Package org.apache.hadoop.util.bloom

Class DynamicBloomFilter

java.lang.Object
org.apache.hadoop.util.bloom.Filter
org.apache.hadoop.util.bloom.DynamicBloomFilter
All Implemented Interfaces:
Writable
@Public @Stable public class DynamicBloomFilter extends Filter
Implements a dynamic Bloom filter, as defined in the INFOCOM 2006 paper.

A dynamic Bloom filter (DBF) makes use of a s * m bit matrix but each of the s rows is a standard Bloom filter. The creation process of a DBF is iterative. At the start, the DBF is a 1 * m bit matrix, i.e., it is composed of a single standard Bloom filter. It assumes that nr elements are recorded in the initial bit vector, where nr <= n (n is the cardinality of the set A to record in the filter).

As the size of A grows during the execution of the application, several keys must be inserted in the DBF. When inserting a key into the DBF, one must first get an active Bloom filter in the matrix. A Bloom filter is active when the number of recorded keys, nr, is strictly less than the current cardinality of A, n. If an active Bloom filter is found, the key is inserted and nr is incremented by one. On the other hand, if there is no active Bloom filter, a new one is created (i.e., a new row is added to the matrix) according to the current size of A and the element is added in this new Bloom filter and the nr value of this new Bloom filter is set to one. A given key is said to belong to the DBF if the k positions are set to one in one of the matrix rows.

Originally created by European Commission One-Lab Project 034819.

See Also:

  • Constructor Details

    • DynamicBloomFilter

      public DynamicBloomFilter()
      Zero-args constructor for the serialization.

    • DynamicBloomFilter

      public DynamicBloomFilter(int vectorSize, int nbHash, int hashType, int nr)
      Constructor.

      Builds an empty Dynamic Bloom filter.

      Parameters:
      vectorSize - The number of bits in the vector.
      nbHash - The number of hash function to consider.
      hashType - type of the hashing function (see Hash).
      nr - The threshold for the maximum number of keys to record in a dynamic Bloom filter row.

  • 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

    • 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.