| #pragma once |
| |
| #ifndef GEODE_CACHELOADER_H_ |
| #define GEODE_CACHELOADER_H_ |
| |
| /* |
| * Licensed to the Apache Software Foundation (ASF) under one or more |
| * contributor license agreements. See the NOTICE file distributed with |
| * this work for additional information regarding copyright ownership. |
| * The ASF licenses this file to You 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. |
| */ |
| |
| /** |
| * @file |
| */ |
| |
| #include "CacheableKey.hpp" |
| #include "Serializable.hpp" |
| #include "internal/geode_globals.hpp" |
| |
| namespace apache { |
| namespace geode { |
| namespace client { |
| class Region; |
| |
| /** |
| * @class CacheLoader CacheLoader.hpp |
| * An application plug-in that can be installed on a region. Loaders |
| * facilitate loading of data into the cache. When an application does a |
| * lookup for a key in a region and it does not exist, the system checks to |
| * see if any loaders are available for the region in the system and |
| * invokes them to get the value for the key into the cache. |
| * Allows data to be loaded from a 3rd party data source and placed |
| * into the region |
| * When {@link Region::get} is called for a region |
| * entry that has a <code>nullptr</code> value, the |
| * {@link CacheLoader::load} method of the |
| * region's cache loader is invoked. The <code>load</code> method |
| * creates the value for the desired key by performing an operation such |
| * as a database query. |
| * |
| * @see RegionAttributesFactory::setCacheLoader |
| * @see RegionAttributes::getCacheLoader |
| */ |
| class APACHE_GEODE_EXPORT CacheLoader { |
| public: |
| virtual ~CacheLoader() = default; |
| CacheLoader(const CacheLoader& other) = delete; |
| void operator=(const CacheLoader& other) = delete; |
| |
| /**Loads a value. Application writers should implement this |
| * method to customize the loading of a value. This method is called |
| * by the caching service when the requested value is not in the cache. |
| * Any exception thrown by this method is propagated back to and thrown |
| * by the invocation of {@link Region::get} that triggered this load. |
| * @param rp a Region Pointer for which this is called. |
| * @param key the key for the cacheable |
| * @param helper any related user data, or nullptr |
| * @return the value supplied for this key, or nullptr if no value can be |
| * supplied. |
| * |
| *@see Region::get . |
| */ |
| virtual std::shared_ptr<Cacheable> load( |
| Region& rp, const std::shared_ptr<CacheableKey>& key, |
| const std::shared_ptr<Serializable>& aCallbackArgument) = 0; |
| |
| /** Called when the region containing this callback is destroyed, when |
| * the cache is closed. |
| * |
| * <p>Implementations should clean up any external |
| * resources, such as database connections. Any runtime exceptions this method |
| * throws will be logged. |
| * |
| * <p>It is possible for this method to be called multiple times on a single |
| * callback instance, so implementations must be tolerant of this. |
| * |
| * @param rp the region pointer |
| * |
| * @see Cache::close |
| * @see Region::destroyRegion |
| */ |
| virtual void close(Region& rp); |
| |
| protected: |
| CacheLoader() = default; |
| }; |
| } // namespace client |
| } // namespace geode |
| } // namespace apache |
| |
| #endif // GEODE_CACHELOADER_H_ |