DATAREDIS-529 - Polishing.

Accept varargs byte arrays instead of Collection of byte arrays. Bypass own routing for exists single-slot execution in Redis Cluster. Replace parallel stream execution of exists(…) with sequential ClusterCommandExecutor dispatch.

Reorder methods in ClusterConnectionTests by name. Adapt Javadoc.

Original pull request: #281.

src/main/java/org/springframework/data/redis/connection/DefaultStringRedisConnection.java

@@ -300,15 +300,15 @@ public class DefaultStringRedisConnection implements StringRedisConnection, Deco
 	 */
 	@Override
 	public Long exists(String... keys) {
-		return convertAndReturn(delegate.exists(Arrays.asList(serializeMulti(keys))), identityConverter);
+		return convertAndReturn(delegate.exists(serializeMulti(keys)), identityConverter);
 	}
 
 	/*
 	 * (non-Javadoc)
-	 * @see org.springframework.data.redis.connection.RedisKeyCommands#exists(java.util.Collection)
+	 * @see org.springframework.data.redis.connection.RedisKeyCommands#exists(byte[][])
 	 */
 	@Override
-	public Long exists(Collection<byte[]> keys) {
+	public Long exists(byte[]... keys) {
 		return convertAndReturn(delegate.exists(keys), identityConverter);
 	}
 

src/main/java/org/springframework/data/redis/connection/DefaultedRedisConnection.java

@@ -15,7 +15,6 @@
  */
 package org.springframework.data.redis.connection;
 
-import java.util.Collection;
 import java.util.List;
 import java.util.Map;
 import java.util.Map.Entry;
@@ -58,7 +57,7 @@ public interface DefaultedRedisConnection extends RedisConnection {
 	/** @deprecated in favor of {@link RedisConnection#keyCommands()}. */
 	@Override
 	@Deprecated
-	default Long exists(Collection<byte[]> keys) {
+	default Long exists(byte[]... keys) {
 		return keyCommands().exists(keys);
 	}
 

src/main/java/org/springframework/data/redis/connection/RedisKeyCommands.java

@@ -15,8 +15,6 @@
  */
 package org.springframework.data.redis.connection;
 
-import java.util.Collection;
-import java.util.Collections;
 import java.util.List;
 import java.util.Set;
 import java.util.concurrent.TimeUnit;
@@ -46,20 +44,21 @@ public interface RedisKeyCommands {
 	default Boolean exists(byte[] key) {
 
 		Assert.notNull(key, "Key must not be null!");
-		Long count = exists(Collections.singleton(key));
+		Long count = exists(new byte[][] { key });
 		return count != null ? count > 0 : null;
 	}
 
 	/**
-	 * Count how many of the given {@code keys} exists. Providing the very same {@code key} more than once also counts
+	 * Count how many of the given {@code keys} exist. Providing the very same {@code key} more than once also counts
 	 * multiple times.
 	 *
 	 * @param keys must not be {@literal null}.
-	 * @return the number of keys existing among the ones specified as arguments.
+	 * @return the number of keys existing among the ones specified as arguments. {@literal null} when used in pipeline /
+	 *         transaction.
 	 * @since 2.1
 	 */
 	@Nullable
-	Long exists(Collection<byte[]> keys);
+	Long exists(byte[]... keys);
 
 	/**
 	 * Delete given {@code keys}.

src/main/java/org/springframework/data/redis/connection/StringRedisConnection.java

@@ -92,12 +92,12 @@ public interface StringRedisConnection extends RedisConnection {
 	Boolean exists(String key);
 
 	/**
-	 * Count how many of the if given {@code keys} exists.
+	 * Count how many of the given {@code keys} exist.
 	 *
 	 * @param keys must not be {@literal null}.
 	 * @return
 	 * @see <a href="http://redis.io/commands/exists">Redis Documentation: EXISTS</a>
-	 * @see RedisKeyCommands#exists(java.util.Collection)
+	 * @see RedisKeyCommands#exists(byte[][])
 	 * @since 2.1
 	 */
 	@Nullable

src/main/java/org/springframework/data/redis/connection/jedis/JedisClusterKeyCommands.java

