Package org.apache.hadoop.util.bloom

Class BloomFilter

java.lang.Object
org.apache.hadoop.util.bloom.Filter
org.apache.hadoop.util.bloom.BloomFilter
All Implemented Interfaces:
Writable
Direct Known Subclasses:
RetouchedBloomFilter
@Public @Stable public class BloomFilter extends Filter
Implements a Bloom filter, as defined by Bloom in 1970.

The Bloom filter is a data structure that was introduced in 1970 and that has been adopted by the networking research community in the past decade thanks to the bandwidth efficiencies that it offers for the transmission of set membership information between networked hosts. A sender encodes the information into a bit vector, the Bloom filter, that is more compact than a conventional representation. Computation and space costs for construction are linear in the number of elements. The receiver uses the filter to test whether various elements are members of the set. Though the filter will occasionally return a false positive, it will never return a false negative. When creating the filter, the sender can choose its desired point in a trade-off between the false positive rate and the size.

Originally created by European Commission One-Lab Project 034819.

See Also:

  • Constructor Details

    • BloomFilter

      public BloomFilter()
      Default constructor - use with readFields

    • BloomFilter

      public BloomFilter(int vectorSize, int nbHash, int hashType)
      Constructor
      Parameters:
      vectorSize - The vector size of this filter.
      nbHash - The number of hash function to consider.
      hashType - type of the hashing function (see Hash).

  • Method Details

    • add

      public void add(Key key)
      Description copied from class: Filter
      Adds a key to this filter.
      Specified by:
      add in class Filter
      Parameters:
      key - The key to add.

    • and

      public void and(Filter filter)
      Description copied from class: Filter
      Peforms a logical AND between this filter and a specified filter.

      Invariant: The result is assigned to this filter.

      Specified by:
      and in class Filter
      Parameters:
      filter - The filter to AND with.

    • membershipTest

      public boolean membershipTest(Key key)
      Description copied from class: Filter
      Determines wether a specified key belongs to this filter.
      Specified by:
      membershipTest in class Filter
      Parameters:
      key - The key to test.
      Returns:
      boolean True if the specified key belongs to this filter. False otherwise.

    • not

      public void not()
      Description copied from class: Filter
      Performs a logical NOT on this filter.

      The result is assigned to this filter.

      Specified by:
      not in class Filter

    • or

      public void or(Filter filter)
      Description copied from class: Filter
      Peforms a logical OR between this filter and a specified filter.

      Invariant: The result is assigned to this filter.

      Specified by:
      or in class Filter
      Parameters:
      filter - The filter to OR with.

    • xor

      public void xor(Filter filter)
      Description copied from class: Filter
      Peforms a logical XOR between this filter and a specified filter.

      Invariant: The result is assigned to this filter.

      Specified by:
      xor in class Filter
      Parameters:
      filter - The filter to XOR with.

    • toString

      public String toString()
      Overrides:
      toString in class Object

    • getVectorSize

      public int getVectorSize()
      Returns:
      size of the the bloomfilter

    • write

      public void write(DataOutput out) throws IOException
      Description copied from interface: Writable
      Serialize the fields of this object to out.
      Specified by:
      write in interface Writable
      Overrides:
      write in class Filter
      Parameters:
      out - DataOuput to serialize this object into.
      Throws:
      IOException - any other problem for write.

    • readFields

      public void readFields(DataInput in) throws IOException
      Description copied from interface: Writable
      Deserialize the fields of this object from in.

      For efficiency, implementations should attempt to re-use storage in the existing object where possible.

      Specified by:
      readFields in interface Writable
      Overrides:
      readFields in class Filter
      Parameters:
      in - DataInput to deseriablize this object from.
      Throws:
      IOException - any other problem for readFields.