlockEncoding getEffectiveEncodingInCache(boolean isCompaction);

    HFileBlock.FSReader getUncachedBlockReader();

    boolean prefetchComplete();

    /**
     * To close the stream's socket. Note: This can be concurrently called from multiple threads and
     * implementation should take care of thread safety.
     */
    void unbufferStream();

    ReaderContext getContext();

    HFileInfo getHFileInfo();

    void setDataBlockEncoder(HFileDataBlockEncoder dataBlockEncoder);
  }

  /**
   * Method returns the reader given the specified arguments. TODO This is a bad abstraction. See
   * HBASE-6635.
   * @param context   Reader context info
   * @param fileInfo  HFile info
   * @param cacheConf Cache configuation values, cannot be null.
   * @param conf      Configuration
   * @return an appropriate instance of HFileReader
   * @throws IOException If file is invalid, will throw CorruptHFileException flavored IOException
   */
  @edu.umd.cs.findbugs.annotations.SuppressWarnings(value = "SF_SWITCH_FALLTHROUGH",
      justification = "Intentional")
  public static Reader createReader(ReaderContext context, HFileInfo fileInfo,
    CacheConfig cacheConf, Configuration conf) throws IOException {
    try {
      if (context.getReaderType() == ReaderType.STREAM) {
        // stream reader will share trailer with pread reader, see HFileStreamReader#copyFields
        return new HFileStreamReader(context, fileInfo, cacheConf, conf);
      }
      FixedFileTrailer trailer = fileInfo.getTrailer();
      switch (trailer.getMajorVersion()) {
        case 2:
          LOG.debug("Opening HFile v2 with v3 reader");
          // Fall through. FindBugs: SF_SWITCH_FALLTHROUGH
        case 3:
          return new HFilePreadReader(context, fileInfo, cacheConf, conf);
        default:
          throw new IllegalArgumentException("Invalid HFile version " + trailer.getMajorVersion());
      }
    } catch (Throwable t) {
      IOUtils.closeQuietly(context.getInputStreamWrapper(),
        e -> LOG.warn("failed to close input stream wrapper", e));
      throw new CorruptHFileException(
        "Problem reading HFile Trailer from file " + context.getFilePath(), t);
    } finally {
      context.getInputStreamWrapper().unbuffer();
    }
  }

  /**
   * Creates reader with cache configuration disabled
   * @param fs   filesystem
   * @param path Path to file to read
   * @param conf Configuration
   * @return an active Reader instance
   * @throws IOException Will throw a CorruptHFileException (DoNotRetryIOException subtype) if hfile
   *                     is corrupt/invalid.
   */
  public static Reader createReader(FileSystem fs, Path path, Configuration conf)
    throws IOException {
    // The primaryReplicaReader is mainly used for constructing block cache key, so if we do not use
    // block cache then it is OK to set it as any value. We use true here.
    return createReader(fs, path, CacheConfig.DISABLED, true, conf);
  }

  /**
   * @param fs                   filesystem
   * @param path                 Path to file to read
   * @param cacheConf            This must not be null.
   * @param primaryReplicaReader true if this is a reader for primary replica
   * @param conf                 Configuration
   * @return an active Reader instance
   * @throws IOException Will throw a CorruptHFileException (DoNotRetryIOException subtype) if hfile
   *                     is corrupt/invalid.
   * @see CacheConfig#CacheConfig(Configuration)
   */
  public static Reader createReader(FileSystem fs, Path path, CacheConfig cacheConf,
    boolean primaryReplicaReader, Configuration conf) throws IOException {
    Preconditions.checkNotNull(cacheConf, "Cannot create Reader with null CacheConf");
    FSDataInputStreamWrapper stream = new FSDataInputStreamWrapper(fs, path);
    ReaderContext context =
      new ReaderContextBuilder().withFilePath(path).withInputStreamWrapper(stream)
        .withFileSize(fs.getFileStatus(path).getLen()).withFileSystem(stream.getHfs())
        .withPrimaryReplicaReader(primaryReplicaReader).withReaderType(ReaderType.PREAD).build();
    HFileInfo fileInfo = new HFileInfo(context, conf);
    Reader reader = createReader(context, fileInfo, cacheConf, conf);
    fileInfo.initMetaAndIndex(reader);
    return reader;
  }

