com.gemstone.gemfire.cache.LoaderHelper Maven / Gradle / Ivy
/*
* Copyright (c) 2010-2015 Pivotal Software, Inc. All rights reserved.
*
* 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. See accompanying
* LICENSE file.
*/
package com.gemstone.gemfire.cache;
/** Provides a set of APIs to help the
* implementation of the CacheLoader load method. An instance of LoaderHelper
* is only valid within the {@link CacheLoader#load(LoaderHelper) load}
* method.
*
* @author Dave Monnie
*
* @see CacheLoader#load(LoaderHelper) load
* @since 2.0
*/
public interface LoaderHelper
{
/** Searches other caches for the value to be loaded. If the cache
* is part of a distributed caching system, netSearch
* will try to locate the requested value in any other cache within
* the system. If the search is successful, a reference to a local
* copy of the value is returned. If there is no value for this
* entry present in the system, and doNetLoad is true, GemFire looks
* for and invokes CacheLoaders in other nodes in the
* system. The net load will invoke one loader at a time until a
* loader either returns a non-null value or throws an exception.
* If the object is not found, null is returned.
*
* @param doNetLoad
* if true, and there is no valid value found for this entry
* in the system, then look for and invoke loaders on other
* nodes
*
* @return the requested value or null if not found
*
* @throws TimeoutException if the netSearch times out before
* getting a response from another cache
* @throws CacheLoaderException
* If netSearch is attempted on a {@linkplain
* com.gemstone.gemfire.cache.Scope#LOCAL local} region.
*/
public V netSearch(boolean doNetLoad)
throws CacheLoaderException, TimeoutException;
/**
* Returns the key for the value being loaded.
*
* @return the name Object for the object being loaded
* @see CacheLoader#load(LoaderHelper) load
*/
public K getKey();
/**
* Returns the region to which the entry belongs.
*
* @return the name of the region for the object being loaded
* @see CacheLoader#load(LoaderHelper) load
*/
public Region getRegion();
/** Return the argument object for the load method that was passed in from
* application code. This object is passed in as aLoaderArgument in
* {@link Region#get(Object, Object) get}.
* @return the argument or null if one was not supplied
*/
public Object getArgument();
}