/**
    *
    * 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.ByteArrayInputStream;
  import java.io.Closeable;
  import java.io.DataInput;
  import java.io.DataInputStream;
  import java.io.DataOutputStream;
  import java.io.IOException;
  import java.io.SequenceInputStream;
  import java.net.InetSocketAddress;
  import java.nio.ByteBuffer;
  import java.util.ArrayList;
  import java.util.Collection;
  import java.util.Comparator;
  import java.util.List;
  import java.util.Map;
  import java.util.Set;
  import java.util.SortedMap;
  import java.util.TreeMap;
  
  import org.apache.commons.logging.Log;
  import org.apache.commons.logging.LogFactory;
  import org.apache.hadoop.hbase.classification.InterfaceAudience;
  import org.apache.hadoop.conf.Configuration;
  import org.apache.hadoop.fs.FSDataInputStream;
  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.HConstants;
  import org.apache.hadoop.hbase.KeyValue;
  import org.apache.hadoop.hbase.KeyValue.KVComparator;
  import org.apache.hadoop.hbase.fs.HFileSystem;
  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.protobuf.ProtobufUtil;
  import org.apache.hadoop.hbase.protobuf.generated.HBaseProtos;
  import org.apache.hadoop.hbase.protobuf.generated.HBaseProtos.BytesBytesPair;
  import org.apache.hadoop.hbase.protobuf.generated.HFileProtos;
  import org.apache.hadoop.hbase.util.BloomFilterWriter;
  import org.apache.hadoop.hbase.util.ByteStringer;
  import org.apache.hadoop.hbase.util.Bytes;
  import org.apache.hadoop.hbase.util.Counter;
  import org.apache.hadoop.hbase.util.FSUtils;
  import org.apache.hadoop.io.Writable;
  
  import 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 class HFile {
   // LOG is being used in HFileBlock and CheckSumUtil
   static final Log LOG = LogFactory.getLog(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 Counter CHECKSUM_FAILURES = new Counter();
 
   // For tests. Gets incremented when we read a block whether from HDFS or from Cache.
   public static final Counter DATABLOCK_READ_COUNT = new Counter();
 
   /** Static instance for the metrics so that HFileReaders access the same instance */
   static final MetricsIO metrics = new MetricsIO(new MetricsIOWrapperImpl());
 
   /**
    * Number of checksum verification failures. It also
    * clears the counter.
    */
   public static final long getAndResetChecksumFailuresCount() {
     long count = CHECKSUM_FAILURES.get();
     CHECKSUM_FAILURES.set(0);
     return count;
   }
 
   /**
    * Number of checksum verification failures.
    */
   public static final long getChecksumFailuresCount() {
     long count = CHECKSUM_FAILURES.get();
     return count;
   }
 
   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 {
 
     /** Add an element to the file info map. */
     void appendFileInfo(byte[] key, byte[] value) throws IOException;
 
     void append(Cell cell) throws IOException;
 
     /** @return 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 abstract class WriterFactory {
     protected final Configuration conf;
     protected final CacheConfig cacheConf;
     protected FileSystem fs;
     protected Path path;
     protected FSDataOutputStream ostream;
     protected KVComparator comparator = KeyValue.COMPARATOR;
     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 withComparator(KVComparator comparator) {
       Preconditions.checkNotNull(comparator);
       this.comparator = comparator;
       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 = AbstractHFileWriter.createOutputStream(conf, fs, path, favoredNodes);
         try {
           ostream.setDropBehind(shouldDropBehind && cacheConf.shouldDropBehindCompaction());
         } catch (UnsupportedOperationException uoe) {
           if (LOG.isTraceEnabled()) LOG.trace("Unable to set drop behind on " + path, uoe);
           else if (LOG.isDebugEnabled()) LOG.debug("Unable to set drop behind on " + path);
         }
       }
       return createWriter(fs, path, ostream,
                    comparator, fileContext);
     }
 
     protected abstract Writer createWriter(FileSystem fs, Path path, FSDataOutputStream ostream,
         KVComparator comparator, HFileContext fileContext) throws IOException;
   }
 
   /** 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) {
     Configuration tempConf = new Configuration(conf);
     tempConf.setFloat(HConstants.HFILE_BLOCK_CACHE_SIZE_KEY, 0.0f);
     return HFile.getWriterFactory(conf, new CacheConfig(tempConf));
   }
 
   /**
    * 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:
       return new HFileWriterV2.WriterFactoryV2(conf, cacheConf);
     case 3:
       return new HFileWriterV3.WriterFactoryV3(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 cacheBlock
      * @param pread
      * @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.
      * @throws IOException
      */
     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();
 
