org.apache.hadoop.hbase.util

Class BloomFilterChunk

java.lang.Object

org.apache.hadoop.hbase.util.BloomFilterChunk

All Implemented Interfaces:

BloomFilterBase

@InterfaceAudience.Private
public class BloomFilterChunk
extends Object
implements BloomFilterBase

The basic building block for the CompoundBloomFilter

Field Summary

Fields

Modifier and Type	Field and Description
protected ByteBuffer	bloom Bloom bits
protected BloomType	bloomType The type of bloom
protected long	byteSize Bytes (B) in the array.
protected Hash	hash Hash Function
protected int	hashCount Number of hash functions
protected int	hashType Hash type
protected int	keyCount Keys currently in the bloom
protected int	maxKeys Max Keys expected for the bloom

Constructor Summary

Constructors

Constructor and Description
BloomFilterChunk(DataInput meta) Loads bloom filter meta data from file input.
BloomFilterChunk(int hashType, BloomType bloomType)
BloomFilterChunk(int maxKeys, double errorRate, int hashType, int foldFactor) Determines & initializes bloom filter meta data from user config.

Method Summary

Modifier and Type	Method and Description
double	actualErrorRate() Computes the error rate for this Bloom filter, taking into account the actual number of hash functions and keys inserted.
void	add(Cell cell)
void	allocBloom()
void	compactBloom()
BloomFilterChunk	createAnother() Creates another similar Bloom filter.
long	getByteSize() Returns Size of the bloom, in bytes
int	getHashCount()
int	getHashType()
long	getKeyCount() Returns The number of keys added to the bloom
long	getMaxKeys() Returns The max number of keys that can be inserted to maintain the desired error rate
String	toString()
void	writeBloom(DataOutput out) Writes just the bloom filter to the output array

Methods inherited from class java.lang.Object

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

Field Detail

byteSize

protected long byteSize

Bytes (B) in the array. This actually has to fit into an int.

hashCount

protected int hashCount

Number of hash functions

hashType

protected final int hashType

Hash type

hash

protected final Hash hash

Hash Function

keyCount

protected int keyCount

Keys currently in the bloom

maxKeys

protected int maxKeys

Max Keys expected for the bloom

bloom

protected ByteBuffer bloom

Bloom bits

bloomType

protected BloomType bloomType

The type of bloom

Constructor Detail

BloomFilterChunk

public BloomFilterChunk(DataInput meta)
                 throws IOException,
                        IllegalArgumentException

Loads bloom filter meta data from file input.

Parameters:

meta - stored bloom meta data

Throws:

IllegalArgumentException - meta data is invalid

IOException

BloomFilterChunk

public BloomFilterChunk(int hashType,
                        BloomType bloomType)

BloomFilterChunk

public BloomFilterChunk(int maxKeys,
                        double errorRate,
                        int hashType,
                        int foldFactor)
                 throws IllegalArgumentException

Determines & initializes bloom filter meta data from user config. Call allocBloom() to allocate bloom filter data.

Parameters:

maxKeys - Maximum expected number of keys that will be stored in this bloom

errorRate - Desired false positive error rate. Lower rate = more storage required

hashType - Type of hash function to use

foldFactor - When finished adding entries, you may be able to 'fold' this bloom to save space. Tradeoff potentially excess bytes in bloom for ability to fold if keyCount is exponentially greater than maxKeys.

Throws:

IllegalArgumentException

Method Detail

actualErrorRate

public double actualErrorRate()

Computes the error rate for this Bloom filter, taking into account the actual number of hash functions and keys inserted. The return value of this function changes as a Bloom filter is being populated. Used for reporting the actual error rate of compound Bloom filters when writing them out.

Returns:

error rate for this particular Bloom filter

createAnother

public BloomFilterChunk createAnother()

Creates another similar Bloom filter. Does not copy the actual bits, and sets the new filter's key count to zero.

Returns:

a Bloom filter with the same configuration as this

allocBloom

public void allocBloom()

add

public void add(Cell cell)

getKeyCount

public long getKeyCount()

Description copied from interface: BloomFilterBase

Returns The number of keys added to the bloom

Specified by:

getKeyCount in interface BloomFilterBase

getMaxKeys

public long getMaxKeys()

Description copied from interface: BloomFilterBase

Returns The max number of keys that can be inserted to maintain the desired error rate

Specified by:

getMaxKeys in interface BloomFilterBase

getByteSize

public long getByteSize()

Description copied from interface: BloomFilterBase

Returns Size of the bloom, in bytes

Specified by:

getByteSize in interface BloomFilterBase

getHashType

public int getHashType()

compactBloom

public void compactBloom()

writeBloom

public void writeBloom(DataOutput out)
                throws IOException

Writes just the bloom filter to the output array

Parameters:

out - OutputStream to place bloom

Throws:

IOException - Error writing bloom array

getHashCount

public int getHashCount()

toString

public String toString()

Overrides:

toString in class Object