@@ -15,6 +15,8 @@
  */
 package org.springframework.data.redis.connection.jedis;
 
+import redis.clients.jedis.BinaryJedis;
+
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Collection;
@@ -62,7 +64,8 @@ class JedisClusterKeyCommands implements RedisKeyCommands {
 	@Override
 	public Long del(byte[]... keys) {
 
-		Assert.noNullElements(keys, "Keys must not be null or contain null key!");
+		Assert.notNull(keys, "Keys must not be null!");
+		Assert.noNullElements(keys, "Keys must not contain null elements!");
 
 		if (ClusterSlotHashUtil.isSameSlotForAllKeys(keys)) {
 			try {
@@ -473,26 +476,26 @@ class JedisClusterKeyCommands implements RedisKeyCommands {
 
 	/*
 	 * (non-Javadoc)
-	 * @see org.springframework.data.redis.connection.RedisKeyCommands#exists(java.util.Collection)
+	 * @see org.springframework.data.redis.connection.RedisKeyCommands#exists(byte[][])
 	 */
 	@Nullable
 	@Override
-	public Long exists(Collection<byte[]> keys) {
+	public Long exists(byte[]... keys) {
 
 		Assert.notNull(keys, "Keys must not be null!");
+		Assert.noNullElements(keys, "Keys must not contain null elements!");
 
-		try {
-
-			return keys.stream() //
-					.parallel()
-					.map(key -> connection.getClusterCommandExecutor()
-							.executeCommandOnSingleNode((JedisClusterCommandCallback<Boolean>) client -> client.exists(key),
-									connection.getTopologyProvider().getTopology().getKeyServingMasterNode(key))
-							.getValue())
-					.mapToLong(val -> ObjectUtils.nullSafeEquals(val, Boolean.TRUE) ? 1L : 0L).sum();
-		} catch (Exception ex) {
-			throw convertJedisAccessException(ex);
+		if (ClusterSlotHashUtil.isSameSlotForAllKeys(keys)) {
+			try {
+				return connection.getCluster().exists(keys);
+			} catch (Exception ex) {
+				throw convertJedisAccessException(ex);
+			}
 		}
+
+		return connection.getClusterCommandExecutor()
+				.executeMultiKeyCommand((JedisMultiKeyClusterCommandCallback<Boolean>) BinaryJedis::exists, Arrays.asList(keys))
+				.resultsAsList().stream().mapToLong(val -> ObjectUtils.nullSafeEquals(val, Boolean.TRUE) ? 1 : 0).sum();
 	}
 
 	private DataAccessException convertJedisAccessException(Exception ex) {

src/main/java/org/springframework/data/redis/connection/jedis/JedisKeyCommands.java

@@ -20,7 +20,6 @@ import lombok.RequiredArgsConstructor;
 import redis.clients.jedis.ScanParams;
 import redis.clients.jedis.SortingParams;
 
-import java.util.Collection;
 import java.util.List;
 import java.util.Set;
 import java.util.concurrent.TimeUnit;
@@ -73,26 +72,27 @@ class JedisKeyCommands implements RedisKeyCommands {
 
 	/*
 	 * (non-Javadoc)
-	 * @see org.springframework.data.redis.connection.RedisKeyCommands#exists(java.util.Collection)
+	 * @see org.springframework.data.redis.connection.RedisKeyCommands#exists(byte[][])
 	 */
 	@Nullable
 	@Override
-	public Long exists(Collection<byte[]> keys) {
+	public Long exists(byte[]... keys) {
 
