org.apache.hadoop.hbase.codec.prefixtree

Class PrefixTreeSeeker

java.lang.Object

org.apache.hadoop.hbase.codec.prefixtree.PrefixTreeSeeker

All Implemented Interfaces:

DataBlockEncoder.EncodedSeeker

@InterfaceAudience.Private
public class PrefixTreeSeeker
extends Object
implements DataBlockEncoder.EncodedSeeker

These methods have the same definition as any implementation of the EncodedSeeker. In the future, the EncodedSeeker could be modified to work with the Cell interface directly. It currently returns a new KeyValue object each time getKeyValue is called. This is not horrible, but in order to create a new KeyValue object, we must first allocate a new byte[] and copy in the data from the PrefixTreeCell. It is somewhat heavyweight right now.

Field Summary

Fields

Modifier and Type	Field and Description
protected ByteBuffer	block
protected boolean	includeMvccVersion
protected boolean	movedToPrevious
protected PrefixTreeArraySearcher	ptSearcher

Constructor Summary

Constructors

Constructor and Description
PrefixTreeSeeker(boolean includeMvccVersion)

Method Summary

Methods

Modifier and Type	Method and Description
boolean	advance()
int	compareKey(KeyValue.KVComparator comparator, byte[] key, int offset, int length) Compare the given key against the current key
Cell	get() Currently unused.
ByteBuffer	getKeyDeepCopy() Does a deep copy of the key at the current position.
KeyValue	getKeyValue() currently must do deep copy into new array
ByteBuffer	getKeyValueBuffer() currently must do deep copy into new array
ByteBuffer	getValueShallowCopy() Does a shallow copy of the value at the current position.
boolean	next() Move to next position
void	releaseCurrentSearcher() Currently unused.
void	rewind() Set position to beginning of given block
int	seekToKeyInBlock(byte[] keyOnlyBytes, int offset, int length, boolean forceBeforeOnExactMatch) Seek forward only (should be called reseekToKeyInBlock?).
protected int	seekToOrBeforeUsingPositionAtOrAfter(byte[] keyOnlyBytes, int offset, int length, boolean seekBefore)
protected int	seekToOrBeforeUsingPositionAtOrBefore(byte[] keyOnlyBytes, int offset, int length, boolean seekBefore)
void	setCurrentBuffer(ByteBuffer fullBlockBuffer) Set on which buffer there will be done seeking.

Methods inherited from class java.lang.Object

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

Field Detail

block

protected ByteBuffer block

includeMvccVersion

protected boolean includeMvccVersion

ptSearcher

protected PrefixTreeArraySearcher ptSearcher

movedToPrevious

protected boolean movedToPrevious

Constructor Detail

PrefixTreeSeeker

public PrefixTreeSeeker(boolean includeMvccVersion)

Method Detail

setCurrentBuffer

public void setCurrentBuffer(ByteBuffer fullBlockBuffer)

Description copied from interface: DataBlockEncoder.EncodedSeeker

Set on which buffer there will be done seeking.

Specified by:

setCurrentBuffer in interface DataBlockEncoder.EncodedSeeker

Parameters:

fullBlockBuffer - Used for seeking.

releaseCurrentSearcher

public void releaseCurrentSearcher()

Currently unused.

TODO performance leak. should reuse the searchers. hbase does not currently have a hook where this can be called

getKeyDeepCopy

public ByteBuffer getKeyDeepCopy()

Description copied from interface: DataBlockEncoder.EncodedSeeker

Does a deep copy of the key at the current position. A deep copy is necessary because buffers are reused in the decoder.

Specified by:

getKeyDeepCopy in interface DataBlockEncoder.EncodedSeeker

Returns:

key at current position

getValueShallowCopy

public ByteBuffer getValueShallowCopy()

Description copied from interface: DataBlockEncoder.EncodedSeeker

Does a shallow copy of the value at the current position. A shallow copy is possible because the returned buffer refers to the backing array of the original encoded buffer.

Specified by:

getValueShallowCopy in interface DataBlockEncoder.EncodedSeeker

Returns:

value at current position

getKeyValueBuffer

public ByteBuffer getKeyValueBuffer()

currently must do deep copy into new array

Specified by:

getKeyValueBuffer in interface DataBlockEncoder.EncodedSeeker

Returns:

key value at current position with position set to limit

getKeyValue

public KeyValue getKeyValue()

currently must do deep copy into new array

Specified by:

getKeyValue in interface DataBlockEncoder.EncodedSeeker

Returns:

the KeyValue object at the current position. Includes memstore timestamp.

get

public Cell get()

Currently unused.

A nice, lightweight reference, though the underlying cell is transient. This method may return the same reference to the backing PrefixTreeCell repeatedly, while other implementations may return a different reference for each Cell.

The goal will be to transition the upper layers of HBase, like Filters and KeyValueHeap, to use this method instead of the getKeyValue() methods above.

rewind

public void rewind()

Description copied from interface: DataBlockEncoder.EncodedSeeker

Set position to beginning of given block

Specified by:

rewind in interface DataBlockEncoder.EncodedSeeker

next

public boolean next()

Description copied from interface: DataBlockEncoder.EncodedSeeker

Move to next position

Specified by:

next in interface DataBlockEncoder.EncodedSeeker

Returns:

true on success, false if there is no more positions.

advance

public boolean advance()

seekToKeyInBlock

public int seekToKeyInBlock(byte[] keyOnlyBytes,
                   int offset,
                   int length,
                   boolean forceBeforeOnExactMatch)

Seek forward only (should be called reseekToKeyInBlock?).

If the exact key is found look at the seekBefore variable and:
- if true: go to the previous key if it's true
- if false: stay on the exact key

If the exact key is not found, then go to the previous key *if possible*, but remember to leave the scanner in a valid state if possible.

Specified by:

seekToKeyInBlock in interface DataBlockEncoder.EncodedSeeker

Parameters:

keyOnlyBytes - KeyValue format of a Cell's key at which to position the seeker

offset - offset into the keyOnlyBytes array

length - number of bytes of the keyOnlyBytes array to use

forceBeforeOnExactMatch - if an exact match is found and seekBefore=true, back up 1 Cell

Returns:

0 if the seeker is on the exact key
1 if the seeker is not on the key for any reason, including seekBefore being true

seekToOrBeforeUsingPositionAtOrBefore

protected int seekToOrBeforeUsingPositionAtOrBefore(byte[] keyOnlyBytes,
                                        int offset,
                                        int length,
                                        boolean seekBefore)

seekToOrBeforeUsingPositionAtOrAfter

protected int seekToOrBeforeUsingPositionAtOrAfter(byte[] keyOnlyBytes,
                                       int offset,
                                       int length,
                                       boolean seekBefore)

compareKey

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

Description copied from interface: DataBlockEncoder.EncodedSeeker

Compare the given key against the current key

Specified by:

compareKey in interface DataBlockEncoder.EncodedSeeker

Returns:

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