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/*
* Copyright DataStax, Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
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
}