DATAREDIS-375 - Avoid repeatedly decorating a cache.

Previously a transactional RedisCacheManager decorated a cache with the TransactionAwareCacheDecorator twice. We now make sure that a particular cache is only decorated once with a TransactionAwareCacheDecorator. Original Pull Request: spring-projects#128

Author: Thomas Darimont

src/main/java/org/springframework/data/redis/cache/RedisCacheManager.java

@@ -300,4 +300,22 @@ public void afterPropertiesSet() {
 
 super.afterPropertiesSet();
 }
+
+/* (non-Javadoc)
+* @see
+org.springframework.cache.transaction.AbstractTransactionSupportingCacheManager#decorateCache(org.springframework.cache.Cache)
+*/
+@Override
+protected Cache decorateCache(Cache cache) {
+
+if (isCacheAlreadyDecorated(cache)) {
+return cache;
+}
+
+return super.decorateCache(cache);
+}
+
+protected boolean isCacheAlreadyDecorated(Cache cache) {
+return isTransactionAware() && cache instanceof TransactionAwareCacheDecorator;
+}
 }

src/test/java/org/springframework/data/redis/cache/RedisCacheManagerTransactionalUnitTests.java

@@ -0,0 +1,126 @@
+/*
+ * Copyright 2015 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
+ *
+ * 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.springframework.data.redis.cache;
+
+import static org.junit.Assert.*;
+import static org.mockito.Mockito.*;
+
+import java.sql.Connection;
+import java.sql.SQLException;
+import java.util.Arrays;
+
+import javax.sql.DataSource;
+
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.springframework.beans.DirectFieldAccessor;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.cache.Cache;
+import org.springframework.cache.CacheManager;
+import org.springframework.cache.annotation.EnableCaching;
+import org.springframework.cache.transaction.TransactionAwareCacheDecorator;
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
+import org.springframework.data.redis.connection.RedisConnection;
+import org.springframework.data.redis.connection.RedisConnectionFactory;
+import org.springframework.data.redis.core.RedisTemplate;
+import org.springframework.data.redis.test.util.RelaxedJUnit4ClassRunner;
+import org.springframework.jdbc.datasource.DataSourceTransactionManager;
+import org.springframework.test.context.ContextConfiguration;
+import org.springframework.test.context.transaction.TransactionConfiguration;
+import org.springframework.transaction.PlatformTransactionManager;
+import org.springframework.transaction.annotation.Transactional;
+
+/**
+ * @author Thomas Darimont
+ */
+@RunWith(RelaxedJUnit4ClassRunner.class)
+@ContextConfiguration
+@Transactional
+@TransactionConfiguration(transactionManager = "transactionManager")
+public class RedisCacheManagerTransactionalUnitTests {
+
+@Autowired protected CacheManager cacheManager;
+
+private final static String cacheName = "cache-name";
+
+@Configuration
+@EnableCaching
+public static class Config {
+
+@Bean
+public PlatformTransactionManager transactionManager() throws SQLException {
+
+DataSourceTransactionManager txmgr = new DataSourceTransactionManager();
+txmgr.setDataSource(dataSource());
+txmgr.afterPropertiesSet();
+
+return txmgr;
+}
+
+@Bean
+public DataSource dataSource() throws SQLException {
+
+DataSource dataSourceMock = mock(DataSource.class);
+when(dataSourceMock.getConnection()).thenReturn(mock(Connection.class));
+
+return dataSourceMock;
+}
+
+@Bean
+public CacheManager cacheManager() {
+
+RedisCacheManager cacheManager = new RedisCacheManager(redisTemplate());
+cacheManager.setTransactionAware(true);
+cacheManager.setCacheNames(Arrays.asList(cacheName));
+return cacheManager;
+}
+
+@SuppressWarnings({ "rawtypes" })
+@Bean
+public RedisTemplate redisTemplate() {
+
+RedisConnection connectionMock = mock(RedisConnection.class);
+RedisConnectionFactory factoryMock = mock(RedisConnectionFactory.class);
+
+when(factoryMock.getConnection()).thenReturn(connectionMock);
+
+RedisTemplate template = new RedisTemplate();
+template.setConnectionFactory(factoryMock);
+
+return template;
+}
+}
+
+/**
+ * @see DATAREDIS-375
+ */
+@Test
+public void testCacheIsNotDecoratedTwiceWithTransactionAwareCacheDecorator() {
+
+Cache cache = cacheManager.getCache(cacheName);
+
+// the cache must be decorated with the TransactionAwareCacheDecorator
+assertTrue(cache instanceof TransactionAwareCacheDecorator);
+TransactionAwareCacheDecorator transactionalCache = (TransactionAwareCacheDecorator) cache;
+
+// get the target cache via reflection
+Object targetCache = new DirectFieldAccessor(transactionalCache).getPropertyValue("targetCache");
+
+// the target cache must be an instance of RedisCache and not TransactionAwareCacheDecorator
+assertTrue(targetCache instanceof RedisCache);
+}
+}