com.datastax.driver.core

Enum HostDistance

java.lang.Object

java.lang.Enum<HostDistance>

com.datastax.driver.core.HostDistance

All Implemented Interfaces:

Serializable, Comparable<HostDistance>

public enum HostDistance
extends Enum<HostDistance>

The distance to a Cassandra node as assigned by a LoadBalancingPolicy (through its distance method).

The distance assigned to an host influences how many connections the driver maintains towards this host. If for a given host the assigned HostDistance is LOCAL or REMOTE, some connections will be maintained by the driver to this host. More active connections will be kept to LOCAL host than to a REMOTE one (and thus well behaving LoadBalancingPolicy should assign a REMOTE distance only to hosts that are the less often queried).

However, if a host is assigned the distance IGNORED, no connection to that host will maintained active. In other words, IGNORED should be assigned to hosts that should not be used by this driver (because they are in a remote data center for instance).

Enum Constant Summary

Enum Constants

Enum Constant and Description
IGNORED
LOCAL
REMOTE

Method Summary

Modifier and Type	Method and Description
static HostDistance	valueOf(String name) Returns the enum constant of this type with the specified name.
static HostDistance[]	values() Returns an array containing the constants of this enum type, in the order they are declared.

Methods inherited from class java.lang.Enum

clone, compareTo, equals, finalize, getDeclaringClass, hashCode, name, ordinal, toString, valueOf

Methods inherited from class java.lang.Object

getClass, notify, notifyAll, wait, wait, wait

Enum Constant Detail

LOCAL

public static final HostDistance LOCAL

REMOTE

public static final HostDistance REMOTE

IGNORED

public static final HostDistance IGNORED

Method Detail

values

public static HostDistance[] values()

Returns an array containing the constants of this enum type, in the order they are declared. This method may be used to iterate over the constants as follows:

for (HostDistance c : HostDistance.values())
    System.out.println(c);

Returns:

an array containing the constants of this enum type, in the order they are declared

valueOf

public static HostDistance valueOf(String name)

Returns the enum constant of this type with the specified name. The string must match exactly an identifier used to declare an enum constant in this type. (Extraneous whitespace characters are not permitted.)

Parameters:

name - the name of the enum constant to be returned.

Returns:

the enum constant with the specified name

Throws:

IllegalArgumentException - if this enum type has no constant with the specified name

NullPointerException - if the argument is null