/*
* JBoss, Home of Professional Open Source.
* Copyright 2015, 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.jboss.as.controller.capability.registry;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ConcurrentMap;
import org.jboss.as.controller.registry.Resource;
/**
* Contextual object that the {@code ModelController} and {@link CapabilityScope} implementations
* can use to temporarily store data during the course of a capability resolution.
*
* @author Brian Stansberry
*/
public abstract class CapabilityResolutionContext {
private final ConcurrentMap<AttachmentKey<?>, Object> contextAttachments = new ConcurrentHashMap<>();
/**
* Gets the root resource of the resource tree in effect during this resolution.
* @return the root resource. Will not return {@code null}
*/
public abstract Resource getResourceRoot();
/**
* Retrieves an object that has been attached to this context.
*
* @param key the key to the attachment.
* @param <V> the value type of the attachment.
*
* @return the attachment if found otherwise {@code null}.
*/
public <V> V getAttachment(final AttachmentKey<V> key) {
assert key != null;
return key.cast(contextAttachments.get(key));
}
/**
* Attaches an arbitrary object to this context.
*
* @param key they attachment key used to ensure uniqueness and used for retrieval of the value.
* @param value the value to store.
* @param <V> the value type of the attachment.
*
* @return the previous value associated with the key or {@code null} if there was no previous value.
*/
public <V> V attach(final AttachmentKey<V> key, final V value) {
assert key != null;
return key.cast(contextAttachments.put(key, value));
}
/**
* Attaches an arbitrary object to this context only if the object was not already attached. If a value has already
* been attached with the key provided, the current value associated with the key is returned.
*
* @param key they attachment key used to ensure uniqueness and used for retrieval of the value.
* @param value the value to store.
* @param <V> the value type of the attachment.
*
* @return the previous value associated with the key or {@code null} if there was no previous value.
*/
public <V> V attachIfAbsent(final AttachmentKey<V> key, final V value) {
assert key != null;
return key.cast(contextAttachments.putIfAbsent(key, value));
}
/**
* Detaches or removes the value from this context.
*
* @param key the key to the attachment.
* @param <V> the value type of the attachment.
*
* @return the attachment if found otherwise {@code null}.
*/
public <V> V detach(final AttachmentKey<V> key) {
assert key != null;
return key.cast(contextAttachments.remove(key));
}
/**
* Resets this object, removing all attachments.
*/
protected void reset() {
contextAttachments.clear();
}
/**
* An attachment key instance.
*
* @param <T> the attachment value type
*/
public static final class AttachmentKey<T> {
private final Class<T> valueClass;
/**
* Construct a new instance.
*
* @param valueClass the value type.
*/
private AttachmentKey(final Class<T> valueClass) {
this.valueClass = valueClass;
}
/**
* Cast the value to the type of this attachment key.
*
* @param value the value
*
* @return the cast value
*/
public T cast(final Object value) {
return valueClass.cast(value);
}
/**
* Construct a new simple attachment key.
*
* @param valueClass the value class
* @param <T> the attachment type
*
* @return the new instance
*/
@SuppressWarnings("unchecked")
public static <T> AttachmentKey<T> create(final Class<? super T> valueClass) {
return new AttachmentKey(valueClass);
}
}
}