Package org.h2.util

Class CacheObject

java.lang.Object

org.h2.util.CacheObject

All Implemented Interfaces:

java.lang.Comparable<CacheObject>

Direct Known Subclasses:

CacheHead

public abstract class CacheObject
extends java.lang.Object
implements java.lang.Comparable<CacheObject>

The base object for all cached objects.

Field Summary

Fields

Modifier and Type	Field	Description
CacheObject	cacheChained	The next element in the hash chain.
CacheObject	cacheNext	The next element in the LRU linked list.
CacheObject	cachePrevious	The previous element in the LRU linked list.
private boolean	changed
private int	pos

Constructor Summary

Constructors

Constructor	Description
CacheObject()

Method Summary

Modifier and Type	Method	Description
abstract boolean	canRemove()	Check if the object can be removed from the cache.
int	compareTo(CacheObject other)
abstract int	getMemory()	Get the estimated used memory.
int	getPos()
boolean	isChanged()	Check if this cache object has been changed and thus needs to be written back to the storage.
boolean	isStream()
void	setChanged(boolean b)
void	setPos(int pos)

Methods inherited from class java.lang.Object

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

Field Detail

cachePrevious

public CacheObject cachePrevious

The previous element in the LRU linked list. If the previous element is the head, then this element is the most recently used object.

cacheNext

public CacheObject cacheNext

The next element in the LRU linked list. If the next element is the head, then this element is the least recently used object.

cacheChained

public CacheObject cacheChained

The next element in the hash chain.

pos

private int pos

changed

private boolean changed

Constructor Detail

CacheObject

public CacheObject()

Method Detail

canRemove

public abstract boolean canRemove()

Check if the object can be removed from the cache. For example pinned objects can not be removed.

Returns:

true if it can be removed

getMemory

public abstract int getMemory()

Get the estimated used memory.

Returns:

number of words (one word is 4 bytes)

setPos

public void setPos(int pos)

getPos

public int getPos()

isChanged

public boolean isChanged()

Check if this cache object has been changed and thus needs to be written back to the storage.

Returns:

if it has been changed

setChanged

public void setChanged(boolean b)

compareTo

public int compareTo(CacheObject other)

Specified by:

compareTo in interface java.lang.Comparable<CacheObject>

isStream

public boolean isStream()