     KVComparator getComparator();
 
     HFileScanner getScanner(boolean cacheBlocks, final boolean pread, final boolean isCompaction);
 
     ByteBuffer getMetaBlock(String metaBlockName, boolean cacheBlock) throws IOException;
 
     Map<byte[], byte[]> loadFileInfo() throws IOException;
 
     byte[] getLastKey();
 
     byte[] midkey() throws IOException;
 
     long length();
 
     long getEntries();
 
     byte[] getFirstKey();
 
     long indexSize();
 
     byte[] getFirstRowKey();
 
     byte[] getLastRowKey();
 
     FixedFileTrailer getTrailer();
 
     HFileBlockIndex.BlockIndexReader getDataBlockIndexReader();
 
     HFileScanner getScanner(boolean cacheBlocks, boolean pread);
 
     Compression.Algorithm getCompressionAlgorithm();
 
     /**
      * 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();
 
     void setPrimaryReplicaReader(boolean isPrimaryReplicaReader);
 
     /**
      * 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();
   }
 
   /**
    * Method returns the reader given the specified arguments.
    * TODO This is a bad abstraction.  See HBASE-6635.
    *
    * @param path hfile's path
    * @param fsdis stream of path's file
    * @param size max size of the trailer.
    * @param cacheConf Cache configuation values, cannot be null.
    * @param hfs
    * @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")
   private static Reader openReader(Path path, FSDataInputStreamWrapper fsdis, long size,
       CacheConfig cacheConf, HFileSystem hfs, Configuration conf) throws IOException {
     FixedFileTrailer trailer = null;
     try {
       boolean isHBaseChecksum = fsdis.shouldUseHBaseChecksum();
       assert !isHBaseChecksum; // Initially we must read with FS checksum.
       trailer = FixedFileTrailer.readFromStream(fsdis.getStream(isHBaseChecksum), size);
       switch (trailer.getMajorVersion()) {
       case 2:
         return new HFileReaderV2(path, trailer, fsdis, size, cacheConf, hfs, conf);
       case 3 :
         return new HFileReaderV3(path, trailer, fsdis, size, cacheConf, hfs, conf);
       default:
         throw new IllegalArgumentException("Invalid HFile version " + trailer.getMajorVersion());
       }
     } catch (Throwable t) {
       try {
         fsdis.close();
       } catch (Throwable t2) {
         LOG.warn("Error closing fsdis FSDataInputStreamWrapper", t2);
       }
       throw new CorruptHFileException("Problem reading HFile Trailer from file " + path, t);
     } finally {
       fsdis.unbuffer();
     }
   }
 
   /**
    * The sockets and the file descriptors held by the method parameter
    * {@code FSDataInputStreamWrapper} passed will be freed after its usage so caller needs to ensure
    * that no other threads have access to the same passed reference.
    * @param fs A file system
    * @param path Path to HFile
    * @param fsdis a stream of path's file
    * @param size max size of the trailer.
    * @param cacheConf Cache configuration for hfile's contents
    * @param conf Configuration
    * @return A version specific Hfile Reader
    * @throws IOException If file is invalid, will throw CorruptHFileException flavored IOException
    */
   public static Reader createReader(FileSystem fs, Path path,
       FSDataInputStreamWrapper fsdis, long size, CacheConfig cacheConf, Configuration conf)
       throws IOException {
     HFileSystem hfs = null;
 
     // If the fs is not an instance of HFileSystem, then create an
     // instance of HFileSystem that wraps over the specified fs.
     // In this case, we will not be able to avoid checksumming inside
     // the filesystem.
     if (!(fs instanceof HFileSystem)) {
       hfs = new HFileSystem(fs);
     } else {
       hfs = (HFileSystem)fs;
     }
     return openReader(path, fsdis, size, cacheConf, hfs, conf);
   }
 
   /**
    *
    * @param fs filesystem
    * @param path Path to file to read
    * @param cacheConf This must not be null.  @see {@link org.apache.hadoop.hbase.io.hfile.CacheConfig#CacheConfig(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, CacheConfig cacheConf, Configuration conf) throws IOException {
     Preconditions.checkNotNull(cacheConf, "Cannot create Reader with null CacheConf");
     FSDataInputStreamWrapper stream = new FSDataInputStreamWrapper(fs, path);
     return openReader(path, stream, fs.getFileStatus(path).getLen(),
       cacheConf, stream.getHfs(), conf);
   }
 
