/*
* 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;
import io.netty.util.concurrent.
EventExecutor;
import io.netty.util.concurrent.
Future;
import io.netty.util.internal.
UnstableApi;
import java.net.
InetAddress;
import java.net.
InetSocketAddress;
/**
* A skeletal {@link NameResolver} implementation that resolves {@link InetAddress}.
*/
@
UnstableApi
public abstract class
InetNameResolver extends
SimpleNameResolver<
InetAddress> {
private volatile
AddressResolver<
InetSocketAddress>
addressResolver;
/**
* @param executor the {@link EventExecutor} which is used to notify the listeners of the {@link Future} returned
* by {@link #resolve(String)}
*/
protected
InetNameResolver(
EventExecutor executor) {
super(
executor);
}
/**
* Return a {@link AddressResolver} that will use this name resolver underneath.
* It's cached internally, so the same instance is always returned.
*/
public
AddressResolver<
InetSocketAddress>
asAddressResolver() {
AddressResolver<
InetSocketAddress>
result =
addressResolver;
if (
result == null) {
synchronized (this) {
result =
addressResolver;
if (
result == null) {
addressResolver =
result = new
InetSocketAddressResolver(
executor(), this);
}
}
}
return
result;
}
}