/*
* The MIT License
*
* Copyright (c) 2004-2011, Oracle Corporation, Kohsuke Kawaguchi, Nikita Levyankov
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
package hudson.util;
import com.thoughtworks.xstream.mapper.CannotResolveClassException;
import com.thoughtworks.xstream.converters.Converter;
import com.thoughtworks.xstream.converters.MarshallingContext;
import com.thoughtworks.xstream.converters.UnmarshallingContext;
import com.thoughtworks.xstream.converters.collections.AbstractCollectionConverter;
import com.thoughtworks.xstream.io.HierarchicalStreamReader;
import com.thoughtworks.xstream.io.HierarchicalStreamWriter;
import com.thoughtworks.xstream.mapper.Mapper;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Collections;
import java.util.Iterator;
import java.util.List;
import java.util.Arrays;
import java.util.logging.Logger;
import org.apache.commons.collections.CollectionUtils;
import static java.util.logging.Level.WARNING;
/**
* {@link List}-like implementation that has copy-on-write semantics.
*
* <p>
* This class is suitable where highly concurrent access is needed, yet
* the write operation is relatively uncommon.
*
* @author Kohsuke Kawaguchi
*/
public class CopyOnWriteList<E> implements Iterable<E> {
private volatile List<? extends E> core;
public CopyOnWriteList(List<E> core) {
this(core,false);
}
private CopyOnWriteList(List<E> core, boolean noCopy) {
this.core = noCopy ? core : new ArrayList<E>(core);
}
public CopyOnWriteList() {
this.core = Collections.emptyList();
}
public synchronized void add(E e) {
List<E> n = new ArrayList<E>(core);
n.add(e);
core = n;
}
public synchronized void addAll(Collection<? extends E> items) {
List<E> n = new ArrayList<E>(core);
n.addAll(items);
core = n;
}
/**
* Removes an item from the list.
*
* @return
* true if the list contained the item. False if it didn't,
* in which case there's no change.
*/
public synchronized boolean remove(E e) {
List<E> n = new ArrayList<E>(core);
boolean r = n.remove(e);
core = n;
return r;
}
/**
* Returns an iterator.
*/
public Iterator<E> iterator() {
final Iterator<? extends E> itr = core.iterator();
return new Iterator<E>() {
private E last;
public boolean hasNext() {
return itr.hasNext();
}
public E next() {
return last=itr.next();
}
public void remove() {
CopyOnWriteList.this.remove(last);
}
};
}
/**
* Completely replaces this list by the contents of the given list.
*/
public void replaceBy(CopyOnWriteList<? extends E> that) {
this.core = that.core;
}
/**
* Completely replaces this list by the contents of the given list.
*/
public void replaceBy(Collection<? extends E> that) {
this.core = new ArrayList<E>(that);
}
/**
* Completely replaces this list by the contents of the given list.
*/
public void replaceBy(E... that) {
replaceBy(Arrays.asList(that));
}
public void clear() {
this.core = new ArrayList<E>();
}
public E[] toArray(E[] array) {
return core.toArray(array);
}
public List<E> getView() {
return Collections.unmodifiableList(core);
}
public void addAllTo(Collection<? super E> dst) {
dst.addAll(core);
}
public E get(int index) {
return core.get(index);
}
public boolean isEmpty() {
return core.isEmpty();
}
public int size() {
return core.size();
}
/**
* {@link Converter} implementation for XStream.
*/
public static final class ConverterImpl extends AbstractCollectionConverter {
public ConverterImpl(Mapper mapper) {
super(mapper);
}
public boolean canConvert(Class type) {
return type==CopyOnWriteList.class;
}
public void marshal(Object source, HierarchicalStreamWriter writer, MarshallingContext context) {
for (Object o : (CopyOnWriteList) source)
writeItem(o, context, writer);
}
@SuppressWarnings("unchecked")
public CopyOnWriteList unmarshal(HierarchicalStreamReader reader, UnmarshallingContext context) {
// read the items from xml into a list
List items = new ArrayList();
while (reader.hasMoreChildren()) {
reader.moveDown();
try {
Object item = readItem(reader, context, items);
items.add(item);
} catch (CannotResolveClassException e) {
LOGGER.log(WARNING,"Failed to resolve class",e);
RobustReflectionConverter.addErrorInContext(context, e);
} catch (LinkageError e) {
LOGGER.log(WARNING,"Failed to resolve class",e);
RobustReflectionConverter.addErrorInContext(context, e);
}
reader.moveUp();
}
return new CopyOnWriteList(items,true);
}
}
@Override
public boolean equals(Object o) {
if (this == o) {
return true;
}
if (o == null || getClass() != o.getClass()) {
return false;
}
CopyOnWriteList that = (CopyOnWriteList) o;
return CollectionUtils.isEqualCollection(this.core, that.core);
}
@Override
public int hashCode() {
return core != null ? core.hashCode() : 0;
}
private static final Logger LOGGER = Logger.getLogger(CopyOnWriteList.class.getName());
}