com.tangosol.util.transformer.ExtractorEventTransformer Maven / Gradle / Ivy
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/*
* Copyright (c) 2000, 2020, Oracle and/or its affiliates.
*
* Licensed under the Universal Permissive License v 1.0 as shown at
* http://oss.oracle.com/licenses/upl.
*/
package com.tangosol.util.transformer;
import com.tangosol.util.ClassHelper;
import com.tangosol.util.ExternalizableHelper;
import com.tangosol.util.MapEvent;
import com.tangosol.util.MapEventTransformer;
import com.tangosol.util.ValueExtractor;
import com.tangosol.util.extractor.ChainedExtractor;
import com.tangosol.util.extractor.MultiExtractor;
import com.tangosol.util.extractor.ReflectionExtractor;
import com.tangosol.io.ExternalizableLite;
import com.tangosol.io.pof.PofReader;
import com.tangosol.io.pof.PofWriter;
import com.tangosol.io.pof.PortableObject;
import java.io.DataInput;
import java.io.DataOutput;
import java.io.IOException;
import javax.json.bind.annotation.JsonbProperty;
/**
* ExtractorEventTransformer is a special purpose {@link MapEventTransformer}
* implementation that transforms emitted events, extracting one or more
* properties from either the OldValue or the NewValue. This transformation
* will generally result in the change of the values' data type.
*
* Example: the following code will register a listener to receive events only
* if the value of the AccountBalance property changes. The transformed event's
* NewValue will be a List containing the LastTransactionTime and AccountBalance
* properties. The OldValue will always be null.
*
* Filter filter = new ValueChangeEventFilter("getAccountBalance");
* ValueExtractor extractor = new MultiExtractor("getLastTransactionTime,getAccountBalance");
* MapEventTransformer transformer = new ExtractorEventTransformer(null, extractor);
*
* cache.addMapListener(listener, new MapEventTransformerFilter(filter, transformer), false);
*
*
* @author gg 2008.06.01
* @since Coherence 3.4
*/
public class ExtractorEventTransformer
extends ExternalizableHelper
implements MapEventTransformer, ExternalizableLite, PortableObject
{
// ----- constructors ---------------------------------------------------
/**
* No-argument constructor for lite deserialization.
*/
public ExtractorEventTransformer()
{
}
/**
* Construct a ExtractorEventTransformer that transforms MapEvent values
* based on the specified extractor.
*
* Note: The specified extractor will be applied to both old and new values.
*
* @param extractor ValueExtractor to extract MapEvent values
*/
public ExtractorEventTransformer(ValueExtractor extractor)
{
this(extractor, extractor);
}
/**
* Construct a ExtractorEventTransformer that transforms MapEvent's values
* based on the specified method name. The name could be a comma-delimited
* sequence of method names which will result in a MultiExtractor that is
* based on a corresponding array of {@link ValueExtractor} objects;
* individual array elements will be either {@link ReflectionExtractor}
* or {@link ChainedExtractor} objects.
*
* Note: The specified extractor will be applied to both old and new values.
*
* @param sMethod the name of the method to invoke via reflection
*/
public ExtractorEventTransformer(String sMethod)
{
this(sMethod.indexOf(',') < 0
? (sMethod.indexOf('.') < 0
? new ReflectionExtractor(sMethod)
: (ValueExtractor) new ChainedExtractor(sMethod))
: new MultiExtractor(sMethod));
}
/**
* Construct a ExtractorEventTransformer that transforms MapEvent values
* based on the specified extractors. Passing null indicates that the
* corresponding values should be skipped completely.
*
* @param extractorOld extractor to extract the OldValue property(s)
* @param extractorNew extractor to extract the NewValue property(s)
*/
public ExtractorEventTransformer(ValueExtractor extractorOld,
ValueExtractor extractorNew)
{
m_extractorOld = extractorOld;
m_extractorNew = extractorNew;
}
// ----- Accessors ------------------------------------------------------
/**
* Return a ValueExtractor used to transfrom the event's OldValue.
*
* @return an extractor from the OldValue
*/
public ValueExtractor getOldValueExtractor()
{
return m_extractorOld;
}
/**
* Return a ValueExtractor used to transfrom the event's NewValue.
