Package org.drools.util.bitmask

Class OpenBitSet

java.lang.Object
org.drools.util.bitmask.OpenBitSet
All Implemented Interfaces:
Serializable, Cloneable, BitMask
public class OpenBitSet extends Object implements BitMask
An "open" BitSet implementation that allows direct access to the array of words storing the bits.

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.

Performance Results

Test system: Pentium 4, Sun Java 1.5_06 -server -Xbatch -Xmx64M
BitSet size = 1,000,000
Results are java.util.BitSet time divided by OpenBitSet time.
cardinality intersect_count union nextSetBit get iterator
50% full 3.36 3.96 1.44 1.46 1.99 1.58
1% full 3.31 3.90   1.04   0.99

Test system: AMD Opteron, 64 bit linux, Sun Java 1.5_06 -server -Xbatch -Xmx64M
BitSet size = 1,000,000
Results are java.util.BitSet time divided by OpenBitSet time.
cardinality intersect_count union nextSetBit get iterator
50% full 2.50 3.50 1.00 1.03 1.12 1.25
1% full 2.51 3.49   1.00   1.02
See Also:

  • Nested Class Summary

    Nested Classes
    Modifier and Type
    Class
    Description
    static final class 
    OpenBitSet.BitUtil
     

  • Field Summary

    Fields
    Modifier and Type
    Field
    Description
    protected long[]
    bits
     
    static final boolean
    JRE_IS_64BIT
    True iff running on a 64bit JVM
    static final boolean
    JRE_IS_MINIMUM_JAVA7
     
    static final boolean
    JRE_IS_MINIMUM_JAVA8
     
    static final int
    NUM_BYTES_LONG
     
    static final String
    OS_ARCH
     
    protected int
    wlen
     

  • Constructor Summary

    Constructors
    Constructor
    Description
    OpenBitSet()
     
    OpenBitSet(long numBits)
    Constructs an OpenBitSet large enough to hold numBits.
    OpenBitSet(long[] bits, int numWords)
    Constructs an OpenBitSet from an existing long[].

  • Method Summary

    Modifier and Type
    Method
    Description
    void
    and(OpenBitSet other)
     
    void
    andNot(OpenBitSet other)
     
    static long
    andNotCount(OpenBitSet a, OpenBitSet b)
    Returns the popcount or cardinality of "a and not b" or "intersection(a, not(b))".
    static int
    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(int startIndex, int endIndex)
    Clears a range of bits.
    void
    clear(long index)
    clears a bit, allowing access beyond the current set size without changing the size.
    void
    clear(long startIndex, long endIndex)
    Clears a range of bits.
    OpenBitSet
    clone()
     
    void
    ensureCapacity(long numBits)
    Ensure that the long[] is big enough to hold numBits, expanding it if necessary.
    void
    ensureCapacityWords(int numWords)
    Expand the long[] with the size given as a number of words (64 bit longs).
    boolean
    equals(Object o)
    returns true if both sets have the same bits set
    protected int
    expandingWordNum(long index)
     
    void
    fastClear(int index)
    clears a bit.
    void
    fastClear(long index)
    clears a bit.
    void
    fastFlip(int index)
    flips a bit.
    void
    fastFlip(long index)
    flips a bit.
    boolean
    fastGet(int index)
    Returns true or false for the specified bit index.
    boolean
    fastGet(long index)
    Returns true or false for the specified bit index.
    void
    fastSet(int index)
    Sets the bit at the specified index.
    void
    fastSet(long index)
    Sets the bit at the specified index.
    void
    flip(long index)
    flips a bit, expanding the set size if necessary
    void
    flip(long startIndex, long endIndex)
    Flips a range of bits, expanding the set size if necessary
    boolean
    flipAndGet(int index)
    flips a bit and returns the resulting bit value.
    boolean
    flipAndGet(long index)
    flips a bit and returns the resulting bit value.
    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
    boolean
    getAndSet(int index)
    Sets a bit and returns the previous value.
    boolean
    getAndSet(long index)
    Sets a bit and returns the previous value.
    int
    getBit(int index)
    returns 1 if the bit is set, 0 if not.
    long[]
    getBits()
    Expert: returns the long[] storing the bits
    String
    getInstancingStatement()
     