   /**
    * This factory method is used only by unit tests. <br/>
    * The sockets and the file descriptors held by the method parameter
    * {@code FSDataInputStreamWrapper} passed will be freed after its usage so caller needs to ensure
    * that no other threads have access to the same passed reference.
    */
   static Reader createReaderFromStream(Path path,
       FSDataInputStream fsdis, long size, CacheConfig cacheConf, Configuration conf)
       throws IOException {
     FSDataInputStreamWrapper wrapper = new FSDataInputStreamWrapper(fsdis);
     return openReader(path, wrapper, size, cacheConf, null, conf);
   }
 
   /**
    * 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();
     FSDataInputStreamWrapper fsdis = new FSDataInputStreamWrapper(fs, path);
     try {
       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;
     } catch (IOException e) {
       throw e;
     } finally {
       try {
         fsdis.close();
       } catch (Throwable t) {
         LOG.warn("Error closing fsdis FSDataInputStreamWrapper: " + path, t);
       }
     }
   }
 
   /**
    * Metadata for this file. Conjured by the writer. Read in by the reader.
    */
   public static class FileInfo implements SortedMap<byte[], byte[]> {
     static final String RESERVED_PREFIX = "hfile.";
     static final byte[] RESERVED_PREFIX_BYTES = Bytes.toBytes(RESERVED_PREFIX);
     static final byte [] LASTKEY = Bytes.toBytes(RESERVED_PREFIX + "LASTKEY");
     static final byte [] AVG_KEY_LEN = Bytes.toBytes(RESERVED_PREFIX + "AVG_KEY_LEN");
     static final byte [] AVG_VALUE_LEN = Bytes.toBytes(RESERVED_PREFIX + "AVG_VALUE_LEN");
     static final byte [] CREATE_TIME_TS = Bytes.toBytes(RESERVED_PREFIX + "CREATE_TIME_TS");
     static final byte [] COMPARATOR = Bytes.toBytes(RESERVED_PREFIX + "COMPARATOR");
     static final byte [] TAGS_COMPRESSED = Bytes.toBytes(RESERVED_PREFIX + "TAGS_COMPRESSED");
     public static final byte [] MAX_TAGS_LEN = Bytes.toBytes(RESERVED_PREFIX + "MAX_TAGS_LEN");
     private final SortedMap<byte [], byte []> map = new TreeMap<byte [], byte []>(Bytes.BYTES_COMPARATOR);
 
     public FileInfo() {
       super();
     }
 
     /**
      * Append the given key/value pair to the file info, optionally checking the
      * key prefix.
      *
      * @param k key to add
      * @param v value to add
      * @param checkPrefix whether to check that the provided key does not start
      *          with the reserved prefix
      * @return this file info object
      * @throws IOException if the key or value is invalid
      */
     public FileInfo append(final byte[] k, final byte[] v,
         final boolean checkPrefix) throws IOException {
       if (k == null || v == null) {
         throw new NullPointerException("Key nor value may be null");
       }
       if (checkPrefix && isReservedFileInfoKey(k)) {
         throw new IOException("Keys with a " + FileInfo.RESERVED_PREFIX
             + " are reserved");
       }
       put(k, v);
       return this;
     }
 
     @Override
     public void clear() {
       this.map.clear();
     }
 
     @Override
     public Comparator<? super byte[]> comparator() {
       return map.comparator();
     }
 
     @Override
     public boolean containsKey(Object key) {
       return map.containsKey(key);
     }
 
     @Override
     public boolean containsValue(Object value) {
       return map.containsValue(value);
     }
 
     @Override
     public Set<java.util.Map.Entry<byte[], byte[]>> entrySet() {
       return map.entrySet();
     }
 
     @Override
     public boolean equals(Object o) {
       return map.equals(o);
     }
 
     @Override
     public byte[] firstKey() {
       return map.firstKey();
     }
 
     @Override
     public byte[] get(Object key) {
       return map.get(key);
     }
 
     @Override
     public int hashCode() {
       return map.hashCode();
     }
 
     @Override
     public SortedMap<byte[], byte[]> headMap(byte[] toKey) {
       return this.map.headMap(toKey);
     }
 
     @Override
     public boolean isEmpty() {
       return map.isEmpty();
     }
 
     @Override
     public Set<byte[]> keySet() {
       return map.keySet();
     }
 
     @Override
     public byte[] lastKey() {
       return map.lastKey();
     }
 
     @Override
     public byte[] put(byte[] key, byte[] value) {
       return this.map.put(key, value);
     }
 
     @Override
     public void putAll(Map<? extends byte[], ? extends byte[]> m) {
       this.map.putAll(m);
     }
 
     @Override
     public byte[] remove(Object key) {
       return this.map.remove(key);
     }
 
