com.datastax.driver.core.policies

Class WhiteListPolicy

java.lang.Object

com.datastax.driver.core.policies.HostFilterPolicy

com.datastax.driver.core.policies.WhiteListPolicy

All Implemented Interfaces:

ChainableLoadBalancingPolicy, LoadBalancingPolicy

public class WhiteListPolicy
extends HostFilterPolicy

A load balancing policy wrapper that ensure that only hosts from a provided white list will ever be returned.

This policy wraps another load balancing policy and will delegate the choice of hosts to the wrapped policy with the exception that only hosts contained in the white list provided when constructing this policy will ever be returned. Any host not in the while list will be considered IGNORED and thus will not be connected to.

This policy can be useful to ensure that the driver only connects to a predefined set of hosts. Keep in mind however that this policy defeats somewhat the host auto-detection of the driver. As such, this policy is only useful in a few special cases or for testing, but is not optimal in general. If all you want to do is limiting connections to hosts of the local data-center then you should use DCAwareRoundRobinPolicy and *not* this policy in particular.

See Also:

HostFilterPolicy

Constructor Summary

Constructors

Constructor and Description
WhiteListPolicy(LoadBalancingPolicy childPolicy, Collection<InetSocketAddress> whiteList) Creates a new policy that wraps the provided child policy but only "allows" hosts from the provided white list.

Method Summary

Modifier and Type	Method and Description
static WhiteListPolicy	ofHosts(LoadBalancingPolicy childPolicy, Iterable<String> hostnames) Creates a new policy that wraps the provided child policy but only "allows" hosts having addresses that match those from the resolved input host names.
static WhiteListPolicy	ofHosts(LoadBalancingPolicy childPolicy, String... hostnames) Creates a new policy with the given host names.

Methods inherited from class com.datastax.driver.core.policies.HostFilterPolicy

close, distance, fromDCBlackList, fromDCWhiteList, getChildPolicy, init, newQueryPlan, onAdd, onDown, onRemove, onUp

Methods inherited from class java.lang.Object

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

Constructor Detail

WhiteListPolicy

public WhiteListPolicy(LoadBalancingPolicy childPolicy,
                       Collection<InetSocketAddress> whiteList)

Creates a new policy that wraps the provided child policy but only "allows" hosts from the provided white list.

Parameters:

childPolicy - the wrapped policy.

whiteList - the white listed hosts. Only hosts from this list may get connected to (whether they will get connected to or not depends on the child policy).

Method Detail

ofHosts

public static WhiteListPolicy ofHosts(LoadBalancingPolicy childPolicy,
                                      String... hostnames)

Creates a new policy with the given host names.

See ofHosts(LoadBalancingPolicy, Iterable) for more details.

ofHosts

public static WhiteListPolicy ofHosts(LoadBalancingPolicy childPolicy,
                                      Iterable<String> hostnames)

Creates a new policy that wraps the provided child policy but only "allows" hosts having addresses that match those from the resolved input host names.

Note that all host names must be non-null and resolvable; if any of them cannot be resolved, this method will fail.

Parameters:

childPolicy - the wrapped policy.

hostnames - list of host names to resolve whitelisted addresses from.

Throws:

IllegalArgumentException - if any of the given hostnames could not be resolved.

NullPointerException - If null was provided for a hostname.

SecurityException - if a security manager is present and permission to resolve the host name is denied.