DATAREDIS-344 - Assert RedisCache works with Spring 4.1.

Added `putIfAbsent` to `RedisCache` to satisfy compatibility with newly introduced method.

Original pull request: #102.

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

@@ -137,6 +137,38 @@ class RedisCache implements Cache {
 		}, true);
 	}
 
+	public ValueWrapper putIfAbsent(Object key, final Object value) {
+
+		final byte[] keyBytes = computeKey(key);
+		final byte[] valueBytes = convertToBytesIfNecessary(template.getValueSerializer(), value);
+
+		return toWrapper(template.execute(new RedisCallback<Object>() {
+			public Object doInRedis(RedisConnection connection) throws DataAccessException {
+
+				waitForLock(connection);
+
+				Object resultValue = value;
+				boolean valueWasSet = connection.setNX(keyBytes, valueBytes);
+				if (valueWasSet) {
+					connection.zAdd(setName, 0, keyBytes);
+					if (expiration > 0) {
+						connection.expire(keyBytes, expiration);
+						// update the expiration of the set of keys as well
+						connection.expire(setName, expiration);
+					}
+				} else {
+					resultValue = deserializeIfNecessary(template.getValueSerializer(), connection.get(keyBytes));
+				}
+
+				return resultValue;
+			}
+		}, true));
+	}
+
+	private ValueWrapper toWrapper(Object value) {
+		return (value != null ? new SimpleValueWrapper(value) : null);
+	}
+
 	public void evict(Object key) {
 		final byte[] k = computeKey(key);
 
@@ -227,4 +259,14 @@ class RedisCache implements Cache {
 
 		return serializer.serialize(value);
 	}
+
+	private Object deserializeIfNecessary(RedisSerializer<byte[]> serializer, byte[] value) {
+
+		if (serializer != null) {
+			return serializer.deserialize(value);
+		}
+
+		return value;
+	}
+
 }

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

@@ -16,14 +16,17 @@
 
 package org.springframework.data.redis.cache;
 
-import static org.hamcrest.core.IsInstanceOf.*;
-import static org.hamcrest.core.IsNull.*;
+import static org.hamcrest.core.IsEqual.equalTo;
+import static org.hamcrest.core.IsInstanceOf.instanceOf;
+import static org.hamcrest.core.IsNot.not;
+import static org.hamcrest.core.IsNull.nullValue;
+import static org.hamcrest.core.IsSame.sameInstance;
 import static org.junit.Assert.assertFalse;
 import static org.junit.Assert.assertNotNull;
 import static org.junit.Assert.assertNull;
 import static org.junit.Assert.assertThat;
 import static org.junit.Assert.assertTrue;
-import static org.junit.Assume.*;
+import static org.junit.Assume.assumeThat;
 import static org.springframework.data.redis.matcher.RedisTestMatchers.isEqual;
 
 import java.util.Collection;
@@ -71,7 +74,7 @@ public class RedisCacheTest extends AbstractNativeCacheTest<RedisTemplate> {
 	}
 
 	@SuppressWarnings("unchecked")
-	protected Cache createCache(RedisTemplate nativeCache) {
+	protected RedisCache createCache(RedisTemplate nativeCache) {
 		return new RedisCache(CACHE_NAME, CACHE_NAME.concat(":").getBytes(), nativeCache, TimeUnit.MINUTES.toSeconds(10));
 	}
 
@@ -246,4 +249,31 @@ public class RedisCacheTest extends AbstractNativeCacheTest<RedisTemplate> {
 		Object invalidKey = template.getKeySerializer() == null ? "spring-data-redis".getBytes() : "spring-data-redis";
 		assertThat(redisCache.get(invalidKey, value.getClass()), nullValue());
 	}
+
+	/**
+	 * @see DATAREDIS-344
+	 */
+	@Test
+	public void putIfAbsentShouldSetValueOnlyIfNotPresent() {
+
+		assumeThat(cache, instanceOf(RedisCache.class));
+
+		RedisCache redisCache = (RedisCache)cache;
+		
+		Object key = getKey();
+		template.delete(key);
+
+		Object value = getValue();
+		ValueWrapper wrapper = redisCache.putIfAbsent(key, value);
+
+		assertThat(wrapper.get(), sameInstance(value));
+
+		ValueWrapper wrapper2 = redisCache.putIfAbsent(key, value);
+
+		if (!(value instanceof Number)) {
+			assertThat(wrapper2.get(), not(sameInstance(value)));
+		}
+
+		assertThat(wrapper2.get(), equalTo(value));
+	}
 }