/* (c) 2014 Open Source Geospatial Foundation - all rights reserved
* (c) 2013 OpenPlans
* This code is licensed under the GPL 2.0 license, available at the root
* application directory.
*/
package org.geoserver.catalog.impl;
import java.io.*;
import java.lang.reflect.Constructor;
import java.lang.reflect.Method;
import java.lang.reflect.Modifier;
import java.math.BigDecimal;
import java.math.BigInteger;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Collections;
import java.util.Comparator;
import java.util.List;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;
import java.util.logging.Level;
import java.util.logging.Logger;
import org.apache.commons.beanutils.ConstructorUtils;
import org.apache.commons.lang.SerializationUtils;
import org.geoserver.catalog.CatalogInfo;
import org.geoserver.config.util.XStreamPersister;
import org.geoserver.config.util.XStreamPersisterFactory;
import org.geotools.util.logging.Logging;
import com.thoughtworks.xstream.XStream;
/**
* Utility class used to wrap/clone objects and collections by various strategies:
* <ul>
* <li>Avoid cloning ModificationProxy proxies, as well as any CatalogInfo object</li>
* <li>Avoid cloning at all well known objects that are known to be immutable (several classes in
* java.lang)</li>
* <li>Wrap in ModificatinoProxy any object that is a CatalogInfo</li>
* <li>Using {@link Cloneable} if available</li>
* <li>Using copy constructors if available</li>
* <li>Falling back on XStream serialization if the above fails
*
* @author Andrea Aime - GeoSolutions
*
*/
class ModificationProxyCloner {
private static final XStreamPersisterFactory XSTREAM_PERSISTER_FACTORY = new XStreamPersisterFactory();
static final Logger LOGGER = Logging.getLogger(ModificationProxyCloner.class);
static final Map<Class, Class> CATALOGINFO_INTERFACE_CACHE = new ConcurrentHashMap<Class, Class>();
/**
* Best effort object cloning utility, tries different lightweight strategies, then falls back
* on copy by XStream serialization (we use that one as we have a number of hooks to avoid deep
* copying the catalog, and re-attaching to it, in there)
*
* @param source
* @return
*/
static <T> T clone(T source) {
// null?
if (source == null) {
return null;
}
// already a modification proxy?
if(ModificationProxy.handler(source) != null) {
return source;
}
// is it a catalog info?
if(source instanceof CatalogInfo) {
// mumble... shouldn't we wrap this one in a modification proxy object?
return (T) ModificationProxy.create(source, getDeepestCatalogInfoInterface((CatalogInfo) source));
}
// if a known immutable?
if (source instanceof String || source instanceof Byte || source instanceof Short
|| source instanceof Integer || source instanceof Float || source instanceof Double
|| source instanceof BigInteger || source instanceof BigDecimal) {
return (T) source;
}
// is it cloneable?
try {
if (source instanceof Cloneable) {
// methodutils does not seem to work against "clone()"...
// return (T) MethodUtils.invokeExactMethod(source, "clone", null, null);
Method method = source.getClass().getDeclaredMethod("clone");
if(Modifier.isPublic(method.getModifiers()) && method.getParameterTypes().length == 0) {
return (T) method.invoke(source);
}
}
} catch (Exception e) {
LOGGER.log(
Level.FINE,
"Source object is cloneable, yet it does not have a public no argument method 'clone'",
e);
}
// does it have a copy constructor?
Constructor copyConstructor = ConstructorUtils.getAccessibleConstructor(source.getClass(),
source.getClass());
if (copyConstructor != null) {
try {
return (T) copyConstructor.newInstance(source);
} catch (Exception e) {
LOGGER.log(Level.FINE,
"Source has a copy constructor, but it failed, skipping to XStream", e);
}
}
if(source instanceof Serializable) {
return (T) cloneSerializable((Serializable)source);
} else {
XStreamPersister persister = XSTREAM_PERSISTER_FACTORY.createXMLPersister();
XStream xs = persister.getXStream();
String xml = xs.toXML(source);
T copy = (T) xs.fromXML(xml);
return copy;
}
}
static <T extends Serializable> T cloneSerializable(T source) {
byte[] bytes = SerializationUtils.serialize(source);
try {
ObjectInputStream input =
new ModProxyObjectInputStream(new ByteArrayInputStream(bytes));
return (T) input.readObject();
} catch (Exception e) {
throw new RuntimeException("Error cloning serializable object", e);
}
}
static Class getDeepestCatalogInfoInterface(CatalogInfo object) {
Class<? extends CatalogInfo> sourceClass = object.getClass();
Class result = CATALOGINFO_INTERFACE_CACHE.get(sourceClass);
if(result == null) {
Class[] interfaces = sourceClass.getInterfaces();
// collect only CatalogInfo related interfaces
List<Class> cis = new ArrayList<Class>();
for (Class clazz : interfaces) {
if(CatalogInfo.class.isAssignableFrom(clazz)) {
cis.add(clazz);
}
}
if(cis.size() == 0) {
result = null;
} else if(cis.size() == 1) {
result = cis.get(0);
} else {
Collections.sort(cis, new Comparator<Class>() {
@Override
public int compare(Class c1, Class c2) {
if(c1.isAssignableFrom(c2)) {
return 1;
} else if(c2.isAssignableFrom(c1)) {
return -1;
} else {
return 0;
}
}
});
result = cis.get(0);
}
CATALOGINFO_INTERFACE_CACHE.put(sourceClass, result);
}
return result;
}
/**
* Shallow or deep copies the provided collection
*
* @param source
* @param deepCopy If true, a deep copy will be done, otherwise the cloned collection will
* contain the exact same objects as the source
* @return
* @throws InstantiationException
* @throws IllegalAccessException
*/
public static <T> Collection<T> cloneCollection(Collection<T> source, boolean deepCopy)
throws InstantiationException, IllegalAccessException {
if (source == null) {
// nothing to copy
return null;
}
Collection<T> copy = source.getClass().newInstance();
if (deepCopy) {
for (T object : source) {
T objectCopy = clone(object);
copy.add(objectCopy);
}
} else {
copy.addAll(source);
}
return copy;
}
/**
* Shallow or deep copies the provided collection
*
* @param <K>
* @param <V>
*
* @param source
* @param deepCopy If true, a deep copy will be done, otherwise the cloned collection will
* contain the exact same objects as the source
* @return
* @throws InstantiationException
* @throws IllegalAccessException
*/
public static <K, V> Map<K, V> cloneMap(Map<K, V> source, boolean deepCopy)
throws InstantiationException, IllegalAccessException {
if (source == null) {
// nothing to copy
return null;
}
Map<K, V> copy = source.getClass().newInstance();
if (deepCopy) {
for (Map.Entry<K, V> entry : source.entrySet()) {
K keyCopy = clone(entry.getKey());
V valueCopy = clone(entry.getValue());
copy.put(keyCopy, valueCopy);
}
} else {
copy.putAll(source);
}
return copy;
}
/**
* Custom object output stream used to ensure a stable class loader used.
*/
static class ModProxyObjectInputStream extends ObjectInputStream {
ClassLoader classLoader;
public ModProxyObjectInputStream(InputStream input) throws IOException {
super(input);
this.classLoader = ModificationProxy.class.getClassLoader();
}
@Override
protected Class<?> resolveClass(ObjectStreamClass desc) throws IOException, ClassNotFoundException {
String name = desc.getName();
try {
return Class.forName(name, false, classLoader);
} catch (ClassNotFoundException ex) {
return super.resolveClass(desc);
}
}
}
}