Hash (Apache HBase 1.2.12 API)

java.lang.Object
- org.apache.hadoop.hbase.util.Hash

Direct Known Subclasses:

JenkinsHash, MurmurHash, MurmurHash3
```
@InterfaceAudience.Private
@InterfaceStability.Stable
public abstract class Hash
extends Object
```
This class represents a common API for hashing functions.

Field Summary

Fields
Modifier and Type	Field and Description
`static int`	`INVALID_HASH` Constant to denote invalid hash type.
`static int`	`JENKINS_HASH` Constant to denote `JenkinsHash`.
`static int`	`MURMUR_HASH` Constant to denote `MurmurHash`.
`static int`	`MURMUR_HASH3` Constant to denote `MurmurHash3`.

Constructor Summary

Constructors
Constructor and Description

Hash()

Constructors
Constructor and Description
`Hash()`

Method Summary

Methods
Modifier and Type	Method and Description
`static int`	`getHashType(org.apache.hadoop.conf.Configuration conf)` This utility method converts the name of the configured hash type to a symbolic constant.
`static Hash`	`getInstance(org.apache.hadoop.conf.Configuration conf)` Get a singleton instance of hash function of a type defined in the configuration.
`static Hash`	`getInstance(int type)` Get a singleton instance of hash function of a given type.
`int`	`hash(byte[] bytes)` Calculate a hash using all bytes from the input argument, and a seed of -1.
`int`	`hash(byte[] bytes, int initval)` Calculate a hash using all bytes from the input argument, and a provided seed value.
`int`	`hash(byte[] bytes, int length, int initval)` Calculate a hash using bytes from 0 to `length`, and the provided seed value
`abstract int`	`hash(byte[] bytes, int offset, int length, int initval)` Calculate a hash using bytes from `offset` to `offset + length`, and the provided seed value.
`static int`	`parseHashType(String name)` This utility method converts String representation of hash function name to a symbolic constant.

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Field Detail
  - INVALID_HASH
```
public static final int INVALID_HASH
```
    Constant to denote invalid hash type.
    
    See Also:
    Constant Field Values
  - JENKINS_HASH
```
public static final int JENKINS_HASH
```
    Constant to denote JenkinsHash.
    
    See Also:
    Constant Field Values
  - MURMUR_HASH
```
public static final int MURMUR_HASH
```
    Constant to denote MurmurHash.
    
    See Also:
    Constant Field Values
  - MURMUR_HASH3
```
public static final int MURMUR_HASH3
```
    Constant to denote MurmurHash3.
    
    See Also:
    Constant Field Values
- Constructor Detail
  - Hash
```
public Hash()
```
- Method Detail
  - parseHashType
```
public static int parseHashType(String name)
```
    This utility method converts String representation of hash function name to a symbolic constant. Currently three function types are supported, "jenkins", "murmur" and "murmur3".
    
    Parameters:
    name - hash function name
    
    Returns:
    one of the predefined constants
  - getHashType
```
public static int getHashType(org.apache.hadoop.conf.Configuration conf)
```
    This utility method converts the name of the configured hash type to a symbolic constant.
    
    Parameters:
    conf - configuration
    
    Returns:
    one of the predefined constants
  - getInstance
```
public static Hash getInstance(int type)
```
    Get a singleton instance of hash function of a given type.
    
    Parameters:
    type - predefined hash type
    
    Returns:
    hash function instance, or null if type is invalid
  - getInstance
```
public static Hash getInstance(org.apache.hadoop.conf.Configuration conf)
```
    Get a singleton instance of hash function of a type defined in the configuration.
    
    Parameters:
    conf - current configuration
    
    Returns:
    defined hash type, or null if type is invalid
  - hash
```
public int hash(byte[] bytes)
```
    Calculate a hash using all bytes from the input argument, and a seed of -1.
    
    Parameters:
    bytes - input bytes
    
    Returns:
    hash value
  - hash
```
public int hash(byte[] bytes,
       int initval)
```
    Calculate a hash using all bytes from the input argument, and a provided seed value.
    
    Parameters:
    bytes - input bytes
    initval - seed value
    
    Returns:
    hash value
  - hash
```
public int hash(byte[] bytes,
       int length,
       int initval)
```
    Calculate a hash using bytes from 0 to length, and the provided seed value
    
    Parameters:
    bytes - input bytes
    length - length of the valid bytes after offset to consider
    initval - seed value
    
    Returns:
    hash value
  - hash
```
public abstract int hash(byte[] bytes,
       int offset,
       int length,
       int initval)
```
    Calculate a hash using bytes from offset to offset + length, and the provided seed value.
    
    Parameters:
    bytes - input bytes
    offset - the offset into the array to start consideration
    length - length of the valid bytes after offset to consider
    initval - seed value
    
    Returns:
    hash value

Class Hash

Field Summary

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Field Detail

INVALID_HASH

JENKINS_HASH

MURMUR_HASH

MURMUR_HASH3

Constructor Detail

Hash

Method Detail

parseHashType

getHashType

getInstance

getInstance

hash

hash

hash

hash