GemFire 6.6.4

com.gemstone.gemfire.cache
Interface CacheListener<K,V>

All Superinterfaces:
CacheCallback
All Known Subinterfaces:
RegionMembershipListener<K,V>, RegionRoleListener<K,V>
All Known Implementing Classes:
CacheListenerAdapter, RegionMembershipListenerAdapter, RegionRoleListenerAdapter

public interface CacheListener<K,V>
extends CacheCallback

A listener to handle region or entry related events.

Instead of implementing this interface it is recommended that you extend the CacheListenerAdapter class.

Avoiding the risk of deadlock

The methods on a CacheListener are invoked while holding a lock on the entry described by the EntryEvent, as a result if the listener method takes a long time to execute then it will cause the operation that caused it to be invoked to take a long time. In addition, listener code which calls Region methods could result in a deadlock. For example, in afterUpdate(EntryEvent) for entry key k1, put(k2, someVal) is called at the same time afterUpdate(EntryEvent) for entry key k2 calls put(k1, someVal) a deadlock may result. This co-key dependency example can be extended to a co-Region dependency where listener code in Region "A" performs Region operations on "B" and listener code in Region "B" performs Region operations on "A". Deadlocks may be either java-level or distributed multi-VM dead locks depending on Region configuration. To be assured of no deadlocks, listener code should cause some other thread to access the region and must not wait for that thread to complete the task.

Concurrency

Multiple events, on different entries, can cause concurrent invocation of CacheListener methods. Any exceptions thrown by the listener are caught by GemFire and logged.

Declaring instances in Cache XML files

To declare a CacheListener in a Cache XML file, it must also implement Declarable

Since:
3.0
See Also:
AttributesFactory.addCacheListener(com.gemstone.gemfire.cache.CacheListener), AttributesFactory.initCacheListeners(com.gemstone.gemfire.cache.CacheListener[]), RegionAttributes.getCacheListeners(), AttributesMutator.addCacheListener(com.gemstone.gemfire.cache.CacheListener), AttributesMutator.removeCacheListener(com.gemstone.gemfire.cache.CacheListener), AttributesMutator.initCacheListeners(com.gemstone.gemfire.cache.CacheListener[])

Method Summary
 void afterCreate(EntryEvent<K,V> event)
          Handles the event of new key being added to a region.
 void afterDestroy(EntryEvent<K,V> event)
          Handles the event of an entry being destroyed.
 void afterInvalidate(EntryEvent<K,V> event)
          Handles the event of an entry's value being invalidated.
 void afterRegionClear(RegionEvent<K,V> event)
          Handles the event of a region being cleared.
 void afterRegionCreate(RegionEvent<K,V> event)
          Handles the event of a region being created.
 void afterRegionDestroy(RegionEvent<K,V> event)
          Handles the event of a region being destroyed.
 void afterRegionInvalidate(RegionEvent<K,V> event)
          Handles the event of a region being invalidated.
 void afterRegionLive(RegionEvent<K,V> event)
          Handles the event of a region being live after receiving the marker from the server.
 void afterUpdate(EntryEvent<K,V> event)
          Handles the event of an entry's value being modified in a region.
 
Methods inherited from interface com.gemstone.gemfire.cache.CacheCallback
close
 

Method Detail

afterCreate

void afterCreate(EntryEvent<K,V> event)
Handles the event of new key being added to a region. The entry did not previously exist in this region in the local cache (even with a null value).

Parameters:
event - the EntryEvent
See Also:
Region.create(Object, Object), Region.put(Object, Object), Region.get(Object)

afterUpdate

void afterUpdate(EntryEvent<K,V> event)
Handles the event of an entry's value being modified in a region. This entry previously existed in this region in the local cache, but its previous value may have been null.

Parameters:
event - the EntryEvent
See Also:
Region.put(Object, Object)

afterInvalidate

void afterInvalidate(EntryEvent<K,V> event)
Handles the event of an entry's value being invalidated.

Parameters:
event - the EntryEvent
See Also:
Region.invalidate(Object)

afterDestroy

void afterDestroy(EntryEvent<K,V> event)
Handles the event of an entry being destroyed.

Parameters:
event - the EntryEvent
See Also:
Region.destroy(Object)

afterRegionInvalidate

void afterRegionInvalidate(RegionEvent<K,V> event)
Handles the event of a region being invalidated. Events are not invoked for each individual value that is invalidated as a result of the region being invalidated. Each subregion, however, gets its own regionInvalidated event invoked on its listener.

Parameters:
event - the RegionEvent
See Also:
Region.invalidateRegion(), Region.localInvalidateRegion()

afterRegionDestroy

void afterRegionDestroy(RegionEvent<K,V> event)
Handles the event of a region being destroyed. Events are not invoked for each individual entry that is destroyed as a result of the region being destroyed. Each subregion, however, gets its own afterRegionDestroyed event invoked on its listener.

Parameters:
event - the RegionEvent
See Also:
Region.destroyRegion(), Region.localDestroyRegion(), Region.close(), RegionService.close()

afterRegionClear

void afterRegionClear(RegionEvent<K,V> event)
Handles the event of a region being cleared. Events are not invoked for each individual entry that is removed as a result of the region being cleared.

Parameters:
event - the RegionEvent
Since:
5.0
See Also:
Region.clear()

afterRegionCreate

void afterRegionCreate(RegionEvent<K,V> event)
Handles the event of a region being created. Events are invoked for each individual region that is created.

Note that this method is only called for creates done in the local vm. To be notified of creates done in remote vms use RegionMembershipListener.afterRemoteRegionCreate(com.gemstone.gemfire.cache.RegionEvent).

Parameters:
event - the RegionEvent
Since:
5.0
See Also:
Cache.createRegion(java.lang.String, com.gemstone.gemfire.cache.RegionAttributes), Region.createSubregion(java.lang.String, com.gemstone.gemfire.cache.RegionAttributes)

afterRegionLive

void afterRegionLive(RegionEvent<K,V> event)
Handles the event of a region being live after receiving the marker from the server.

Parameters:
event - the RegionEvent
Since:
5.5
See Also:
Cache.readyForEvents()

GemFire 6.6.4

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