com.datastax.driver.core.HostDistance Maven / Gradle / Ivy
/*
* Copyright DataStax, Inc.
*
* This software can be used solely with DataStax Enterprise. Please consult the license at
* http://www.datastax.com/terms/datastax-dse-driver-license-terms
*/
package com.datastax.driver.core;
/**
* The distance to a Cassandra node as assigned by a {@link
* com.datastax.driver.core.policies.LoadBalancingPolicy} (through its {@code 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 {@code HostDistance} is {@code LOCAL} or {@code
* REMOTE}, some connections will be maintained by the driver to this host. More active connections
* will be kept to {@code LOCAL} host than to a {@code REMOTE} one (and thus well behaving {@code
* LoadBalancingPolicy} should assign a {@code REMOTE} distance only to hosts that are the less
* often queried).
*
*
However, if a host is assigned the distance {@code IGNORED}, no connection to that host will
* maintained active. In other words, {@code IGNORED} should be assigned to hosts that should not be
* used by this driver (because they are in a remote data center for instance).
*/
public enum HostDistance {
// Note: PoolingOptions rely on the order of the enum.
LOCAL,
REMOTE,
IGNORED
}