OpenBitSet (apache-cassandra API)

java.lang.Object
- org.apache.cassandra.utils.obs.OpenBitSet

All Implemented Interfaces:

java.io.Closeable, java.lang.AutoCloseable, IBitSet
```
public class OpenBitSet
extends java.lang.Object
implements IBitSet
```
An "open" BitSet implementation that allows direct access to the arrays of words storing the bits. Derived from Lucene's OpenBitSet, but with a paged backing array (see bits delaration, below).

Unlike java.util.bitset, the fact that bits are packed into an array of longs is part of the interface. This allows efficient implementation of other algorithms by someone other than the author. It also allows one to efficiently implement alternate serialization or interchange formats.

OpenBitSet is faster than java.util.BitSet in most operations and *much* faster at calculating cardinality of sets and results of set operations. It can also handle sets of larger cardinality (up to 64 * 2**32-1)

The goals of OpenBitSet are the fastest implementation possible, and maximum code reuse. Extra safety and encapsulation may always be built on top, but if that's built in, the cost can never be removed (and hence people re-implement their own version in order to get better performance). If you want a "safe", totally encapsulated (and slower and limited) BitSet class, use java.util.BitSet.

Constructor Summary

Constructors
Constructor and Description

OpenBitSet()

OpenBitSet(long numBits)
Constructs an OpenBitSet large enough to hold numBits.

Constructors
Constructor and Description
`OpenBitSet()`
`OpenBitSet(long numBits)` Constructs an OpenBitSet large enough to hold numBits.

Method Summary

All Methods Static Methods Instance Methods Concrete Methods
Modifier and Type	Method and Description
`void`	`addTo(Ref.IdentityCollection identities)`
`void`	`and(OpenBitSet other)`
`static long`	`bits2words(long numBits)` returns the number of 64 bit words it would take to hold numBits
`long`	`capacity()` Returns the current capacity in bits (1 greater than the index of the last bit)
`long`	`cardinality()`
`void`	`clear()`
`void`	`clear(int index)` clears a bit.
`void`	`clear(int startIndex, int endIndex)` Clears a range of bits.
`void`	`clear(long index)` clears a bit.
`void`	`clear(long startIndex, long endIndex)` Clears a range of bits.
`void`	`close()`
`static OpenBitSet`	`deserialize(java.io.DataInput in)`
`boolean`	`equals(java.lang.Object o)` returns true if both sets have the same bits set
`boolean`	`get(int index)` Returns true or false for the specified bit index.
`boolean`	`get(long index)` Returns true or false for the specified bit index.
`int`	`getNumWords()` Expert: gets the number of longs in the array that are in use
`long[]`	`getPage(int pageIdx)`
`int`	`getPageCount()`
`int`	`getPageSize()`
`int`	`hashCode()`
`void`	`intersect(OpenBitSet other)` this = this AND other
`boolean`	`isEmpty()` Returns true if there are no set bits
`long`	`length()`
`long`	`offHeapSize()` Returns the amount of memory in bytes used off heap.
`void`	`serialize(java.io.DataOutput out)`
`long`	`serializedSize()`
`void`	`set(int index)` Sets the bit at the specified index.
`void`	`set(long index)` Sets the bit at the specified index.
`long`	`size()` Returns the current capacity of this set.
`void`	`trimTrailingZeros()` Lowers numWords, the number of words in use, by checking for trailing zero words.

Methods inherited from class java.lang.Object
clone, finalize, getClass, notify, notifyAll, toString, wait, wait, wait

- Constructor Detail
  - OpenBitSet
```
public OpenBitSet(long numBits)
```
    Constructs an OpenBitSet large enough to hold numBits.
    
    Parameters:
    
    numBits -
  - OpenBitSet
```
public OpenBitSet()
```
- Method Detail
  - getPageSize
```
public int getPageSize()
```
    Returns:
    
    the pageSize
  - getPageCount
```
public int getPageCount()
```
  - getPage
```
public long[] getPage(int pageIdx)
```
  - capacity
```
public long capacity()
```
    Returns the current capacity in bits (1 greater than the index of the last bit)
    
    Specified by:
    
    capacity in interface IBitSet
  - offHeapSize
```
public long offHeapSize()
```
    Description copied from interface: IBitSet
    
    Returns the amount of memory in bytes used off heap.
    
