DATAREDIS-1195 - Make putIfAbsent atomic when TTL is set.

Original pull request: #553.

Author: Andre Prata

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

@@ -45,6 +45,7 @@
  *
  * @author Christoph Strobl
  * @author Mark Paluch
+ * @author André Prata
  * @since 2.0
  */
 class DefaultRedisCacheWriter implements RedisCacheWriter {
@@ -127,11 +128,15 @@ public byte[] putIfAbsent(String name, byte[] key, byte[] value, @Nullable Durat
 			}
 
 			try {
-				if (connection.setNX(key, value)) {
 
-					if (shouldExpireWithin(ttl)) {
-						connection.pExpire(key, ttl.toMillis());
-					}
+				boolean put;
+				if (shouldExpireWithin(ttl)) {
+					put = connection.set(key, value, Expiration.milliseconds(ttl.toMillis()), SetOption.ifAbsent());
+				} else {
+					put = connection.setNX(key, value);
+				}
+
+				if (put) {
 					return null;
 				}