netty5/resolver-dns/src/main/java/io/netty/resolver/dns/RotationalDnsServerAddresses.java

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/*
* Copyright 2015 The Netty Project
*
* The Netty Project 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 io.netty.resolver.dns;
import java.net.InetSocketAddress;
import java.util.List;
import java.util.concurrent.atomic.AtomicIntegerFieldUpdater;
final class RotationalDnsServerAddresses extends DefaultDnsServerAddresses {
private static final AtomicIntegerFieldUpdater<RotationalDnsServerAddresses> startIdxUpdater =
AtomicIntegerFieldUpdater.newUpdater(RotationalDnsServerAddresses.class, "startIdx");
@SuppressWarnings("UnusedDeclaration")
private volatile int startIdx;
RotationalDnsServerAddresses(List<InetSocketAddress> addresses) {
super("rotational", addresses);
}
@Override
public DnsServerAddressStream stream() {
for (;;) {
int curStartIdx = startIdx;
int nextStartIdx = curStartIdx + 1;
if (nextStartIdx >= addresses.size()) {
nextStartIdx = 0;
}
if (startIdxUpdater.compareAndSet(this, curStartIdx, nextStartIdx)) {
return new SequentialDnsServerAddressStream(addresses, curStartIdx);
}
}
}
}