    Specified by:
    
    offHeapSize in interface IBitSet
    
    Returns:
    
    the amount of memory in bytes used off heap
  - addTo
```
public void addTo(Ref.IdentityCollection identities)
```
    Specified by:
    
    addTo in interface IBitSet
  - size
```
public long size()
```
    Returns the current capacity of this set. Included for compatibility. This is *not* equal to cardinality()
  - length
```
public long length()
```
  - isEmpty
```
public boolean isEmpty()
```
    Returns true if there are no set bits
  - getNumWords
```
public int getNumWords()
```
    Expert: gets the number of longs in the array that are in use
  - get
```
public boolean get(int index)
```
    Returns true or false for the specified bit index. The index should be less than the OpenBitSet size
  - get
```
public boolean get(long index)
```
    Returns true or false for the specified bit index. The index should be less than the OpenBitSet size.
    
    Specified by:
    
    get in interface IBitSet
  - set
```
public void set(long index)
```
    Sets the bit at the specified index. The index should be less than the OpenBitSet size.
    
    Specified by:
    
    set in interface IBitSet
  - set
```
public void set(int index)
```
    Sets the bit at the specified index. The index should be less than the OpenBitSet size.
  - clear
```
public void clear(int index)
```
    clears a bit. The index should be less than the OpenBitSet size.
  - clear
```
public void clear(long index)
```
    clears a bit. The index should be less than the OpenBitSet size.
    
    Specified by:
    
    clear in interface IBitSet
  - clear
```
public void clear(int startIndex,
                  int endIndex)
```
    Clears a range of bits. Clearing past the end does not change the size of the set.
    
    Parameters:
    
    startIndex - lower index
    
    endIndex - one-past the last bit to clear
  - clear
```
public void clear(long startIndex,
                  long endIndex)
```
    Clears a range of bits. Clearing past the end does not change the size of the set.
    
    Parameters:
    
    startIndex - lower index
    
    endIndex - one-past the last bit to clear
  - cardinality
```
public long cardinality()
```
    Returns:
    
    the number of set bits
  - intersect
```
public void intersect(OpenBitSet other)
```
    this = this AND other
  - and
```
public void and(OpenBitSet other)
```
  - trimTrailingZeros
```
public void trimTrailingZeros()
```
    Lowers numWords, the number of words in use, by checking for trailing zero words.
  - bits2words
```
public static long bits2words(long numBits)
```
    returns the number of 64 bit words it would take to hold numBits
  - equals
```
public boolean equals(java.lang.Object o)
```
    returns true if both sets have the same bits set
    
    Overrides:
    
    equals in class java.lang.Object
  - hashCode
```
public int hashCode()
```
    Overrides:
    
    hashCode in class java.lang.Object
  - close
```
public void close()
```
    Specified by:
    
    close in interface java.io.Closeable
    
    Specified by:
    
    close in interface java.lang.AutoCloseable
    
    Specified by:
    
    close in interface IBitSet
  - serialize
```
public void serialize(java.io.DataOutput out)
               throws java.io.IOException
```
    Specified by:
    
    serialize in interface IBitSet
    
    Throws:
    
    java.io.IOException
  - serializedSize
```
public long serializedSize()
```
    Specified by:
    
    serializedSize in interface IBitSet
  - clear
```
public void clear()
```
    Specified by:
    
    clear in interface IBitSet
  - deserialize
```
public static OpenBitSet deserialize(java.io.DataInput in)
                              throws java.io.IOException
```
    Throws:
    
    java.io.IOException

Class OpenBitSet

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Constructor Detail

OpenBitSet

OpenBitSet

Method Detail

getPageSize

getPageCount

getPage

capacity

offHeapSize

addTo

size

length

isEmpty

getNumWords

get

get

set

set

clear

clear

clear

clear

cardinality

intersect

and

trimTrailingZeros

bits2words

equals

hashCode

close

serialize

serializedSize

clear

deserialize