io.helidon.webclient.dns.resolver.roundrobin.RoundRobinDnsResolver Maven / Gradle / Ivy
/*
* Copyright (c) 2022, 2023 Oracle and/or its affiliates.
*
* 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 io.helidon.webclient.dns.resolver.roundrobin;
import java.net.InetAddress;
import java.net.UnknownHostException;
import java.util.HashMap;
import java.util.Map;
import java.util.concurrent.atomic.AtomicInteger;
import io.helidon.webclient.api.DnsAddressLookup;
import io.helidon.webclient.api.RuntimeUnknownHostException;
import io.helidon.webclient.spi.DnsResolver;
/**
* Round-robin DNS resolver implementation.
*/
public final class RoundRobinDnsResolver implements DnsResolver {
private final Map hostnameAddresses = new HashMap<>();
private RoundRobinDnsResolver() {
}
/**
* Create new instance.
*
* @return new instance
*/
public static RoundRobinDnsResolver create() {
return new RoundRobinDnsResolver();
}
@Override
public InetAddress resolveAddress(String hostname, DnsAddressLookup dnsAddressLookup) {
HostnameAddresses hostnameAddress = hostnameAddresses.computeIfAbsent(hostname, host -> {
try {
InetAddress[] processed = dnsAddressLookup.filter(InetAddress.getAllByName(host));
if (processed.length == 0) {
throw new RuntimeUnknownHostException("No IP version " + dnsAddressLookup.name() + " found for host " + host);
}
return new HostnameAddresses(new AtomicInteger(), processed);
} catch (UnknownHostException e) {
throw new RuntimeUnknownHostException(e);
}
});
return hostnameAddress.addresses[hostnameAddress.count.getAndIncrement() % hostnameAddress.addresses.length];
}
private record HostnameAddresses(AtomicInteger count, InetAddress[] addresses) {
}
}
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