     @Override
     public int size() {
       return map.size();
     }
 
     @Override
     public SortedMap<byte[], byte[]> subMap(byte[] fromKey, byte[] toKey) {
       return this.map.subMap(fromKey, toKey);
     }
 
     @Override
     public SortedMap<byte[], byte[]> tailMap(byte[] fromKey) {
       return this.map.tailMap(fromKey);
     }
 
     @Override
     public Collection<byte[]> values() {
       return map.values();
     }
 
     /**
      * Write out this instance on the passed in <code>out</code> stream.
      * We write it as a protobuf.
      * @param out
      * @throws IOException
      * @see #read(DataInputStream)
      */
     void write(final DataOutputStream out) throws IOException {
       HFileProtos.FileInfoProto.Builder builder = HFileProtos.FileInfoProto.newBuilder();
       for (Map.Entry<byte [], byte[]> e: this.map.entrySet()) {
         HBaseProtos.BytesBytesPair.Builder bbpBuilder = HBaseProtos.BytesBytesPair.newBuilder();
         bbpBuilder.setFirst(ByteStringer.wrap(e.getKey()));
         bbpBuilder.setSecond(ByteStringer.wrap(e.getValue()));
         builder.addMapEntry(bbpBuilder.build());
       }
       out.write(ProtobufUtil.PB_MAGIC);
       builder.build().writeDelimitedTo(out);
     }
 
     /**
      * Populate this instance with what we find on the passed in <code>in</code> stream.
      * Can deserialize protobuf of old Writables format.
      * @param in
      * @throws IOException
      * @see #write(DataOutputStream)
      */
     void read(final DataInputStream in) throws IOException {
       // This code is tested over in TestHFileReaderV1 where we read an old hfile w/ this new code.
       int pblen = ProtobufUtil.lengthOfPBMagic();
       byte [] pbuf = new byte[pblen];
       if (in.markSupported()) in.mark(pblen);
       int read = in.read(pbuf);
       if (read != pblen) throw new IOException("read=" + read + ", wanted=" + pblen);
       if (ProtobufUtil.isPBMagicPrefix(pbuf)) {
         parsePB(HFileProtos.FileInfoProto.parseDelimitedFrom(in));
       } else {
         if (in.markSupported()) {
           in.reset();
           parseWritable(in);
         } else {
           // We cannot use BufferedInputStream, it consumes more than we read from the underlying IS
           ByteArrayInputStream bais = new ByteArrayInputStream(pbuf);
           SequenceInputStream sis = new SequenceInputStream(bais, in); // Concatenate input streams
           // TODO: Am I leaking anything here wrapping the passed in stream?  We are not calling close on the wrapped
           // streams but they should be let go after we leave this context?  I see that we keep a reference to the
           // passed in inputstream but since we no longer have a reference to this after we leave, we should be ok.
           parseWritable(new DataInputStream(sis));
         }
       }
     }
 
     /** Now parse the old Writable format.  It was a list of Map entries.  Each map entry was a key and a value of
      * a byte [].  The old map format had a byte before each entry that held a code which was short for the key or
      * value type.  We know it was a byte [] so in below we just read and dump it.
      * @throws IOException
      */
     void parseWritable(final DataInputStream in) throws IOException {
       // First clear the map.  Otherwise we will just accumulate entries every time this method is called.
       this.map.clear();
       // Read the number of entries in the map
       int entries = in.readInt();
       // Then read each key/value pair
       for (int i = 0; i < entries; i++) {
         byte [] key = Bytes.readByteArray(in);
         // We used to read a byte that encoded the class type.  Read and ignore it because it is always byte [] in hfile
         in.readByte();
         byte [] value = Bytes.readByteArray(in);
         this.map.put(key, value);
       }
     }
 
     /**
      * Fill our map with content of the pb we read off disk
      * @param fip protobuf message to read
      */
     void parsePB(final HFileProtos.FileInfoProto fip) {
       this.map.clear();
       for (BytesBytesPair pair: fip.getMapEntryList()) {
         this.map.put(pair.getFirst().toByteArray(), pair.getSecond().toByteArray());
       }
     }
   }
 
   /** Return true if the given file info key is reserved for internal use. */
   public static boolean isReservedFileInfoKey(byte[] key) {
     return Bytes.startsWith(key, FileInfo.RESERVED_PREFIX_BYTES);
   }
 
   /**
    * 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.
    */
   static List<Path> getStoreFiles(FileSystem fs, Path regionDir)
       throws IOException {
     List<Path> regionHFiles = new ArrayList<Path>();
     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 main(String[] args) throws Exception {
     // delegate to preserve old behavior
     HFilePrettyPrinter.main(args);
   }
 }