org.archive.util.fingerprint
Class ArrayLongFPCache

java.lang.Object
  org.archive.util.fingerprint.ArrayLongFPCache

All Implemented Interfaces:

LongFPSet

public class ArrayLongFPCache
extends java.lang.Object
implements LongFPSet

Simple long fingerprint cache using a backing array; any long maps to one of 'smear' slots. Longs inserted should be randomly distributed,

Author:

gojomo

Field Summary

(package private) long[]	cache
(package private) int	count
static int	DEFAULT_CAPACITY
static int	DEFAULT_SMEAR
(package private) int	smear

Constructor Summary

ArrayLongFPCache()

Method Summary

boolean	add(long l) Add a fingerprint to the set.
int	cacheLength()
boolean	contains(long l) Does this set contain a given fingerprint.
long	count() get the number of elements in the Set
boolean	quickContains(long fp) Do a contains() check that doesn't require laggy activity (eg disk IO).
boolean	remove(long l) Remove a fingerprint from the set, if it is there
void	setCapacity(int newCapacity)

Methods inherited from class java.lang.Object

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

Field Detail

DEFAULT_CAPACITY

public static final int DEFAULT_CAPACITY

See Also:

Constant Field Values

DEFAULT_SMEAR

public static final int DEFAULT_SMEAR

See Also:

Constant Field Values

cache

long[] cache

smear

int smear

count

int count

Constructor Detail

ArrayLongFPCache

public ArrayLongFPCache()

Method Detail

setCapacity

public void setCapacity(int newCapacity)

add

public boolean add(long l)

Description copied from interface: LongFPSet

Add a fingerprint to the set. Note that subclasses can implement different policies on how to add - some might grow the available space, others might implement some type of LRU caching. In particular, you cannot on the LongFPSet.count() method returning 1 greater than before the addition.

Specified by:

add in interface LongFPSet

Parameters:

l - the fingerprint to add

Returns:

true if set has changed with this addition

contains

public boolean contains(long l)

Description copied from interface: LongFPSet

Does this set contain a given fingerprint.

Specified by:

contains in interface LongFPSet

Parameters:

l - the fingerprint to check for

Returns:

true if the fingerprint is in the set

remove

public boolean remove(long l)

Description copied from interface: LongFPSet

Remove a fingerprint from the set, if it is there

Specified by:

remove in interface LongFPSet

Parameters:

l - the fingerprint to remove

Returns:

true if we removed the fingerprint

count

public long count()

Description copied from interface: LongFPSet

get the number of elements in the Set

Specified by:

count in interface LongFPSet

Returns:

the number of elements in the Set

quickContains

public boolean quickContains(long fp)

Description copied from interface: LongFPSet

Do a contains() check that doesn't require laggy activity (eg disk IO). If this returns true, fp is definitely contained; if this returns false, fp *MAY* still be contained -- must use full-cost contains() to be sure.

Specified by:

quickContains in interface LongFPSet

Parameters:

fp - the fingerprint to check for

Returns:

true if contains the fingerprint

cacheLength

public int cacheLength()