Class BloomFilter
- java.lang.Object
-
- org.apache.accumulo.core.bloomfilter.Filter
-
- org.apache.accumulo.core.bloomfilter.BloomFilter
-
- All Implemented Interfaces:
org.apache.hadoop.io.Writable
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.
-
-
Field Summary
-
Fields inherited from class org.apache.accumulo.core.bloomfilter.Filter
hash, hashType, nbHash, vectorSize
-
-
Constructor Summary
Constructors Constructor Description BloomFilter()
Default constructor - use with readFieldsBloomFilter(int vectorSize, int nbHash, int hashType)
Constructor
-
Method Summary
All Methods Instance Methods Concrete Methods Modifier and Type Method Description boolean
add(org.apache.hadoop.util.bloom.Key key)
Adds a key to this filter.void
and(Filter filter)
Performs a logical AND between this filter and a specified filter.int
getVectorSize()
boolean
membershipTest(org.apache.hadoop.util.bloom.Key key)
Determines whether a specified key belongs to this filter.void
not()
Performs a logical NOT on this filter.void
or(Filter filter)
Performs a logical OR between this filter and a specified filter.void
readFields(DataInput in)
String
toString()
void
write(DataOutput out)
void
xor(Filter filter)
Performs a logical XOR between this filter and a specified filter.-
Methods inherited from class org.apache.accumulo.core.bloomfilter.Filter
getSerialVersion, getVersion
-
-
-
-
Constructor Detail
-
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 (seeHash
).
-
-
Method Detail
-
add
public boolean add(org.apache.hadoop.util.bloom.Key key)
Description copied from class:Filter
Adds a key to this filter.
-
and
public void and(Filter filter)
Description copied from class:Filter
Performs a logical AND between this filter and a specified filter.Invariant: The result is assigned to this filter.
-
membershipTest
public boolean membershipTest(org.apache.hadoop.util.bloom.Key key)
Description copied from class:Filter
Determines whether a specified key belongs to this filter.- Specified by:
membershipTest
in classFilter
- 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.
-
or
public void or(Filter filter)
Description copied from class:Filter
Performs a logical OR between this filter and a specified filter.Invariant: The result is assigned to this filter.
-
xor
public void xor(Filter filter)
Description copied from class:Filter
Performs a logical XOR between this filter and a specified filter.Invariant: The result is assigned to this filter.
-
getVectorSize
public int getVectorSize()
- Returns:
- size of the the bloomfilter
-
write
public void write(DataOutput out) throws IOException
- Specified by:
write
in interfaceorg.apache.hadoop.io.Writable
- Overrides:
write
in classFilter
- Throws:
IOException
-
readFields
public void readFields(DataInput in) throws IOException
- Specified by:
readFields
in interfaceorg.apache.hadoop.io.Writable
- Overrides:
readFields
in classFilter
- Throws:
IOException
-
-