LocalHash (I2P Anonymous Network - Java Documentation - Version 1.5.0)

java.lang.Object
- net.i2p.data.SimpleDataStructure
- - net.i2p.data.Hash
  - - net.i2p.router.networkdb.kademlia.LocalHash

All Implemented Interfaces:

DataStructure
```
class LocalHash
extends Hash
```
Pull the caching used only by KBucketImpl out of Hash and put it here.

Since:

0.7.14

Author:

jrandom, moved from Hash.java by zzz

Field Summary
- Fields inherited from class net.i2p.data.Hash
  FAKE_HASH, HASH_LENGTH
- Fields inherited from class net.i2p.data.SimpleDataStructure
  _data

Constructor Summary

Constructors
Constructor Description

LocalHash(byte[] b)

LocalHash(Hash h)

Method Summary

All Methods Instance Methods Concrete Methods
Modifier and Type	Method	Description
`byte[]`	`cachedXor(Hash key)`	Calculate the xor with the current object and the specified hash, caching values where possible.
`void`	`clearXorCache()`
`void`	`prepareCache()`	Prepare this hash's cache for xor values - very few hashes will need it, so we don't want to waste the memory, and lazy initialization would incur online overhead to verify the initialization.

Methods inherited from class net.i2p.data.Hash
clearCache, create, create, create, hashCode, length, readBytes, setData, toBase32, toBase64

Methods inherited from class net.i2p.data.SimpleDataStructure
calculateHash, equals, fromBase64, fromByteArray, getData, read, toByteArray, toString, writeBytes

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

- Constructor Detail
  - LocalHash
```
public LocalHash(Hash h)
```
  - LocalHash
```
public LocalHash(byte[] b)
```
- Method Detail
  - prepareCache
```
public void prepareCache()
```
    Prepare this hash's cache for xor values - very few hashes will need it, so we don't want to waste the memory, and lazy initialization would incur online overhead to verify the initialization.
  - cachedXor
```
public byte[] cachedXor(Hash key)
                 throws IllegalStateException
```
    Calculate the xor with the current object and the specified hash, caching values where possible. Currently this keeps up to MAX_CACHED_XOR (1024) entries, and uses an essentially random ejection policy. Later perhaps go for an LRU or FIFO?
    
    Throws:
    
    IllegalStateException - if you try to use the cache without first preparing this object's cache via .prepareCache()
  - clearXorCache
```
public void clearXorCache()
```