io.lettuce.core

Class ReadFrom

java.lang.Object

io.lettuce.core.ReadFrom

public abstract class ReadFrom
extends Object

Defines from which Redis nodes data is read.

Since:

4.0

Author:

Mark Paluch, Ryosuke Hasebe, Omer Cilingir, Yohei Ueki

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static interface	ReadFrom.Nodes Descriptor of nodes that are available for the current read operation.

Field Summary

Fields

Modifier and Type	Field and Description
static ReadFrom	ANY Setting to read from any node.
static ReadFrom	ANY_REPLICA Setting to read from any replica node.
static ReadFrom	MASTER Setting to read from the upstream only.
static ReadFrom	MASTER_PREFERRED Setting to read preferred from the upstream and fall back to a replica if the master is not available.
static ReadFrom	NEAREST Setting to read from the nearest node.
static ReadFrom	REPLICA Setting to read from the replica only.
static ReadFrom	REPLICA_PREFERRED Setting to read preferred from replica and fall back to upstream if no replica is not available.
static ReadFrom	SLAVE Deprecated. renamed to REPLICA.
static ReadFrom	SLAVE_PREFERRED Deprecated. Renamed to REPLICA_PREFERRED.
static ReadFrom	UPSTREAM Setting to read from the upstream only.
static ReadFrom	UPSTREAM_PREFERRED Setting to read preferred from the upstream and fall back to a replica if the upstream is not available.

Constructor Summary

Constructors

Constructor and Description
ReadFrom()

Method Summary

Modifier and Type	Method and Description
protected boolean	isOrderSensitive() Returns whether this ReadFrom requires ordering of the resulting nodes.
static ReadFrom	regex(Pattern pattern) Read from any node that has RedisURI matching with the given pattern.
static ReadFrom	regex(Pattern pattern, boolean orderSensitive) Read from any node that has RedisURI matching with the given pattern.
abstract List<RedisNodeDescription>	select(ReadFrom.Nodes nodes) Chooses the nodes from the matching Redis nodes that match this read selector.
static ReadFrom	subnet(String... cidrNotations) Setting to read from any node in the subnets.
static ReadFrom	valueOf(String name) Retrieve the ReadFrom preset by name.

Methods inherited from class java.lang.Object

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

Field Detail

MASTER

public static final ReadFrom MASTER

Setting to read from the upstream only.

MASTER_PREFERRED

public static final ReadFrom MASTER_PREFERRED

Setting to read preferred from the upstream and fall back to a replica if the master is not available.

UPSTREAM

public static final ReadFrom UPSTREAM

Setting to read from the upstream only.

Since:

6.0

UPSTREAM_PREFERRED

public static final ReadFrom UPSTREAM_PREFERRED

Setting to read preferred from the upstream and fall back to a replica if the upstream is not available.

Since:

6.0

REPLICA_PREFERRED

public static final ReadFrom REPLICA_PREFERRED

Setting to read preferred from replica and fall back to upstream if no replica is not available.

Since:

5.2

SLAVE_PREFERRED

@Deprecated
public static final ReadFrom SLAVE_PREFERRED

Deprecated. Renamed to REPLICA_PREFERRED.

Setting to read preferred from replicas and fall back to upstream if no replica is not available.

Since:

4.4

REPLICA

public static final ReadFrom REPLICA

Setting to read from the replica only.

Since:

5.2

SLAVE

@Deprecated
public static final ReadFrom SLAVE

Deprecated. renamed to REPLICA.

Setting to read from the replica only.

NEAREST

public static final ReadFrom NEAREST

Setting to read from the nearest node.

ANY

public static final ReadFrom ANY

Setting to read from any node.

Since:

5.2

ANY_REPLICA

public static final ReadFrom ANY_REPLICA

Setting to read from any replica node.

Since:

6.0.1

Constructor Detail

ReadFrom

public ReadFrom()

Method Detail

subnet

public static ReadFrom subnet(String... cidrNotations)

Setting to read from any node in the subnets.

Parameters:

cidrNotations - CIDR-block notation strings, e.g., "192.168.0.0/16", "2001:db8:abcd:0000::/52". Must not be null.

Returns:

an instance of ReadFromImpl.ReadFromSubnet.

Since:

6.1

regex

public static ReadFrom regex(Pattern pattern)

Read from any node that has RedisURI matching with the given pattern.

Parameters:

pattern - regex pattern, e.g., Pattern.compile(".*region-1.*"). Must not be null.

Returns:

an instance of ReadFromImpl.ReadFromRegex.

Since:

6.1

regex

public static ReadFrom regex(Pattern pattern,
                             boolean orderSensitive)

Read from any node that has RedisURI matching with the given pattern.

Parameters:

pattern - regex pattern, e.g., Pattern.compile(".*region-1.*"). Must not be null.

orderSensitive - true to attempt reads in the order of hosts returned by select(Nodes); false to apply randomization.

Returns:

an instance of ReadFromImpl.ReadFromRegex.

Since:

6.1

select

public abstract List<RedisNodeDescription> select(ReadFrom.Nodes nodes)

Chooses the nodes from the matching Redis nodes that match this read selector.

Parameters:

nodes - set of nodes that are suitable for reading

Returns:

List of RedisNodeDescriptions that are selected for reading

isOrderSensitive

protected boolean isOrderSensitive()

Returns whether this ReadFrom requires ordering of the resulting nodes.

Returns:

true if code using ReadFrom should retain ordering or false to allow reordering of nodes.

Since:

5.2

valueOf

public static ReadFrom valueOf(String name)

Retrieve the ReadFrom preset by name.

Parameters:

name - the name of the read from setting

Returns:

the ReadFrom preset

Throws:

IllegalArgumentException - if name is empty, null or the ReadFrom preset is unknown.