freenet.support

Class BloomFilter

java.lang.Object

freenet.support.BloomFilter

Direct Known Subclasses:

BinaryBloomFilter, CountingBloomFilter, NullBloomFilter

public abstract class BloomFilter
extends java.lang.Object

Field Summary

Fields

Modifier and Type	Field and Description
protected java.nio.ByteBuffer	filter
protected BloomFilter	forkedFilter
protected int	k Number of hash functions
protected int	length
protected java.util.concurrent.locks.ReadWriteLock	lock
protected boolean	needRebuild

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	BloomFilter(int length, int k)

Method Summary

Modifier and Type	Method and Description
void	addKey(byte[] key)
void	addKeyForked(byte[] key)
boolean	checkFilter(byte[] key)
void	close()
int	copyTo(byte[] buf, int offset)
static BloomFilter	createFilter(java.io.File file, int length, int k, boolean counting)
static BloomFilter	createFilter(int length, int k, boolean counting)
void	discard()
protected void	finalize()
void	force()
abstract void	fork(int k) Create an empty, in-memory copy of bloom filter.
protected abstract boolean	getBit(int offset)
int	getFilledCount()
protected java.util.Random	getHashes(byte[] key)
int	getK()
int	getLength()
int	getSizeBytes()
void	init()
void	merge()
boolean	needRebuild()
static int	optimialK(int filterLength, long maxKey) Calculate optimal K value
void	removeKey(byte[] key)
protected abstract void	setBit(int offset)
void	unsetAll()
protected abstract void	unsetBit(int offset)
void	writeTo(java.io.OutputStream cos)

Methods inherited from class java.lang.Object

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

Field Detail

filter

protected java.nio.ByteBuffer filter

k

protected final int k

Number of hash functions

length

protected final int length

lock

protected transient java.util.concurrent.locks.ReadWriteLock lock

forkedFilter

protected BloomFilter forkedFilter

needRebuild

protected boolean needRebuild

Constructor Detail

BloomFilter

protected BloomFilter(int length,
                      int k)

Method Detail

init

public void init()

createFilter

public static BloomFilter createFilter(int length,
                                       int k,
                                       boolean counting)

createFilter

public static BloomFilter createFilter(java.io.File file,
                                       int length,
                                       int k,
                                       boolean counting)
                                throws java.io.IOException

Throws:

java.io.IOException

addKey

public void addKey(byte[] key)

addKeyForked

public void addKeyForked(byte[] key)

checkFilter

public boolean checkFilter(byte[] key)

removeKey

public void removeKey(byte[] key)

getBit

protected abstract boolean getBit(int offset)

setBit

protected abstract void setBit(int offset)

unsetBit

protected abstract void unsetBit(int offset)

unsetAll

public void unsetAll()

getHashes

protected java.util.Random getHashes(byte[] key)

fork

public abstract void fork(int k)

Create an empty, in-memory copy of bloom filter. New updates are written to both filters. This is written back to disk on #merge()

merge

public void merge()

discard

public void discard()

optimialK

public static int optimialK(int filterLength,
                            long maxKey)

Calculate optimal K value

Parameters:

filterLength - filter length in bits

maxKey -

Returns:

optimal K

getK

public int getK()

needRebuild

public boolean needRebuild()

force

public void force()

close

public void close()

finalize

protected void finalize()
                 throws java.lang.Throwable

Overrides:

finalize in class java.lang.Object

Throws:

java.lang.Throwable

getSizeBytes

public int getSizeBytes()

getLength

public int getLength()

getFilledCount

public int getFilledCount()

copyTo

public int copyTo(byte[] buf,
                  int offset)

writeTo

public void writeTo(java.io.OutputStream cos)
             throws java.io.IOException

Throws:

java.io.IOException