DATAREDIS-775 - Expose Lettuce RedisClient through RedisClientProvider.

We now expose the underlying Redis Client instance via RedisClientProvider.getRedisClient() to components that require direct client interaction. The client is exposed through ClusterConnectionProvider and now also through LettucePoolingConnectionProvider.

Exposing the client via LettucePoolingConnectionProvider allows Redis Cluster usage with connection pooling.

Original Pull Request: #316

src/main/java/org/springframework/data/redis/connection/lettuce/ClusterConnectionProvider.java

@@ -15,6 +15,7 @@
  */
 package org.springframework.data.redis.connection.lettuce;
 
+import io.lettuce.core.AbstractRedisClient;
 import io.lettuce.core.ReadFrom;
 import io.lettuce.core.api.StatefulConnection;
 import io.lettuce.core.cluster.RedisClusterClient;
@@ -34,7 +35,7 @@ import org.springframework.util.Assert;
  * @author Christoph Strobl
  * @since 2.0
  */
-class ClusterConnectionProvider implements LettuceConnectionProvider {
+class ClusterConnectionProvider implements LettuceConnectionProvider, RedisClientProvider {
 
 	private final RedisClusterClient client;
 	private final RedisCodec<?, ?> codec;
@@ -91,7 +92,12 @@ class ClusterConnectionProvider implements LettuceConnectionProvider {
 		throw new UnsupportedOperationException("Connection type " + connectionType + " not supported!");
 	}
 
-	public RedisClusterClient getClient() {
+	/*
+	 * (non-Javadoc)
+	 * @see org.springframework.data.redis.connection.lettuce.RedisClientProvider#getRedisClient()
+	 */
+	@Override
+	public AbstractRedisClient getRedisClient() {
 		return client;
 	}
 }

src/main/java/org/springframework/data/redis/connection/lettuce/LettuceClusterConnection.java

@@ -154,7 +154,15 @@ public class LettuceClusterConnection extends LettuceConnection implements Defau
 	 * @return access to {@link RedisClusterClient} for non-connection access.
 	 */
 	private RedisClusterClient getClient() {
-		return ((ClusterConnectionProvider) getConnectionProvider()).getClient();
+
+		LettuceConnectionProvider connectionProvider = getConnectionProvider();
+
+		if (connectionProvider instanceof RedisClientProvider) {
+			return (RedisClusterClient) ((RedisClientProvider) getConnectionProvider()).getRedisClient();
+		}
+
+		throw new IllegalStateException(String.format("Connection provider %s does not implement RedisClientProvider!",
+				connectionProvider.getClass().getName()));
 	}
 
 	/*

src/main/java/org/springframework/data/redis/connection/lettuce/LettucePoolingConnectionProvider.java

@@ -15,6 +15,7 @@
  */
 package org.springframework.data.redis.connection.lettuce;
 
+import io.lettuce.core.AbstractRedisClient;
 import io.lettuce.core.api.StatefulConnection;
 import io.lettuce.core.support.ConnectionPoolSupport;
 
@@ -42,7 +43,7 @@ import org.springframework.util.Assert;
  * @since 2.0
  * @see #getConnection(Class)
  */
-class LettucePoolingConnectionProvider implements LettuceConnectionProvider, DisposableBean {
+class LettucePoolingConnectionProvider implements LettuceConnectionProvider, RedisClientProvider,  DisposableBean {
 
 	private final static Log log = LogFactory.getLog(LettucePoolingConnectionProvider.class);
 
@@ -86,6 +87,22 @@ class LettucePoolingConnectionProvider implements LettuceConnectionProvider, Dis
 		}
 	}
 
+	/*
+	 * (non-Javadoc)
+	 * @see org.springframework.data.redis.connection.lettuce.RedisClientProvider#getRedisClient()
+	 */
+	@Override
+	public AbstractRedisClient getRedisClient() {
+
+		if (connectionProvider instanceof RedisClientProvider) {
+			return ((RedisClientProvider) connectionProvider).getRedisClient();
+		}
+
+		throw new IllegalStateException(
+				String.format("Undyerlying connection provider %s does not implement RedisClientProvider!",
+						connectionProvider.getClass().getName()));
+	}
+
 	/*
 	 * (non-Javadoc)
 	 * @see org.springframework.data.redis.connection.lettuce.LettuceConnectionProvider#release(io.lettuce.core.api.StatefulConnection)

src/main/java/org/springframework/data/redis/connection/lettuce/RedisClientProvider.java

@@ -0,0 +1,34 @@
+/*
+ * Copyright 2018 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.connection.lettuce;
+
+import io.lettuce.core.AbstractRedisClient;
+
+/**
+ * Extension to {@link LettuceConnectionProvider} for providers exposing {@link io.lettuce.core.RedisClient}.
+ *
+ * @author Mark Paluch
+ * @since 2.0.5
+ */
+interface RedisClientProvider {
+
+	/**
+	 * Returns the underlying Redis Client.
+	 *
+	 * @return the {@link AbstractRedisClient}.
+	 */
+	AbstractRedisClient getRedisClient();
+}