Package io.lettuce.core

Class ScanStream

java.lang.Object

io.lettuce.core.ScanStream

public abstract class ScanStream
extends Object

Scan command support exposed through Flux.

ScanStream uses reactive command interfaces to scan over keys (SCAN), sets (SSCAN), sorted sets ( ZSCAN), and hashes (HSCAN).

Use ScanArgs.limit(long) to set the batch size.

Data structure scanning is progressive and stateful and demand-aware. It supports full iterations (until all received cursors are exhausted) and premature termination. Subsequent scan commands to fetch the cursor data get only issued if the subscriber signals demand.

Since:

5.1

Author:

Mark Paluch, Mikhael Sokolov

Method Summary

Modifier and Type	Method	Description
static <K,V> Flux<KeyValue<K,V>>	hscan(RedisHashReactiveCommands<K,V> commands, K key)	Sequentially iterate over entries in a hash identified by key.
static <K,V> Flux<KeyValue<K,V>>	hscan(RedisHashReactiveCommands<K,V> commands, K key, ScanArgs scanArgs)	Sequentially iterate over entries in a hash identified by key.
static <K,V> Flux<K>	scan(RedisKeyReactiveCommands<K,V> commands)	Sequentially iterate over keys in the keyspace.
static <K,V> Flux<K>	scan(RedisKeyReactiveCommands<K,V> commands, ScanArgs scanArgs)	Sequentially iterate over keys in the keyspace.
static <K,V> Flux<V>	sscan(RedisSetReactiveCommands<K,V> commands, K key)	Sequentially iterate over elements in a set identified by key.
static <K,V> Flux<V>	sscan(RedisSetReactiveCommands<K,V> commands, K key, ScanArgs scanArgs)	Sequentially iterate over elements in a set identified by key.
static <K,V> Flux<ScoredValue<V>>	zscan(RedisSortedSetReactiveCommands<K,V> commands, K key)	Sequentially iterate over elements in a set identified by key.
static <K,V> Flux<ScoredValue<V>>	zscan(RedisSortedSetReactiveCommands<K,V> commands, K key, ScanArgs scanArgs)	Sequentially iterate over elements in a set identified by key.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Method Detail

scan

public static <K,V> Flux<K> scan(RedisKeyReactiveCommands<K,V> commands)

Sequentially iterate over keys in the keyspace. This method uses SCAN to perform an iterative scan.

Type Parameters:

K - Key type.

V - Value type.

Parameters:

commands - the commands interface, must not be null.

Returns:

a new Flux.

scan

public static <K,V> Flux<K> scan(RedisKeyReactiveCommands<K,V> commands,
                                       ScanArgs scanArgs)

Sequentially iterate over keys in the keyspace. This method uses SCAN to perform an iterative scan.

Type Parameters:

K - Key type.

V - Value type.

Parameters:

commands - the commands interface, must not be null.

scanArgs - the scan arguments, must not be null.

Returns:

a new Flux.

hscan

public static <K,V> Flux<KeyValue<K,V>> hscan(RedisHashReactiveCommands<K,V> commands,
                                                          K key)

Sequentially iterate over entries in a hash identified by key. This method uses HSCAN to perform an iterative scan.

Type Parameters:

K - Key type.

V - Value type.

Parameters:

commands - the commands interface, must not be null.

key - the hash to scan.

Returns:

a new Flux.

hscan

public static <K,V> Flux<KeyValue<K,V>> hscan(RedisHashReactiveCommands<K,V> commands,
                                                          K key,
                                                          ScanArgs scanArgs)

Sequentially iterate over entries in a hash identified by key. This method uses HSCAN to perform an iterative scan.

Type Parameters:

K - Key type.

V - Value type.

Parameters:

commands - the commands interface, must not be null.

key - the hash to scan.

scanArgs - the scan arguments, must not be null.

Returns:

a new Flux.

sscan

public static <K,V> Flux<V> sscan(RedisSetReactiveCommands<K,V> commands,
                                        K key)

Sequentially iterate over elements in a set identified by key. This method uses SSCAN to perform an iterative scan.

Type Parameters:

K - Key type.

V - Value type.

Parameters:

commands - the commands interface, must not be null.

key - the set to scan.

Returns:

a new Flux.

sscan

public static <K,V> Flux<V> sscan(RedisSetReactiveCommands<K,V> commands,
                                        K key,
                                        ScanArgs scanArgs)

Sequentially iterate over elements in a set identified by key. This method uses SSCAN to perform an iterative scan.

Type Parameters:

K - Key type.

V - Value type.

Parameters:

commands - the commands interface, must not be null.

key - the set to scan.

scanArgs - the scan arguments, must not be null.

Returns:

a new Flux.

zscan

public static <K,V> Flux<ScoredValue<V>> zscan(RedisSortedSetReactiveCommands<K,V> commands,
                                                     K key)

Sequentially iterate over elements in a set identified by key. This method uses SSCAN to perform an iterative scan.

Type Parameters:

K - Key type.

V - Value type.

Parameters:

commands - the commands interface, must not be null.

key - the sorted set to scan.

Returns:

a new Flux.

zscan

public static <K,V> Flux<ScoredValue<V>> zscan(RedisSortedSetReactiveCommands<K,V> commands,
                                                     K key,
                                                     ScanArgs scanArgs)

Sequentially iterate over elements in a set identified by key. This method uses SSCAN to perform an iterative scan.

Type Parameters:

K - Key type.

V - Value type.

Parameters:

commands - the commands interface, must not be null.

key - the sorted set to scan.

scanArgs - the scan arguments, must not be null.

Returns:

a new Flux.