    int
    getNumWords()
    Expert: gets the number of longs in the array that are in use
    static long[]
    grow(long[] array, int minSize)
     
    int
    hashCode()
     
    void
    intersect(OpenBitSet other)
    this = this AND other
    static long
    intersectionCount(OpenBitSet a, OpenBitSet b)
    Returns the popcount or cardinality of the intersection of the two sets.
    boolean
    intersects(BitMask mask)
     
    boolean
    intersects(OpenBitSet other)
    returns true if the sets have any elements in common
    boolean
    isAllSet()
     
    boolean
    isEmpty()
    Returns true if there are no set bits
    boolean
    isSet(int index)
     
    int
    length()
     
    int
    nextSetBit(int index)
    Returns the index of the first set bit starting at the index specified.
    long
    nextSetBit(long index)
    Returns the index of the first set bit starting at the index specified.
    void
    or(OpenBitSet other)
     
    static int
    oversize(int minTargetSize, int bytesPerElement)
    Returns an array size >= minTargetSize, generally over-allocating exponentially to achieve amortized linear-time cost as the array grows.
    int
    prevSetBit(int index)
    Returns the index of the first set bit starting downwards at the index specified.
    long
    prevSetBit(long index)
    Returns the index of the first set bit starting downwards at the index specified.
    void
    remove(OpenBitSet other)
    Remove all elements set in other.
    BitMask
    reset(int index)
     
    BitMask
    resetAll(BitMask mask)
     
    BitMask
    set(int index)
     
    void
    set(long index)
    sets a bit, expanding the set size if necessary
    void
    set(long startIndex, long endIndex)
    Sets a range of bits, expanding the set size if necessary
    BitMask
    setAll(BitMask mask)
     
    void
    setBits(long[] bits)
    Expert: sets a new long[] to use as the bit storage
    void
    setNumWords(int nWords)
    Expert: sets the number of longs in the array that are in use
    long
    size()
    Returns the current capacity of this set.
    String
    toString()
     
    void
    trimTrailingZeros()
    Lowers numWords, the number of words in use, by checking for trailing zero words.
    void
    union(OpenBitSet other)
    this = this OR other
    static long
    unionCount(OpenBitSet a, OpenBitSet b)
    Returns the popcount or cardinality of the union of the two sets.
    void
    xor(OpenBitSet other)
    this = this XOR other
    static long
    xorCount(OpenBitSet a, OpenBitSet b)
    Returns the popcount or cardinality of the exclusive-or of the two sets.

    Methods inherited from class java.lang.Object

    finalize, getClass, notify, notifyAll, wait, wait, wait

  • Field Details

    • bits

      protected long[] bits

    • wlen

      protected int wlen

    • NUM_BYTES_LONG

      public static final int NUM_BYTES_LONG
      See Also:

    • OS_ARCH

      public static final String OS_ARCH

    • JRE_IS_MINIMUM_JAVA7

      public static final boolean JRE_IS_MINIMUM_JAVA7

    • JRE_IS_MINIMUM_JAVA8

      public static final boolean JRE_IS_MINIMUM_JAVA8

    • JRE_IS_64BIT

      public static final boolean JRE_IS_64BIT
      True iff running on a 64bit JVM

  • Constructor Details

    • OpenBitSet

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

    • OpenBitSet

      public OpenBitSet()

    • OpenBitSet

      public OpenBitSet(long[] bits, int numWords)
      Constructs an OpenBitSet from an existing long[].
      The first 64 bits are in long[0], with bit index 0 at the least significant bit, and bit index 63 at the most significant. Given a bit index, the word containing it is long[index/64], and it is at bit number index%64 within that word.

      numWords are the number of elements in the array that contain set bits (non-zero longs). numWords should be &lt= bits.length, and any existing words in the array at position &gt= numWords should be zero.

