org.apache.hadoop.hbase.io.hfile

Class HFileReaderV2.ScannerV2

java.lang.Object

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

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

org.apache.hadoop.hbase.io.hfile.HFileReaderV2.ScannerV2

All Implemented Interfaces:

HFileScanner

Direct Known Subclasses:

HFileReaderV3.ScannerV3

Enclosing class:

HFileReaderV2

protected static class HFileReaderV2.ScannerV2
extends HFileReaderV2.AbstractScannerV2

Implementation of HFileScanner interface.

Field Summary

Fields inherited from class org.apache.hadoop.hbase.io.hfile.HFileReaderV2.AbstractScannerV2

block, nextIndexedKey

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

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

Constructor Summary

Constructors

Constructor and Description
HFileReaderV2.ScannerV2(HFileReaderV2 r, boolean cacheBlocks, boolean pread, boolean isCompaction)

Method Summary

Methods

Modifier and Type	Method and Description
protected int	blockSeek(byte[] key, int offset, int length, boolean seekBefore) Within a loaded block, seek looking for the last key that is smaller than (or equal to?) the key we are interested in.
int	compareKey(KeyValue.KVComparator comparator, byte[] key, int offset, int length) Compare the given key against the current key
protected int	getCellBufSize()
protected ByteBuffer	getFirstKeyInBlock(HFileBlock curBlock)
ByteBuffer	getKey() Gets a buffer view to the current key.
String	getKeyString() Convenience method to get a copy of the key as a string - interpreting the bytes as UTF8.
KeyValue	getKeyValue()
protected int	getNextCellStartPosition()
ByteBuffer	getValue() Gets a buffer view to the current value.
String	getValueString() Convenience method to get a copy of the value as a string - interpreting the bytes as UTF8.
protected int	loadBlockAndSeekToKey(HFileBlock seekToBlock, byte[] nextIndexedKey, boolean rewind, byte[] key, int offset, int length, boolean seekBefore)
boolean	next() Go to the next key/value in the block section.
protected void	readKeyValueLen()
protected void	readMvccVersion()
boolean	seekTo() Positions this scanner at the start of the file.
protected void	setNonSeekedState()
protected void	updateCurrBlock(HFileBlock newBlock) Updates the current block to be the given HFileBlock.

Methods inherited from class org.apache.hadoop.hbase.io.hfile.HFileReaderV2.AbstractScannerV2

readNextDataBlock, reseekTo, seekBefore, seekTo, seekTo

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

Constructor Detail

HFileReaderV2.ScannerV2

public HFileReaderV2.ScannerV2(HFileReaderV2 r,
                       boolean cacheBlocks,
                       boolean pread,
                       boolean isCompaction)

Method Detail

getKeyValue

public KeyValue getKeyValue()

Returns:

Instance of KeyValue.

getCellBufSize

protected int getCellBufSize()

getKey

public ByteBuffer getKey()

Description copied from interface: HFileScanner

Gets a buffer view to the current key. You must call HFileScanner.seekTo(byte[]) before this method.

Returns:

byte buffer for the key. The limit is set to the key size, and the position is 0, the start of the buffer view.

compareKey

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

Description copied from class: HFileReaderV2.AbstractScannerV2

Compare the given key against the current key

Specified by:

compareKey in class HFileReaderV2.AbstractScannerV2

Returns:

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

getValue

public ByteBuffer getValue()

Description copied from interface: HFileScanner

Gets a buffer view to the current value. You must call HFileScanner.seekTo(byte[]) before this method.

Returns:

byte buffer for the value. The limit is set to the value size, and the position is 0, the start of the buffer view.

setNonSeekedState

protected void setNonSeekedState()

next

public boolean next()
             throws IOException

Go to the next key/value in the block section. Loads the next block if necessary. If successful, getKey() and getValue() can be called.

Returns:

true if successfully navigated to the next key/value

Throws:

IOException

getNextCellStartPosition

protected int getNextCellStartPosition()

seekTo

public boolean seekTo()
               throws IOException

Positions this scanner at the start of the file.

Returns:

false if empty file; i.e. a call to next would return false and the current key and value are undefined.

Throws:

IOException

loadBlockAndSeekToKey

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

Specified by:

loadBlockAndSeekToKey in class HFileReaderV2.AbstractScannerV2

Throws:

IOException

updateCurrBlock

protected void updateCurrBlock(HFileBlock newBlock)

Updates the current block to be the given HFileBlock. Seeks to the the first key/value pair.

Parameters:

newBlock - the block to make current

readKeyValueLen

protected void readKeyValueLen()

readMvccVersion

protected void readMvccVersion()

blockSeek

protected int blockSeek(byte[] key,
            int offset,
            int length,
            boolean seekBefore)

Within a loaded block, seek looking for the last key that is smaller than (or equal to?) the key we are interested in. A note on the seekBefore: if you have seekBefore = true, AND the first key in the block = key, then you'll get thrown exceptions. The caller has to check for that case and load the previous block as appropriate.

Parameters:

key - the key to find

seekBefore - find the key before the given key in case of exact match.

Returns:

0 in case of an exact key match, 1 in case of an inexact match, -2 in case of an inexact match and furthermore, the input key less than the first key of current block(e.g. using a faked index key)

getFirstKeyInBlock

protected ByteBuffer getFirstKeyInBlock(HFileBlock curBlock)

Specified by:

getFirstKeyInBlock in class HFileReaderV2.AbstractScannerV2

getKeyString

public String getKeyString()

Description copied from interface: HFileScanner

Convenience method to get a copy of the key as a string - interpreting the bytes as UTF8. You must call HFileScanner.seekTo(byte[]) before this method.

Returns:

key as a string

getValueString

public String getValueString()

Description copied from interface: HFileScanner

Convenience method to get a copy of the value as a string - interpreting the bytes as UTF8. You must call HFileScanner.seekTo(byte[]) before this method.

Returns:

value as a string