org.apache.hadoop.hbase.io.hfile

Class HFileReaderV2.AbstractScannerV2

java.lang.Object

org.apache.hadoop.hbase.io.hfile.AbstractHFileReader.Scanner

org.apache.hadoop.hbase.io.hfile.HFileReaderV2.AbstractScannerV2

All Implemented Interfaces:

HFileScanner

Direct Known Subclasses:

HFileReaderV2.EncodedScannerV2, HFileReaderV2.ScannerV2

Enclosing class:

HFileReaderV2

protected abstract static class HFileReaderV2.AbstractScannerV2
extends AbstractHFileReader.Scanner

Field Summary

Fields

Modifier and Type	Field and Description
protected HFileBlock	block
protected byte[]	nextIndexedKey The next indexed key is to keep track of the indexed key of the next data block.

Fields inherited from class org.apache.hadoop.hbase.io.hfile.AbstractHFileReader.Scanner

blockBuffer, blockFetches, cacheBlocks, currKeyLen, currMemstoreTS, currMemstoreTSLen, currValueLen, isCompaction, pread, reader

Constructor Summary

Constructors

Constructor and Description
HFileReaderV2.AbstractScannerV2(HFileReaderV2 r, boolean cacheBlocks, boolean pread, boolean isCompaction)

Method Summary

Methods

Modifier and Type	Method and Description
abstract int	compareKey(KeyValue.KVComparator comparator, byte[] key, int offset, int length) Compare the given key against the current key
protected abstract ByteBuffer	getFirstKeyInBlock(HFileBlock curBlock)
protected abstract int	loadBlockAndSeekToKey(HFileBlock seekToBlock, byte[] nextIndexedKey, boolean rewind, byte[] key, int offset, int length, boolean seekBefore)
protected HFileBlock	readNextDataBlock() Scans blocks in the "scanned" section of the HFile until the next data block is found.
int	reseekTo(byte[] key, int offset, int length)
boolean	seekBefore(byte[] key, int offset, int length)
int	seekTo(byte[] key, int offset, int length)
protected int	seekTo(byte[] key, int offset, int length, boolean rewind) An internal API function.

Methods inherited from class org.apache.hadoop.hbase.io.hfile.AbstractHFileReader.Scanner

assertSeeked, getReader, isSeeked, reseekTo, seekBefore, seekTo, toString

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.apache.hadoop.hbase.io.hfile.HFileScanner

getKey, getKeyString, getKeyValue, getValue, getValueString, next, seekTo

Field Detail

block

protected HFileBlock block

nextIndexedKey

protected byte[] nextIndexedKey

The next indexed key is to keep track of the indexed key of the next data block. If the nextIndexedKey is HConstants.NO_NEXT_INDEXED_KEY, it means that the current data block is the last data block. If the nextIndexedKey is null, it means the nextIndexedKey has not been loaded yet.

Constructor Detail

HFileReaderV2.AbstractScannerV2

public HFileReaderV2.AbstractScannerV2(HFileReaderV2 r,
                               boolean cacheBlocks,
                               boolean pread,
                               boolean isCompaction)

Method Detail

seekTo

protected int seekTo(byte[] key,
         int offset,
         int length,
         boolean rewind)
              throws IOException

An internal API function. Seek to the given key, optionally rewinding to the first key of the block before doing the seek.

Parameters:

key - key byte array

offset - key offset in the key byte array

length - key length

rewind - whether to rewind to the first key of the block before doing the seek. If this is false, we are assuming we never go back, otherwise the result is undefined.

Returns:

-1 if the key is earlier than the first key of the file, 0 if we are at the given key, 1 if we are past the given key -2 if the key is earlier than the first key of the file while using a faked index key

Throws:

IOException

getFirstKeyInBlock

protected abstract ByteBuffer getFirstKeyInBlock(HFileBlock curBlock)

loadBlockAndSeekToKey

protected abstract int loadBlockAndSeekToKey(HFileBlock seekToBlock,
                        byte[] nextIndexedKey,
                        boolean rewind,
                        byte[] key,
                        int offset,
                        int length,
                        boolean seekBefore)
                                      throws IOException

Throws:

IOException

seekTo

public int seekTo(byte[] key,
         int offset,
         int length)
           throws IOException

Throws:

IOException

reseekTo

public int reseekTo(byte[] key,
           int offset,
           int length)
             throws IOException

Throws:

IOException

seekBefore

public boolean seekBefore(byte[] key,
                 int offset,
                 int length)
                   throws IOException

Throws:

IOException

readNextDataBlock

protected HFileBlock readNextDataBlock()
                                throws IOException

Scans blocks in the "scanned" section of the HFile until the next data block is found.

Returns:

the next block, or null if there are no more data blocks

Throws:

IOException

compareKey

public abstract int compareKey(KeyValue.KVComparator comparator,
             byte[] key,
             int offset,
             int length)

Compare the given key against the current key

Parameters:

comparator -

key -

offset -

length -

Returns:

-1 is the passed key is smaller than the current key, 0 if equal and 1 if greater