DATAREDIS-688 - Return delete result via RedisOperations.delete(…).

We now return the deletion count for multi-key deletes and whether a single key was deleted for RedisOperations.delete(…).

Original Pull Request: #276

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

@@ -159,10 +159,10 @@ public interface RedisOperations<K, V> {
 	 * Delete given {@code key}.
 	 *
 	 * @param key must not be {@literal null}.
-	 * @return The number of keys that were removed.
+	 * @return {@literal true} if the key was removed.
 	 * @see <a href="http://redis.io/commands/del">Redis Documentation: DEL</a>
 	 */
-	void delete(K key);
+	Boolean delete(K key);
 
 	/**
 	 * Delete given {@code keys}.
@@ -171,7 +171,7 @@ public interface RedisOperations<K, V> {
 	 * @return The number of keys that were removed.
 	 * @see <a href="http://redis.io/commands/del">Redis Documentation: DEL</a>
 	 */
-	void delete(Collection<K> keys);
+	Long delete(Collection<K> keys);
 
 	/**
 	 * Determine the type stored at {@code key}.

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

@@ -692,14 +692,13 @@ public class RedisTemplate<K, V> extends RedisAccessor implements RedisOperation
 	 * @see org.springframework.data.redis.core.RedisOperations#delete(java.lang.Object)
 	 */
 	@Override
-	public void delete(K key) {
+	public Boolean delete(K key) {
 
 		byte[] rawKey = rawKey(key);
 
-		execute(connection -> {
-			connection.del(rawKey);
-			return null;
-		}, true);
+		Long result = execute(connection -> connection.del(rawKey), true);
+
+		return result != null && result.intValue() == 1;
 	}
 
 	/*
@@ -707,18 +706,15 @@ public class RedisTemplate<K, V> extends RedisAccessor implements RedisOperation
 	 * @see org.springframework.data.redis.core.RedisOperations#delete(java.util.Collection)
 	 */
 	@Override
-	public void delete(Collection<K> keys) {
+	public Long delete(Collection<K> keys) {
 
 		if (CollectionUtils.isEmpty(keys)) {
-			return;
+			return 0L;
 		}
 
 		byte[][] rawKeys = rawKeys(keys);
 
-		execute(connection -> {
-			connection.del(rawKeys);
-			return null;
-		}, true);
+		return execute(connection -> connection.del(rawKeys), true);
 	}
 
 	/*