Add RegionConfigurer to register a SD CrudRepository as a Region CacheWriter to write-through to an external data source for Inline Caching.

spring-geode/src/main/java/org/springframework/geode/cache/RepositoryCacheWriterRegionConfigurer.java

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+/*
+ * Copyright 2019 the original author or authors.
+ *
+ * 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
+ *
+ *     https://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.springframework.geode.cache;
+
+import java.util.function.Predicate;
+
+import org.apache.geode.cache.CacheWriter;
+import org.apache.geode.cache.Region;
+
+import org.springframework.data.gemfire.PeerRegionFactoryBean;
+import org.springframework.data.gemfire.client.ClientRegionFactoryBean;
+import org.springframework.data.gemfire.config.annotation.RegionConfigurer;
+import org.springframework.data.repository.CrudRepository;
+import org.springframework.util.Assert;
+
+/**
+ * The RepositoryCacheWriterRegionConfigurer class...
+ *
+ * @author John Blum
+ * @since 1.0.0
+ */
+public class RepositoryCacheWriterRegionConfigurer<T, ID> implements RegionConfigurer {
+
+	public static <T, ID> RepositoryCacheWriterRegionConfigurer<T, ID> create(CrudRepository<T, ID> repository,
+			Predicate<String> regionBeanName) {
+
+		return new RepositoryCacheWriterRegionConfigurer<>(repository, regionBeanName);
+	}
+
+	public static <T, ID> RepositoryCacheWriterRegionConfigurer<T, ID> create(CrudRepository<T, ID> repository,
+			String regionBeanName) {
+
+		return new RepositoryCacheWriterRegionConfigurer<>(repository, Predicate.isEqual(regionBeanName));
+	}
+
+	private final CrudRepository<T, ID> repository;
+
+	private final Predicate<String> regionBeanName;
+
+	/**
+	 * Constructs a new instance of {@link RepositoryCacheWriterRegionConfigurer} initialized with the given Spring Data
+	 * {@link CrudRepository} used to write {@link Region} values to a backend data source/data store along with
+	 * a given {@link Predicate} to identify/qualify the {@link Region} on which the {@link CrudRepository} will be
+	 * registered and used as a {@link CacheWriter}.
+	 *
+	 * @param repository {@link CrudRepository} used to write {@link Region} values to a backend data source.
+	 * @param regionBeanName {@link Predicate} used to identify/qualify the {@link Region} on which
+	 * the {@link CrudRepository} will be registered and used as a {@link CacheWriter}.
+	 * @throws IllegalArgumentException if {@link CrudRepository} is {@literal null}.
+	 * @see org.springframework.data.repository.CrudRepository
+	 * @see java.util.function.Predicate
+	 */
+	public RepositoryCacheWriterRegionConfigurer(CrudRepository<T, ID> repository, Predicate<String> regionBeanName) {
+
+		Assert.notNull(repository, "CrudRepository is required");
+
+		this.repository = repository;
+
+		this.regionBeanName = regionBeanName != null
+			? regionBeanName
+			: beanName -> false;
+	}
+
+	/**
+	 * Returns the configured {@link Predicate} used to identify/qualify the {@link Region}
+	 * on which the {@link CrudRepository} will be registered as a {@link CacheWriter} for write through.
+	 *
+	 * @return the configured {@link Predicate} used to identify/qualify the {@link Region}
+	 * targeted for the {@link CacheWriter} registration.
+	 * @see java.util.function.Predicate
+	 */
+	protected Predicate<String> getRegionBeanName() {
+		return regionBeanName;
+	}
+
+	/**
+	 * Returns the configured Spring Data {@link CrudRepository} adapted/wrapped as a {@link CacheWriter}
+	 * and used to write {@link Region} values to a backend data source/data store.
+	 *
+	 * @return the configured {@link CrudRepository} used to write {@link Region} values to a backend data source.
+	 * @see org.springframework.data.repository.CrudRepository
+	 */
+	protected CrudRepository<T, ID> getRepository() {
+		return this.repository;
+	}
+
+	@Override
+	@SuppressWarnings("unchecked")
+	public void configure(String beanName, ClientRegionFactoryBean<?, ?> bean) {
+
+		if (getRegionBeanName().test(beanName)) {
+			bean.setCacheWriter(newRepositoryCacheWriter());
+		}
+	}
+
+	@Override
+	@SuppressWarnings("unchecked")
+	public void configure(String beanName, PeerRegionFactoryBean<?, ?> bean) {
+
+		if (getRegionBeanName().test(beanName)) {
+			bean.setCacheWriter(newRepositoryCacheWriter());
+		}
+	}
+
+	/**
+	 * Constructs a new instance of {@link RepositoryCacheWriter} adapting the {@link CrudRepository}
+	 * as an instance of a {@link CacheWriter}.
+	 *
+	 * @return a new {@link RepositoryCacheWriter}.
+	 * @see org.springframework.geode.cache.RepositoryCacheWriter
+	 * @see org.springframework.data.repository.CrudRepository
+	 * @see org.apache.geode.cache.CacheWriter
+	 * @see #getRepository()
+	 */
+	protected RepositoryCacheWriter newRepositoryCacheWriter() {
+		return new RepositoryCacheWriter<>(getRepository());
+	}
+}