@InterfaceAudience.Private @InterfaceStability.Stable public class JenkinsHash extends Hash
lookup3.c, by Bob Jenkins, May 2006, Public Domain. You can use this free for any purpose. It's in the public domain. It has no warranty.
Modifier and Type | Field and Description |
---|---|
private static JenkinsHash |
_instance |
private static int |
BYTE_MASK |
INVALID_HASH, JENKINS_HASH, MURMUR_HASH, MURMUR_HASH3
Constructor and Description |
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JenkinsHash() |
Modifier and Type | Method and Description |
---|---|
static Hash |
getInstance() |
<T> int |
hash(HashKey<T> hashKey,
int initval)
taken from hashlittle() -- hash a variable-length key into a 32-bit value
|
static void |
main(String[] args)
Compute the hash of the specified file
|
getHashType, getInstance, getInstance, parseHashType
private static final int BYTE_MASK
private static JenkinsHash _instance
public JenkinsHash()
public static Hash getInstance()
public static void main(String[] args) throws IOException
args
- name of file to compute hash of.IOException
- epublic <T> int hash(HashKey<T> hashKey, int initval)
hash
in class Hash
hashKey
- the key to extract the bytes for hash algoinitval
- can be any integer value
The best hash table sizes are powers of 2. There is no need to do mod a prime (mod is
sooo slow!). If you need less than 32 bits, use a bitmask. For example, if you need
only 10 bits, do h = (h & hashmask(10));
In which case, the hash table
should have hashsize(10) elements.
If you are hashing n strings byte[][] k, do it like this: for (int i = 0, h = 0; i < n; ++i) h = hash( k[i], h);
By Bob Jenkins, 2006. bob_jenkins@burtleburtle.net. You may use this code any way you wish, private, educational, or commercial. It's free.
Use for hash table lookup, or anything where one collision in 2^^32 is acceptable. Do NOT use for cryptographic purposes.
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