org.apache.hadoop.hbase.io.hfile

Class HFileBlockIndex.BlockIndexReader

java.lang.Object

org.apache.hadoop.hbase.io.hfile.HFileBlockIndex.BlockIndexReader

All Implemented Interfaces:

HeapSize

Enclosing class:

HFileBlockIndex

public static class HFileBlockIndex.BlockIndexReader
extends Object
implements HeapSize

The reader will always hold the root level index in the memory. Index blocks at all other levels will be cached in the LRU cache in practice, although this API does not enforce that. All non-root (leaf and intermediate) index blocks contain what we call a "secondary index": an array of offsets to the entries within the block. This allows us to do binary search for the entry corresponding to the given key without having to deserialize the block.

Constructor Summary

Constructors

Constructor and Description
HFileBlockIndex.BlockIndexReader(KeyValue.KVComparator c, int treeLevel)
HFileBlockIndex.BlockIndexReader(KeyValue.KVComparator c, int treeLevel, HFile.CachingBlockReader cachingBlockReader)

Method Summary

Methods

Modifier and Type	Method and Description
void	ensureNonEmpty() Verifies that the block index is non-empty and throws an IllegalStateException otherwise.
int	getRootBlockCount()
int	getRootBlockDataSize(int i)
byte[]	getRootBlockKey(int i)
long	getRootBlockOffset(int i)
long	heapSize()
boolean	isEmpty()
BlockWithScanInfo	loadDataBlockWithScanInfo(byte[] key, int keyOffset, int keyLength, HFileBlock currentBlock, boolean cacheBlocks, boolean pread, boolean isCompaction) Return the BlockWithScanInfo which contains the DataBlock with other scan info such as nextIndexedKey.
byte[]	midkey() An approximation to the HFile's mid-key.
void	readMultiLevelIndexRoot(HFileBlock blk, int numEntries) Read the root-level metadata of a multi-level block index.
void	readRootIndex(DataInput in, int numEntries) Read in the root-level index from the given input stream.
DataInputStream	readRootIndex(HFileBlock blk, int numEntries) Read in the root-level index from the given input stream.
int	rootBlockContainingKey(byte[] key, int offset, int length) Finds the root-level index block containing the given key.
HFileBlock	seekToDataBlock(byte[] key, int keyOffset, int keyLength, HFileBlock currentBlock, boolean cacheBlocks, boolean pread, boolean isCompaction) Return the data block which contains this key.
String	toString()

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Constructor Detail

HFileBlockIndex.BlockIndexReader

public HFileBlockIndex.BlockIndexReader(KeyValue.KVComparator c,
                                int treeLevel,
                                HFile.CachingBlockReader cachingBlockReader)

HFileBlockIndex.BlockIndexReader

public HFileBlockIndex.BlockIndexReader(KeyValue.KVComparator c,
                                int treeLevel)

Method Detail

isEmpty

public boolean isEmpty()

Returns:

true if the block index is empty.

ensureNonEmpty

public void ensureNonEmpty()

Verifies that the block index is non-empty and throws an IllegalStateException otherwise.

seekToDataBlock

public HFileBlock seekToDataBlock(byte[] key,
                         int keyOffset,
                         int keyLength,
                         HFileBlock currentBlock,
                         boolean cacheBlocks,
                         boolean pread,
                         boolean isCompaction)
                           throws IOException

Return the data block which contains this key. This function will only be called when the HFile version is larger than 1.

Parameters:

key - the key we are looking for

keyOffset - the offset of the key in its byte array

keyLength - the length of the key

currentBlock - the current block, to avoid re-reading the same block

Returns:

reader a basic way to load blocks

Throws:

IOException

loadDataBlockWithScanInfo

public BlockWithScanInfo loadDataBlockWithScanInfo(byte[] key,
                                          int keyOffset,
                                          int keyLength,
                                          HFileBlock currentBlock,
                                          boolean cacheBlocks,
                                          boolean pread,
                                          boolean isCompaction)
                                            throws IOException

Return the BlockWithScanInfo which contains the DataBlock with other scan info such as nextIndexedKey. This function will only be called when the HFile version is larger than 1.

Parameters:

key - the key we are looking for

keyOffset - the offset of the key in its byte array

keyLength - the length of the key

currentBlock - the current block, to avoid re-reading the same block

cacheBlocks -

pread -

isCompaction -

Returns:

the BlockWithScanInfo which contains the DataBlock with other scan info such as nextIndexedKey.

Throws:

IOException

midkey

public byte[] midkey()
              throws IOException

An approximation to the HFile's mid-key. Operates on block boundaries, and does not go inside blocks. In other words, returns the first key of the middle block of the file.

Returns:

the first key of the middle block

Throws:

IOException

getRootBlockKey

public byte[] getRootBlockKey(int i)

Parameters:

i - from 0 to - 1

getRootBlockOffset

public long getRootBlockOffset(int i)

Parameters:

i - from 0 to - 1

getRootBlockDataSize

public int getRootBlockDataSize(int i)

Parameters:

i - zero-based index of a root-level block

Returns:

the on-disk size of the root-level block for version 2, or the uncompressed size for version 1

getRootBlockCount

public int getRootBlockCount()

Returns:

the number of root-level blocks in this block index

rootBlockContainingKey

public int rootBlockContainingKey(byte[] key,
                         int offset,
                         int length)

Finds the root-level index block containing the given key.

Parameters:

key - Key to find

Returns:

Offset of block containing key (between 0 and the number of blocks - 1) or -1 if this file does not contain the request.

readRootIndex

public void readRootIndex(DataInput in,
                 int numEntries)
                   throws IOException

Read in the root-level index from the given input stream. Must match what was written into the root level by HFileBlockIndex.BlockIndexWriter.writeIndexBlocks(FSDataOutputStream) at the offset that function returned.

Parameters:

in - the buffered input stream or wrapped byte input stream

numEntries - the number of root-level index entries

Throws:

IOException

readRootIndex

public DataInputStream readRootIndex(HFileBlock blk,
                            int numEntries)
                              throws IOException

Read in the root-level index from the given input stream. Must match what was written into the root level by HFileBlockIndex.BlockIndexWriter.writeIndexBlocks(FSDataOutputStream) at the offset that function returned.

Parameters:

blk - the HFile block

numEntries - the number of root-level index entries

Returns:

the buffered input stream or wrapped byte input stream

Throws:

IOException

readMultiLevelIndexRoot

public void readMultiLevelIndexRoot(HFileBlock blk,
                           int numEntries)
                             throws IOException

Read the root-level metadata of a multi-level block index. Based on readRootIndex(DataInput, int), but also reads metadata necessary to compute the mid-key in a multi-level index.

Parameters:

blk - the HFile block

numEntries - the number of root-level index entries

Throws:

IOException

toString

public String toString()

Overrides:

toString in class Object

heapSize

public long heapSize()

Specified by:

heapSize in interface HeapSize

Returns:

Approximate 'exclusive deep size' of implementing object. Includes count of payload and hosting object sizings.