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Oracle Coherence Community Edition
/*
* 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.processor;
import com.tangosol.io.ExternalizableLite;
import com.tangosol.io.pof.PofReader;
import com.tangosol.io.pof.PofWriter;
import com.tangosol.io.pof.PortableObject;
import com.tangosol.util.ExternalizableHelper;
import com.tangosol.util.InvocableMap;
import com.tangosol.util.ValueUpdater;
import com.tangosol.util.extractor.CompositeUpdater;
import com.tangosol.util.extractor.ReflectionUpdater;
import java.io.DataInput;
import java.io.DataOutput;
import java.io.IOException;
import javax.json.bind.annotation.JsonbProperty;
/**
* UpdaterProcessor is an EntryProcessor implementations that updates an
* attribute of an object cached in an InvocableMap. A common usage pattern
* is:
*
* cache.invoke(oKey, new UpdaterProcessor(updater, value));
*
* which is functionally equivalent to the following operation:
*
* V target = cache.get(key);
* updater.update(target, value);
* cache.put(key, target);
*
* The major difference is that for clustered caches using the UpdaterProcessor
* allows avoiding explicit concurrency control and could significantly reduce
* the amount of network traffic.
*
* @author gg 2006.07.25
*/
public class UpdaterProcessor
extends AbstractProcessor
implements ExternalizableLite, PortableObject
{
/**
* Default constructor (necessary for the ExternalizableLite interface).
*/
public UpdaterProcessor()
{
}
/**
* Construct an UpdaterProcessor based on the specified ValueUpdater.
*
* @param updater a ValueUpdater object; passing null will simpy replace
* the entry's value with the specified one instead of
* updating it
* @param value the value to update the target entry with
*/
public UpdaterProcessor(ValueUpdater updater, T value)
{
m_updater = updater;
m_value = value;
}
/**
* Construct an UpdaterProcessor for a given method name. The method
* must have a single parameter of a Java type compatible with the
* specified value type.
*
* @param sMethod a method name to make a
* {@link com.tangosol.util.extractor.ReflectionUpdater}
* for; this parameter can also be a dot-delimited sequence
* of method names which would result in using a
* {@link com.tangosol.util.extractor.CompositeUpdater}
* @param value the value to update the target entry with
*/
public UpdaterProcessor(String sMethod, T value)
{
azzert(sMethod != null && sMethod.length() != 0, "Invalid method name");
m_updater = sMethod.indexOf('.') < 0 ?
new ReflectionUpdater(sMethod) :
(ValueUpdater) new CompositeUpdater(sMethod);
m_value = value;
}
// ----- ValueUpdater interface ---------------------------------------
/**
* {@inheritDoc}
*/
public Boolean process(InvocableMap.Entry entry)
{
ValueUpdater updater = m_updater;
if (updater == null)
{
//NOTE: a possibly unsafe cast from T to V
entry.setValue((V) m_value, false);
}
else if (entry.isPresent())
{
entry.update(updater, m_value);
}
else
{
return Boolean.FALSE;
}
return Boolean.TRUE;
}
// ----- Object methods -------------------------------------------------
/**
* Compare the UpdaterProcessor with another object to determine equality.
*
* @return true iff this UpdaterProcessor and the passed object are
* equivalent UpdaterProcessor
*/
public boolean equals(Object o)
{
if (o instanceof UpdaterProcessor)
{
UpdaterProcessor that = (UpdaterProcessor) o;
return equals(this.m_updater, that.m_updater) &&
equals(this.m_value, that.m_value);
}
return false;
}
/**
* Determine a hash value for the UpdaterProcessor object according to the
* general {@link Object#hashCode()} contract.
*
* @return an integer hash value for this UpdaterProcessor object
*/
public int hashCode()
{
return m_updater.hashCode();
}
/**
* Return a human-readable description for this UpdaterProcessor.
*
* @return a String description of the UpdaterProcessor
*/
public String toString()
{
return "UpdaterProcessor(" + m_updater + ", " + m_value + ')';
}
// ----- ExternalizableLite interface -----------------------------------
/**
* {@inheritDoc}
*/
public void readExternal(DataInput in)
throws IOException
{
m_updater = (ValueUpdater) ExternalizableHelper.readObject(in);
m_value = (T) ExternalizableHelper.readObject(in);
}
/**
* {@inheritDoc}
*/
public void writeExternal(DataOutput out)
throws IOException
{
ExternalizableHelper.writeObject(out, m_updater);
ExternalizableHelper.writeObject(out, m_value);
}
// ----- PortableObject interface ---------------------------------------
/**
* {@inheritDoc}
*/
public void readExternal(PofReader in)
throws IOException
{
m_updater = (ValueUpdater) in.readObject(0);
m_value = (T) in.readObject(1);
}
/**
* {@inheritDoc}
*/
public void writeExternal(PofWriter out)
throws IOException
{
out.writeObject(0, m_updater);
out.writeObject(1, m_value);
}
// ----- data fields ----------------------------------------------------
/**
* The underlying ValueUpdater.
*/
@JsonbProperty("updater")
protected ValueUpdater m_updater;
/**
* A value to update the entry's value with.
*/
@JsonbProperty("value")
protected T m_value;
}