org.apache.ignite.cache.eviction.lru

Class LruEvictionPolicy<K,V>

java.lang.Object

org.apache.ignite.cache.eviction.AbstractEvictionPolicy<K,V>

org.apache.ignite.cache.eviction.lru.LruEvictionPolicy<K,V>

All Implemented Interfaces:

Externalizable, Serializable, EvictionPolicy<K,V>, IgniteMBeanAware

public class LruEvictionPolicy<K,V>
extends AbstractEvictionPolicy<K,V>
implements IgniteMBeanAware

Eviction policy based on Least Recently Used (LRU) algorithm and supports batch eviction.

The eviction starts in the following cases:

• The cache size becomes batchSize elements greater than the maximum size.
• The size of cache entries in bytes becomes greater than the maximum memory size. The size of cache entry calculates as sum of key size and value size.

Note:Batch eviction is enabled only if maximum memory limit isn't set (maxMemSize == 0). batchSize elements will be evicted in this case. The default batchSize value is 1. This implementation is very efficient since it is lock-free and does not create any additional table-like data structures. The LRU ordering information is maintained by attaching ordering metadata to cache entries.

See Also:

Serialized Form

Field Summary

Fields inherited from class org.apache.ignite.cache.eviction.AbstractEvictionPolicy

memSize

Constructor Summary

Constructors

Constructor and Description
LruEvictionPolicy() Constructs LRU eviction policy with all defaults.
LruEvictionPolicy(int max) Constructs LRU eviction policy with maximum size.

Method Summary

Modifier and Type	Method and Description
int	getCurrentSize()
Object	getMBean()
Collection<EvictableEntry<K,V>>	queue() Gets read-only view on internal FIFO queue in proper order.
protected boolean	removeMeta(Object meta)
LruEvictionPolicy<K,V>	setBatchSize(int batchSize) Sets batch size.
LruEvictionPolicy<K,V>	setMaxMemorySize(long maxMemSize) Sets maximum allowed cache size in bytes.
LruEvictionPolicy<K,V>	setMaxSize(int max) Sets maximum allowed size of cache before entry will start getting evicted.
protected int	shrink0() Tries to remove one item from queue.
String	toString()
protected boolean	touch(EvictableEntry<K,V> entry)

Methods inherited from class org.apache.ignite.cache.eviction.AbstractEvictionPolicy

getBatchSize, getCurrentMemorySize, getMaxMemorySize, getMaxSize, onEntryAccessed, readExternal, shrink, writeExternal

Methods inherited from class java.lang.Object

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

Constructor Detail

LruEvictionPolicy

public LruEvictionPolicy()

Constructs LRU eviction policy with all defaults.

LruEvictionPolicy

public LruEvictionPolicy(int max)

Constructs LRU eviction policy with maximum size.

Parameters:

max - Maximum allowed size of cache before entry will start getting evicted.

Method Detail

getCurrentSize

public int getCurrentSize()

Specified by:

getCurrentSize in class AbstractEvictionPolicy<K,V>

Returns:

Size of the container with trackable entries.

setMaxMemorySize

public LruEvictionPolicy<K,V> setMaxMemorySize(long maxMemSize)

Sets maximum allowed cache size in bytes.

Overrides:

setMaxMemorySize in class AbstractEvictionPolicy<K,V>

Returns:

this for chaining.

setMaxSize

public LruEvictionPolicy<K,V> setMaxSize(int max)

Sets maximum allowed size of cache before entry will start getting evicted.

Overrides:

setMaxSize in class AbstractEvictionPolicy<K,V>

Parameters:

max - Maximum allowed size of cache before entry will start getting evicted.

Returns:

this for chaining.

setBatchSize

public LruEvictionPolicy<K,V> setBatchSize(int batchSize)

Sets batch size.

Overrides:

setBatchSize in class AbstractEvictionPolicy<K,V>

Parameters:

batchSize - Batch size.

Returns:

this for chaining.

queue

public Collection<EvictableEntry<K,V>> queue()

Gets read-only view on internal FIFO queue in proper order.

Returns:

Read-only view ono internal 'FIFO' queue.

removeMeta

protected boolean removeMeta(Object meta)

Specified by:

removeMeta in class AbstractEvictionPolicy<K,V>

Parameters:

meta - Meta-information shipped to an entry.

Returns:

True if meta was successfully removed from the container.

touch

protected boolean touch(EvictableEntry<K,V> entry)

Specified by:

touch in class AbstractEvictionPolicy<K,V>

Parameters:

entry - Entry to touch.

Returns:

True if new node has been added to queue by this call.

shrink0

protected int shrink0()

Tries to remove one item from queue.

Specified by:

shrink0 in class AbstractEvictionPolicy<K,V>

Returns:

number of bytes that was free. -1 if queue is empty.

getMBean

public Object getMBean()

Specified by:

getMBean in interface IgniteMBeanAware

Returns:

MBean for this object.

toString

public String toString()

Overrides:

toString in class Object