Package org.apache.hadoop.hbase.io.hfile

Class HFileBlockIndex.BlockIndexWriter

java.lang.Object
org.apache.hadoop.hbase.io.hfile.HFileBlockIndex.BlockIndexWriter
All Implemented Interfaces:
InlineBlockWriter
Enclosing class:
HFileBlockIndex
public static class HFileBlockIndex.BlockIndexWriter extends Object implements InlineBlockWriter
Writes the block index into the output stream. Generate the tree from bottom up. The leaf level is written to disk as a sequence of inline blocks, if it is larger than a certain number of bytes. If the leaf level is not large enough, we write all entries to the root level instead. After all leaf blocks have been written, we end up with an index referencing the resulting leaf index blocks. If that index is larger than the allowed root index size, the writer will break it up into reasonable-size intermediate-level index block chunks write those chunks out, and create another index referencing those chunks. This will be repeated until the remaining index is small enough to become the root index. However, in most practical cases we will only have leaf-level blocks and the root index, or just the root index.

  • Field Details

    • rootChunk

      private BlockIndexChunk rootChunk
      While the index is being written, this represents the current block index referencing all leaf blocks, with one exception. If the file is being closed and there are not enough blocks to complete even a single leaf block, no leaf blocks get written and this contains the entire block index. After all levels of the index were written by writeIndexBlocks(FSDataOutputStream), this contains the final root-level index.

    • curInlineChunk

      private BlockIndexChunk curInlineChunk
      Current leaf-level chunk. New entries referencing data blocks get added to this chunk until it grows large enough to be written to disk.

    • numLevels

      private int numLevels
      The number of block index levels. This is one if there is only root level (even empty), two if there a leaf level and root level, and is higher if there are intermediate levels. This is only final after writeIndexBlocks(FSDataOutputStream) has been called. The initial value accounts for the root level, and will be increased to two as soon as we find out there is a leaf-level in blockWritten(long, int, int).

    • blockWriter

      private HFileBlock.Writer blockWriter

    • firstKey

      private byte[] firstKey

    • totalNumEntries

      private long totalNumEntries
      The total number of leaf-level entries, i.e. entries referenced by leaf-level blocks. For the data block index this is equal to the number of data blocks.

    • totalBlockOnDiskSize

      private long totalBlockOnDiskSize
      Total compressed size of all index blocks.

    • totalBlockUncompressedSize

      private long totalBlockUncompressedSize
      Total uncompressed size of all index blocks.

    • maxChunkSize

      private int maxChunkSize
      The maximum size guideline of all multi-level index blocks.

    • minIndexNumEntries

      private int minIndexNumEntries
      The maximum level of multi-level index blocks

    • singleLevelOnly

      private boolean singleLevelOnly
      Whether we require this block index to always be single-level.

    • cacheConf

      private CacheConfig cacheConf
      CacheConfig, or null if cache-on-write is disabled

    • nameForCaching

      private String nameForCaching
      Name to use for computing cache keys

    • indexBlockEncoder

      private HFileIndexBlockEncoder indexBlockEncoder
      Type of encoding used for index blocks in HFile

  • Constructor Details

    • BlockIndexWriter

      public BlockIndexWriter()
      Creates a single-level block index writer

    • BlockIndexWriter

      public BlockIndexWriter(HFileBlock.Writer blockWriter, CacheConfig cacheConf, String nameForCaching, HFileIndexBlockEncoder indexBlockEncoder)
      Creates a multi-level block index writer.
      Parameters:
      blockWriter - the block writer to use to write index blocks
      cacheConf - used to determine when and how a block should be cached-on-write.

