Hash64 (Spectator)

java.lang.Object
- com.netflix.spectator.impl.Hash64

```
public final class Hash64
extends Object
```
Helper to compute a 64-bit hash incrementally based on a set of primitives and primitive arrays. It is currently using the XXH64 algorithm. See the spec for more details.
This class is an internal implementation detail only intended for use within spectator. It is subject to change without notice.

Constructor Summary

Constructors
Constructor and Description

Hash64()
Create a new instance with a seed of zero.

Hash64(long seed)
Create a new instance.

Constructors
Constructor and Description
`Hash64()` Create a new instance with a seed of zero.
`Hash64(long seed)` Create a new instance.

Method Summary

All Methods Static Methods Instance Methods Concrete Methods
Modifier and Type	Method and Description
`long`	`compute()` Compute and return the final hash value.
`long`	`computeAndReset()` Compute the final hash value and reset the hash accumulator.
`static long`	`hashBytes(byte[] bytes)` xxHash64 of `bytes` with seed 0.
`static long`	`hashBytes(byte[] bytes, int offset, int length)` xxHash64 of `bytes[offset, offset+length)` with seed 0.
`static long`	`hashBytes(byte[] bytes, int offset, int length, long seed)` xxHash64 of `bytes[offset, offset+length)` with the given seed.
`static long`	`hashBytes(byte[] bytes, long seed)` xxHash64 of `bytes` with the given seed.
`static long`	`hashInt(int value)` xxHash64 of a single `int` value with seed 0.
`static long`	`hashInt(int value, long seed)` xxHash64 of a single `int` value with the given seed.
`static long`	`hashLong(long value)` xxHash64 of a single `long` value with seed 0.
`static long`	`hashLong(long value, long seed)` xxHash64 of a single `long` value with the given seed.
`static long`	`hashString(CharSequence str)` xxHash64 of the UTF-8 byte sequence of `str` with seed 0.
`static long`	`hashString(CharSequence str, long seed)` xxHash64 of the UTF-8 byte sequence of `str` with the given seed.
`static int`	`reduce(int hash, int n)` Helper to efficiently reduce hash from to range of `[0, n)`.
`static int`	`reduce(long hash, int n)` Helper to efficiently reduce hash from to range of `[0, n)`.
`void`	`reset()` Reset so it can be reused for computing another hash.
`Hash64`	`updateBoolean(boolean value)` Update the hash with the specified boolean value.
`Hash64`	`updateBooleans(boolean[] values)` Update the hash with the specified boolean values.
`Hash64`	`updateBooleans(boolean[] values, int offset, int length)` Update the hash with the specified boolean values.
`Hash64`	`updateByte(byte value)` Update the hash with the specified byte value.
`Hash64`	`updateBytes(byte[] values)` Update the hash with the specified byte values.
`Hash64`	`updateBytes(byte[] values, int offset, int length)` Update the hash with the specified byte values.
`Hash64`	`updateChar(char value)` Update the hash with the specified character value.
`Hash64`	`updateChars(char[] values)` Update the hash with the specified character values.
`Hash64`	`updateChars(char[] values, int offset, int length)` Update the hash with the specified character values.
`Hash64`	`updateDouble(double value)` Update the hash with the specified double value.
`Hash64`	`updateDoubles(double[] values)` Update the hash with the specified double values.
`Hash64`	`updateDoubles(double[] values, int offset, int length)` Update the hash with the specified double values.
`Hash64`	`updateFloat(float value)` Update the hash with the specified float value.
`Hash64`	`updateFloats(float[] values)` Update the hash with the specified float values.
`Hash64`	`updateFloats(float[] values, int offset, int length)` Update the hash with the specified float values.
`Hash64`	`updateInt(int value)` Update the hash with the specified int value.
`Hash64`	`updateInts(int[] values)` Update the hash with the specified int values.
`Hash64`	`updateInts(int[] values, int offset, int length)` Update the hash with the specified int values.
`Hash64`	`updateLong(long value)` Update the hash with the specified long value.
`Hash64`	`updateLongs(long[] values)` Update the hash with the specified long values.
`Hash64`	`updateLongs(long[] values, int offset, int length)` Update the hash with the specified long values.
`Hash64`	`updateShort(short value)` Update the hash with the specified short value.
`Hash64`	`updateShorts(short[] values)` Update the hash with the specified short values.
`Hash64`	`updateShorts(short[] values, int offset, int length)` Update the hash with the specified short values.
`Hash64`	`updateString(CharSequence str)` Update the hash with the specified character sequence value.

