one.nio.mem

Class OffheapBitSet

java.lang.Object

one.nio.mem.OffheapBitSet

All Implemented Interfaces:

java.io.Closeable, java.lang.AutoCloseable

public class OffheapBitSet
extends java.lang.Object
implements java.io.Closeable

An offheap implementation of a bit set. Especially useful for large bloom filters, e.g. in Cassandra. This implementation is not meant to be modified concurrently. However it can be read concurrently. Current implementation supports only reversed byte order (i.e. Big endian on x86).

See Also:

BitSet

Field Summary

Fields

Modifier and Type	Field and Description
protected long	baseAddr
protected long	size

Constructor Summary

Constructors

Constructor and Description
OffheapBitSet(long numBits)
OffheapBitSet(long address, long sizeBytes)

Method Summary

Modifier and Type	Method and Description
static long	bits2words(long numBits)
long	capacity()
protected long	checkBounds(long index)
void	clear()
void	clear(long index) clears the bit.
void	close()
boolean	get(long index) Returns true or false for the specified bit index.
void	set(long index) Sets the bit at the specified index.
void	unsafeClear(long index)
boolean	unsafeGet(long index) Same as get(long) but does not check for index within capacity bounds.
void	unsafeSet(long index)

Methods inherited from class java.lang.Object

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

Field Detail

baseAddr

protected long baseAddr

size

protected long size

Constructor Detail

OffheapBitSet

public OffheapBitSet(long numBits)

OffheapBitSet

public OffheapBitSet(long address,
                     long sizeBytes)

Method Detail

bits2words

public static long bits2words(long numBits)

Parameters:

numBits - a number of bits to hold

Returns:

the number of 64 bit words it would take to hold numBits

close

public void close()

Specified by:

close in interface java.io.Closeable

Specified by:

close in interface java.lang.AutoCloseable

capacity

public long capacity()

get

public boolean get(long index)

Returns true or false for the specified bit index. The index should be less than the capacity.

Parameters:

index - the bit index

Returns:

the value of the bit with the specified index

Throws:

java.lang.IndexOutOfBoundsException - if the index is out of range

unsafeGet

public boolean unsafeGet(long index)

Same as get(long) but does not check for index within capacity bounds. This allows to make it few ticks faster in exchange to seg fault possibility. Use when going out of capacity is ensured by other means outside of this method

Parameters:

index - a bit index

Returns:

the value of the bit with the specified index

set

public void set(long index)

Sets the bit at the specified index. The index should be less than the capacity.

Parameters:

index - a bit index

Throws:

java.lang.IndexOutOfBoundsException - if the index is out of range

unsafeSet

public void unsafeSet(long index)

clear

public void clear(long index)

clears the bit. The index should be less than the capacity.

Parameters:

index - a bit index

unsafeClear

public void unsafeClear(long index)

clear

public void clear()

checkBounds

protected long checkBounds(long index)