 		Assert.notNull(keys, "Keys must not be null!");
+		Assert.noNullElements(keys, "Keys must not contain null elements!");
 
 		try {
 			if (isPipelined()) {
 				pipeline(
-						connection.newJedisResult(connection.getRequiredPipeline().exists(keys.toArray(new byte[keys.size()][]))));
+						connection.newJedisResult(connection.getRequiredPipeline().exists(keys)));
 				return null;
 			}
 			if (isQueueing()) {
 				transaction(connection
-						.newJedisResult(connection.getRequiredTransaction().exists(keys.toArray(new byte[keys.size()][]))));
+						.newJedisResult(connection.getRequiredTransaction().exists(keys)));
 				return null;
 			}
-			return connection.getJedis().exists(keys.toArray(new byte[keys.size()][]));
+			return connection.getJedis().exists(keys);
 		} catch (Exception ex) {
 			throw connection.convertJedisAccessException(ex);
 		}

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

@@ -23,7 +23,6 @@ import io.lettuce.core.cluster.api.sync.RedisClusterCommands;
 import lombok.NonNull;
 import lombok.RequiredArgsConstructor;
 
-import java.util.Collection;
 import java.util.List;
 import java.util.Set;
 import java.util.concurrent.TimeUnit;
@@ -80,24 +79,25 @@ class LettuceKeyCommands implements RedisKeyCommands {
 
 	/*
 	 * (non-Javadoc)
-	 * @see org.springframework.data.redis.connection.RedisKeyCommands#exists(java.util.Collection)
+	 * @see org.springframework.data.redis.connection.RedisKeyCommands#exists(byte[][])
 	 */
 	@Nullable
 	@Override
-	public Long exists(Collection<byte[]> keys) {
+	public Long exists(byte[]... keys) {
 
 		Assert.notNull(keys, "Keys must not be null!");
+		Assert.noNullElements(keys, "Keys must not contain null elements!");
 
 		try {
 			if (isPipelined()) {
-				pipeline(connection.newLettuceResult(getAsyncConnection().exists(keys.toArray(new byte[keys.size()][]))));
+				pipeline(connection.newLettuceResult(getAsyncConnection().exists(keys)));
 				return null;
 			}
 			if (isQueueing()) {
-				transaction(connection.newLettuceTxResult(getAsyncConnection().exists(keys.toArray(new byte[keys.size()][]))));
+				transaction(connection.newLettuceTxResult(getAsyncConnection().exists(keys)));
 				return null;
 			}
-			return getConnection().exists(keys.toArray(new byte[keys.size()][]));
+			return getConnection().exists(keys);
 		} catch (Exception ex) {
 			throw convertLettuceAccessException(ex);
 		}

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

@@ -163,7 +163,7 @@ public interface RedisOperations<K, V> {
 	Boolean hasKey(K key);
 
 	/**
-	 * Count the number of {@code keys} that exists.
+	 * Count the number of {@code keys} that exist.
 	 *
 	 * @param keys must not be {@literal null}.
 	 * @return The number of keys existing among the ones specified as arguments. Keys mentioned multiple times and

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

@@ -18,7 +18,6 @@ package org.springframework.data.redis.core;
 import java.io.Closeable;
 import java.lang.reflect.Proxy;
 import java.util.ArrayList;
-import java.util.Arrays;
 import java.util.Collection;
 import java.util.Collections;
 import java.util.Date;
@@ -750,7 +749,7 @@ public class RedisTemplate<K, V> extends RedisAccessor implements RedisOperation
 		Assert.notNull(keys, "Keys must not be null!");
 
 		byte[][] rawKeys = rawKeys(keys);
-		return execute(connection -> connection.exists(Arrays.asList(rawKeys)), true);
+		return execute(connection -> connection.exists(rawKeys), true);
 	}
 
 	/*
@@ -1327,7 +1326,7 @@ public class RedisTemplate<K, V> extends RedisAccessor implements RedisOperation
 	 * Set the {@link ClassLoader} to be used for the default {@link JdkSerializationRedisSerializer} in case no other
 	 * {@link RedisSerializer} is explicitly set as the default one.
 	 *
-	 * @param resourceLoader can be {@literal null}.
+	 * @param classLoader can be {@literal null}.
 	 * @see org.springframework.beans.factory.BeanClassLoaderAware#setBeanClassLoader
 	 * @since 1.8
 	 */