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

- Constructor Detail
  - Hash64
```
public Hash64()
```
    Create a new instance with a seed of zero.
  - Hash64
```
public Hash64(long seed)
```
    Create a new instance.
- Method Detail
  - reset
```
public void reset()
```
    Reset so it can be reused for computing another hash.
  - updateBoolean
```
public Hash64 updateBoolean(boolean value)
```
    Update the hash with the specified boolean value.
  - updateBooleans
```
public Hash64 updateBooleans(boolean[] values,
                             int offset,
                             int length)
```
    Update the hash with the specified boolean values.
  - updateBooleans
```
public Hash64 updateBooleans(boolean[] values)
```
    Update the hash with the specified boolean values.
  - updateChar
```
public Hash64 updateChar(char value)
```
    Update the hash with the specified character value.
  - updateChars
```
public Hash64 updateChars(char[] values,
                          int offset,
                          int length)
```
    Update the hash with the specified character values.
  - updateChars
```
public Hash64 updateChars(char[] values)
```
    Update the hash with the specified character values.
  - updateString
```
public Hash64 updateString(CharSequence str)
```
    Update the hash with the specified character sequence value. The string is hashed as its UTF-8 byte sequence. The result matches updateBytes(s.getBytes(UTF_8)) bit-for-bit, so output is portable to other languages that hash UTF-8 bytes.
    For short strings (length ≤ ) and any non-String CharSequence, encodes in-place via a char loop with no transient byte array. For longer String inputs, falls back to getBytes(UTF_8) followed by the 8-byte-stride updateBytes path — that one allocates a transient byte[] (typically JIT-scalar-replaced) but throughput is 2–3× higher on long strings.
  - updateByte
```
public Hash64 updateByte(byte value)
```
    Update the hash with the specified byte value.
  - updateBytes
```
public Hash64 updateBytes(byte[] values,
                          int offset,
                          int length)
```
    Update the hash with the specified byte values.
  - updateBytes
```
public Hash64 updateBytes(byte[] values)
```
    Update the hash with the specified byte values.
  - updateShort
```
public Hash64 updateShort(short value)
```
    Update the hash with the specified short value.
  - updateShorts
```
public Hash64 updateShorts(short[] values,
                           int offset,
                           int length)
```
    Update the hash with the specified short values.
  - updateShorts
```
public Hash64 updateShorts(short[] values)
```
    Update the hash with the specified short values.
  - updateInt
```
public Hash64 updateInt(int value)
```
    Update the hash with the specified int value.
  - updateInts
```
public Hash64 updateInts(int[] values,
                         int offset,
                         int length)
```
    Update the hash with the specified int values.
  - updateInts
```
public Hash64 updateInts(int[] values)
```
    Update the hash with the specified int values.
  - updateLong
```
public Hash64 updateLong(long value)
```
    Update the hash with the specified long value.
  - updateLongs
```
public Hash64 updateLongs(long[] values,
                          int offset,
                          int length)
```
    Update the hash with the specified long values.
  - updateLongs
```
public Hash64 updateLongs(long[] values)
```
    Update the hash with the specified long values.
  - updateFloat
```
public Hash64 updateFloat(float value)
```
    Update the hash with the specified float value.
  - updateFloats
```
public Hash64 updateFloats(float[] values,
                           int offset,
                           int length)
```
    Update the hash with the specified float values.
  - updateFloats
```
public Hash64 updateFloats(float[] values)
```
    Update the hash with the specified float values.
  - updateDouble
```
public Hash64 updateDouble(double value)
```
    Update the hash with the specified double value.
  - updateDoubles
```
public Hash64 updateDoubles(double[] values,
                            int offset,
                            int length)
```
    Update the hash with the specified double values.
  - updateDoubles
```
public Hash64 updateDoubles(double[] values)
```
    Update the hash with the specified double values.
  - compute
```
public long compute()
```
    Compute and return the final hash value.
  - computeAndReset
```
public long computeAndReset()
```
    Compute the final hash value and reset the hash accumulator.
  - hashLong
```
public static long hashLong(long value)
```
    xxHash64 of a single long value with seed 0. Allocation-free.
  - hashLong
```
public static long hashLong(long value,
                            long seed)
```
    xxHash64 of a single long value with the given seed. Allocation-free.
  - hashInt
```
public static long hashInt(int value)
```
    xxHash64 of a single int value with seed 0. Allocation-free.
  - hashInt
```
public static long hashInt(int value,
                           long seed)
```
    xxHash64 of a single int value with the given seed. Allocation-free.
  - hashBytes
```
public static long hashBytes(byte[] bytes)
```
    xxHash64 of bytes with seed 0. Allocation-free.
  - hashBytes
```
public static long hashBytes(byte[] bytes,
                             long seed)
```
    xxHash64 of bytes with the given seed. Allocation-free.
  - hashBytes
```
public static long hashBytes(byte[] bytes,
                             int offset,
                             int length)
```
    xxHash64 of bytes[offset, offset+length) with seed 0. Allocation-free.
  - hashBytes
```
public static long hashBytes(byte[] bytes,
                             int offset,
                             int length,
                             long seed)
```
    xxHash64 of bytes[offset, offset+length) with the given seed. Allocation-free.
  - hashString
```
public static long hashString(CharSequence str)
```
    xxHash64 of the UTF-8 byte sequence of str with seed 0.
    Allocation behavior: a String longer than chars routes through getBytes(UTF_8) + hashBytes for throughput (allocates a transient byte[], matches updateString(CharSequence)'s hybrid). All other inputs — short Strings and any non-String CharSequence regardless of length — take the inline UTF-8 encoder and allocate nothing. Long non-String CharSequences pay the inline path's throughput cost since getBytes is not available on them.
  - hashString
```
public static long hashString(CharSequence str,
                              long seed)
```
    xxHash64 of the UTF-8 byte sequence of str with the given seed. See hashString(CharSequence) for allocation behavior.
  - reduce
```
public static int reduce(long hash,
                         int n)
```
    Helper to efficiently reduce hash from to range of [0, n). Based on fast alternative to modulo reduction post.
  - reduce
```
public static int reduce(int hash,
                         int n)
```
    Helper to efficiently reduce hash from to range of [0, n). Based on fast alternative to modulo reduction post.

Class Hash64

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Constructor Detail

Hash64

Hash64

Method Detail

reset

updateBoolean

updateBooleans

updateBooleans

updateChar

updateChars

updateChars

updateString

updateByte

updateBytes

updateBytes

updateShort

updateShorts

updateShorts

updateInt

updateInts

updateInts

updateLong

updateLongs

updateLongs

updateFloat

updateFloats

updateFloats

updateDouble

updateDoubles

updateDoubles

compute

computeAndReset

hashLong

hashLong

hashInt

hashInt

hashBytes

hashBytes

hashBytes

hashBytes

hashString

hashString

reduce

reduce