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com.tangosol.util.processor
Class ExtractorProcessor

java.lang.Object
com.tangosol.util.Base
com.tangosol.util.processor.AbstractProcessor
com.tangosol.util.processor.ExtractorProcessor

All Implemented Interfaces:

ExternalizableLite, PortableObject, InvocableMap.EntryProcessor, java.io.Serializable

public class ExtractorProcessor

extends AbstractProcessor

implements ExternalizableLite, PortableObject

ExtractorProcessor is an EntryProcessor implementations that extracts a value from an object cached in an InvocableMap. A common usage pattern is:

   cache.invoke(oKey, new ExtractorProcessor(extractor));
 

which is functionally equivalent to the following operation:

   extractor.extract(cache.get(oKey));
 

The major difference is that for clustered caches using the ExtractorProcessor could significantly reduce the amount of network traffic.

An alternative (and superior) approach would be to use the ReducerAggregator

Author:

gg 2005.11.30

Field Summary

protected ValueExtractor

m_extractor The underlying value extractor.

Constructor Summary

ExtractorProcessor()
Default constructor (necessary for the ExternalizableLite interface).

ExtractorProcessor(java.lang.String sMethod)
Construct an ExtractorProcessor for a given method name.

ExtractorProcessor(ValueExtractor extractor)
Construct an ExtractorProcessor based on the specified ValueExtractor.

Method Summary

boolean	equals(java.lang.Object o) Compare the ExtractorProcessor with another object to determine equality.
int	hashCode() Determine a hash value for the ExtractorProcessor object according to the general Object.hashCode() contract.
java.lang.Object	process(InvocableMap.Entry entry) Process a Map.Entry object.
void	readExternal(java.io.DataInput in) Restore the contents of this object by loading the object's state from the passed DataInput object.
void	readExternal(PofReader in) Restore the contents of a user type instance by reading its state using the specified PofReader object.
java.lang.String	toString() Return a human-readable description for this ExtractorProcessor.
void	writeExternal(java.io.DataOutput out) Save the contents of this object by storing the object's state into the passed DataOutput object.
void	writeExternal(PofWriter out) Save the contents of a POF user type instance by writing its state using the specified PofWriter object.

Methods inherited from class com.tangosol.util.processor.AbstractProcessor

processAll

Field Detail

m_extractor

protected ValueExtractor m_extractor

The underlying value extractor.

Constructor Detail

ExtractorProcessor

public ExtractorProcessor()

Default constructor (necessary for the ExternalizableLite interface).

ExtractorProcessor

public ExtractorProcessor(ValueExtractor extractor)

Construct an ExtractorProcessor based on the specified ValueExtractor.

Parameters:

extractor - a ValueExtractor object; passing null is equivalent to using the IdentityExtractor

ExtractorProcessor

public ExtractorProcessor(java.lang.String sMethod)

Construct an ExtractorProcessor for a given method name.

Parameters:

sMethod - a method name to make a ReflectionExtractor for; this parameter can also be a dot-delimited sequence of method names which would result in an ExtractorProcessor based on the ChainedExtractor that is based on an array of corresponding ReflectionExtractor objects

Method Detail

process

public java.lang.Object process(InvocableMap.Entry entry)

Process a Map.Entry object.

Specified by:

process in interface InvocableMap.EntryProcessor

Parameters:

entry - the Entry to process Note: if this method throws an exception, all modifications to the supplied entry or any other entries retrieved via the BackingMapContext.getBackingMapEntry(java.lang.Object) API will be rolled back leaving all underlying values unchanged.

Returns:

the result of the processing, if any

equals

public boolean equals(java.lang.Object o)

Compare the ExtractorProcessor with another object to determine equality.

Returns:

true iff this ExtractorProcessor and the passed object are equivalent ExtractorProcessor objects

hashCode

public int hashCode()

Determine a hash value for the ExtractorProcessor object according to the general Object.hashCode() contract.

Returns:

an integer hash value for this ExtractorProcessor object

toString

public java.lang.String toString()

Return a human-readable description for this ExtractorProcessor.

Returns:

a String description of the ExtractorProcessor

readExternal

public void readExternal(java.io.DataInput in)
                  throws java.io.IOException

Restore the contents of this object by loading the object's state from the passed DataInput object.

Specified by:

readExternal in interface ExternalizableLite

Parameters:

in - the DataInput stream to read data from in order to restore the state of this object

Throws:

java.io.IOException - if an I/O exception occurs

java.io.NotActiveException - if the object is not in its initial state, and therefore cannot be deserialized into

writeExternal

public void writeExternal(java.io.DataOutput out)
                   throws java.io.IOException

Save the contents of this object by storing the object's state into the passed DataOutput object.

Specified by:

writeExternal in interface ExternalizableLite

Parameters:

out - the DataOutput stream to write the state of this object to

Throws:

java.io.IOException - if an I/O exception occurs

readExternal

public void readExternal(PofReader in)
                  throws java.io.IOException

Restore the contents of a user type instance by reading its state using the specified PofReader object.

Specified by:

readExternal in interface PortableObject

Parameters:

in - the PofReader from which to read the object's state

Throws:

java.io.IOException - if an I/O error occurs

writeExternal

public void writeExternal(PofWriter out)
                   throws java.io.IOException

Save the contents of a POF user type instance by writing its state using the specified PofWriter object.

Specified by:

writeExternal in interface PortableObject

Parameters:

out - the PofWriter to which to write the object's state

Throws:

java.io.IOException - if an I/O error occurs

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