LruHashMap.Entry (Apache HBase 1.2.12 API)

java.lang.Object
- org.apache.hadoop.hbase.regionserver.LruHashMap.Entry<K,V>

All Implemented Interfaces:

Map.Entry<K,V>, HeapSize

Enclosing class:

LruHashMap<K extends HeapSize,V extends HeapSize>
```
protected static class LruHashMap.Entry<K extends HeapSize,V extends HeapSize>
extends Object
implements Map.Entry<K,V>, HeapSize
```
Entry to store key/value mappings.
Contains previous and next pointers for the doubly linked-list which is used for LRU eviction.
Instantiations of this class are memory aware. Both the key and value classes used must also implement HeapSize.

Field Summary

Fields
Modifier and Type	Field and Description
`protected int`	`hash` The hash value for this entries key
`protected long`	`heapSize` The precomputed heap size of this entry
`protected K`	`key` The key
`protected LruHashMap.Entry<K,V>`	`next` The next entry in the hash chain (for collisions)
`protected LruHashMap.Entry<K,V>`	`nextPtr` The next entry in the LRU list (towards MRU)
`(package private) static int`	`OVERHEAD` The baseline overhead memory usage of this class
`protected LruHashMap.Entry<K,V>`	`prevPtr` The previous entry in the LRU list (towards LRU)
`protected V`	`value` The value

Constructor Summary

Constructors
Constructor and Description
`LruHashMap.Entry(int h, K k, V v, LruHashMap.Entry<K,V> nextChainPtr, LruHashMap.Entry<K,V> prevLruPtr)` Create a new entry.

Method Summary

Methods
Modifier and Type	Method and Description
`boolean`	`equals(Object o)` Returns true is the specified entry has the same key and the same value as this entry.
`K`	`getKey()` Get the key of this entry.
`protected LruHashMap.Entry<K,V>`	`getNextPtr()` Returns the next pointer for the entry in teh LRU.
`protected LruHashMap.Entry<K,V>`	`getPrevPtr()` Returns the previous pointer for the entry in the LRU.
`V`	`getValue()` Get the value of this entry.
`int`	`hashCode()` Returns the hash code of the entry by xor'ing the hash values of the key and value of this entry.
`long`	`heapSize()` Returns the pre-computed and "deep" size of the Entry
`protected long`	`replaceValue(V newValue)` Replace the value of this entry.
`protected void`	`setNextPtr(LruHashMap.Entry<K,V> nextPtr)` Sets the next pointer for the entry in the LRU.
`protected void`	`setPrevPtr(LruHashMap.Entry<K,V> prevPtr)` Sets the previous pointer for the entry in the LRU.
`V`	`setValue(V newValue)` Set the value of this entry.
`String`	`toString()` Returns String representation of the entry in form "key=value"

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

- Field Detail
  - OVERHEAD
```
static final int OVERHEAD
```
    The baseline overhead memory usage of this class
  - key
```
protected final K extends HeapSize key
```
    The key
  - value
```
protected V extends HeapSize value
```
    The value
  - hash
```
protected final int hash
```
    The hash value for this entries key
  - next
```
protected LruHashMap.Entry<K extends HeapSize,V extends HeapSize> next
```
    The next entry in the hash chain (for collisions)
  - prevPtr
```
protected LruHashMap.Entry<K extends HeapSize,V extends HeapSize> prevPtr
```
    The previous entry in the LRU list (towards LRU)
  - nextPtr
```
protected LruHashMap.Entry<K extends HeapSize,V extends HeapSize> nextPtr
```
    The next entry in the LRU list (towards MRU)
  - heapSize
```
protected long heapSize
```
    The precomputed heap size of this entry
- Constructor Detail
  - LruHashMap.Entry
```
LruHashMap.Entry(int h,
                K k,
                V v,
                LruHashMap.Entry<K,V> nextChainPtr,
                LruHashMap.Entry<K,V> prevLruPtr)
```
    Create a new entry.
    
    Parameters:
    h - the hash value of the key
    k - the key
    v - the value
    nextChainPtr - the next entry in the hash chain, null if none
    prevLruPtr - the previous entry in the LRU
- Method Detail
  - getKey
```
public K getKey()
```
    Get the key of this entry.
    
    Specified by:
    
    getKey in interface Map.Entry<K extends HeapSize,V extends HeapSize>
    
    Returns:
    the key associated with this entry
  - getValue
```
public V getValue()
```
    Get the value of this entry.
    
    Specified by:
    
    getValue in interface Map.Entry<K extends HeapSize,V extends HeapSize>
    
    Returns:
    the value currently associated with this entry
  - setValue
```
public V setValue(V newValue)
```
    Set the value of this entry. It is not recommended to use this method when changing the value. Rather, using replaceValue will return the difference in heap usage between the previous and current values.
    
    Specified by:
    
    setValue in interface Map.Entry<K extends HeapSize,V extends HeapSize>
    
    Parameters:
    newValue - the new value to associate with this entry
    
    Returns:
    the value previously associated with this entry
  - replaceValue
```
protected long replaceValue(V newValue)
```
    Replace the value of this entry. Computes and returns the difference in heap size when changing the value associated with this entry.
    
    Parameters:
    newValue - the new value to associate with this entry
    
    Returns:
    the change in heap usage of this entry in bytes
  - equals
```
public boolean equals(Object o)
```
    Returns true is the specified entry has the same key and the same value as this entry.
    
    Specified by:
    
    equals in interface Map.Entry<K extends HeapSize,V extends HeapSize>
    
    Overrides:
    
    equals in class Object
    
    Parameters:
    o - entry to test against current
    
    Returns:
    true is entries have equal key and value, false if no
  - hashCode
```
public int hashCode()
```
    Returns the hash code of the entry by xor'ing the hash values of the key and value of this entry.
    
    Specified by:
    
    hashCode in interface Map.Entry<K extends HeapSize,V extends HeapSize>
    
    Overrides:
    
    hashCode in class Object
    
    Returns:
    hash value of this entry
  - toString
```
public String toString()
```
    Returns String representation of the entry in form "key=value"
    
    Overrides:
    
    toString in class Object
    
    Returns:
    string value of entry
  - setPrevPtr
```
protected void setPrevPtr(LruHashMap.Entry<K,V> prevPtr)
```
    Sets the previous pointer for the entry in the LRU.
    
    Parameters:
    prevPtr - previous entry
  - getPrevPtr
```
protected LruHashMap.Entry<K,V> getPrevPtr()
```
    Returns the previous pointer for the entry in the LRU.
    
    Returns:
    previous entry
  - setNextPtr
```
protected void setNextPtr(LruHashMap.Entry<K,V> nextPtr)
```
    Sets the next pointer for the entry in the LRU.
    
    Parameters:
    nextPtr - next entry
  - getNextPtr
```
protected LruHashMap.Entry<K,V> getNextPtr()
```
    Returns the next pointer for the entry in teh LRU.
    
    Returns:
    next entry
  - heapSize
```
public long heapSize()
```
    Returns the pre-computed and "deep" size of the Entry
    
    Specified by:
    
    heapSize in interface HeapSize
    
    Returns:
    size of the entry in bytes

Class LruHashMap.Entry<K extends HeapSize,V extends HeapSize>

Field Summary

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Field Detail

OVERHEAD

key

value

hash

next

prevPtr

nextPtr

heapSize

Constructor Detail

LruHashMap.Entry

Method Detail

getKey

getValue

setValue

replaceValue

equals

hashCode

toString

setPrevPtr

getPrevPtr

setNextPtr

getNextPtr

heapSize