org.elasticsearch.client.NodeSelector Maven / Gradle / Ivy
/*
* Licensed to Elasticsearch under one or more contributor
* license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright
* ownership. Elasticsearch 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 org.elasticsearch.client;
import java.util.Iterator;
/**
* Selects nodes that can receive requests. Used to keep requests away
* from master nodes or to send them to nodes with a particular attribute.
* Use with {@link RestClientBuilder#setNodeSelector(NodeSelector)}.
*/
public interface NodeSelector {
/**
* Select the {@link Node}s to which to send requests. This is called with
* a mutable {@link Iterable} of {@linkplain Node}s in the order that the
* rest client would prefer to use them and implementers should remove
* nodes from the that should not receive the request. Implementers may
* iterate the nodes as many times as they need.
*
* This may be called twice per request: first for "living" nodes that
* have not been blacklisted by previous errors. If the selector removes
* all nodes from the list or if there aren't any living nodes then the
* {@link RestClient} will call this method with a list of "dead" nodes.
*
* Implementers should not rely on the ordering of the nodes.
*/
void select(Iterable nodes);
/*
* We were fairly careful with our choice of Iterable here. The caller has
* a List but reordering the list is likely to break round robin. Luckily
* Iterable doesn't allow any reordering.
*/
/**
* Selector that matches any node.
*/
NodeSelector ANY = new NodeSelector() {
@Override
public void select(Iterable nodes) {
// Intentionally does nothing
}
@Override
public String toString() {
return "ANY";
}
};
/**
* Selector that matches any node that has metadata and doesn't
* have the {@code master} role OR it has the data {@code data}
* role.
*/
NodeSelector SKIP_DEDICATED_MASTERS = new NodeSelector() {
@Override
public void select(Iterable nodes) {
for (Iterator itr = nodes.iterator(); itr.hasNext();) {
Node node = itr.next();
if (node.getRoles() == null) continue;
if (node.getRoles().isMasterEligible()
&& false == node.getRoles().isData()
&& false == node.getRoles().isIngest()) {
itr.remove();
}
}
}
@Override
public String toString() {
return "SKIP_DEDICATED_MASTERS";
}
};
}