Package org.apache.pinot.common.utils

Class HashUtil

java.lang.Object

org.apache.pinot.common.utils.HashUtil

public class HashUtil
extends Object

Field Summary

Fields

Modifier and Type	Field	Description
static int	MIN_FASTUTIL_HASHSET_SIZE	Tests show that even for smaller set sizes, setting the hash size to this min value improves performance at an insignificant increase of memory footprint.

Method Summary

Modifier and Type	Method	Description
static long	compute(ByteBuffer buff)
static long	compute(IntBuffer buff)
static int	getHashMapCapacity(int expectedSize)	Returns a capacity that is sufficient to keep the map from being resized as long as it grows no larger than expectedSize and the load factor is >= its default (0.75).
static int	getMinHashSetSize(int expected)	Returns the min size for the fast-util hash-set given the expected size of values stored in the hash-set.
static long	hash64(byte[] data, int length)
static long	hash64(byte[] data, int length, int seed)
static int	murmur2(byte[] data)	Generates 32 bit murmur2 hash from byte array

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

MIN_FASTUTIL_HASHSET_SIZE

public static final int MIN_FASTUTIL_HASHSET_SIZE

Tests show that even for smaller set sizes, setting the hash size to this min value improves performance at an insignificant increase of memory footprint.

See Also:

Constant Field Values

Method Detail

getMinHashSetSize

public static int getMinHashSetSize(int expected)

Returns the min size for the fast-util hash-set given the expected size of values stored in the hash-set.

Parameters:

expected - the expected/actual number of values to be stored

Returns:

the optimal min value

getHashMapCapacity

public static int getHashMapCapacity(int expectedSize)

Returns a capacity that is sufficient to keep the map from being resized as long as it grows no larger than expectedSize and the load factor is >= its default (0.75).

compute

public static long compute(IntBuffer buff)

compute

public static long compute(ByteBuffer buff)

hash64

public static long hash64(byte[] data,
                          int length)

hash64

public static long hash64(byte[] data,
                          int length,
                          int seed)

murmur2

public static int murmur2(byte[] data)

Generates 32 bit murmur2 hash from byte array

Parameters:

data - byte array to hash

Returns:

32 bit hash of the given array