PersistenceContext.java

package com.avaje.ebean.bean;

/**
 * Holds entity beans by there type and id.
 * <p>
 * This is used to ensure only one instance for a given entity type and id is
 * used to build object graphs from queries and lazy loading.
 * </p>
 */
public interface PersistenceContext {

  /**
   * Put the entity bean into the PersistanceContext.
   */
  public void put(Object id, Object bean);

  /**
   * Put the entity bean into the PersistanceContext if one is not already
   * present (for this id).
   * <p>
   * Returns an existing entity bean (if one is already there) and otherwise
   * returns null.
   * </p>
   */
  public Object putIfAbsent(Object id, Object bean);

  /**
   * Return an object given its type and unique id.
   */
  public Object get(Class<?> beanType, Object uid);

  /**
   * Clear all the references.
   */
  public void clear();

  /**
   * Clear all the references for a given type of entity bean.
   */
  public void clear(Class<?> beanType);

  /**
   * Clear the reference to a specific entity bean.
   */
  public void clear(Class<?> beanType, Object uid);

  /**
   * Return the number of beans of the given type in the persistence context.
   */
  public int size(Class<?> beanType);

}