Package com.tangosol.util

Class AbstractKeyBasedMap.DeferredCacheEvent<K,V>

java.lang.Object

java.util.EventObject

com.tangosol.util.MapEvent<K,V>

com.tangosol.net.cache.CacheEvent<K,V>

com.tangosol.util.AbstractKeyBasedMap.DeferredCacheEvent<K,V>

All Implemented Interfaces:

PortableObject, Serializable

Enclosing class:

AbstractKeyBasedMap<K,V>

protected abstract static class AbstractKeyBasedMap.DeferredCacheEvent<K,V>
extends CacheEvent<K,V>

A DeferredCacheEvent is a CacheEvent object that defers the loading of the old value.

This event has two predominant states; active and inactive. The event is active from incarnation and can transition to inactive (via deactivate()) but not vice-versa. Being active allows the getOldValue implementation to load the value from underlying map, thus all consumers of this event must ensure they call getOldValue prior to returning control when this event is dispatched.

Once inactive the correct value may no longer be available in the map thus in this state a getOldValue will return either null or the cached old value.

See Also:

Serialized Form

Nested Class Summary

Nested classes/interfaces inherited from class com.tangosol.net.cache.CacheEvent

CacheEvent.TransformationState

Field Summary

Fields

Modifier and Type	Field	Description
protected boolean	m_fActive	Whether the DeferredCacheEvent is in an active or inactive state.

Fields inherited from class com.tangosol.net.cache.CacheEvent

EXPIRED, m_nFlags, m_transformState, PRIMING, SYNTHETIC

Fields inherited from class com.tangosol.util.MapEvent

ENTRY_DELETED, ENTRY_INSERTED, ENTRY_UPDATED, m_key, m_nId, m_nPartition, m_nVersion, m_valueNew, m_valueOld

Fields inherited from class java.util.EventObject

source

Constructor Summary

Constructors

Constructor	Description
DeferredCacheEvent(ObservableMap<K,V> map, int nId, K oKey, V oValueOld, V oValueNew, boolean fSynthetic)	Constructs a new DeferredCacheEvent.

Method Summary

Modifier and Type	Method	Description
void	deactivate()	Deactivate this DeferredCacheEvent instance.
V	getOldValue()	Return an old value associated with this event.
protected abstract V	readOldValue()	Perform a deferred read for the old value in a usage-specific way.

Methods inherited from class com.tangosol.net.cache.CacheEvent

getDescription, getTransformationState, isExpired, isPriming, isSynthetic, isVersionUpdate, shouldDispatch, with

Methods inherited from class com.tangosol.util.MapEvent

dispatch, dispatch, dispatch, getDescription, getId, getKey, getMap, getNewEntry, getNewValue, getOldEntry, getPartition, getVersion, isDelete, isInsert, isUpdate, readExternal, toString, writeExternal

Methods inherited from class java.util.EventObject

getSource

Methods inherited from class java.lang.Object

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

Field Detail

m_fActive

protected volatile boolean m_fActive

Whether the DeferredCacheEvent is in an active or inactive state.

Constructor Detail

DeferredCacheEvent

public DeferredCacheEvent(ObservableMap<K,V> map,
                          int nId,
                          K oKey,
                          V oValueOld,
                          V oValueNew,
                          boolean fSynthetic)

Constructs a new DeferredCacheEvent.

Parameters:

map - the ObservableMap

nId - this event's id, one of MapEvent.ENTRY_INSERTED, MapEvent.ENTRY_UPDATED or MapEvent.ENTRY_DELETED

oKey - the key into the map

oValueOld - the old value (for update and delete events)

oValueNew - the new value (for insert and update events)

fSynthetic - true iff the event is caused by the cache internal processing such as eviction or loading

Method Detail

getOldValue

public V getOldValue()

Return an old value associated with this event.

The old value represents a value deleted from or updated in a map. It is always null for "insert" notifications.

Overrides:

getOldValue in class MapEvent<K,V>

Returns:

an old value

readOldValue

protected abstract V readOldValue()

Perform a deferred read for the old value in a usage-specific way.

Returns:

the old value

deactivate

public void deactivate()

Deactivate this DeferredCacheEvent instance. This is used to prevent future getOldValue() calls using the underlying map *after* the event dispatching code returned and the content of the map had been changed to a new value.

The contract between the DeferredCacheEvent and consumers of the event states that consumers must call getOldValue prior to returning from event dispatching logic.