DATAREDIS-531 - Scan commands should use a dedicated bound connection.

SCAN, SSCAN, HSCAN and ZSCAN now reference a dedicated connection that is bound to the Cursor. This allows creation of multiple cursors for different threads without the risk of potentially sharing a single connection. As before the caller is responsible for closing the Cursor correctly after usage.

Original pull request: #218.

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

@@ -3790,6 +3790,10 @@ public class JedisConnection extends AbstractRedisConnection {
 						JedisConverters.stringListToByteList().convert(result.getResult()));
 			}
 
+			protected void doClose() {
+				JedisConnection.this.close();
+			};
+
 		}.open();
 
 	}
@@ -3828,6 +3832,10 @@ public class JedisConnection extends AbstractRedisConnection {
 						JedisConverters.tuplesToTuples().convert(result.getResult()));
 			}
 
+			protected void doClose() {
+				JedisConnection.this.close();
+			};
+
 		}.open();
 	}
 
@@ -3863,6 +3871,10 @@ public class JedisConnection extends AbstractRedisConnection {
 				redis.clients.jedis.ScanResult<byte[]> result = jedis.sscan(key, JedisConverters.toBytes(cursorId), params);
 				return new ScanIteration<byte[]>(Long.valueOf(result.getStringCursor()), result.getResult());
 			}
+
+			protected void doClose() {
+				JedisConnection.this.close();
+			};
 		}.open();
 	}
 
@@ -3898,6 +3910,11 @@ public class JedisConnection extends AbstractRedisConnection {
 				ScanResult<Entry<byte[], byte[]>> result = jedis.hscan(key, JedisConverters.toBytes(cursorId), params);
 				return new ScanIteration<Map.Entry<byte[], byte[]>>(Long.valueOf(result.getStringCursor()), result.getResult());
 			}
+
+			protected void doClose() {
+				JedisConnection.this.close();
+			};
+
 		}.open();
 	}
 

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

@@ -3719,6 +3719,11 @@ public class LettuceConnection extends AbstractRedisConnection {
 
 				return new ScanIteration<byte[]>(Long.valueOf(nextCursorId), (keys));
 			}
+
+			protected void doClose() {
+				LettuceConnection.this.close();
+			}
+
 		}.open();
 
 	}
@@ -3759,6 +3764,10 @@ public class LettuceConnection extends AbstractRedisConnection {
 				return new ScanIteration<Entry<byte[], byte[]>>(Long.valueOf(nextCursorId), values.entrySet());
 			}
 
+			protected void doClose() {
+				LettuceConnection.this.close();
+			}
+
 		}.open();
 	}
 
@@ -3798,6 +3807,11 @@ public class LettuceConnection extends AbstractRedisConnection {
 				List<byte[]> values = failsafeReadScanValues(valueScanCursor.getValues(), null);
 				return new ScanIteration<byte[]>(Long.valueOf(nextCursorId), values);
 			}
+
+			protected void doClose() {
+				LettuceConnection.this.close();
+			}
+
 		}.open();
 	}
 
@@ -3839,6 +3853,11 @@ public class LettuceConnection extends AbstractRedisConnection {
 				List<Tuple> values = failsafeReadScanValues(result, LettuceConverters.scoredValuesToTupleList());
 				return new ScanIteration<Tuple>(Long.valueOf(nextCursorId), values);
 			}
+
+			protected void doClose() {
+				LettuceConnection.this.close();
+			}
+
 		}.open();
 	}
 

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

@@ -235,7 +235,7 @@ class DefaultHashOperations<K, HK, HV> extends AbstractOperations<K, Object> imp
 	public Cursor<Entry<HK, HV>> scan(K key, final ScanOptions options) {
 
 		final byte[] rawKey = rawKey(key);
-		return execute(new RedisCallback<Cursor<Map.Entry<HK, HV>>>() {
+		return template.executeWithStickyConnection(new RedisCallback<Cursor<Map.Entry<HK, HV>>>() {
 
 			@Override
 			public Cursor<Entry<HK, HV>> doInRedis(RedisConnection connection) throws DataAccessException {
@@ -268,7 +268,7 @@ class DefaultHashOperations<K, HK, HV> extends AbstractOperations<K, Object> imp
 						});
 			}
 
-		}, true);
+		});
 
 	}
 }

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

@@ -255,7 +255,7 @@ class DefaultSetOperations<K, V> extends AbstractOperations<K, V> implements Set
 	public Cursor<V> scan(K key, final ScanOptions options) {
 
 		final byte[] rawKey = rawKey(key);
-		return execute(new RedisCallback<Cursor<V>>() {
+		return template.executeWithStickyConnection(new RedisCallback<Cursor<V>>() {
 
 			@Override
 			public Cursor<V> doInRedis(RedisConnection connection) throws DataAccessException {
@@ -267,7 +267,7 @@ class DefaultSetOperations<K, V> extends AbstractOperations<K, V> implements Set
 					}
 				});
 			}
-		}, true);
+		});
 