  • Method Details

    • capacity

      public long capacity()
      Returns the current capacity in bits (1 greater than the index of the last bit)

    • size

      public long size()
      Returns the current capacity of this set. Included for compatibility. This is *not* equal to cardinality()

    • length

      public int length()

    • isEmpty

      public boolean isEmpty()
      Returns true if there are no set bits
      Specified by:
      isEmpty in interface BitMask

    • getBits

      public long[] getBits()
      Expert: returns the long[] storing the bits

    • setBits

      public void setBits(long[] bits)
      Expert: sets a new long[] to use as the bit storage

    • getNumWords

      public int getNumWords()
      Expert: gets the number of longs in the array that are in use

    • setNumWords

      public void setNumWords(int nWords)
      Expert: sets 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.

    • fastGet

      public boolean fastGet(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

    • fastGet

      public boolean fastGet(long index)
      Returns true or false for the specified bit index. The index should be less than the OpenBitSet size.

    • getBit

      public int getBit(int index)
      returns 1 if the bit is set, 0 if not. The index should be less than the OpenBitSet size

    • set

      public void set(long index)
      sets a bit, expanding the set size if necessary

    • fastSet

      public void fastSet(int index)
      Sets the bit at the specified index. The index should be less than the OpenBitSet size.

    • fastSet

      public void fastSet(long index)
      Sets the bit at the specified index. The index should be less than the OpenBitSet size.

    • set

      public void set(long startIndex, long endIndex)
      Sets a range of bits, expanding the set size if necessary
      Parameters:
      startIndex - lower index
      endIndex - one-past the last bit to set

    • expandingWordNum

      protected int expandingWordNum(long index)

    • fastClear

      public void fastClear(int index)
      clears a bit. The index should be less than the OpenBitSet size.

    • fastClear

      public void fastClear(long index)
      clears a bit. The index should be less than the OpenBitSet size.

    • clear

      public void clear(long index)
      clears a bit, allowing access beyond the current set size without changing the size.

    • 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

    • getAndSet

      public boolean getAndSet(int index)
      Sets a bit and returns the previous value. The index should be less than the OpenBitSet size.

    • getAndSet

      public boolean getAndSet(long index)
      Sets a bit and returns the previous value. The index should be less than the OpenBitSet size.

    • fastFlip

      public void fastFlip(int index)
      flips a bit. The index should be less than the OpenBitSet size.

    • fastFlip

      public void fastFlip(long index)
      flips a bit. The index should be less than the OpenBitSet size.

    • flip

      public void flip(long index)
      flips a bit, expanding the set size if necessary

    • flipAndGet

      public boolean flipAndGet(int index)
      flips a bit and returns the resulting bit value. The index should be less than the OpenBitSet size.

    • flipAndGet

      public boolean flipAndGet(long index)
      flips a bit and returns the resulting bit value. The index should be less than the OpenBitSet size.

    • flip

      public void flip(long startIndex, long endIndex)
      Flips a range of bits, expanding the set size if necessary
      Parameters:
      startIndex - lower index
      endIndex - one-past the last bit to flip

    • cardinality

      public long cardinality()
      Returns:
      the number of set bits

    • intersectionCount

      public static long intersectionCount(OpenBitSet a, OpenBitSet b)
      Returns the popcount or cardinality of the intersection of the two sets. Neither set is modified.

    • unionCount

      public static long unionCount(OpenBitSet a, OpenBitSet b)
      Returns the popcount or cardinality of the union of the two sets. Neither set is modified.

    • andNotCount

      public static long andNotCount(OpenBitSet a, OpenBitSet b)
      Returns the popcount or cardinality of "a and not b" or "intersection(a, not(b))". Neither set is modified.

