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/* Licensed 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 org.activiti.engine.impl.persistence.cache;

import java.util.Collection;
import java.util.List;
import java.util.Map;

import org.activiti.engine.impl.interceptor.Command;
import org.activiti.engine.impl.interceptor.Session;
import org.activiti.engine.impl.persistence.entity.Entity;

/**
 * This is a cache for {@link Entity} instances during the execution of one {@link Command}.
 * 

 */
public interface EntityCache extends Session {
  
  /**
   * Returns all cached {@link Entity} instances as a map 
   * with following structure: { entityClassName, {entityId, entity} }
   */
  Map, Map> getAllCachedEntities();
  
  /**
   * Adds the gives {@link Entity} to the cache.
   * 
   * @param entity The {@link Entity} instance
   * @param storeState If true, the current state {@link Entity#getPersistentState()} will be stored for future diffing.
   *                   Note that, if false, the {@link Entity} will always be seen as changed.
   * @return Returns a {@link CachedEntity} instance, which can be enriched later on.                   
   */
  CachedEntity put(Entity entity, boolean storeState);
  
  /**
   * Returns the cached {@link Entity} instance of the given class with the provided id.
   * Returns null if such a {@link Entity} cannot be found. 
   */
   T findInCache(Class entityClass, String id);
  
  /**
   * Returns all cached {@link Entity} instances of a given type.
   * Returns an empty list if no instances of the given type exist.
   */
   List findInCache(Class entityClass);

  /**
   * Returns all {@link CachedEntity} instances for the given type.
   * The difference with {@link #findInCache(Class)} is that here the whole {@link CachedEntity}
   * is returned, which gives access to the persistent state at the moment of putting it in the cache.  
   */
   Collection findInCacheAsCachedObjects(Class entityClass);
  
  /**
   * Removes the {@link Entity} of the given type with the given id from the cache. 
   */
  void cacheRemove(Class entityClass, String entityId);

}