/*
* Copyright (C) 2003-2011 eXo Platform SAS.
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU Affero General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program 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 Affero General Public License for more details.
*
* You should have received a copy of the GNU Affero General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
package org.etk.storage.plugins.cache.loader;
/**
* The loader interface is used by the future cache to retrieves the value from the key when it does not exist.
*
* @param <K> the key type parameter
* @param <V> the value type parameter
* @param <C> the context type parameter
*/
public interface LoaderVisitor<K, V, C> {
/**
* Retrieves the value from the key within the specified context. If the
* resource is not found then the value null must be returned.
*
* @param context the context
* @param key the key
* @return the value
* @throws Exception any exception that would prevent the value to be loaded
*/
V accept(C context, K key) throws Exception;
}