//
// Licensed to the Apache Software Foundation (ASF) under one
// or more contributor license agreements. See the NOTICE file
// distributed with this work for additional information
// regarding copyright ownership. The ASF licenses this file
// to you under the Apache License, Version 2.0 (the
// "License"); you may not use this file except in compliance
// with the License. You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing,
// software distributed under the License is distributed on an
// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
// KIND, either express or implied. See the License for the
// specific language governing permissions and limitations
// under the License.
//
package com.cloud.resource;
import java.text.MessageFormat;
import java.util.Hashtable;
import java.util.Set;
import org.apache.log4j.Logger;
import com.cloud.agent.api.Answer;
import com.cloud.agent.api.Command;
public abstract class RequestWrapper {
private static final Logger s_logger = Logger.getLogger(RequestWrapper.class);
@SuppressWarnings("rawtypes")
protected Hashtable<Class<? extends ServerResource>, Hashtable<Class<? extends Command>, CommandWrapper>> resources = new Hashtable<Class<? extends ServerResource>, Hashtable<Class<? extends Command>, CommandWrapper>>();
/**
* @param command to be executed.
* @return an Answer for the executed command.
*/
public abstract Answer execute(Command command, ServerResource serverResource);
@SuppressWarnings({ "rawtypes", "unchecked" })
protected Hashtable<Class<? extends Command>, CommandWrapper> retrieveResource(final Command command, final Class<? extends ServerResource> resourceClass) {
Class<? extends ServerResource> keepResourceClass = resourceClass;
Hashtable<Class<? extends Command>, CommandWrapper> resource = resources.get(keepResourceClass);
while (resource == null) {
try {
final Class<? extends ServerResource> keepResourceClass2 = (Class<? extends ServerResource>) keepResourceClass.getSuperclass();
resource = resources.get(keepResourceClass2);
keepResourceClass = keepResourceClass2;
} catch (final ClassCastException e) {
throw new NullPointerException("No key found for '" + command.getClass() + "' in the Map!");
}
}
return resource;
}
@SuppressWarnings({ "rawtypes", "unchecked" })
protected CommandWrapper<Command, Answer, ServerResource> retrieveCommands(final Class<? extends Command> commandClass,
final Hashtable<Class<? extends Command>, CommandWrapper> resourceCommands) {
Class<? extends Command> keepCommandClass = commandClass;
CommandWrapper<Command, Answer, ServerResource> commandWrapper = resourceCommands.get(keepCommandClass);
while (commandWrapper == null) {
try {
final Class<? extends Command> commandClass2 = (Class<? extends Command>) keepCommandClass.getSuperclass();
if (commandClass2 == null) {
throw new NullPointerException("All the COMMAND hierarchy tree has been visited but no compliant key has been found for '" + commandClass + "'.");
}
commandWrapper = resourceCommands.get(commandClass2);
keepCommandClass = commandClass2;
} catch (final ClassCastException e) {
throw new NullPointerException("No key found for '" + keepCommandClass.getClass() + "' in the Map!");
} catch (final NullPointerException e) {
// Will now traverse all the resource hierarchy. Returning null
// is not a problem.
// It is all being nicely checked and in case we do not have a
// resource, an Unsupported answer will be thrown by the base
// class.
return null;
}
}
return commandWrapper;
}
@SuppressWarnings({ "rawtypes", "unchecked" })
protected CommandWrapper<Command, Answer, ServerResource> retryWhenAllFails(final Command command, final Class<? extends ServerResource> resourceClass,
final Hashtable<Class<? extends Command>, CommandWrapper> resourceCommands) {
Class<? extends ServerResource> keepResourceClass = resourceClass;
CommandWrapper<Command, Answer, ServerResource> commandWrapper = resourceCommands.get(command.getClass());
while (commandWrapper == null) {
// Could not find the command in the given resource, will traverse
// the family tree.
try {
final Class<? extends ServerResource> resourceClass2 = (Class<? extends ServerResource>) keepResourceClass.getSuperclass();
if (resourceClass2 == null) {
throw new NullPointerException("All the SERVER-RESOURCE hierarchy tree has been visited but no compliant key has been found for '" + command.getClass() + "'.");
}
final Hashtable<Class<? extends Command>, CommandWrapper> resourceCommands2 = retrieveResource(command,
(Class<? extends ServerResource>) keepResourceClass.getSuperclass());
keepResourceClass = resourceClass2;
commandWrapper = retrieveCommands(command.getClass(), resourceCommands2);
} catch (final ClassCastException e) {
throw new NullPointerException("No key found for '" + command.getClass() + "' in the Map!");
} catch (final NullPointerException e) {
throw e;
}
}
return commandWrapper;
}
@SuppressWarnings("rawtypes")
protected Hashtable<Class<? extends Command>, CommandWrapper> processAnnotations(final Set<Class<? extends CommandWrapper>> wrappers) {
final String errorMessage = "Error when adding Xen command to map ==> '{0}'. CommandWrapper class is ==> '{1}'";
final Hashtable<Class<? extends Command>, CommandWrapper> commands = new Hashtable<Class<? extends Command>, CommandWrapper>();
for (final Class<? extends CommandWrapper> wrapper : wrappers) {
final ResourceWrapper annotation = wrapper.getAnnotation(ResourceWrapper.class);
if (annotation == null) {
// Just in case people add classes without the annotation in the package and we don't see it.
continue;
}
try {
commands.put(annotation.handles(), wrapper.newInstance());
} catch (final InstantiationException e) {
s_logger.warn(MessageFormat.format(errorMessage, e.getLocalizedMessage(), wrapper.toString()));
} catch (final IllegalAccessException e) {
s_logger.warn(MessageFormat.format(errorMessage, e.getLocalizedMessage(), wrapper.toString()));
}
}
return commands;
}
}