DATAREDIS-548 - Release connection after command execution in read-only transactions.

We now unbind and release the connection from the transaction resources after a Redis command is invoked. Redis read operations return always null while using RedisTemplate in a transaction so Redis read transactions are not useful.

Previously, RedisConnection's were bound as transactional resource when used in the scope of a @Transactional(readOnly = true) method but not released on transaction completion. This was, because connections are not registered with a transaction synchronizer.

Original Pull Request: #214

src/main/java/org/springframework/data/redis/core/RedisConnectionUtils.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2011-2015 the original author or authors.
+ * Copyright 2011-2016 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.
@@ -39,6 +39,7 @@ import org.springframework.util.Assert;
  * @author Costin Leau
  * @author Christoph Strobl
  * @author Thomas Darimont
+ * @author Mark Paluch
  */
 public abstract class RedisConnectionUtils {
 
@@ -199,8 +200,12 @@ public abstract class RedisConnectionUtils {
 			return;
 		}
 
-		// Only release non-transactional/non-bound connections.
-		if (!isConnectionTransactional(conn, factory)) {
+		// release transactional/read-only and non-transactional/non-bound connections.
+		// transactional connections for read-only transactions get no synchronizer registered
+		if (isConnectionTransactional(conn, factory)
+				&& TransactionSynchronizationManager.isCurrentTransactionReadOnly()) {
+			unbindConnection(factory);
+		} else if (!isConnectionTransactional(conn, factory)) {
 			if (log.isDebugEnabled()) {
 				log.debug("Closing Redis Connection");
 			}

src/main/java/org/springframework/data/redis/core/RedisTemplate.java

@@ -74,6 +74,7 @@ import org.springframework.util.CollectionUtils;
  * @author Christoph Strobl
  * @author Ninad Divadkar
  * @author Anqing Shao
+ * @author Mark Paluch
  * @param <K> the Redis key type against which the template works (usually a String)
  * @param <V> the Redis value type against which the template works
  * @see StringRedisTemplate
@@ -212,10 +213,7 @@ public class RedisTemplate<K, V> extends RedisAccessor implements RedisOperation
 			// TODO: any other connection processing?
 			return postProcessResult(result, connToUse, existingConnection);
 		} finally {
-
-			if (!enableTransactionSupport) {
-				RedisConnectionUtils.releaseConnection(conn, factory);
-			}
+			RedisConnectionUtils.releaseConnection(conn, factory);
 		}
 	}