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LinkedHashMapExternalizer.java
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LinkedHashMapExternalizer.java
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/*
* JBoss, Home of Professional Open Source.
* Copyright 2019, Red Hat, Inc., and individual contributors
* as indicated by the @author tags. See the copyright.txt file in the
* distribution for a full listing of individual contributors.
*
* This is free software; you can redistribute it and/or modify it
* under the terms of the GNU Lesser General Public License as
* published by the Free Software Foundation; either version 2.1 of
* the License, or (at your option) any later version.
*
* This software is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this software; if not, write to the Free
* Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
* 02110-1301 USA, or see the FSF site: http://www.fsf.org.
*/
package org.wildfly.clustering.marshalling.spi.util;
import java.io.IOException;
import java.io.ObjectInput;
import java.io.ObjectOutput;
import java.util.Iterator;
import java.util.LinkedHashMap;
import java.util.function.Function;
/**
* @author Paul Ferraro
*/
public class LinkedHashMapExternalizer extends MapExternalizer<LinkedHashMap<Object, Object>, Boolean> {
public LinkedHashMapExternalizer() {
super(LinkedHashMap.class, new Function<Boolean, LinkedHashMap<Object, Object>>() {
@Override
public LinkedHashMap<Object, Object> apply(Boolean accessOrder) {
// Use capacity and load factor defaults
return new LinkedHashMap<>(16, 0.75f, accessOrder);
}
});
}
@Override
protected void writeContext(ObjectOutput output, LinkedHashMap<Object, Object> map) throws IOException {
Object insertOrder = new Object();
Object accessOrder = new Object();
map.put(insertOrder, null);
map.put(accessOrder, null);
// Access first inserted entry
// If map uses access order, this element will move to the tail of the map
map.get(insertOrder);
Iterator<Object> keys = map.keySet().iterator();
Object element = keys.next();
while ((element != insertOrder) && (element != accessOrder)) {
element = keys.next();
}
map.remove(insertOrder);
map.remove(accessOrder);
// Map uses access order if previous access changed iteration order
output.writeBoolean(element == accessOrder);
}
@Override
protected Boolean readContext(ObjectInput input) throws IOException {
return input.readBoolean();
}
}