    • xorCount

      public static long xorCount(OpenBitSet a, OpenBitSet b)
      Returns the popcount or cardinality of the exclusive-or of the two sets. Neither set is modified.

    • nextSetBit

      public int nextSetBit(int index)
      Returns the index of the first set bit starting at the index specified. -1 is returned if there are no more set bits.

    • nextSetBit

      public long nextSetBit(long index)
      Returns the index of the first set bit starting at the index specified. -1 is returned if there are no more set bits.

    • prevSetBit

      public int prevSetBit(int index)
      Returns the index of the first set bit starting downwards at the index specified. -1 is returned if there are no more set bits.

    • prevSetBit

      public long prevSetBit(long index)
      Returns the index of the first set bit starting downwards at the index specified. -1 is returned if there are no more set bits.

    • clone

      public OpenBitSet clone()
      Specified by:
      clone in interface BitMask
      Overrides:
      clone in class Object

    • intersect

      public void intersect(OpenBitSet other)
      this = this AND other

    • union

      public void union(OpenBitSet other)
      this = this OR other

    • remove

      public void remove(OpenBitSet other)
      Remove all elements set in other. this = this AND_NOT other

    • xor

      public void xor(OpenBitSet other)
      this = this XOR other

    • and

      public void and(OpenBitSet other)

    • or

      public void or(OpenBitSet other)

    • andNot

      public void andNot(OpenBitSet other)

    • intersects

      public boolean intersects(OpenBitSet other)
      returns true if the sets have any elements in common

    • ensureCapacityWords

      public void ensureCapacityWords(int numWords)
      Expand the long[] with the size given as a number of words (64 bit longs). getNumWords() is unchanged by this call.

    • grow

      public static long[] grow(long[] array, int minSize)

    • oversize

      public static int oversize(int minTargetSize, int bytesPerElement)
      Returns an array size >= minTargetSize, generally over-allocating exponentially to achieve amortized linear-time cost as the array grows. NOTE: this was originally borrowed from Python 2.4.2 listobject.c sources (attribution in LICENSE.txt), but has now been substantially changed based on discussions from java-dev thread with subject "Dynamic array reallocation algorithms", started on Jan 12 2010.
      Parameters:
      minTargetSize - Minimum required value to be returned.
      bytesPerElement - Bytes used by each element of the array.

    • ensureCapacity

      public void ensureCapacity(long numBits)
      Ensure that the long[] is big enough to hold numBits, expanding it if necessary. getNumWords() is unchanged by this call.

    • trimTrailingZeros

      public void trimTrailingZeros()
      Lowers numWords, the number of words in use, by checking for trailing zero words.

    • bits2words

      public static int bits2words(long numBits)
      returns the number of 64 bit words it would take to hold numBits

    • equals

      public boolean equals(Object o)
      returns true if both sets have the same bits set
      Overrides:
      equals in class Object

    • hashCode

      public int hashCode()
      Overrides:
      hashCode in class Object

    • toString

      public String toString()
      Overrides:
      toString in class Object

    • set

      public BitMask set(int index)
      Specified by:
      set in interface BitMask

    • setAll

      public BitMask setAll(BitMask mask)
      Specified by:
      setAll in interface BitMask

    • reset

      public BitMask reset(int index)
      Specified by:
      reset in interface BitMask

    • resetAll

      public BitMask resetAll(BitMask mask)
      Specified by:
      resetAll in interface BitMask

    • isSet

      public boolean isSet(int index)
      Specified by:
      isSet in interface BitMask

    • isAllSet

      public boolean isAllSet()
      Specified by:
      isAllSet in interface BitMask

    • intersects

      public boolean intersects(BitMask mask)
      Specified by:
      intersects in interface BitMask

    • getInstancingStatement

      public String getInstancingStatement()
      Specified by:
      getInstancingStatement in interface BitMask