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com.tangosol.util
Interface MapTrigger

All Superinterfaces:

Serializable

All Known Implementing Classes:

FilterTrigger

public interface MapTrigger

extends Serializable

MapTrigger represents a functional agent that allows to validate, reject or modify mutating operations against an underlying map. The trigger operates on an MapTrigger.Entry object that represents a pending mutation that is about to be committed to the underlying map. A MapTrigger could be registered with any ObservableMap using the MapTriggerListener class:

   NamedCache cache = CacheFactory.getCache(sCacheName);
   MapTrigger trigger = new MyCustomTrigger();
   cache.addMapListener(new MapTriggerListener(trigger));
 

Note: In a clustered environment, MapTrigger registration process requires triggers to be serializable and providing a non-default implementation of the hashCode() and equals() methods. Failure to do so may result in duplicate registration and a redundant entry processing by equivalent, but "not equal" MapTrigger objects.

Since:

Coherence 3.4

Author:

cp/gg 2008.03.11

See Also:

FilterTrigger

Nested Class Summary

static interface

MapTrigger.Entry A MapTrigger Entry represents a pending change to an Entry that is about to committed to the underlying Map.

Method Summary

void	process(MapTrigger.Entry entry) This method is called before the result of a mutating operation represented by the specified Entry object is committed into the underlying map.

Method Detail

process

void process(MapTrigger.Entry entry)

This method is called before the result of a mutating operation represented by the specified Entry object is committed into the underlying map. <p/> An implementation of this method can evaluate the change by analyzing the original and the new value, and can perform any of the following:

• override the requested change by calling InvocableMap.Entry.setValue(java.lang.Object) with a different value;
• undo the pending change by resetting the entry value to the original value obtained from MapTrigger.Entry.getOriginalValue();
• remove the entry from the underlying map by calling InvocableMap.Entry.remove(boolean);
• reject the pending change by throwing a RuntimeException, which will prevent any changes from being committed, and will result in the exception being thrown from the operation that attempted to modify the map; or
• do nothing, thus allowing the pending change to be committed to the underlying map.

Parameters:

entry - a MapTrigger.Entry object that represents the pending change to be committed to the map, as well as the original state of the Entry

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