/*
* Copyright (C) 2012 eXo Platform SAS.
*
* 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.crsh.util;
import org.crsh.shell.ErrorKind;
import org.crsh.shell.impl.command.spi.CommandException;
import org.crsh.plugin.PluginContext;
import org.crsh.plugin.ResourceKind;
import org.crsh.vfs.Resource;
import java.io.UnsupportedEncodingException;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;
public class ClassCache<T> {
/** . */
private final ClassFactory<T> classFactory;
/** . */
private final Map<String, TimestampedObject<Class<? extends T>>> classes = new ConcurrentHashMap<String, TimestampedObject<Class<? extends T>>>();
/** . */
private final PluginContext context;
/** . */
private final ResourceKind kind;
public ClassCache(PluginContext context, ClassFactory<T> classFactory, ResourceKind kind) {
this.classFactory = classFactory;
this.context = context;
this.kind = kind;
}
private TimestampedObject<Class<? extends T>> loadClass(String name) {
return classes.get(name);
}
private void saveClass(String name, TimestampedObject<Class<? extends T>> clazz) {
classes.put(name, clazz);
}
private Resource getResource(String name) {
return context.loadResource(name, kind);
}
public TimestampedObject<Class<? extends T>> getClass(String name) throws CommandException, NullPointerException {
if (name == null) {
throw new NullPointerException("No null argument allowed");
}
TimestampedObject<Class<? extends T>> providerRef = loadClass(name);
//
Resource script = getResource(name);
//
if (script != null) {
if (providerRef != null) {
if (script.getTimestamp() != providerRef.getTimestamp()) {
providerRef = null;
}
}
//
if (providerRef == null) {
//
String source;
try {
source = new String(script.getContent(), "UTF-8");
}
catch (UnsupportedEncodingException e) {
throw new CommandException(ErrorKind.INTERNAL, "Could not compile command script " + name, e);
}
//
Class<? extends T> clazz = classFactory.parse(name, source);
providerRef = new TimestampedObject<Class<? extends T>>(script.getTimestamp(), clazz);
saveClass(name, providerRef);
}
}
//
if (providerRef == null) {
return null;
}
//
return providerRef;
}
}