com.datastax.oss.driver.api.core.metadata.NodeState Maven / Gradle / Ivy
/*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you 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.oss.driver.api.core.metadata;
import com.datastax.oss.driver.api.core.loadbalancing.LoadBalancingPolicy;
import com.datastax.oss.driver.internal.core.metadata.TopologyEvent;
import java.net.InetSocketAddress;
/** The state of a node, as viewed from the driver. */
public enum NodeState {
/**
* The driver has never tried to connect to the node, nor received any topology events about it.
*
* This happens when nodes are first added to the cluster, and will persist if your {@link
* LoadBalancingPolicy} decides to ignore them. Since the driver does not connect to them, the
* only way it can assess their states is from topology events.
*/
UNKNOWN,
/**
* A node is considered up in either of the following situations: 1) the driver has at least one
* active connection to the node, or 2) the driver is not actively trying to connect to the node
* (because it's ignored by the {@link LoadBalancingPolicy}), but it has received a topology event
* indicating that the node is up.
*/
UP,
/**
* A node is considered down in either of the following situations: 1) the driver has lost all
* connections to the node (and is currently trying to reconnect), or 2) the driver is not
* actively trying to connect to the node (because it's ignored by the {@link
* LoadBalancingPolicy}), but it has received a topology event indicating that the node is down.
*/
DOWN,
/**
* The node was forced down externally, the driver will never try to reconnect to it, whatever the
* {@link LoadBalancingPolicy} says.
*
*
This is used for edge error cases, for example when the driver detects that it's trying to
* connect to a node that does not belong to the Cassandra cluster (e.g. a wrong address was
* provided in the contact points). It can also be {@link
* TopologyEvent#forceDown(InetSocketAddress) triggered explicitly} by components (for example a
* custom load balancing policy) that want to limit the number of nodes that the driver connects
* to.
*/
FORCED_DOWN,
}