*
* @return an extractor from the NewValue
*/
public ValueExtractor getNewValueExtractor()
{
return m_extractorNew;
}
// ----- MapEventTransformer methods ------------------------------------
/**
* Transform the specified MapEvent using the corresponding extractors.
*
* @param event MapEvent object to transform
*
* @return a modified MapEvent object that contains extracted values
*/
public MapEvent transform(MapEvent event)
{
ValueExtractor extractorOld = getOldValueExtractor();
ValueExtractor extractorNew = getNewValueExtractor();
return new MapEvent(event.getMap(), event.getId(), event.getKey(),
extractorOld == null ? null : extractorOld.extract(event.getOldValue()),
extractorNew == null ? null : extractorNew.extract(event.getNewValue()));
}
// ----- ExternalizableLite methods -------------------------------------
/**
* {@inheritDoc}
*/
public void readExternal(DataInput in)
throws IOException
{
boolean fSame = in.readBoolean();
m_extractorOld = ExternalizableHelper.readObject(in);
m_extractorNew = fSame ? m_extractorOld :
(ValueExtractor) ExternalizableHelper.readObject(in);
}
/**
* {@inheritDoc}
*/
public void writeExternal(DataOutput out)
throws IOException
{
ValueExtractor extractorOld = m_extractorOld;
ValueExtractor extractorNew = m_extractorNew;
if (equals(extractorOld, extractorNew))
{
out.writeBoolean(true);
ExternalizableHelper.writeObject(out, extractorOld);
}
else
{
out.writeBoolean(false);
ExternalizableHelper.writeObject(out, extractorOld);
ExternalizableHelper.writeObject(out, extractorNew);
}
}
// ----- PortableObject methods -----------------------------------------
/**
* {@inheritDoc}
*/
public void readExternal(PofReader in)
throws IOException
{
boolean fSame = in.readBoolean(0);
m_extractorOld = in.readObject(1);
m_extractorNew = fSame ? m_extractorOld :
(ValueExtractor) in.readObject(2);
}
/**
* {@inheritDoc}
*/
public void writeExternal(PofWriter out)
throws IOException
{
ValueExtractor extractorOld = m_extractorOld;
ValueExtractor extractorNew = m_extractorNew;
if (equals(extractorOld, extractorNew))
{
out.writeBoolean(0, true);
out.writeObject(1, extractorNew);
}
else
{
out.writeBoolean(0, false);
out.writeObject(1, extractorOld);
out.writeObject(2, extractorNew);
}
}
// ----- Object methods -------------------------------------------------
/**
* Compare the ExtractorEventTransformer with another object to determine
* equality.
*
* @return true iff this ExtractorEventTransformer and the passed object are
* equivalent
*/
public boolean equals(Object o)
{
if (o instanceof ExtractorEventTransformer)
{
ExtractorEventTransformer that = (ExtractorEventTransformer) o;
return equals(this.m_extractorOld, that.m_extractorOld)
&& equals(this.m_extractorNew, that.m_extractorNew);
}
return false;
}
/**
* Determine a hash value for the ExtractorEventTransformer object according
* to the general {@link Object#hashCode()} contract.
*
* @return an integer hash value for this object
*/
public int hashCode()
{
ValueExtractor extractorOld = m_extractorOld;
ValueExtractor extractorNew = m_extractorNew;
return (extractorOld == null ? 0 : extractorOld.hashCode()) +
(extractorNew == null ? 0 : extractorNew.hashCode());
}
/**
* Provide a human-readable representation of this object.
*
* @return a String whose contents represent the value of this object
*/
public String toString()
{
ValueExtractor extractorOld = getOldValueExtractor();
ValueExtractor extractorNew = getNewValueExtractor();
StringBuilder sb = new StringBuilder(ClassHelper.getSimpleName(getClass()));
sb.append('{');
if (equals(extractorOld, extractorNew))
{
sb.append("extractors=")
.append(extractorOld);
}
else
{
sb.append("extractor old=")
.append(extractorOld)
.append(", extractor new=")
.append(extractorNew);
}
sb.append('}');
return sb.toString();
}
// ----- data fields ----------------------------------------------------
/**
* The OldValue extractor.
*/
@JsonbProperty("extractorOld")
private ValueExtractor m_extractorOld;
/**
* The NewValue extractor.
*/
@JsonbProperty("extractorNew")
private ValueExtractor m_extractorNew;
}