public class BloomFilter extends Filter
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.
hash, hashType, nbHash, vectorSize
Constructor and Description |
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BloomFilter()
Default constructor - use with readFields
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BloomFilter(int vectorSize,
int nbHash,
int hashType)
Constructor
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Modifier and Type | Method and Description |
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boolean |
add(org.apache.hadoop.util.bloom.Key key)
Adds a key to this filter.
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void |
and(Filter filter)
Peforms a logical AND between this filter and a specified filter.
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int |
getVectorSize() |
boolean |
membershipTest(org.apache.hadoop.util.bloom.Key key)
Determines whether a specified key belongs to this filter.
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void |
not()
Performs a logical NOT on this filter.
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void |
or(Filter filter)
Peforms a logical OR between this filter and a specified filter.
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void |
readFields(DataInput in) |
String |
toString() |
void |
write(DataOutput out) |
void |
xor(Filter filter)
Peforms a logical XOR between this filter and a specified filter.
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getSerialVersion, getVersion
public BloomFilter()
public BloomFilter(int vectorSize, int nbHash, int hashType)
vectorSize
- The vector size of this filter.nbHash
- The number of hash function to consider.hashType
- type of the hashing function (see Hash
).public boolean add(org.apache.hadoop.util.bloom.Key key)
Filter
public void and(Filter filter)
Filter
Invariant: The result is assigned to this filter.
public boolean membershipTest(org.apache.hadoop.util.bloom.Key key)
Filter
membershipTest
in class Filter
key
- The key to test.public void not()
Filter
The result is assigned to this filter.
public void or(Filter filter)
Filter
Invariant: The result is assigned to this filter.
public void xor(Filter filter)
Filter
Invariant: The result is assigned to this filter.
public int getVectorSize()
public void write(DataOutput out) throws IOException
write
in interface org.apache.hadoop.io.Writable
write
in class Filter
IOException
public void readFields(DataInput in) throws IOException
readFields
in interface org.apache.hadoop.io.Writable
readFields
in class Filter
IOException
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