  /**
   * Returns true if the specified file has a valid HFile Trailer.
   * @param fs   filesystem
   * @param path Path to file to verify
   * @return true if the file has a valid HFile Trailer, otherwise false
   * @throws IOException if failed to read from the underlying stream
   */
  public static boolean isHFileFormat(final FileSystem fs, final Path path) throws IOException {
    return isHFileFormat(fs, fs.getFileStatus(path));
  }

  /**
   * Returns true if the specified file has a valid HFile Trailer.
   * @param fs         filesystem
   * @param fileStatus the file to verify
   * @return true if the file has a valid HFile Trailer, otherwise false
   * @throws IOException if failed to read from the underlying stream
   */
  public static boolean isHFileFormat(final FileSystem fs, final FileStatus fileStatus)
    throws IOException {
    final Path path = fileStatus.getPath();
    final long size = fileStatus.getLen();
    try (FSDataInputStreamWrapper fsdis = new FSDataInputStreamWrapper(fs, path)) {
      boolean isHBaseChecksum = fsdis.shouldUseHBaseChecksum();
      assert !isHBaseChecksum; // Initially we must read with FS checksum.
      FixedFileTrailer.readFromStream(fsdis.getStream(isHBaseChecksum), size);
      return true;
    } catch (IllegalArgumentException e) {
      return false;
    }
  }

  /**
   * Get names of supported compression algorithms. The names are acceptable by HFile.Writer.
   * @return Array of strings, each represents a supported compression algorithm. Currently, the
   *         following compression algorithms are supported.
   *         <ul>
   *         <li>"none" - No compression.
   *         <li>"gz" - GZIP compression.
   *         </ul>
   */
  public static String[] getSupportedCompressionAlgorithms() {
    return Compression.getSupportedAlgorithms();
  }

  // Utility methods.
  /*
   * @param l Long to convert to an int.
   * @return <code>l</code> cast as an int.
   */
  static int longToInt(final long l) {
    // Expecting the size() of a block not exceeding 4GB. Assuming the
    // size() will wrap to negative integer if it exceeds 2GB (From tfile).
    return (int) (l & 0x00000000ffffffffL);
  }

  /**
   * Returns all HFiles belonging to the given region directory. Could return an empty list.
   * @param fs        The file system reference.
   * @param regionDir The region directory to scan.
   * @return The list of files found.
   * @throws IOException When scanning the files fails.
   */
  public static List<Path> getStoreFiles(FileSystem fs, Path regionDir) throws IOException {
    List<Path> regionHFiles = new ArrayList<>();
    PathFilter dirFilter = new FSUtils.DirFilter(fs);
    FileStatus[] familyDirs = fs.listStatus(regionDir, dirFilter);
    for (FileStatus dir : familyDirs) {
      FileStatus[] files = fs.listStatus(dir.getPath());
      for (FileStatus file : files) {
        if (
          !file.isDirectory()
            && (!file.getPath().toString().contains(HConstants.HREGION_OLDLOGDIR_NAME))
            && (!file.getPath().toString().contains(HConstants.RECOVERED_EDITS_DIR))
        ) {
          regionHFiles.add(file.getPath());
        }
      }
    }
    return regionHFiles;
  }

  /**
   * Checks the given {@link HFile} format version, and throws an exception if invalid. Note that if
   * the version number comes from an input file and has not been verified, the caller needs to
   * re-throw an {@link IOException} to indicate that this is not a software error, but corrupted
   * input.
   * @param version an HFile version
   * @throws IllegalArgumentException if the version is invalid
   */
  public static void checkFormatVersion(int version) throws IllegalArgumentException {
    if (version < MIN_FORMAT_VERSION || version > MAX_FORMAT_VERSION) {
      throw new IllegalArgumentException("Invalid HFile version: " + version + " (expected to be "
        + "between " + MIN_FORMAT_VERSION + " and " + MAX_FORMAT_VERSION + ")");
    }
  }

  public static void checkHFileVersion(final Configuration c) {
    int version = c.getInt(FORMAT_VERSION_KEY, MAX_FORMAT_VERSION);
    if (version < MAX_FORMAT_VERSION || version > MAX_FORMAT_VERSION) {
      throw new IllegalArgumentException(
        "The setting for " + FORMAT_VERSION_KEY + " (in your hbase-*.xml files) is " + version
          + " which does not match " + MAX_FORMAT_VERSION
          + "; are you running with a configuration from an older or newer hbase install (an "
          + "incompatible hbase-default.xml or hbase-site.xml on your CLASSPATH)?");
    }
  }

  public static void main(String[] args) throws Exception {
    // delegate to preserve old behavior
    HFilePrettyPrinter.main(args);
  }
}