  • Method Details

    • setMaxChunkSize

      public void setMaxChunkSize(int maxChunkSize)

    • setMinIndexNumEntries

      public void setMinIndexNumEntries(int minIndexNumEntries)

    • writeIndexBlocks

      public long writeIndexBlocks(org.apache.hadoop.fs.FSDataOutputStream out) throws IOException
      Writes the root level and intermediate levels of the block index into the output stream, generating the tree from bottom up. Assumes that the leaf level has been inline-written to the disk if there is enough data for more than one leaf block. We iterate by breaking the current level of the block index, starting with the index of all leaf-level blocks, into chunks small enough to be written to disk, and generate its parent level, until we end up with a level small enough to become the root level. If the leaf level is not large enough, there is no inline block index anymore, so we only write that level of block index to disk as the root level.
      Parameters:
      out - FSDataOutputStream
      Returns:
      position at which we entered the root-level index.
      Throws:
      IOException

    • writeSingleLevelIndex

      public void writeSingleLevelIndex(DataOutput out, String description) throws IOException
      Writes the block index data as a single level only. Does not do any block framing.
      Parameters:
      out - the buffered output stream to write the index to. Typically a stream writing into an HFile block.
      description - a short description of the index being written. Used in a log message.
      Throws:
      IOException

    • writeIntermediateLevel

      private BlockIndexChunk writeIntermediateLevel(org.apache.hadoop.fs.FSDataOutputStream out, BlockIndexChunk currentLevel) throws IOException
      Split the current level of the block index into intermediate index blocks of permitted size and write those blocks to disk. Return the next level of the block index referencing those intermediate-level blocks.
      Parameters:
      currentLevel - the current level of the block index, such as the a chunk referencing all leaf-level index blocks
      Returns:
      the parent level block index, which becomes the root index after a few (usually zero) iterations
      Throws:
      IOException

    • writeIntermediateBlock

      private void writeIntermediateBlock(org.apache.hadoop.fs.FSDataOutputStream out, BlockIndexChunk parent, BlockIndexChunk curChunk) throws IOException
      Throws:
      IOException

    • getNumRootEntries

      public final int getNumRootEntries()
      Returns how many block index entries there are in the root level

    • getNumLevels

      public int getNumLevels()
      Returns the number of levels in this block index.

    • expectNumLevels

      private void expectNumLevels(int expectedNumLevels)

    • shouldWriteBlock

      public boolean shouldWriteBlock(boolean closing)
      Whether there is an inline block ready to be written. In general, we write an leaf-level index block as an inline block as soon as its size as serialized in the non-root format reaches a certain threshold.
      Specified by:
      shouldWriteBlock in interface InlineBlockWriter

    • writeInlineBlock

      public void writeInlineBlock(DataOutput out) throws IOException
      Write out the current inline index block. Inline blocks are non-root blocks, so the non-root index format is used.
      Specified by:
      writeInlineBlock in interface InlineBlockWriter
      Throws:
      IOException

    • blockWritten

      public void blockWritten(long offset, int onDiskSize, int uncompressedSize)
      Called after an inline block has been written so that we can add an entry referring to that block to the parent-level index.
      Specified by:
      blockWritten in interface InlineBlockWriter
      Parameters:
      offset - the offset of the block in the stream
      onDiskSize - the on-disk size of the block
      uncompressedSize - the uncompressed size of the block

    • getInlineBlockType

      public BlockType getInlineBlockType()
      Description copied from interface: InlineBlockWriter
      The type of blocks this block writer produces.
      Specified by:
      getInlineBlockType in interface InlineBlockWriter

    • addEntry

      public void addEntry(byte[] firstKey, long blockOffset, int blockDataSize)
      Add one index entry to the current leaf-level block. When the leaf-level block gets large enough, it will be flushed to disk as an inline block.
      Parameters:
      firstKey - the first key of the data block
      blockOffset - the offset of the data block
      blockDataSize - the on-disk size of the data block (HFile format version 2), or the uncompressed size of the data block ( HFile format version 1).

    • ensureSingleLevel

      public void ensureSingleLevel() throws IOException
      Throws:
      IOException - if we happened to write a multi-level index.

    • getCacheOnWrite

      public boolean getCacheOnWrite()
      Description copied from interface: InlineBlockWriter
      Returns true if inline blocks produced by this writer should be cached
      Specified by:
      getCacheOnWrite in interface InlineBlockWriter
      Returns:
      true if we are using cache-on-write. This is configured by the caller of the constructor by either passing a valid block cache or null.

    • getTotalUncompressedSize

      public long getTotalUncompressedSize()
      The total uncompressed size of the root index block, intermediate-level index blocks, and leaf-level index blocks.
      Returns:
      the total uncompressed size of all index blocks