 	}
 }

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

@@ -409,13 +409,13 @@ class DefaultZSetOperations<K, V> extends AbstractOperations<K, V> implements ZS
 	public Cursor<TypedTuple<V>> scan(K key, final ScanOptions options) {
 
 		final byte[] rawKey = rawKey(key);
-		Cursor<Tuple> cursor = execute(new RedisCallback<Cursor<Tuple>>() {
+		Cursor<Tuple> cursor = template.executeWithStickyConnection(new RedisCallback<Cursor<Tuple>>() {
 
 			@Override
 			public Cursor<Tuple> doInRedis(RedisConnection connection) throws DataAccessException {
 				return connection.zScan(rawKey, options);
 			}
-		}, true);
+		});
 
 		return new ConvertingCursor<Tuple, TypedTuple<V>>(cursor, new Converter<Tuple, TypedTuple<V>>() {
 

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

@@ -150,7 +150,8 @@ public interface HashOperations<H, HK, HV> {
 	RedisOperations<H, ?> getOperations();
 
 	/**
-	 * Use a {@link Cursor} to iterate over entries in hash at {@code key}.
+	 * Use a {@link Cursor} to iterate over entries in hash at {@code key}. <br />
+	 * <strong>Important:</strong> Call {@link Cursor#close()} when done to avoid resource leak.
 	 *
 	 * @since 1.4
 	 * @param key must not be {@literal null}.

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

@@ -15,6 +15,7 @@
  */
 package org.springframework.data.redis.core;
 
+import java.io.Closeable;
 import java.util.Collection;
 import java.util.Date;
 import java.util.List;
@@ -22,6 +23,7 @@ import java.util.Set;
 import java.util.concurrent.TimeUnit;
 
 import org.springframework.data.redis.connection.DataType;
+import org.springframework.data.redis.connection.RedisConnection;
 import org.springframework.data.redis.core.query.SortQuery;
 import org.springframework.data.redis.core.script.RedisScript;
 import org.springframework.data.redis.core.types.RedisClientInfo;
@@ -129,6 +131,16 @@ public interface RedisOperations<K, V> {
 	<T> T execute(RedisScript<T> script, RedisSerializer<?> argsSerializer, RedisSerializer<T> resultSerializer,
 			List<K> keys, Object... args);
 
+	/**
+	 * Allocates and binds a new {@link RedisConnection} to the actual return type of the method. It is up to the caller
+	 * to free resources after use.
+	 *
+	 * @param callback must not be {@literal null}.
+	 * @return
+	 * @since 1.8
+	 */
+	<T extends Closeable> T executeWithStickyConnection(RedisCallback<T> callback);
+
 	Boolean hasKey(K key);
 
 	void delete(K key);

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

@@ -15,6 +15,7 @@
  */
 package org.springframework.data.redis.core;
 
+import java.io.Closeable;
 import java.lang.reflect.Proxy;
 import java.util.ArrayList;
 import java.util.Collection;
@@ -304,6 +305,23 @@ public class RedisTemplate<K, V> extends RedisAccessor implements RedisOperation
 		return scriptExecutor.execute(script, argsSerializer, resultSerializer, keys, args);
 	}
 
+	/*
+	 * (non-Javadoc)
+	 * @see org.springframework.data.redis.core.RedisOperations#executeWithStickyConnection(org.springframework.data.redis.core.RedisCallback)
+	 */
+	public <T extends Closeable> T executeWithStickyConnection(RedisCallback<T> callback) {
+
+		Assert.isTrue(initialized, "template not initialized; call afterPropertiesSet() before using it");
+		Assert.notNull(callback, "Callback object must not be null");
+
+		RedisConnectionFactory factory = getConnectionFactory();
+
+		RedisConnection connection = preProcessConnection(RedisConnectionUtils.doGetConnection(factory, true, false, false),
+				false);
+
+		return callback.doInRedis(connection);
+	}
+
 	private Object executeSession(SessionCallback<?> session) {
 		return session.execute(this);
 	}

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2011-2014 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.
@@ -75,8 +75,9 @@ public interface SetOperations<K, V> {
 	RedisOperations<K, V> getOperations();
 
 	/**
-	 * Iterate over elements in set at {@code key}.
-	 * 
+	 * Iterate over elements in set at {@code key}. <br />
+	 * <strong>Important:</strong> Call {@link Cursor#close()} when done to avoid resource leak.
+	 *
 	 * @since 1.4
 	 * @param key
 	 * @param options

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

@@ -136,6 +136,9 @@ public interface ZSetOperations<K, V> {
 	RedisOperations<K, V> getOperations();
 
 	/**
+	 * Iterate over elements in zset at {@code key}. <br />
+	 * <strong>Important:</strong> Call {@link Cursor#close()} when done to avoid resource leak.
+	 *
 	 * @since 1.4
 	 * @param key
 	 * @param options