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java.lang.Objectorg.xlattice.crypto.filters.KeySelector
Given a key, populates arrays determining word and bit offsets into a Bloom filter.
Nested Class Summary | |
static interface |
KeySelector.BitSelector
|
class |
KeySelector.GenericBitSelector
Extracts the k bit offsets from a key, suitable for general values of m and k. |
class |
KeySelector.GenericWordSelector
Extracts the k word offsets from a key. |
static interface |
KeySelector.WordSelector
|
Field Summary | |
static int[] |
MASK
AND with byte to zero out index-many bits |
static int |
TWO_UP_15
|
static int[] |
UNMASK
AND with byte to expose index-many bits |
Constructor Summary | |
KeySelector(int m,
int k,
int[] bitOffset,
int[] wordOffset)
Creates a key selector for a Bloom filter. |
Method Summary | |
(package private) java.lang.String |
btoh(byte b)
|
void |
getOffsets(byte[] key)
Given a key, populate the word and bit offset arrays, each of which has k elements. |
(package private) java.lang.String |
itoh(int i)
|
Methods inherited from class java.lang.Object |
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait |
Field Detail |
public static final int[] UNMASK
public static final int[] MASK
public static final int TWO_UP_15
Constructor Detail |
public KeySelector(int m, int k, int[] bitOffset, int[] wordOffset)
m
- size of the filter as a power of 2k
- number of 'hash functions'bitOffset
- array of k bit offsets (offset of flag bit in word)wordOffset
- array of k word offsets (offset of word flag is in)Method Detail |
public void getOffsets(byte[] key)
key
- cryptographic key used in populating the arraysjava.lang.String itoh(int i)
java.lang.String btoh(byte b)
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